Withstand voltage testing apparatus and withstand voltage testing method

Abstract

To provide a dielectric strength test device that can accurately measure the leakage current flowing through a test specimen. [Solution] The withstand voltage test apparatus includes a transformer 21 having a primary winding 21a to which an AC voltage from an AC power supply 10 is supplied to input terminals 21a1 and 21a2, and a secondary winding 21b to which output terminals 21b1 and 21b2 are connected to input terminals 100a and 100b of a test specimen 100 via a cable 300; a test voltage application circuit 20 having a current detector 22 for detecting the current flowing through the circuit, and a voltage detector 23 for detecting the voltage between test voltage output terminals 20c and 20d; and a withstand voltage determination unit 30 which calculates the phase angle of the current detection signal and the voltage detection signal from the current detection signal output from the current detection signal 22 and the voltage detection signal output from the voltage detector 23, and calculates the current value flowing through the capacitive component and the current value flowing through the resistive component in the current detection signal based on the current value indicated by the current detection signal and the calculated phase angle.

Description

Technical Field

[0001] The present disclosure relates to a withstand voltage test device and a withstand voltage test method for performing a withstand voltage test by applying a high voltage to a specimen to be subjected to a withstand voltage test.

Background Art

[0002] A withstand voltage test device is a test device that determines whether a specimen meets various safety standards such as JIS standards and UL standards by applying an alternating high voltage required by those standards to the specimen for a certain period of time and determining the withstand voltage performance of the specimen. The quality determination is performed by measuring the leakage current flowing through the specimen during the withstand voltage test. This type of withstand voltage test device is shown in Patent Document 1.

[0003] The withstand voltage test device shown in Patent Document 1 is a withstand voltage test device that excites a transformer with a sine wave signal from an AC signal source to obtain a high voltage, applies the high voltage to a specimen, and measures the current flowing through a current detector. The withstand voltage test device shown in Patent Document 1 opens the output terminals to which the specimen is connected, separates and extracts the current detected by the current detector into a component with a 0-degree phase and a component with a 90-degree phase by a first phase detector circuit and a second phase detector circuit, converts the separated and extracted 0-degree phase component and 90-degree phase component into DC by a first integrator and a second integrator, digitizes them with a first A / D converter and a second A / D converter, and stores the respective digital values as first detection values in storage means.

[0004] When a specimen is connected between the output terminals and an alternating high voltage is applied, the current flowing is input to a first phase detector circuit and a second phase detector circuit. After the output of each phase detector circuit is converted into DC by a first integrator and a second integrator, it is digitized by a first A / D converter and a second A / D converter, and the respective digital values are used as second detection values. After subtracting the current values ​​flowing only through the resistive component and the current values ​​flowing only through the capacitive component, which are included in the first and second digitized detected values, a calculation means calculates a vector composite value based on these subtracted values. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2003-21660 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In recent years, Y-capacitors have been incorporated into test specimens between the internal circuitry and the enclosure as a measure against electrical interference (EMI), and a large leakage current flows through the Y-capacitor during the withstand voltage test of the test specimen. Furthermore, the busbar voltage has been increased and its insulation performance has been improved, resulting in even higher test voltages applied to the test specimens and a tendency for leakage current to increase.

[0007] Generally, the capacitance value of a Y capacitor varies by about ±20%, and assuming that the equivalent series resistance (ESR) also varies, the method of separating and extracting the current detected by the current detector shown in Patent Document 1 into a 0-degree phase component and a 90-degree phase component to remove measurement errors is considered difficult to accurately determine between 1mA and 10mA by correcting for measurement errors caused by currents flowing through the stray capacitance component and insulation resistance component distributed within the withstand voltage test device due to the aforementioned variations. Furthermore, the withstand voltage test apparatus shown in Patent Document 1 has a complex circuit configuration consisting of "a timing pulse generator, a phase detection circuit that switches between output inversion and non-inversion, and an integration circuit."

[0008] This disclosure has been made in view of the above-mentioned points, and aims to provide a dielectric strength test device that can accurately measure the leakage current flowing through a test specimen by applying a test voltage. [Means for solving the problem]

[0009] The withstand voltage test apparatus according to this disclosure comprises a transformer having a primary winding to which an AC voltage from an AC power source is supplied to an input terminal and a secondary winding to which an output terminal is connected to a test voltage output terminal to which an output terminal is connected to the input terminal of a test specimen via a cable; a current detector for detecting current flowing through the circuit; and a voltage detector for detecting the voltage between the test voltage output terminals; and a withstand voltage determination unit that calculates the phase angle of the current detection signal and the voltage detection signal from the current detection signal output from the current detector and calculates the current value flowing through the capacitive component and the current value flowing through the resistive component in the current detection signal output from the current detector based on the current value indicated by the current detection signal output from the current detector and the calculated phase angle. [Effects of the Invention]

[0010] According to this disclosure, the leakage current flowing through the test specimen can be measured with high accuracy by determining the phase difference between the detected voltage and the detected current from the voltage and current detected in the withstand voltage test path including the test specimen, and then using this phase difference to calculate and correct the current for the capacitive component and the current for the resistive component from the current detected in the withstand voltage test path including the test specimen. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows a dielectric strength test apparatus according to Embodiment 1. [Figure 2] This figure shows the circuit configuration of the waveform detection unit in the voltage withstand test apparatus according to Embodiment 1. [Figure 3] This diagram shows the voltage withstand determination unit in the voltage withstand test apparatus according to Embodiment 1. [Figure 4] This figure shows the relationship between the detected current Io, the current IC flowing through the capacitive component, and the current IR flowing through the resistive component in the withstand voltage test apparatus according to Embodiment 1. [Figure 5]In the withstand voltage test device according to Embodiment 1, it is a diagram showing the waveform of the test voltage Vo applied to the specimen and the waveform of the current IC flowing through the capacitance component, and the waveform of the shaped test voltage Vo and the waveform of the current IC flowing through the capacitance component. [Figure 6] It is a flowchart showing the withstand voltage test method of the withstand voltage test device according to Embodiment 1. [Figure 7] It is a diagram showing the withstand voltage determination unit in the withstand voltage test device according to Embodiment 2. [Figure 8] It is a flowchart showing the withstand voltage test method of the withstand voltage test device according to Embodiment 2. [Figure 9] It is a diagram showing the withstand voltage determination unit in the withstand voltage test device according to Embodiment 3. [Figure 10] It is a diagram showing the withstand voltage determination unit in the withstand voltage test device according to Embodiment 3. [Figure 11] It is a flowchart showing the withstand voltage test method of the withstand voltage test device according to Embodiment 3.

Embodiments for Carrying Out the Invention

[0012] Embodiment 1. The withstand voltage test device according to Embodiment 1 will be described with reference to FIGS. 1 to 6. The withstand voltage test device according to Embodiment 1 is a withstand voltage test device that applies a high voltage to the specimen 100 that is the object of the withstand voltage test and measures the leakage current flowing through the specimen 100 to perform a withstand voltage test.

[0013] The withstand voltage test device according to Embodiment 1 applies an alternating high voltage to the specimen 100. In the measurement of the minute current, which is the leakage current flowing through the specimen 100, it corrects the measurement error caused by the measurement error factor current flowing through the stray capacitance component (hereinafter simply referred to as the capacitance component) and the insulation resistance component (hereinafter simply referred to as the resistance component) existing in the test voltage application circuit in the withstand voltage test device, calculates the leakage current It flowing through the specimen 100, and determines the withstand voltage based on the magnitude of the leakage current.

[0014] The leakage current It flowing through the specimen 100 is a combined current of the current ICt flowing through the capacitive component and the current IRt flowing through the resistive component in the specimen 100. In the description, "current" may indicate "current value" and "voltage" may indicate "voltage value". However, to avoid complexity, except when clearly explaining, the expressions "current" and "voltage" are simply used even when indicating "current value" and "voltage value".

[0015] The specimen 100 is, for example, an inverter product in which a Y capacitor (not shown) is built in between the internal circuit 101 and the housing. The withstand voltage test device according to Embodiment 1 is installed, for example, on the production line of an inverter product, and performs a withstand voltage test on the completed inverter product which is the specimen 100 on the production line.

[0016] The upper-level system 200 performs production management in the manufacture of the specimen 100 on the production line. The upper-level system 200 receives various information such as the model information and manufacturing condition information of the specimen 100 produced on the production line. The upper-level system 200 outputs information such as output voltage instruction information indicating an output voltage setting value according to the withstand voltage test voltage for the specimen 100 to the withstand voltage test device. The upper-level system 200 is composed of a programmable controller (PLC: Programmable Logic Controller), a graphic operation terminal (GOT: Graphic Operation Terminal), or a personal computer (PC: Personal Computer).

[0017] The withstand voltage test device according to Embodiment 1 includes an AC power supply 10, a test voltage application circuit 20, and a withstand voltage determination unit 30. The AC power supply 10 uses a commercial AC power supply as the primary power source, can change the AC frequency and AC voltage from the commercial AC power supply, and can set the withstand voltage test voltage in the withstand voltage test according to the specimen 100 and supply a sinusoidal AC voltage to the test voltage application circuit 20. It is a variable AC power supply. The AC power supply 10 receives output voltage instruction information from the higher-level system 200 that matches the model and type of the test specimen 100, and outputs a sinusoidal AC voltage with a frequency and voltage based on the input output voltage instruction information.

[0018] The test voltage application circuit 20 includes a transformer 21, a current detector 22, and a voltage detector 23. The transformer 21 has a primary winding 21a and a secondary winding 21b, and generates a withstand voltage test voltage Vo (hereinafter simply referred to as the test voltage value Vo) for the test specimen 100. A pair of primary winding terminals 21a1 and 21a2 of the primary winding 21a are electrically connected to a pair of input terminals 20a and 20b of the test voltage application circuit 20.

[0019] A switch 26 is interposed between one primary winding terminal 21a1 of the primary winding 21a and one input terminal 20a of the test voltage application circuit 20. An AC voltage from the AC power supply 10 is supplied to a pair of input terminals 20a and 20b of the test voltage application circuit 20.

[0020] A pair of secondary winding terminals 21b1 and 21b2 of the secondary winding 21b are electrically connected to a pair of test voltage output terminals 20c and 20d of the test voltage application circuit 20. A pair of secondary winding terminals 21b1 and 21b2 are electrically connected to a pair of test voltage output terminals 20c and 20d by a pair of power lines 24 and 25.

[0021] In short, the transformer 21 has a primary winding 21a to which an AC voltage from the AC power supply 10 is supplied to primary winding terminals 21a1 and 21a2, and a secondary winding 21b to which secondary winding terminals 21b1 and 21b2 are connected via cable 300 to test voltage output terminals 20c and 20d, which are connected to input terminals 100a and 100b of the test specimen 100. The other input terminal 100b of the test specimen 100 is a ground terminal.

[0022] Cable 300 is a coaxial cable, in which the core wire electrically connects one test voltage output terminal 20c to one input terminal 100a of the test specimen 100, and the shielding outer conductor electrically connects the other test voltage output terminal 20d to the other input terminal 100b of the test specimen 100. While a coaxial cable is preferred for cable 300, a single-strand cable is also acceptable.

[0023] At the secondary winding terminals 21b1 and 21b2 of the secondary winding 21b, an AC voltage appears which is obtained by boosting the AC voltage applied to the primary winding terminals 21a1 and 21a2 of the primary winding 21a. The other test voltage output terminal 20d is grounded, and one test voltage output terminal 20c functions as the P-side output terminal, while the other test voltage output terminal 20d functions as the N-side output terminal. Furthermore, one power line 24 functions as the P-side power line, and the other power line 25 functions as the N-side power line.

[0024] The current detector 22 detects the current Io flowing through the test voltage application circuit 20 in order to measure the leakage current It flowing through the test specimen 100, and outputs a current detection signal AD10 (current detection signal AD11 and current detection signal AD12). The current detector 22 is positioned between the other secondary winding terminal 21b2 and the other test voltage output terminal 20d of the secondary winding 21b of the transformer 21. The current detector 22 can be a commonly known type, such as a resistor like a coaxial shunt, or a non-contact sensor using the Hall effect.

[0025] The voltage detector 23 detects the test voltage value Vo applied to the test specimen 100. The voltage detector 23 detects the test voltage value Vo output between the test voltage output terminals 20c and 20d connected to a pair of secondary winding terminals 21b1 and 21b2 of the secondary winding 21b of the transformer 21, and outputs a voltage detection signal AD20 (voltage detection signal AD21 and voltage detection signal AD22). The voltage detector 23 can be any commonly known type.

[0026] Here, we will describe the detected current Io detected by the current detector 22 when the input terminals 100a and 100b of the test specimen 100 are connected to the pair of test voltage output terminals 20c and 20d of the test voltage application circuit 20 via a cable 300, and a test voltage value Vo is applied between the pair of test voltage output terminals 20c and 20d.

[0027] Stray capacitance Cs is distributed in the test voltage application circuit 20. Hereafter, stray capacitance will be referred to as stray capacitance. The stray capacitance Cs is the combined capacitance of C1, which exists between the secondary winding 21b and ground in the transformer 21, and the stray capacitances C2 and C3, which exist between the power line 24 connecting the secondary winding terminal 21b1 and one of the test voltage output terminals 20c, and ground.

[0028] Furthermore, a stray capacitance Ca exists between the core wire and the outer conductor of cable 300, and a capacitive component Ct exists in the test specimen 100, which is the sum of the Y capacitor and the stray capacitance. The capacitive component Ct is mainly the capacitance of the Y capacitor. The total volume component C of the test pathway for specimen 100 is expressed by the following equation (1). C = Cs + Ca + Ct ... (1) The current IC (effective value) flowing through the capacitance component C of the entire test path is expressed by the following equation (2). IC = ICs + ICa + ICt ... (2)

[0029] ICs (effective value) is the current flowing through the stray capacitance Cs distributed in the test voltage application circuit 20, and is expressed by the following equation (3). ICs=Vrms / (1 / ωCs)=Vrms·ωCs ···(3) Vrms is the RMS value of the test voltage Vo, and 1 / ωCs is the reactance of the stray capacitance Cs.

[0030] ICa (effective value) is the current flowing through the stray capacitance Ca distributed in cable 300, and is expressed by the following equation (4). ICa=Vrms / (1 / ωCa)=Vrms·ωCa ···(4) 1 / ωCa is the reactance of the stray capacitance Ca.

[0031] ICt (effective value) is the current flowing through the capacitive component Ct relative to the test specimen 100, and is expressed by the following equation (5). ICt=Vrms / (1 / ωCt)=Vrms·ωCt ···(5) 1 / ωCt is the reactance of the capacitance component Ct. In equations (3) through (5) above, the subscript rms is used to indicate the effective value. However, unless otherwise specified, even if the voltage and current values ​​represent the effective value, the subscript rms is omitted in the following explanation to avoid complicating the explanation.

[0032] Furthermore, in the test voltage application circuit 20, a resistance component Rf exists between one power line 24 connecting the secondary winding terminal 21b1 of the secondary winding 21b of the transformer 21 to one of the test voltage output terminals 20c, and ground. A resistive component Ra exists between the core wire and the outer conductor of cable 300, and a resistive component Rt exists in the test specimen 100.

[0033] The resistance component R of the entire test path for specimen 100 is expressed by the following equation (6). 1 / R = 1 / Rf + 1 / Ra + 1 / Rt ... (6) The current IR (effective value) flowing through the resistance component R of the entire test path is expressed by the following equation (7). IR = IRf + IRa + IRt ... (7)

[0034] IRf (effective value) is the current flowing through the resistive component Rf present in the test voltage application circuit 20, IRa (effective value) is the current flowing through the resistive component Ra present in the cable 300, and IRt (effective value) is the current flowing through the resistive component Rt present in the test specimen 100.

[0035] As shown in Figure 4, the current IC flowing through the capacitive component C has a 90° leading phase with respect to the current IR flowing through the resistive component R, and the current IR flowing through the resistive component R has a 90° lagging phase with respect to the current IC flowing through the capacitive component C. Therefore, the detected current Io (effective value) detected by the current detector 22 is the vector sum of current IC and current IR, and is expressed by the following equation (8). Io = √((IR)) 2 +(IC) 2 ) ···(8)

[0036] In Figure 4, the horizontal axis represents the resistance axis and the vertical axis represents the reactance axis. θ is the phase angle between the current IC flowing through the capacitive component C and the current IR flowing through the resistive component R, indicating that the detected current Io detected by the current detector 22 leads the current IR flowing through the resistive component R by a phase angle θ. Furthermore, the current IR flowing through the resistive component R is in phase with the test voltage value Vo.

[0037] On the other hand, the current IC flowing through the capacitive component C can be calculated from the detected current Io by knowing the phase angle θ, using equation (9), and the current IR flowing through the resistive component R can be calculated from the detected current Io by knowing the phase angle θ, using equation (10). IC = Io × sinθ ... (9) IR = Io × cosθ ... (10)

[0038] The withstand voltage determination unit 30 calculates the phase angle θ with respect to the current detection signal and the voltage detection signal from the current detection signal output from the current detector 22 and the voltage detection signal output from the voltage detector 23 in the test voltage application circuit 20. Using the current value Io indicated by the current detection signal output from the current detector 22 and the calculated phase angle θ, it calculates the current value IC flowing through the capacitive component and the current value IR flowing through the resistive component in the current detection signal output from the current detector 22. Using the calculated current value IC flowing through the capacitive component and the current value IR flowing through the resistive component, it obtains the leakage current value It (ICt and IRt) in the withstand voltage test of the test specimen and determines whether the withstand voltage is good or bad.

[0039] The voltage withstand determination unit 30 is installed in conjunction with the higher-level system 200. The withstand voltage determination unit 30 includes a signal detection unit 31, a withstand voltage determination unit 32, and a storage unit 33. The signal detection unit 31 shapes the current detection signal AD10 output from the current detector 22 and the voltage detection signal AD20 output from the voltage detector 23 from sine waves into square waves, and converts them into digital information, namely current detection information and voltage detection information.

[0040] The signal detection unit 31 includes a waveform detection unit 311 and an analog-to-digital converter (ADC) 312. The waveform detection unit 311 receives the current detection signals AD10 (AD11, AD12) output from the current detector 22 and the voltage detection signals AD20 (AD21, AD22) output from the voltage detector 23, and outputs the sinusoidal current detection signals AD10 and AD20 respectively as a waveform-shaped rectangular wave, the current detection rectangular signal AD10b and the voltage detection rectangular signal AD20b, which have a positive current value set to high.

[0041] As shown in Figure 2, the waveform detection unit 311 includes a current clamp circuit 3111, a current-side differential amplifier 3112, a current-side comparator 3113, a current-side resistive element 3114, a voltage clamp circuit 3115, a voltage-side differential amplifier 3116, a voltage-side comparator 3117, and a voltage-side resistive element 3118.

[0042] The current clamp circuit 3111, in order to protect the current-side differential amplifier 3112 and the current-side comparator 3113 from damage caused by excessive current, ensures that the current value of the current detection signal AD10 output from the current detector 22 does not exceed a set threshold. The current-side differential amplifier 3112 differentially amplifies the current detection signal AD10 (AD11, AD12) to obtain the sinusoidal current detection signal AD10a shown in Figure 5.

[0043] The current-side comparator 3113 receives the current detection signal AD10a at its non-inverting input terminal +, and its inverting input terminal - is grounded. The current detection signal AD10a is compared with the ground level voltage value, and the comparator outputs the current detection rectangular signal AD10b, which is a rectangular wave as shown in Figure 5. The current detection rectangular signal AD10b is a signal obtained by shaping the waveform of the sinusoidal waveform of the current detection signal AD10a by setting the positive current value to high (Hi) at the zero-crossing point, thereby creating a rectangular wave.

[0044] The voltage clamp circuit 3115, in order to protect the voltage detection signal AD20 (AD21, AD22) output from the voltage detector 23 from damage caused by excessive voltage, ensures that the voltage value of the voltage detection signal AD20 does not exceed a set threshold. The voltage-side differential amplifier 3116 differentially amplifies the voltage detection signal AD20 (AD21, AD22) to obtain the sine wave voltage detection signal AD20a shown in Figure 5.

[0045] In Figure 5, the difference in amplitude between the sinusoidal current detection signal AD10a and the voltage detection signal AD20a is for convenience, to make them easier to distinguish, and does not have any special meaning.

[0046] The voltage-side comparator 3117 receives the voltage detection signal AD20a at its non-inverting input terminal +, and its inverting input terminal - is grounded. The voltage detection signal AD20a is compared with the ground-level voltage value, and the comparator outputs the voltage detection rectangular signal AD20b, which is a rectangular wave as shown in Figure 5. The voltage detection rectangular signal AD20b is a signal obtained by shaping the waveform of the sinusoidal waveform of the voltage detection signal AD20a by setting the positive voltage value to high (Hi) at the zero-crossing point, thereby creating a rectangular wave.

[0047] The ADC312 converts the current detection rectangular signal AD10b and the voltage detection rectangular signal AD20b from the waveform detection unit 311 into digital information, namely current detection information and voltage detection information, and outputs them to the withstand voltage determination unit 32 and the storage unit 33. Furthermore, the ADC312 outputs current detection information from the differential amplifier 3112 of the waveform detection unit 311 as digital information indicating the current Io detected by the current detector 22 to the withstand voltage determination unit 32 and the storage unit 33, and outputs voltage detection information from the differential amplifier 3116 as digital information indicating the voltage Vo detected by the voltage detector 23 to the withstand voltage determination unit 32 and the storage unit 33.

[0048] In Embodiment 1, the ADC 312 obtains current detection information and voltage detection information, which are digital information, using the current detection rectangular signal AD10b and voltage detection rectangular signal AD20b from the waveform detection unit 311. However, the current detection information and voltage detection information, which are digital information, may also be obtained using the current detection signal AD10a from the current-side differential amplifier 3112 and the voltage detection signal AD20a from the voltage-side differential amplifier 3116.

[0049] The withstand voltage determination unit 32 calculates the phase angle θ of the current detection signal AD10 and the voltage detection signal AD20 from the current detection information corresponding to the current detection signal AD10 output from the current detector 22 and the voltage detection information corresponding to the voltage detection signal AD20 output from the voltage detector 23. Using the current value Io indicated by the current detection signal AD10 output from the current detector 22 and the calculated phase angle θ, it calculates the current value IC flowing through the capacitive component and the current value IR flowing through the resistive component of the current detection signal AD10 output from the current detector 22. Using the calculated current value IC flowing through the capacitive component and the current value IR flowing through the resistive component, it obtains the leakage current value It (ICt and IRt) in the withstand voltage test of the test specimen 100 and determines whether the withstand voltage is good or bad.

[0050] The hardware of the voltage withstand determination unit 32 is comprised of, for example, a programmable controller or a personal computer. The withstand voltage determination unit 32 has the function of calculating the phase angle θ, the function of calculating the current value IC flowing through the capacitive component and the current value IR flowing through the resistive component, the function of calculating the leakage current value It in the withstand voltage test of the test specimen 100, and the function of determining whether the test specimen 100 is good or bad in relation to the withstand voltage.

[0051] As shown in Figure 3, the withstand voltage determination unit 32 includes a phase angle calculation unit 321, a component current calculation unit 322, a leakage current calculation unit 323, and a determination unit 324. The phase angle calculation unit 321 uses current detection information indicating the detected current from the current detector 22 of the waveform detection unit 311 and voltage detection information indicating the detected voltage from the voltage detector 23 to calculate the phase angle θ with respect to the detected current and detected voltage.

[0052] As shown in Figure 5, the phase angle calculation unit 321 determines the time T1 corresponding to one period from the rising edge to the next rising edge of the voltage detection rectangular signal AD20b indicated by the voltage detection information, determines the phase difference detection time T2 from the rising edge of the voltage detection rectangular signal AD20b to the rising edge of the current detection rectangular signal AD10b indicated by the current detection information, and calculates the phase angle θ using the following equation (11). θ=360(°)-{(T2÷T1)×360(°)} (11) The phase angle θ, which is the result of the calculation by the phase angle calculation unit 321, is digital information and is stored in the storage unit 33.

[0053] The component current calculation unit 322 uses the digital information indicated by the effective value Io due to the detected current detected by the current detector 22 and the phase angle θ which is the result of the calculation by the phase angle calculation unit 321 to calculate the current IC (digital information) flowing through the capacitive component C and the current IR (digital information) flowing through the resistive component R using equations (9) and (10) above.

[0054] The current IC flowing through the capacitance component C and the current IR flowing through the resistance component R, which are the calculation results, are stored in the memory unit 33. The phase angle calculation unit 321 and the component current calculation unit 322 constitute a calculation unit that obtains the current IC for the capacitive component and the current IR for the resistive component in the withstand voltage test path including the test specimen 100.

[0055] The leakage current calculation unit 323 subtracts correction values ​​(ICc, IRc) from the current IC flowing through the capacitive component C and the current IR flowing through the resistive component R, which are the calculation results from the component current calculation unit 322, to calculate the leakage current It (the leakage current ICt flowing through the capacitive component C and the leakage current IRt flowing through the resistive component R). The resulting leakage current It(ICt, IRt) is stored in the memory unit 33.

[0056] The correction values ​​(ICc, IRc) are calculated in advance as follows: With the pair of test voltage output terminals 20c and 20d of the test voltage application circuit 20 open, or with the pair of test voltage output terminals 20c and 20d connected to the pair of test voltage output terminals 20c and 20d, and the input terminals 100a and 100b of the test specimen 100 open, a test voltage value Vo is applied from the AC power supply 10 via the transformer 21 between the pair of test voltage output terminals 20c and 20d. The phase angle θc is determined by the withstand voltage determination unit 30 using the detected current Ioc detected by the current detector 22 and the detected voltage Vo detected by the voltage detector 23. Furthermore, the withstand voltage determination unit 30 calculates the current ICc for the capacitive component and the current IRc for the resistive component in the withstand voltage test path when the test specimen 100 is not connected, using the detected current Ioc and phase angle θc. The calculation results are used as correction values ​​(ICc, IRc). The correction values ​​(ICc, IRc) are stored in the memory unit 33.

[0057] Furthermore, it is preferable to connect the cable 300 to the pair of test voltage output terminals 20c and 20d, and leave the input terminals 100a and 100b of the test specimen 100 open to obtain the correction values ​​(ICc, IRc), as this allows for obtaining correction values ​​for leakage current including the cable 300, and thus more accurate correction values ​​(ICc, IRc).

[0058] In Embodiment 1, the test voltage value Vo is applied between a pair of test voltage output terminals 20c and 20d to obtain the correction values ​​(ICc, IRc). However, the correction values ​​(ICc, IRc) may also be obtained by applying a voltage lower than the test voltage value Vo, for example, a low voltage VL that is considered a safe voltage that does not pose a danger to the human body, between the pair of test voltage output terminals 20c and 20d.

[0059] The correction values ​​(ICc, IRc) at this time are obtained by multiplying the values ​​(ILCc, ILRc) obtained by applying a low voltage VL between a pair of test voltage output terminals 20c and 20d by the voltage ratio (Vo / VL). By using a low voltage, the device remains safe for humans even if the pair of test voltage output terminals 20c, 20d or the input terminals 100a, 100b of the test specimen 100 are open.

[0060] The determination unit 324 compares the current IRt, which is the resistance component of the leakage current It flowing through the test specimen 100 during the withstand voltage test and is calculated by the leakage current calculation unit 323, with a set determination value (threshold). If the current IRt is less than the determination value, the determination unit 324 determines that the test specimen 100 is a good product for withstand voltage. If the current IRt is equal to or greater than the determination value, the determination unit 324 determines that the test specimen 100 is a defective product for withstand voltage and outputs the determination result to an output unit (not shown), such as a display device.

[0061] In some cases, the leakage current ICt for the capacitive component of the leakage current It flowing through the test specimen 100 is further compared with a set judgment value (threshold). If the current ICt is less than the judgment value, the test specimen 100 is considered good in terms of withstand voltage; if the current ICt is equal to or greater than the judgment value, the test specimen 100 is considered defective in terms of withstand voltage.

[0062] Next, the dielectric strength test method using the dielectric strength test apparatus according to Embodiment 1 will be explained with reference to Figure 6. Before performing the withstand voltage test on the test specimen 100, correction values ​​for the withstand voltage test path when the test specimen 100 is not connected, that is, the current ICc for the capacitive component and the current IRc for the resistive component in the withstand voltage test path when the test specimen 100 is not connected, are obtained using the withstand voltage test apparatus according to Embodiment 1.

[0063] Before performing the withstand voltage test, the test specimen 100 is connected to the pair of test voltage output terminals 20c and 20d of the test voltage application circuit via the cable 300 (step ST01). To supply a withstand voltage test voltage Vo between a pair of test voltage output terminals 20c and 20d, an AC voltage consisting of a sinusoidal wave is supplied from the AC power supply 10 to the primary winding 21a of the transformer 21, generating a test voltage Vo in the secondary winding 21b of the transformer 21, and applying the test voltage Vo to the pair of test voltage output terminals 20c and 20d. As a result, a test voltage Vo is applied to the pair of input terminals 100a and 100b of the test specimen 100 via the cable 300 (step ST02).

[0064] In step ST1, the current detector 22 detects the current flowing through the test specimen 100, that is, the current Io in the withstand voltage test path including the test specimen 100, and outputs the detected current Io to the withstand voltage determination unit 30. In addition, the voltage detector 23 detects the test voltage Vo between the pair of test voltage output terminals 20c and 20d, and outputs the detected voltage Vo to the withstand voltage determination unit 30.

[0065] In step ST2, the waveform detection unit 311 of the signal detection unit 31 in the withstand voltage determination unit 30 shapes the detected current Io and detected voltage Vo into waveforms, and the ADC 312 converts them into digital information, namely current detection information and voltage detection information. At the same time, the withstand voltage determination unit 30 converts the effective value of the detected current Io into digital information.

[0066] In step ST3, the phase angle calculation unit 321 of the withstand voltage determination unit 32 in the withstand voltage determination unit 30 calculates the phase difference θ using the current detection information indicating the detected current Io and the voltage detection information indicating the detected voltage Vo according to the above equation (11). The calculated phase difference θ is set as the phase angle θ between the current IC for the capacitive component and the current IR for the resistive component in the withstand voltage test path.

[0067] In step ST4, the component current calculation unit 322 of the withstand voltage determination unit 32 in the withstand voltage determination unit 30 calculates the current value IC for the capacitive component in the withstand voltage test path (detected current Io) using equation (9) above, and the current value IR for the resistive component using equation (10) above, based on the set phase angle θ and the effective value of the detected current Io.

[0068] In step ST5, the leakage current calculation unit 323 of the withstand voltage determination unit 32 in the withstand voltage determination unit 30 subtracts a correction value from the current IC for the capacitive component and the current IR for the resistive component in the withstand voltage test path to calculate the leakage current It for the test specimen 100 (leakage current ICt flowing through the capacitive component Ct and leakage current IRt flowing through the resistive component Rt).

[0069] The correction values ​​are obtained by using the withstand voltage test apparatus according to Embodiment 1, connecting the cable 300 to the pair of test voltage output terminals 20c and 20d of the test voltage application circuit 20, leaving the input terminals 100a and 100b of the test specimen 100 open, and determining the phase angle θc using the detected current Ioc detected by the current detector 22 and the detected voltage Vo detected by the voltage detector 23. The correction values ​​are the leakage current ICc for the capacitive component and the leakage current IRc for the resistive component in the withstand voltage test path when the test specimen 100 is not connected, determined from the effective value of the detected current Ioc and the phase angle θc.

[0070] In step ST6, the determination unit 324 of the withstand voltage determination unit 32 in the withstand voltage determination unit 30 compares the leakage current It for the test specimen 100 with the determination value to determine whether the test specimen 100 is good or bad. The determination of whether a test specimen is good or bad is as follows: if the leakage current IRt relative to the resistive component is less than the judgment value, the test specimen 100 is good in terms of withstand voltage; if the leakage current IRt is equal to or greater than the judgment value, the test specimen 100 is bad in terms of withstand voltage.

[0071] In some cases, the leakage current ICt for the capacitive component of the leakage current It flowing through the test specimen 100 is further compared with a set judgment value (threshold). If the current ICt is less than the judgment value, the test specimen 100 is considered good in terms of withstand voltage; if the current ICt is equal to or greater than the judgment value, the test specimen 100 is considered defective in terms of withstand voltage.

[0072] Steps ST3 to ST6 are stored in the memory unit 33 of the programmable controller or personal computer that constitutes the withstand voltage determination unit 30 as a withstand voltage test program that indicates the procedure to be executed by the computer.

[0073] The withstand voltage test apparatus according to Embodiment 1 is a withstand voltage test apparatus that performs a withstand voltage test by applying a high AC voltage Vo to a test specimen 100 that is the subject of the withstand voltage test, and measuring (detecting) the leakage current Io flowing through the withstand voltage test path to which the test specimen 100 is connected using a current detector 22. The apparatus is equipped with a voltage detector 23 that detects the voltage between the test voltage output terminals 20c and 20d of the test voltage application circuit 20, and calculates the phase angle θ of the current detection signal and the voltage detection signal from the current detection signal output from the current detector 22 and the voltage detection signal output from the voltage detector 23, and the current value indicated by the current detection signal output from the current detector 22 is used to determine the current value. The system includes a withstand voltage determination unit that calculates the current value IC flowing through the capacitive component and the current value IR flowing through the resistive component in the current detection signal output from the current detector 22 based on the phase angle θ, and uses the calculated current value IC flowing through the capacitive component and the current value IR flowing through the resistive component to obtain the leakage current value It in the withstand voltage test of the test specimen 100. Therefore, the leakage current Io flowing through the withstand voltage test path to which the test specimen 100 is connected can be corrected for the leakage current Ioc flowing through the withstand voltage test path to which the test specimen 100 is not connected, which is a measurement error, using the test voltage Vo detected by the voltage detector 23, and the leakage current flowing through the test specimen 100 can be measured with high accuracy.

[0074] Embodiment 2. The dielectric strength test apparatus according to Embodiment 2 will be described with reference to Figures 7 and 8. The withstand voltage test apparatus according to Embodiment 2 differs from the withstand voltage test apparatus according to Embodiment 1 in that the withstand voltage determination unit 30, in particular, the withstand voltage determination section 32 in the withstand voltage determination unit 30, but the other configurations are the same. Therefore, the explanation will focus on the withstand voltage determination unit 32A.

[0075] Furthermore, since the overall configuration of the withstand voltage test apparatus according to Embodiment 2 is substantially identical to the overall configuration of the withstand voltage test apparatus according to Embodiment 1 in terms of the drawings, Figure 1 will be used as a reference when explaining the overall configuration. Furthermore, in Figures 7 and 8, the same reference numerals as those used in Figures 1 to 6 indicate the same or corresponding parts.

[0076] The withstand voltage determination unit 30A, under the control of the higher-level system, determines at the beginning of the withstand voltage test whether the current value IL indicated by the low-voltage current detection signal output from the current detector 22 in the test voltage application circuit 20 is within the set range. It calculates the low-voltage phase angle θL of the low-voltage detection signal and the low-voltage current detection signal from the low-voltage detection signal and the low-voltage current detection signal output from the voltage detector 23. It calculates the low-voltage current value ILR flowing through the resistive component and the low-voltage current value ILC flowing through the capacitive component of the low-voltage current detection signal using the current value IL indicated by the low-voltage current detection signal and the calculated low-voltage phase angle θL. The system determines whether the low-voltage current value ILC flowing through the circuit is within the respective set ranges, determines whether the current value Io indicated by the current detection signal output from the current detector 22 is within the set range in the withstand voltage test, calculates the phase angle θ with respect to the voltage detection signal and the current detection signal from the voltage detection signal and the current detection signal output from the voltage detector 23, calculates the current value IC flowing through the capacitive component and the current value IR flowing through the resistive component in the current detection signal using the current value Io indicated by the current detection signal and the calculated phase angle θ, determines whether the voltage value Vo indicated by the voltage detection signal, the phase angle θ, the current value IR flowing through the resistive component, and the current value IC flowing through the capacitive component are within their respective set ranges, and determines whether the test specimen 100 is a good or bad product in terms of withstand voltage.

[0077] The withstand voltage determination unit 30A performs the following determinations: whether the low voltage current value IL is within the set range using equation (12); whether the detected low voltage value VL is within the set range using equation (13); whether the low voltage phase angle θL is within the set range using equation (14); whether the low voltage current value ILR is within the set range using equation (15); and whether the low voltage current value ILC is within the set range using equation (16). An AC voltage VL lower than the voltage used in the withstand voltage test is considered a safe voltage that poses no danger to the human body.

[0078] ILmin ≤ IL ≤ ILmax (12) VLmin ≤ VL ≤ VLmax (13) θLmin ≤ θL ≤ θLmax (14) ILRmin ≤ ILR ≤ ILRmax (15) ILCmin ≤ ILC ≤ ILCmax (16)

[0079] Note that the current values ​​IL, ILR, and ILC and the voltage value VL shown in equations (12) to (16) above are RMS values. Furthermore, ILmin represents the lower threshold of the low-voltage current value IL, ILmax represents the upper threshold of the low-voltage current value IL, VLmin represents the lower threshold of the low-voltage value VL, VLmax represents the upper threshold of the low-voltage value VL, θLmin represents the lower threshold of the low-voltage phase angle θL, θLmax represents the upper threshold of the low-voltage phase angle θL, ILRmin represents the lower threshold of the low-voltage current value ILR, ILRmax represents the upper threshold of the low-voltage current value ILR, ILCmin represents the lower threshold of the low-voltage current value ILC, and ILCmax represents the upper threshold of the low-voltage current value ILC.

[0080] The withstand voltage determination unit 30A performs the following determinations: whether the current value Io is within the set range using equation (17); whether the detected AC voltage Vo is within the set range using equation (18); whether the phase angle θ is within the set range using equation (19); whether the current value IR is within the set range using equation (20); and whether the current value IC is within the set range using equation (21).

[0081] Iomin ≤ Io ≤ Iomax (17) Vomin≦Vo≦Vomax (18) θmin ≤ θ ≤ θmax (19) IRmin ≤ IR ≤ IRmax (20) ICmin ≤ IC ≤ ICmax (21)

[0082] Note that the current values ​​Io, IR, and IC, and the voltage value Vo shown in equations (17) to (21) above are RMS values. Furthermore, Iomin represents the lower threshold for the current value Io, Iomax represents the upper threshold for the current value Io, Vomin represents the lower threshold for the voltage value Vo, Vomax represents the upper threshold for the voltage value Vo, θmin represents the lower threshold for the phase angle θ, θmax represents the upper threshold for the phase angle θ, IRmin represents the lower threshold for the current value IR, IRmax represents the upper threshold for the current value IR, ICmin represents the lower threshold for the current value IC, and ICmax represents the upper threshold for the current value IC.

[0083] Iomin, Iomax, Vomin, Vomax, IRmin, IRmax, ICmin, and ICmax are values ​​obtained by multiplying ILmin, ILmax, VLmin, VLmax, ILRmin, ILRmax, ILCmin, and ILCmax, respectively, by the voltage ratio (Vo / VL). Furthermore, it is preferable to use a value that provides an offset amount based on the capacitance component C in the withstand voltage test path to the current value Io indicated by the current detection signal output from the current detector 22, in order to determine whether or not the current value Io is within the set range indicated by Iomin and Iomax.

[0084] Furthermore, it is preferable to set the current value Io, indicated by Iomin and Iomax, based on the estimated value Ioe, which is obtained by multiplying the low-voltage current value IL by the voltage ratio (Vo / VL). The setting range for the current value IR, indicated by IRmin and IRmax, is more preferably set based on IRe, which is an estimated value obtained by multiplying the low-voltage current value ILR by the voltage ratio (Vo / VL). The setting range for the current value IC, indicated by ICmin and ICmax, is more preferably set based on ICe, which is an estimated value obtained by multiplying the low-voltage current value ILC by the voltage ratio (Vo / VL).

[0085] The capacitance component C is calculated using the following equation (22), which is the current value IL (effective value) indicated by the current detection signal output from the current detector 22 and the voltage value VL (effective value) indicated by the voltage detection signal output from the voltage detector 23. C = IL / (ω × VL) (22) In equation (22) above, ω is 2πf, and f is the frequency.

[0086] In a voltage withstand test of a test specimen 100 in which a Y capacitor is built between the internal circuit and the enclosure, variations in the capacitance value of the built-in Y capacitor can be offset by adding an offset amount to the current value Io indicated by the current detection signal output from the current detector 22, thereby avoiding errors in the voltage withstand test. The current value Io with an offset is obtained by adding ±α (a positive value) based on the calculated capacitance component C to the current value Io indicated by the current detection signal output from the current detector 22, or by multiplying it by a coefficient β (for example, a value in the range of 0.8 to 1.2).

[0087] Since the current value Io used to determine whether or not the current is within the set range is an offset current value Io, the offset current value Io is also used to calculate the current IR flowing through the resistive component and the current IC flowing through the capacitive component in equations (20) and (21) above, which determine whether or not the current is within the set range.

[0088] Alternatively, values ​​may be used to provide an offset amount that is set based on the capacitance component C for Iomin and Iomax, which are thresholds for determining whether the current value Io indicated by the current detection signal output from the current detector 22 is within the set range. In this case as well, in a voltage withstand test of test specimen 100, which has a Y capacitor built in between the internal circuit and the enclosure, the variation in the capacitance value of the built-in Y capacitor can be offset from the set range Iomin and Iomax to avoid the influence of errors on the voltage withstand test.

[0089] Iomin and Iomax, which indicate the setting range with an offset amount, are obtained by multiplying ILmin and ILmax, which indicate the setting range at low voltage, by the voltage ratio (Vo / VL), and then adding ±γ (a positive value) based on the calculated capacitance component C, or by multiplying by a coefficient δ (for example, a value in the range of 0.8 to 1.2). By using the setting range with an offset amount for Iomin and Iomax, the setting range with an offset amount is also used for ILRmin and ILRmax, and ILCmin and ILCmax.

[0090] Furthermore, it is preferable to set the current value Io indicated by Iomin and Iomax based on the estimated current value Ioe, which is obtained by multiplying the low-voltage current value IL by the voltage ratio (Vo / VL). In other words, it is obtained by adding ±ε (a positive value) to the estimated current value Ioe, or by multiplying it by a coefficient ζ (for example, a value in the range of 0.8 to 1.2).

[0091] In short, let Iomin = Ioe - ε, Iomax = Ioe + ε, or Iomin = Ioe × ζ (ζ < 1), Iomax = Ioe × ζ (ζ > 1). By determining the setting range of the current value Io based on the estimated current value Ioe, which is obtained by multiplying the low-voltage current value IL by the voltage ratio, it is possible to avoid the influence of errors in the withstand voltage test due to variations in the capacitance value of the built-in Y capacitor.

[0092] The setting range for the current value IR, indicated by IRmin and IRmax, is more preferably set based on ILRe, which is the estimated current value obtained by multiplying the low-voltage current value ILR by the voltage ratio (Vo / VL). In other words, it is obtained by adding ±η (a positive value) to the estimated current value ILRe, or by multiplying it by a coefficient ι (for example, a value in the range of 0.8 to 1.2). In short, let IRmin = ILRe - η, IRmax = ILRe + η, or IRmin = ILRe × ι (ι < 1), IRmax = ILRe × ι (ι > 1).

[0093] The setting range for the current values ​​IC, indicated by ICmin and ICmax, is more preferably set based on ILCe, which is the estimated current value obtained by multiplying the low-voltage current value ILC by the voltage ratio (Vo / VL). In other words, it is obtained by adding ±κ (a positive value) to the estimated current value ILCe, or by multiplying it by a coefficient λ (for example, a value in the range of 0.8 to 1.2). In short, let ICmin = ILCe - κ, ICmax = ILCe + κ, or ICmin = ILCe × λ (λ < 1), ICmax = ILCe × λ (λ > 1).

[0094] The voltage withstand judgment unit 30A is installed in conjunction with the higher-level system 200. The withstand voltage determination unit 30A includes a signal detection unit 31, a withstand voltage determination unit 32A, and a storage unit 33. The signal detection unit 31 is substantially the same as the signal detection unit 31 in the withstand voltage test apparatus according to Embodiment 1, so its description will be omitted.

[0095] The withstand voltage determination unit 32A determines whether the current value IL indicated by the low voltage current detection information corresponding to the low voltage current detection signal AD10 output from the current detector 22 is within the set range. It calculates the low voltage phase angle θL of the low voltage detection signal AD20 and the low voltage current detection signal AD10 from the low voltage detection information corresponding to the low voltage detection signal AD20 output from the voltage detector 23 and the low voltage current detection information corresponding to the low voltage current detection signal AD10. It calculates the low voltage current value ILR flowing through the resistive component and the low voltage current value ILC flowing through the capacitive component of the low voltage current detection signal AD10 using the current value IL indicated by the low voltage current detection signal AD10 and the calculated low voltage phase angle θL. The system determines whether the current value Io indicated by the current detection information corresponding to the current detection signal AD10 during the withstand voltage test output from the current detector 22 is within the set range. The system calculates the phase angle θ for the current detection signal AD10 and the voltage detection signal AD20 from the voltage detection information corresponding to the voltage detection signal AD20 during the withstand voltage test output from the voltage detector 23 and the current detection information corresponding to the current detection signal AD10 during the withstand voltage test. The system calculates the current value IC flowing through the capacitive component and the current value IR flowing through the resistive component in the current detection signal AD10 using the current value Io indicated by the current detection signal AD10 and the calculated phase angle θ. The system determines whether the voltage value Vo indicated by the voltage detection signal AD20, the phase angle θ, the current value IR flowing through the resistive component, and the current value IC flowing through the capacitive component are within their respective set ranges, and determines whether the test specimen 100 is a good or bad product in terms of withstand voltage.

[0096] The withstand voltage determination unit 32A performs the following: determination of whether the low voltage current value IL is within the set range using equation (12) above; determination of whether the detected AC voltage VL is within the set range using equation (13) above; determination of whether the low voltage phase angle θL is within the set range using equation (14) above; determination of whether the low voltage current value ILR is within the set range using equation (15) above; and determination of whether the low voltage current value ILC is within the set range using equation (16) above.

[0097] The withstand voltage determination unit 32A performs the following: determination of whether the current value Io is within the set range using equation (17) above; determination of whether the detected AC voltage Vo is within the set range using equation (18) above; determination of whether the phase angle θ is within the set range using equation (19) above; determination of whether the current value IR is within the set range using equation (20) above; and determination of whether the current value IC is within the set range using equation (21) above.

[0098] The current value Io used to determine whether or not it is within the set range may be a current value with an offset amount, and the current value IR and the current value IC used to determine whether or not it is within the set range may also be current values ​​with an offset amount. Furthermore, the setting range for the current value Io may also be a setting range with an offset amount, and the setting ranges for the current value IR and the setting range for the current value IC may also be setting ranges with an offset amount.

[0099] The hardware of the voltage withstand determination unit 32A is comprised of, for example, a programmable controller or a personal computer. The withstand voltage determination unit 32A has the functions to calculate the phase angle θ, the current value IC flowing through the capacitive component and the current value IR flowing through the resistive component, the phase angle θL at low voltage, the current value ILC flowing through the capacitive component and the current value ILR flowing through the resistive component at low voltage, the function to determine the current value Io, the function to determine the voltage value Vo, the phase angle θ, the current value IC, and the current value IR, the function to determine the current value IL at low voltage, and the function to determine the low voltage value VL, the phase angle θL at low voltage, the current value ILR, and the current value ILC at low voltage.

[0100] As shown in Figure 7, the withstand voltage determination unit 32A includes a phase angle calculation unit 321, a component current calculation unit 322, a detected current determination unit 325, a set value determination unit 326, a low voltage phase angle calculation unit 321L, a low voltage component current calculation unit 322L, a low voltage detected current determination unit 325L, and a low voltage set value determination unit 326L. Since the phase angle calculation unit 321 and the component current calculation unit 322 are substantially the same as those in the withstand voltage test apparatus according to Embodiment 1, a detailed explanation will be omitted.

[0101] As shown in Figure 5, the phase angle calculation unit 321 determines the time T1 corresponding to one period from the rising edge to the next rising edge of the voltage detection rectangular signal AD20b indicated by the voltage detection information, determines the phase difference detection time T2 from the rising edge of the voltage detection rectangular signal AD20b to the rising edge of the current detection rectangular signal AD10b indicated by the current detection information, and calculates the phase angle θ using the above equation (11). The phase angle θ, which is the result of the calculation by the phase angle calculation unit 321, is digital information and is stored in the storage unit 33.

[0102] The component current calculation unit 322 uses the digital information indicated by the effective value Io due to the detected current detected by the current detector 22 and the phase angle θ which is the result of the calculation by the phase angle calculation unit 321 to calculate the current IC (digital information) flowing through the capacitive component C and the current IR (digital information) flowing through the resistive component R using equations (9) and (10) above.

[0103] The current IC flowing through the capacitance component C and the current IR flowing through the resistance component R, which are the calculation results, are stored in the memory unit 33. The phase angle calculation unit 321 and the component current calculation unit 322 constitute a calculation unit that obtains the current IC for the capacitive component and the current IR for the resistive component in the withstand voltage test path including the test specimen 100.

[0104] The current detection determination unit 325 determines whether the current value Io indicated by the current detection signal AD10 output from the current detector 22 is within the set range shown in equation (17) above. If it is within the set range, the test is to continue; if it is outside the set range, it outputs a signal indicating the end of the test, that is, a signal indicating that the test specimen 100 is defective in terms of withstand voltage.

[0105] The current value Io may be a current value to which an offset amount has been given. Furthermore, the setting range may also be a setting range for which an offset amount is given. In the following explanation, to avoid complexity, we will simply refer to the current value Io and the setting range, but this includes the current value with an offset and the setting range with an offset.

[0106] The setting value determination unit 326 determines whether the voltage value Vo indicated by the voltage detection signal AD20 output from the voltage detector 23 is within the setting range shown in equation (18), whether the phase angle θ calculated by the phase angle calculation unit 321 is within the setting range shown in equation (19), whether the current value IR calculated by the component current calculation unit 322 is within the setting range shown in equation (20), and whether the current value IC calculated by the component current calculation unit 322 is within the setting range shown in equation (21). If all determinations are within the setting range, the unit outputs a signal indicating that the test specimen 100 is a good product in terms of withstand voltage and terminates the withstand voltage test. If at least one determination is outside the setting range, the unit outputs a signal indicating the end of the test, that is, a signal indicating that the test specimen 100 is a defective product in terms of withstand voltage.

[0107] The low-voltage phase angle calculation unit 321L has the same function as the phase angle calculation unit 321, and calculates the low-voltage phase angle θL using the above equation (11) when the voltage is low. The low-voltage phase angle θL is also digital information and is stored in the memory unit 33. Since the phase angle θL at low voltage and the phase angle θ are essentially the same, the phase angle calculation unit 321 may be omitted, and the phase angle θL at low voltage may be treated as the phase angle.

[0108] In this case, the phase angle θ experienced by the component current calculation unit 322 is the low-voltage phase angle θL, which is the result of calculation by the low-voltage phase angle calculation unit 321L. Furthermore, the setting value determination unit 326 does not need to determine whether the phase angle θ is within the setting range shown in equation (19) above.

[0109] The low-voltage component current calculation unit 322L has the same function as the component current calculation unit 322. At low voltage, the current ILC (digital information) flowing through the capacitive component C and the current ILR (digital information) flowing through the resistive component R are calculated using equations (9) and (10) above, based on the digital information indicated by the effective value IL due to the detected current detected by the current detector 22 and the low-voltage phase angle θL which is the result of calculation by the low-voltage phase angle calculation unit 321L.

[0110] The calculation results, namely the current ILC flowing through the capacitive component C and the current ILR flowing through the resistive component R, are stored in the memory unit 33. The low-voltage phase angle calculation unit 321L and the low-voltage component current calculation unit 322L constitute a calculation unit that obtains the current ILC for the capacitive component and the current ILR for the resistive component at low voltage in the withstand voltage test path including the test specimen 100.

[0111] The low-voltage detection current determination unit 325L has the same function as the detection current determination unit 325. When the voltage is low, it determines whether the low-voltage current value IL indicated by the current detection signal AD10 output from the current detector 22 is within the set range shown in equation (12) above. If it is within the set range, it continues the test; if it is outside the set range, it outputs a signal indicating the end of the test, that is, a signal indicating that the test specimen 100 is defective in terms of withstand voltage.

[0112] The low-voltage setting value determination unit 326L has the same function as the setting value determination unit 326. When the voltage is low, it determines whether the low voltage value VL indicated by the voltage detection signal AD20 output from the voltage detector 23 is within the setting range shown in equation (13), whether the low-voltage phase angle θL calculated by the low-voltage phase angle calculation unit 321L is within the setting range shown in equation (14), whether the low-voltage current value ILR calculated by the low-voltage component current calculation unit 322L is within the setting range shown in equation (15), and whether the low-voltage current value ILC calculated by the low-voltage component current calculation unit 322L is within the setting range shown in equation (16). If all determinations are within the setting range, the test is continued. If at least one determination is outside the setting range, it outputs a signal indicating the end of the test, that is, a signal indicating that the test specimen 100 is defective in terms of withstand voltage.

[0113] Next, the voltage withstand test method using the voltage withstand test apparatus according to Embodiment 2 will be explained with reference to Figure 8. The input terminals 100a and 100b of the test specimen 100 are connected to the test voltage output terminals 20c and 20d of the test voltage application circuit 20 via the cable 300. In order to supply a voltage VL lower than the withstand test voltage Vo between the test voltage output terminals 20c and 20d, under the control of the higher-level system 200, a low AC voltage consisting of a sinusoid is supplied from the AC power supply 10 to the primary winding 21a of the transformer 21, generating a low voltage VL in the secondary winding 21b of the transformer 21, and applying the low voltage VL to the pair of test voltage output terminals 20c and 20d (step ST02L). As a result, a low voltage VL is applied to the pair of input terminals 100a and 100b of the test specimen 100 via the cable 300. Step ST02L is a step in which a low voltage VL is output to be applied to the test specimen 100.

[0114] The current detector 22 detects the current flowing through the test specimen 100, that is, the current IL in the withstand voltage test path including the test specimen 100, and outputs the detected current IL to the withstand voltage determination unit 30. The voltage detector 23 detects the test voltage VL between the pair of test voltage output terminals 20c and 20d, and outputs the detected voltage VL to the withstand voltage determination unit 30.

[0115] In step ST11, the waveform detection unit 311 of the signal detection unit 31 in the withstand voltage determination unit 30 shapes the detected current IL and detected voltage VL into waveforms, and the ADC 312 converts them into digital information, namely current detection information and voltage detection information. Simultaneously, the withstand voltage determination unit 30 converts the effective values ​​of the detected current IL and detected voltage VL into digital information. The effective values ​​of the detected current IL and detected voltage VL are stored in the storage unit 33. In other words, step ST11 is a step in which a low voltage current value IL, which is digital information representing the effective value, is obtained from the low voltage current detection signal from the current detector 22, and a low voltage value VL, which is digital information representing the effective value, is obtained from the low voltage detection signal from the voltage detector 23.

[0116] In step ST12, the low-voltage detection current determination unit 325L of the withstand voltage determination unit 32A in the withstand voltage determination unit 30 determines whether the low-voltage current value IL is within the set range shown in equation (12) above. If the low-voltage current value IL is within the set range shown in equation (12) above, the test continues and proceeds to step ST13. If the current value IL at low voltage is outside the set range shown in equation (12) above, the test specimen 100 outputs a test NG signal, which is a signal indicating a defective product in terms of withstand voltage, and the withstand voltage test is terminated.

[0117] The low-voltage detection current determination unit 325L multiplies ILmin and ILmax, which indicate the setting range for the low-voltage current value IL, by the voltage ratio (Vo / VL) to obtain the setting range for the current value Io when the high voltage Vo during the withstand voltage test is applied. The setting range for the current value Io is preferably determined by multiplying ILmin and ILmax by the voltage ratio (Vo / VL) and then adding an offset amount based on the capacitive component C.

[0118] Furthermore, the setting range for the current value Io is obtained by adding ±ε (a positive value) based on the capacitance component C, or by multiplying by a coefficient ζ (for example, a value in the range of 0.8 to 1.2), based on the value Ioe (estimated value) obtained by multiplying the low-voltage current value IL by the voltage ratio (Vo / VL). That is, let Iomin = Ioe - ε, Iomax = Ioe + ε, or Iomin = Ioe × ζ (ζ < 1), Iomax = Ioe × ζ (ζ > 1).

[0119] In step ST13, the low-voltage phase angle calculation unit 321L of the withstand voltage determination unit 32A calculates the low-voltage phase angle θL using the current detection information indicating the low-voltage current value IL and the voltage detection information indicating the low-voltage value VL according to the above equation (11). The calculated low-voltage phase angle θL is set as the low-voltage phase angle θL of the current ILC for the capacitive component and the current ILR for the resistive component in the withstand voltage test path at low voltage, and is stored in the memory unit 33.

[0120] If the phase angle calculation unit 321 is not provided, the low-voltage phase angle θL is used as the phase angle θ for obtaining the current IC for the capacitive component and the current IR for the resistive component in the detected current Io when the high voltage Vo is applied during the withstand voltage test.

[0121] In step ST14, the low-voltage component current calculation unit 322L of the withstand voltage determination unit 32A calculates the low-voltage current value ILC for the capacitive component in the withstand voltage test path (low-voltage current value IL) using equation (9) above, based on the low-voltage phase angle θL and the effective value of the low-voltage current value IL set by the withstand voltage determination unit 32A, and calculates the low-voltage current value ILR for the resistive component using equation (10) above, and proceeds to step ST15. The low-voltage current values ​​ILC and ILR are stored in the memory unit 33.

[0122] In step ST15, the low-voltage setting value determination unit 326L of the withstand voltage determination unit 32A determines whether the low voltage value VL is within the setting range shown by equation (13) above, whether the low-voltage phase angle θL is within the setting range shown by equation (14) above, whether the low-voltage current value ILR is within the setting range shown by equation (15) above, and whether the low-voltage current value ILC is within the setting range shown by equation (16) above.

[0123] The low-voltage setting value determination unit 326L multiplies ILRmin and ILRmax, which indicate the setting range for the low-voltage current value ILR, and ILCmin and ILCmax, which indicate the setting range for the low-voltage current value ILC, by the voltage ratio (Vo / VL) to obtain the values ​​IRmin and IRmax, which indicate the setting range for the current value IR, and ICmin and ICmax, which indicate the setting range for the current value IC, when the high voltage Vo during the withstand voltage test is applied. The setting ranges IRmin and IRmax, which indicate the setting range for the current value IR, and ICmin and ICmax, which indicate the setting range for the current value IC, may also be set ranges with an offset amount.

[0124] The setting range for the current value IR, indicated by IRmin and IRmax, is more preferably set based on ILRe, which is the estimated current value obtained by multiplying the low-voltage current value ILR by the voltage ratio (Vo / VL). In other words, it is obtained by adding ±η (a positive value) to the estimated current value ILRe, or by multiplying it by a coefficient ι (for example, a value in the range of 0.8 to 1.2). In short, let IRmin = ILRe - η, IRmax = ILRe + η, or IRmin = ILRe × ι (ι < 1), IRmax = ILRe × ι (ι > 1).

[0125] The setting range for the current values ​​IC, indicated by ICmin and ICmax, is more preferably set based on ILCe, which is the estimated current value obtained by multiplying the low-voltage current value ILC by the voltage ratio (Vo / VL). In other words, it is obtained by adding ±κ (a positive value) to the estimated current value ILCe, or by multiplying it by a coefficient λ (for example, a value in the range of 0.8 to 1.2). In short, let ICmin = ILCe - κ, ICmax = ILCe + κ, or ICmin = ILCe × λ (λ < 1), ICmax = ILCe × λ (λ > 1).

[0126] If all judgments are within the set range, the test continues and proceeds to step ST02. If at least one determination is outside the set range, the test specimen 100 outputs a test NG signal, which indicates a defective product in terms of withstand voltage, and the withstand voltage test is terminated.

[0127] In step ST02, in order to supply a withstand voltage test voltage Vo between the test voltage output terminals 20c and 20d, under the control of the higher-level system 200, an AC voltage for withstand voltage testing consisting of a sinusoid is supplied from the AC power supply 10 to the primary winding 21a of the transformer 21, generating a test voltage Vo in the secondary winding 21b of the transformer 21, and applying the test voltage Vo to the pair of test voltage output terminals 20c and 20d. As a result, a test voltage Vo is applied to the pair of input terminals 100a and 100b of the test specimen 100 via the cable 300. Step ST02 is the step of outputting a high voltage Vo to be applied to the test specimen 100.

[0128] The current detector 22 detects the current flowing through the test specimen 100, that is, the current Io in the withstand voltage test path including the test specimen 100, and outputs the detected current Io to the withstand voltage determination unit 30. The voltage detector 23 detects the test voltage Vo between the pair of test voltage output terminals 20c and 20d, and outputs the detected voltage Vo to the withstand voltage determination unit 30.

[0129] In step ST16, the waveform detection unit 311 of the signal detection unit 31 in the withstand voltage determination unit 30 shapes the detected current Io and detected voltage Vo into waveforms, and the ADC 312 converts them into digital information, namely current detection information and voltage detection information. Simultaneously, the withstand voltage determination unit 30 converts the effective values ​​of the detected current Io and detected voltage Vo into digital information.

[0130] The effective values ​​of the detected current Io and detected voltage Vo are stored in the storage unit 33. In other words, step ST16 is a step in which a current value Io, which is digital information representing the effective value, is obtained from the current detection signal from the current detector 22, and a voltage value Vo, which is digital information representing the effective value, is obtained from the voltage detection signal from the voltage detector 23.

[0131] In step ST17, the current detection unit 325 of the voltage withstand determination unit 32A in the voltage withstand determination unit 30 determines whether the current value Io is within the set range shown in equation (17) above. If the current value Io is within the setting range shown in equation (17) above, the test continues and proceeds to step ST18. If the current value Io is outside the set range shown in equation (17) above, the test specimen 100 outputs a test NG signal, which is a signal indicating a defective product in terms of withstand voltage, and the withstand voltage test is terminated.

[0132] In step ST18, the phase angle calculation unit 321 of the withstand voltage determination unit 32A calculates the phase angle θ using the current detection information indicating the current value Io and the voltage detection information indicating the low voltage value Vo, according to the above equation (11). The component current calculation unit 322 of the withstand voltage determination unit 32A calculates the low voltage current value IC for the capacitive component in the withstand voltage test path (current value Io) using equation (9) above, and the low voltage current value IR for the resistive component using equation (10) above, and proceeds to step ST19.

[0133] If the phase angle calculation unit 321 is not provided, the component current calculation unit 322 uses the low-voltage phase angle θL calculated by the low-voltage phase angle calculation unit 321L in place of the phase angle θ to obtain the low-voltage current value IR for the resistive component and the current IC for the capacitive component of the current value Io from the effective value of the current value Io using equations (9) and (10) above.

[0134] In step ST19, the setting value determination unit 326 of the withstand voltage determination unit 32A determines whether the voltage value Vo is within the setting range shown by equation (18) above, whether the phase angle θ is within the setting range shown by equation (19) above, whether the current value IR is within the setting range shown by equation (20) above, and whether the low voltage current value IC is within the setting range shown by equation (21) above.

[0135] If all judgments are within the set range, the test specimen 100 outputs a signal indicating that it is a good product for withstand voltage, and the withstand voltage test is terminated. If at least one of the judgments is outside the set range, the test specimen 100 outputs a test NG signal, which indicates a defective product in terms of withstand voltage, and the withstand voltage test is terminated. If the phase angle calculation unit 321 is not provided, it is unnecessary to determine whether the phase angle θ is within the setting range shown in equation (19) above.

[0136] Steps ST12 to ST15 and steps ST17 to ST19 are stored in the memory unit 33 of the programmable controller or personal computer constituting the withstand voltage determination unit 30A as a withstand voltage test program that indicates the procedure to be executed by the computer.

[0137] The withstand voltage test apparatus according to Embodiment 2 is a withstand voltage test apparatus that performs a withstand voltage test by applying an AC voltage to a test specimen 100 which is the subject of the withstand voltage test, and measuring (detecting) the leakage current Io flowing through the withstand voltage test path to which the test specimen 100 is connected using a current detector 22. The apparatus is equipped with a voltage detector 23 that detects the voltage between the test voltage output terminals 20c and 20d of the test voltage application circuit 20, applies a low AC voltage VL to the test specimen 100, calculates the phase angle θL of the current detection signal and the voltage detection signal from the current detection signal output from the current detector 22 and the voltage detection signal output from the voltage detector 23, calculates the low voltage current value ILC flowing through the capacitive component and the low voltage current value ILR flowing through the resistive component in the current detection signal output from the current detector 22, and at low voltage, the current detector 22 The system includes a withstand voltage determination unit that determines whether the low voltage current value IL indicated by the current detection signal output from the current detector 22 is within the set range, determines whether the low voltage value VL, phase angle θ, low voltage current value ILC, and low voltage current value ILR are within their respective set ranges, applies an AC test voltage (high voltage) Vo to the test specimen 100, calculates the current value IC flowing through the capacitive component and the current value IR flowing through the resistive component in the current detection signal output from the current detector 22, and determines whether the voltage value Vo, current value IC, and current value IR are within their respective set ranges in the withstand voltage test. Therefore, withstand voltage tests can be performed with high accuracy for leakage current Io flowing through the withstand voltage test path to which the test specimen 100 is connected.

[0138] Furthermore, since the initial withstand voltage test is performed using a low voltage VL, which can be considered a safe voltage for the human body, test specimens 100 that are defective in terms of initial withstand voltage can be excluded. Furthermore, in low-voltage testing, if a person accidentally comes into contact with the withstand voltage test path, the withstand voltage test will be terminated, thus serving as a warning against high-voltage withstand voltage testing.

[0139] Embodiment 3. The dielectric strength test apparatus according to Embodiment 3 will be described with reference to Figures 9 to 11. The withstand voltage test apparatus according to Embodiment 3 differs from the withstand voltage test apparatus according to Embodiment 1 in that the withstand voltage determination unit 30, in particular, the signal detection unit 31 and the withstand voltage determination unit 32 in the withstand voltage determination unit 30, but the other configurations are the same. Therefore, the explanation will focus on the signal detection unit 31B and the withstand voltage determination unit 32B.

[0140] Furthermore, since the overall configuration of the withstand voltage test apparatus according to Embodiment 3 is substantially identical to the overall configuration of the withstand voltage test apparatus according to Embodiment 1 in terms of the drawings, Figure 1 will be used as a reference when explaining the overall configuration. Furthermore, in Figures 9 to 11, the same reference numerals as those used in Figures 1 to 6 indicate the same or corresponding parts.

[0141] The withstand voltage determination unit 30B determines whether the current value IL indicated by the low-voltage current detection signal output from the current detector 22 in the test voltage application circuit 20 is within the set range, calculates the capacitance component C in the withstand voltage test path including the test specimen 100 using the current value IL and the voltage value VL indicated by the low-voltage detection signal output from the voltage detector 23, calculates the estimated current value Iog when the test voltage Vo is applied using the calculated capacitance component C and the voltage value VL indicated by the low-voltage detection signal, sets the set range for the current Io flowing through the withstand voltage test path including the test specimen 100, determines whether the current value Io indicated by the current detection signal output from the current detector 22 is within the set range, and determines whether the test specimen 100 is a good or bad product in terms of withstand voltage.

[0142] The withstand voltage determination unit 30B determines whether the current value IL is within the set range using the above equation (12). The withstand voltage determination unit 30B calculates the capacitance component C in the withstand voltage test path including the test specimen 100 using the low voltage current value IL and the low voltage value VL according to equation (22) above.

[0143] Equation (22) above can be obtained as follows. In other words, if the current value is I, the voltage value is V, and the capacitor capacitance value is C, then the following general relationship (23) is obtained. I = C × dV / dt (23)

[0144] In a sinusoidal alternating current, the voltage value V is expressed by equation (24), and the current value I is expressed by equation (25). V = √2 × Vrms × sin(ωt) (24) I=C×ω×√2×Vrms×cos(ωt) (25)

[0145] Using the effective voltage value Vrms and the effective current value Irms, the capacitance value C is obtained from equation (25) above as follows (26). C = Irms / (ω × Vrms) (26) Therefore, from equation (26) above, the capacitance component C when a low voltage VL is applied in the withstand voltage test path including the test specimen 100 can be determined by equation (22) above.

[0146] The withstand voltage determination unit 30B calculates the estimated current value Iog when the test voltage Vo is applied, using the capacitance component C and the voltage value VL. In other words, since the current flowing through the capacitive component C is proportional to the voltage, the estimated current value Iog can be obtained by substituting the capacitive component C and the test voltage Vo into equation (26) above.

[0147] The withstand voltage determination unit 30B sets the setting range for the current Io flowing through the withstand voltage test path including the test specimen 100, that is, Iomin and Iomax in equation (17) above. In equation (17) above, Iomin is a threshold value for the lower limit of the current value Io, based on the estimated current value Iog, for example, -5% for a variation of the capacitance value of the Y capacitor built into the test specimen 100, which is -20%, and Iomax is a threshold value for the upper limit of the current value Io, based on the estimated current value Iog, for example, +5% for a variation of the capacitance value of the Y capacitor built into the test specimen 100, which is +20%.

[0148] The capacitance component C is calculated when a low voltage VL is applied, and Iomin and Iomax, which indicate the setting range of the current value Io, are determined based on the estimated current value Iog calculated using the calculated capacitance component C. Therefore, while the variation in the capacitance value of the Y capacitor is ±20%, the setting range of the current value Io can be narrowed to ±5% based on the estimated current value Iog, allowing the current value Io to be determined within a narrow setting range.

[0149] The withstand voltage determination unit 30B determines whether the current Io is within the set range using the above equation (17), and determines whether the test specimen 100 is a good or bad product in terms of withstand voltage. The current value Io used to determine whether Iomin and Iomax are within the set range is preferably a value that gives an offset amount based on the capacitance component C obtained by equation (22) above in the withstand voltage test path to the current value Io indicated by the current detection signal output from the current detector 22.

[0150] In a voltage withstand test of a test specimen 100 in which a Y capacitor is built between the internal circuit and the enclosure, variations in the capacitance value of the built-in Y capacitor can be offset by adding an offset amount to the current value Io indicated by the current detection signal output from the current detector 22, thereby avoiding errors in the voltage withstand test. The current value Io with an offset is obtained by adding ±α (a positive value) based on the calculated capacitance component C to the current value Io indicated by the current detection signal output from the current detector 22, or by multiplying it by a coefficient β (for example, a value in the range of 0.8 to 1.2).

[0151] Alternatively, values ​​may be used to provide an offset amount that is set based on the capacitance component C for Iomin and Iomax, which are thresholds for determining whether the current value Io indicated by the current detection signal output from the current detector 22 is within the set range. In this case as well, in a voltage withstand test of test specimen 100, which has a Y capacitor built in between the internal circuit and the enclosure, the variation in the capacitance value of the built-in Y capacitor can be offset from the set range Iomin and Iomax to avoid the influence of errors on the voltage withstand test.

[0152] The voltage withstand determination unit 30B is installed in conjunction with the higher-level system 200. As shown in Figure 9, the withstand voltage determination unit 30B includes a signal detection unit 31B, a withstand voltage determination unit 32B, and a storage unit 33. The signal detection unit 31B includes a waveform detection unit 311B and an ADC 312B. The waveform detection unit 311B, similar to the waveform detection unit 311 in Embodiment 1, includes a current clamp circuit 3111, a current-side differential amplifier 3112, a voltage clamp circuit 3115, and a voltage-side differential amplifier 3116. It calculates the effective value of the current detection signal consisting of a sine wave from the current-side differential amplifier 3112 and outputs it to the ADC 312B as the effective current value. It also calculates the effective value of the voltage detection signal consisting of a sine wave from the voltage-side differential amplifier 3116 and outputs it to the ADC 312B as the effective voltage value.

[0153] The ADC312B outputs the analog effective current value and effective voltage value, respectively, as current detection information indicating the effective current value and effective voltage information indicating the effective voltage value to the withstand voltage determination unit 32B and the storage unit 33, respectively.

[0154] The withstand voltage determination unit 32B, under the control of a higher-level system, controls the voltage of the AC power supply 10 at the beginning of the withstand voltage test, and when an AC voltage VL lower than the test voltage Vo during the withstand voltage test is applied to a pair of test voltage output terminals 2c and 2d, it determines whether the low voltage current value IL indicated by the low voltage current detection signal output from the current detector 22 is within the set range according to equation (12) above. Using the low voltage current value IL and the voltage value VL indicated by the low voltage detection signal output from the voltage detector 23, it calculates the capacitance component C in the withstand voltage test path including the test specimen 100 using equation (22) above. Using the voltage value VL, the estimated current value Iog when the test voltage Vo is applied is calculated, and Iomin and Iomax (set range) in equation (17) above are set for the current Io flowing through the withstand voltage test path including the test specimen 100. Under the control of the higher-level system that performs the withstand voltage test, the voltage of the AC power supply 10 is controlled, and with the test voltage Vo applied to the pair of test voltage output terminals 2c and 2d, it is determined whether the current value Io indicated by the current detection signal output from the current detector 22 is within the set range in equation (17) above, and the test specimen 100 is determined to be good or bad in terms of withstand voltage. An AC voltage VL lower than the voltage Vo used in the withstand voltage test is considered a safe voltage that poses no danger to the human body.

[0155] The dielectric strength determination unit 32B performs the following: determination of whether the low voltage current value IL is within the set range using equation (12) above; calculation of the capacitance component C in the dielectric strength test path including the test specimen 100 using equation (22) above; calculation of the estimated current value Iog when the test voltage Vo is applied; setting of the set range for the current Io shown by equation (17) above; and determination of whether the current value Io is within the set range using equation (17) above. The current value Io used to determine whether or not it is within the set range may be a current value to which an offset amount has been given. Furthermore, the setting range for the current value Io may also be a setting range given an offset amount.

[0156] The hardware of the voltage withstand determination unit 32B is comprised of, for example, a programmable controller or a personal computer. As shown in Figure 10, the withstand voltage determination unit 32B includes a low voltage detection current determination unit 325L, a capacitance component calculation unit 327, a setting range setting unit 328, and a good / defective product determination unit 329. The low-voltage detection current determination unit 325L determines whether the low-voltage detection current value IL from the ADC312B is within the set range according to equation (12) above. If it is outside the set range, it outputs a test NG signal, that is, a signal indicating that the test specimen 100 is defective in terms of withstand voltage, and terminates the withstand voltage test.

[0157] The capacitance component calculation unit 327 receives the low voltage detected current value IL and the low voltage detected voltage value VL from the ADC312B, calculates the capacitance component C in the withstand voltage test path including the test specimen 100 using the above equation (22), and stores the capacitance component C in the storage unit 33. The setting range setting unit 328 receives the capacitance component C calculated by the capacitance component calculation unit 327 and the low voltage detection voltage value VL from the ADC312B, calculates the estimated current value Iog when the test voltage Vo is applied, and sets the setting range of the current Io flowing through the withstand voltage test path including the test specimen 100 in the withstand voltage test, as shown in equation (17) above. The estimated current value Iog and the setting range for current Io are stored in the memory unit 33.

[0158] The good / bad product determination unit 329 receives the set range set by the set range setting unit 328 and the detected current value Io from the ADC312B, and determines whether the detected current value Io is within the set range. If it is within the set range, it outputs a test OK signal, that is, a signal indicating that the test specimen 100 is a good product in terms of withstand voltage. If it is outside the set range, it outputs a test NG signal, that is, a signal indicating that the test specimen 100 is a defective product in terms of withstand voltage, and terminates the withstand voltage test.

[0159] The current value Io used to determine whether or not the current is within the set range may be a current value to which an offset amount has been applied to the detected current value Io. Furthermore, the setting range may also be a setting range for which an offset amount is given. In the following explanation, to avoid complexity, we will simply refer to them as the current value Io and the setting range, but we will assume that the current value and the setting range are given an offset amount.

[0160] Next, the voltage withstand test method using the voltage withstand test apparatus according to Embodiment 3 will be explained with reference to Figure 11. The input terminals 100a and 100b of the test specimen 100 are connected to the test voltage output terminals 20c and 20d of the test voltage application circuit 20 via the cable 300. In order to supply a voltage VL lower than the withstand test voltage Vo between the test voltage output terminals 20c and 20d, under the control of the higher-level system 200, a low AC voltage consisting of a sinusoid is supplied from the AC power supply 10 to the primary winding 21a of the transformer 21, generating a low voltage VL in the secondary winding 21b of the transformer 21, and applying the low voltage VL to the pair of test voltage output terminals 20c and 20d (step ST02L). As a result, a low voltage VL is applied to the pair of input terminals 100a and 100b of the test specimen 100 via the cable 300. Step ST02L is a step in which a low voltage VL is output to be applied to the test specimen 100.

[0161] The current detector 22 detects the current flowing through the test specimen 100, that is, the current IL in the withstand voltage test path including the test specimen 100, and outputs the detected current IL to the withstand voltage determination unit 30. The voltage detector 23 detects the test voltage VL between the pair of test voltage output terminals 20c and 20d, and outputs the detected voltage VL to the withstand voltage determination unit 30.

[0162] In step ST11, the waveform detection unit 311 of the signal detection unit 31 in the withstand voltage determination unit 30 shapes the detected current IL and detected voltage VL into waveforms, and the ADC 312 converts them into digital information, namely current detection information and voltage detection information. Simultaneously, the withstand voltage determination unit 30 converts the effective values ​​of the detected current IL and detected voltage VL into digital information. The effective values ​​of the detected current IL and detected voltage VL are stored in the storage unit 33. In other words, step ST11 is a step in which a low voltage current value IL, which is digital information representing the effective value, is obtained from the low voltage current detection signal from the current detector 22, and a low voltage value VL, which is digital information representing the effective value, is obtained from the low voltage detection signal from the voltage detector 23.

[0163] In step ST12, the low-voltage detection current determination unit 325L of the withstand voltage determination unit 32B in the withstand voltage determination unit 30 determines whether the low-voltage current value IL is within the set range shown in equation (12) above. If the low-voltage current value IL is within the setting range shown in equation (12) above, the test continues and proceeds to step ST21. If the current value IL at low voltage is outside the set range shown in equation (12) above, the test specimen 100 outputs a test NG signal, which is a signal indicating a defective product in terms of withstand voltage, and the withstand voltage test is terminated.

[0164] In step ST21, the capacitance component calculation unit 327 of the withstand voltage determination unit 32B receives the low voltage detected current value IL and the low voltage detected voltage value VL from the ADC312B, and calculates the capacitance component C in the withstand voltage test path including the test specimen 100 using the above equation (22). The capacity component C is stored in the memory unit 33.

[0165] In step ST21, the setting range setting unit 328 of the withstand voltage determination unit 32B receives the capacitance component C and the low voltage detection voltage value VL from the ADC312B, calculates the estimated current value Iog when the test voltage Vo is applied, and sets the setting range of the current Io flowing through the withstand voltage test path including the test specimen 100 in the withstand voltage test in the withstand voltage test. The estimated current value Iog and the setting range for current Io are stored in the memory unit 33.

[0166] In step ST02, in order to supply a withstand voltage test voltage Vo between the test voltage output terminals 20c and 20d, under the control of the higher-level system 200, an AC voltage for withstand voltage testing consisting of a sinusoid is supplied from the AC power supply 10 to the primary winding 21a of the transformer 21, generating a test voltage Vo in the secondary winding 21b of the transformer 21, and applying the test voltage Vo to the pair of test voltage output terminals 20c and 20d. As a result, a test voltage Vo is applied to the pair of input terminals 100a and 100b of the test specimen 100 via the cable 300. Step ST02 is the step of outputting a high voltage Vo to be applied to the test specimen 100.

[0167] In step ST22, the waveform detection unit 311B of the signal detection unit 31B in the withstand voltage determination unit 30B shapes the detected current Io into a waveform, and the ADC 312B converts it into current detection information, which is digital information. At the same time, the withstand voltage determination unit 30B converts the effective value of the detected current Io into digital information. The effective value of the detected current Io is stored in the memory unit 33. In other words, step ST22 is a step in which a current value Io, which is an effective value and is digital information, is obtained from the current detection signal from the current detector 22.

[0168] In step ST23, the good / defective product determination unit 329 of the withstand voltage determination unit 32B receives the set range of the detected current Io set by the set range setting unit 328 and the detected current value Io from the ADC312B, and determines whether the detected current value Io is within the set range. If the detected current value Io is within the set range, a test OK signal is output, that is, a signal indicating that the test specimen 100 is in good condition for withstand voltage, and the withstand voltage test is terminated. If the detected current value Io is outside the set range, a test NG signal is output, indicating that the test specimen 100 is defective in terms of withstand voltage, and the withstand voltage test is terminated.

[0169] Note that step ST24 may be added after step ST23. Step 24 is a step in which it is determined whether the capacitance component C in the withstand voltage test path including the test specimen 100, which was calculated in Step 21, is an abnormal value.

[0170] Steps ST12, ST21, and ST23 are stored in the memory unit 33 of the programmable controller or personal computer constituting the withstand voltage determination unit 30B as a withstand voltage test program that indicates the procedure to be executed by the computer.

[0171] The withstand voltage test apparatus according to Embodiment 3 is a withstand voltage test apparatus that performs a withstand voltage test by applying an AC voltage to a test specimen 100 that is the subject of the withstand voltage test, and measuring (detecting) the leakage current Io flowing through the withstand voltage test path to which the test specimen 100 is connected using a current detector 22. The apparatus is equipped with a voltage detector 23 that detects the voltage between the test voltage output terminals 20c and 20d of the test voltage application circuit 20, applies a low AC voltage VL to the test specimen 100, determines whether the low voltage current value IL indicated by the current detection signal output from the current detector 22 is within a set range, and calculates whether the low voltage current value IL and the voltage detector The system includes a voltage withstand determination unit that calculates the capacitance component C in the withstand voltage test path including the test specimen 100 using the low voltage value VL indicated by the output voltage detection signal, calculates the estimated current value Iog when the withstand voltage test voltage Vo is applied using the calculated capacitance component C and the low voltage value VL, sets a setting range for the current Io flowing through the withstand voltage test path including the test specimen 100, and determines whether the current value Io indicated by the current detection signal output from the current detector 22 is within the set setting range. Therefore, a voltage withstand test can be performed with high accuracy for leakage current Io flowing through the withstand voltage test path to which the test specimen 100 is connected.

[0172] Furthermore, since the initial withstand voltage test is performed using a low voltage VL, which can be considered a safe voltage for the human body, test specimens 100 that are defective in terms of initial withstand voltage can be excluded. Furthermore, in low-voltage testing, if a person accidentally comes into contact with the withstand voltage test path, the withstand voltage test will be terminated, thus serving as a warning against high-voltage withstand voltage testing.

[0173] Furthermore, it is possible to freely combine the embodiments, modify any component of each embodiment, or omit any component of each embodiment. [Industrial applicability]

[0174] The dielectric strength test apparatus described herein is applicable to a dielectric strength test apparatus that performs a dielectric strength test by applying a high voltage to a test specimen that is the subject of the dielectric strength test and measuring the leakage current flowing through the test specimen. [Explanation of Symbols]

[0175] 100 Test specimen, 200 Higher-level system, 300 Cable, 10 AC power supply, 20 Test voltage application circuit, 30, 30A, 30B Withstand voltage determination unit, 31, 31B Signal detection unit, 32, 32A, 32B Withstand voltage determination unit, 33 Memory unit.

Claims

1. A transformer having a primary winding to which an AC voltage from an AC power source is supplied to the input terminal and a secondary winding to which the output terminal is connected to a test voltage output terminal which is connected to the input terminal of the test specimen via a cable; a current detector for detecting the current flowing through the circuit; and a voltage detector for detecting the voltage between the test voltage output terminals, A voltage withstand determination unit calculates the phase angle between the current detection signal and the voltage detection signal from the current detection signal output from the current detector, and calculates the current value flowing through the capacitive component and the current value flowing through the resistive component of the current detection signal output from the current detector, based on the current value indicated by the current detection signal output from the current detector and the calculated phase angle. A voltage withstand test apparatus equipped with the following features.

2. The withstand voltage determination unit has a signal detection unit and a withstand voltage determination unit. The signal detection unit converts the current detection signal, which is an analog signal output from the current detector, into current detection information, which is a digital signal, and converts the voltage detection signal, which is an analog signal output from the voltage detector, into voltage detection information, which is a digital signal. The voltage withstand determination unit obtains a phase angle from the current detection information and voltage detection information from the signal detection unit. The withstand voltage test apparatus according to claim 1.

3. The signal detection unit includes a waveform detection unit and an analog-to-digital conversion unit. The waveform detection unit receives the current detection signal output from the current detector and the voltage detection signal output from the voltage detector, and outputs the sinusoidal current detection signal and voltage detection signal, respectively, as a current detection rectangular signal and a voltage detection rectangular signal, which are waveform-shaped rectangular waves with a positive current value set to high. The analog-to-digital conversion unit outputs the current detection rectangular signal and voltage detection rectangular signal output by the waveform detection unit as current detection information and voltage detection information, respectively. The withstand voltage test apparatus according to claim 2.

4. The dielectric strength determination unit calculates the low voltage phase angle of the low voltage detection signal and the low voltage phase angle of the low voltage detection signal from the low voltage detection signal output from the voltage detector that detects an AC voltage lower than the voltage during the dielectric strength test and the low voltage current detection signal output from the current detector when the low AC voltage is applied to the output terminal for the test voltage, and calculates the low voltage current value flowing through the capacitive component and the low voltage current value flowing through the resistive component in the low voltage current detection signal output from the current detector from the low voltage current value indicated by the low voltage current detection signal output from the current detector and the calculated low voltage phase angle, and obtains the current value flowing through the capacitive component of the test specimen by subtracting the low voltage current value flowing through the capacitive component from the calculated current value flowing through the capacitive component and the current value flowing through the resistive component of the test specimen by subtracting the low voltage current value flowing through the resistive component from the calculated current value flowing through the resistive component, as described in claim 1.

5. The voltage withstand determination unit calculates the phase angle of the low voltage current detection signal and the low voltage detection signal from the low voltage detection signal output from the voltage detector that detects an AC voltage lower than the voltage during the voltage withstand test and the low voltage current detection signal output from the current detector when the low AC voltage is applied to the test voltage output terminal. Based on the low voltage current value indicated by the low voltage current detection signal output from the current detector and the calculated low voltage phase angle, the unit determines the low voltage current value flowing through the capacitive component and the low voltage current flowing through the resistive component in the low voltage current detection signal output from the current detector. The voltage withstand test apparatus according to claim 1, comprising: calculating the voltage current value; determining whether the low voltage current value indicated by the low voltage current detection signal is within a set range; determining whether the low voltage value indicated by the low voltage detection signal, the phase angle, the low voltage current value flowing through the resistive component, and the low voltage current value flowing through the capacitive component are within their respective set ranges; determining whether the current value indicated by the current detection signal is within a set range; and determining whether the voltage value indicated by the voltage detection signal, the current value flowing through the resistive component, and the current value flowing through the capacitive component are within their respective set ranges.

6. The dielectric strength test apparatus according to claim 5, wherein the current value indicated by the current detection signal, which is used to determine whether or not it is within a set range, is a current value to which an offset amount has been given to the current value indicated by the current detection signal output from the current detector.

7. The voltage withstand test apparatus according to claim 5, wherein the setting range for the current value indicated by the current detection signal output from the current detector is a setting range obtained by multiplying the setting range for the low voltage current value indicated by the low voltage current detection signal by the ratio of the voltage during the voltage withstand test to the low voltage, and then adding an offset amount to that value.

8. The dielectric strength test apparatus according to any one of claims 5 to 7, wherein the phase angle of the current detection signal and the voltage detection signal calculated from the current detection signal output from the current detector and the voltage detection signal output from the voltage detector is the phase angle of the low voltage current detection signal and the low voltage detection signal calculated from the low voltage detection signal output from the voltage detector and the low voltage current detection signal output from the current detector.

9. A transformer having a primary winding to which an AC voltage from an AC power source is supplied to the input terminal and a secondary winding to which the output terminal is connected to a test voltage output terminal which is connected to the input terminal of the test specimen via a cable; a current detector for detecting the current flowing through the circuit; and a voltage detector for detecting the voltage between the test voltage output terminals, A voltage withstand determination unit that determines whether the low voltage current value indicated by the low voltage current detection signal output from the current detector is within a set range, sets a set range for the current flowing through the voltage withstand test path including the test specimen when the voltage withstand test voltage is applied, based on an estimated current value obtained by multiplying the low voltage current value by the voltage ratio of the voltage withstand test voltage to the low voltage, and determines whether the current value indicated by the current detection signal output from the current detector is within the set range. A voltage withstand test apparatus equipped with the following features.

10. A transformer having a primary winding to which an AC voltage from an AC power source is supplied to the input terminal and a secondary winding to which the output terminal is connected to a test voltage output terminal which is connected to the input terminal of the test specimen via a cable; a current detector for detecting the current flowing through the circuit; and a voltage detector for detecting the voltage between the test voltage output terminals, A voltage withstand determination unit that determines whether the low voltage current value indicated by the low voltage current detection signal output from the current detector is within a set range, calculates the capacitance component in the voltage withstand test path including the test specimen using the low voltage current value indicated by the low voltage current detection signal and the low voltage value indicated by the low voltage detection signal output from the voltage detector, calculates the estimated current value when the voltage withstand test voltage is applied using the calculated capacitance component and the low voltage value indicated by the low voltage detection signal to set a set range for the current flowing through the voltage withstand test path including the test specimen, and determines whether the current value indicated by the current detection signal output from the current detector is within the set set range. A voltage withstand test apparatus equipped with the following features.

11. The dielectric strength test apparatus according to claim 10, wherein the current value indicated by the current detection signal, which is used to determine whether or not it is within a set range, is a current value to which an offset amount has been given to the current value indicated by the current detection signal output from the current detector.

12. The dielectric strength test apparatus according to claim 10, wherein the setting range of the current flowing through the dielectric strength test path including the test specimen is a setting range with an offset amount.

13. A method for performing a voltage withstand test using a voltage withstand test apparatus, which involves applying a high AC voltage to a test specimen that is the subject of the voltage withstand test and measuring the leakage current flowing through the test specimen, The steps include: calculating the phase angle between the detected current and the detected voltage based on the detected current flowing through the test specimen and the detected test voltage applied to the test specimen; The steps include calculating the effective current value for the capacitive component and the effective current value for the resistive component in the detected current based on the effective value of the detected current and the phase angle, A dielectric strength test method comprising the following features.

14. The steps include: calculating the low-voltage phase angle of the low-voltage detected current and the low-voltage detected voltage based on the low-voltage detected current obtained by detecting the current flowing through the test specimen when an AC voltage lower than the voltage during the withstand voltage test is applied to the test specimen, and the low-voltage detected voltage obtained by detecting the low AC voltage applied to the test specimen; The steps include calculating the effective current value for the capacitive component and the effective current value for the resistive component in the low-voltage detection current based on the effective current value of the low-voltage detection current and the phase angle at low voltage, The steps include obtaining the effective current value flowing through the capacitive component of the specimen by subtracting the effective current value for the capacitive component in the low-voltage detection current from the effective current value for the capacitive component in the detection current, and obtaining the effective current value for the resistive component of the specimen by subtracting the effective current value for the resistive component in the low-voltage detection current from the effective current value for the resistive component in the detection current, The dielectric strength test method according to claim 13, comprising:

15. The steps include determining whether the low-voltage current value, which is the current flowing through the test specimen when an AC voltage lower than the voltage used during the withstand voltage test is applied to the test specimen, falls within a set range, The steps include: calculating the low-voltage phase angle of the low-voltage detected current and the low-voltage detected voltage based on the low-voltage detected current and low-voltage detected voltage obtained by detecting the current flowing through the test specimen when the low AC voltage is applied; The steps include calculating the current value for the capacitive component and the current value for the resistive component in the low-voltage detection current based on the effective current value of the low-voltage detection current and the phase angle at low voltage, The steps include determining whether the low voltage detection voltage indicated by the low voltage detection signal, the low voltage phase angle, the low voltage current value flowing through the resistive component, and the low voltage current value flowing through the capacitive component are within their respective set ranges, The steps include determining whether the current value indicated by the current detection signal is within a set range, The steps include determining whether the voltage value indicated by the voltage detection signal, the current value flowing through the resistive component, and the current value flowing through the capacitive component are within their respective set ranges, The dielectric strength test method according to claim 13, comprising:

16. The dielectric strength test method according to claim 15, wherein in the step of determining whether the current value indicated by the current detection signal is within a set range, the current value to be determined is a current value to which an offset amount has been given to the current value indicated by the current detection signal output from the current detector.

17. The dielectric strength test method according to claim 15, wherein in the step of determining whether the current value indicated by the current detection signal is within a set range, the set range is a set range to which an offset amount is given to a value obtained by multiplying the set range for the low voltage current value indicated by the low voltage current detection signal by the ratio of the voltage during the dielectric strength test to the low voltage.

18. A method for performing a voltage withstand test using a voltage withstand test apparatus, which involves applying a high AC voltage to a test specimen that is the subject of the voltage withstand test and measuring the leakage current flowing through the test specimen, The steps include determining whether the current value indicated by the low-voltage detection current, which is the current flowing through the test specimen when a low voltage lower than the high voltage is applied, falls within a set range, The steps include setting a range for the current flowing through the withstand voltage test path, including the test specimen, when the high voltage is applied, based on an estimated current value obtained by multiplying the current value indicated by the low voltage detection current by the voltage ratio of the high voltage to the low voltage, The steps include determining whether the current value indicated by the detected current, which is the current flowing through the test specimen when the high voltage is applied, falls within the set range, A dielectric strength test method comprising the following features.

19. A method for performing a voltage withstand test using a voltage withstand test apparatus, which involves applying a high AC voltage to a test specimen that is the subject of the voltage withstand test and measuring the leakage current flowing through the test specimen, The steps include determining whether the current value indicated by the low-voltage detection current, which is the current flowing through the test specimen when a low voltage lower than the high voltage is applied, falls within a set range, The steps include: calculating the capacitance component in the withstand voltage test path including the test specimen using the current value indicated by the low voltage detection current and the low voltage value detected when the low voltage is applied to the test specimen; The steps include: calculating the estimated current value when the withstand voltage test voltage is applied using the calculated capacitance component and low voltage value, and setting the setting range for the current flowing through the withstand voltage test path including the test specimen; The steps include determining whether the current value indicated by the detected current, which is the current flowing through the test specimen when the high voltage is applied, falls within the set range, A dielectric strength test method comprising the following features.

20. The dielectric strength test method according to claim 19, in the step of determining whether the current value indicated by the detected current, which is the current flowing through the test specimen when the high voltage is applied, is within the set range, wherein the current value to be determined is the current value to which an offset amount is given to the current value indicated by the current detection signal output from the current detector.

21. The dielectric strength test method according to claim 19, in the step of determining whether the current value indicated by the detected current, which is the current flowing through the test specimen when the high voltage is applied, is within the set range, wherein the set range is a set range to which an offset amount is given.

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