Insulation monitoring device and insulation monitoring method

Abstract

The insulation monitoring device of the present invention monitors a leakage current relating to a switching device that controls power supply from a power source to a load, and comprises: a leakage current acquisition unit that acquires a leakage current value detected by a leakage current detection unit provided between the switching device and the load and / or between the switching device and a primary side; a primary-side voltage acquisition unit that acquires a power supply voltage value, which is a voltage value of the power supply; and a period determination unit that determines an ON period, which is a period during which power is supplied to the load by the switching device. And an estimation unit that estimates a normalized leakage current value, which is an effective value of the leakage current value when the on-period is 100%, on the basis of the leakage current value during the on-period, using the power supply voltage value as a reference, with a period during which power is not supplied to the load by the switching device as an off-period.

Description

Technical Field

[0001] The invention relates to an insulation monitoring device and an insulation monitoring method. Background Art

[0002] In order to operate industrial equipment safely, it is necessary to ensure the prescribed insulation performance. Since the insulation performance decreases due to the aging of materials, etc., it is desirable to evaluate the insulation performance regularly. Patent document 1 discloses the following circuit breaker: characterized by including a switch unit for switching on and off the load current of the main circuit, a load current detection unit for detecting the magnitude of the load current, and a leakage current detection unit for detecting the magnitude of the leakage current of the load current.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-304148 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] In the invention described in Patent Document 1, there is room for improvement in the method of calculating the leakage current.

[0008] Technical solutions to solve problems

[0009] The insulation monitoring device of the first embodiment of the present invention monitors the leakage current of the switching device that controls the power supply from the power supply to the load, and includes: a leakage current acquisition unit, which acquires the leakage current value detected by the leakage current detection unit arranged at least one of the switching device and the load and the switching device and the primary side; a primary side voltage acquisition unit that acquires the voltage value of the power supply, that is, the power supply voltage value; and a period determination unit that determines the period during which the power is supplied to the load through the switching device, that is, the conduction period, and regards the period during which the power is not supplied to the load through the switching device as the off period, and also includes an estimation unit, which estimates a normalized leakage current value as the effective value of the leakage current value when the conduction period is 100% based on the leakage current value during the conduction period and with the power supply voltage value as a reference.

[0010] The second mode of the insulation monitoring method of the present invention is performed by an insulation monitoring device, which monitors the leakage current of a switching device that controls the power supply from a power supply to a load, and the insulation monitoring method includes: a leakage current detection step of acquiring a leakage current value detected by a leakage current detection unit provided at least one of between the switching device and the load and between the switching device and the primary side; a primary side voltage acquisition step of acquiring a voltage value of the power supply, i.e., a power supply voltage value; and a period determination step of determining a period during which the load is powered by the switching device, i.e., an on period, wherein the period during which the load is not powered by the switching device is regarded as an off period, and further includes an estimation step of estimating a normalized leakage current value as an effective value of the leakage current value when the on period is 100%, based on the leakage current value during the on period and with the power supply voltage value as a reference.

[0011] Effects of the Invention

[0012] According to the present invention, the leakage current can be accurately calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a hardware configuration diagram of the insulation monitoring system according to the first embodiment.

[0014] Figure 2 This is the hardware structure diagram of the insulation monitoring device.

[0015] Figure 3 This is a functional block diagram of an insulation monitoring device.

[0016] Figure 4 This is a diagram for explaining the operation of the insulation monitoring device.

[0017] Figure 5 : is a flowchart showing the frequency determination process.

[0018] Figure 6 This is a flowchart showing the measurement process.

[0019] Figure 7 This is a hardware configuration diagram of the insulation monitoring system according to the second embodiment.

[0020] Figure 8 This is a hardware configuration diagram of the insulation monitoring system according to the third embodiment.

[0021] Fig. 9 This is a hardware configuration diagram of an insulation monitoring system according to a modified example of the third embodiment.

[0022] Fig.10 This is a hardware configuration diagram of the insulation monitoring system according to the fourth embodiment.

[0023] Fig.11This is a hardware configuration diagram of an insulation monitoring system according to a modified example of the fourth embodiment. DETAILED DESCRIPTION

[0024] - First Embodiment -

[0025] Below, refer to Figure 1 to Figure 6 , a first embodiment of the insulation monitoring device of the present invention is described.

[0026] Figure 1 1 is a hardware configuration diagram of the insulation monitoring system of the first embodiment. The insulation monitoring device system 100 includes: an insulation monitoring device 1, a thyristor regulator 2 as a switching device, a power supply 91, a primary voltmeter 92, a load current meter 93, a leakage current detection device 94, a heating element 95, and a notification device 96. Figure 1 In FIG. 1 , the solid line indicates the path of power, and the dotted line indicates the path of the signal. However, since the current value or voltage value may be used in the transmission of the signal, there may be a case where power flows in the path of the signal indicated by the dotted line. In the information transmission from the primary voltmeter 92, the load current meter 93, and the leakage current detection device 94 to the insulation monitoring device 1, analog communication or digital communication may be used. The so-called digital communication is PROFIBUS or IEEE802.3, etc.

[0027] For the sake of caution, it is recorded below that the primary voltmeter 92, the load current meter 93, and the leakage current detection device 94 may not be independently used devices, for example, they may not have a display unit. The primary voltmeter 92 may also be referred to as a "voltage measurement unit" or a "voltage measurement module". The load current meter 93 may also be referred to as a "current measurement unit" or a "current measurement module". The leakage current detection device 94 may also be referred to as a "leakage current measurement unit" or a "leakage current measurement module".

[0028] The power supply 91 is an AC power supply that supplies power to the heating element 95. The power supply 91 is grounded. In the present embodiment, the side closer to the power supply 91 than the thyristor regulator 2 in the power path is referred to as the "primary side", and the side closer to the heating element 95 than the thyristor regulator 2 is referred to as the "secondary side". The primary voltmeter 92 measures the voltage on the primary side and outputs the information to the insulation monitoring device 1. The primary voltmeter 92 measures the voltage at a high frequency, and the measurement frequency is, for example, several times or more of the power supply frequency. For example, when the power supply frequency is 50 Hz, the primary voltmeter 92 measures at 1 kHz or more.

[0029] The load current meter 93 measures the current (hereinafter referred to as "load current") flowing from the power supply 91 to the heating element 95 as a load, and outputs the measured current value to the insulation monitoring device 1. Since the load current meter 93 repeatedly performs measurement, the insulation monitoring device 1 obtains the current value of the time series, that is, the waveform of the current value as described later. The leakage current detection device 94 measures the leakage current, and outputs the measured leakage current value to the insulation monitoring device 1. Since the leakage current detection device 94 repeatedly performs measurement, the insulation monitoring device 1 obtains the leakage current value of the time series, that is, the waveform of the leakage current value as described later. Among them, "leakage current" is also referred to as "leakage current". In the present embodiment, the leakage current detection device 94 measures the leakage current generated in the heating element 95. The leakage current detection device 94 is, for example, a zero phase current transformer (Zero phase Current Transformer, ZCT).

[0030] The heating element 95 is connected to the power supply 91 in such a manner that the thyristor regulator 2 is sandwiched therebetween. That is, the heating element 95 is arranged on the secondary side of the thyristor regulator 2. The heating element 95 generates heat due to the power supply. Due to the operation of the thyristor regulator 2, the heating element 95 has a period when it receives power and a period when the power supply is blocked. Hereinafter, the period when the power supply is received is referred to as the "on period", and the period when the power supply is blocked is referred to as the "off period". The notification device 96 is a device that uses at least one of, for example, sound, vibration, light, and image to notify an abnormality. The notification device 96 is, for example, a speaker, a lamp, a liquid crystal display, etc.

[0031] The thyristor regulator 2 includes: a CPU 21, a voltmeter 22, and a thyristor 23. The CPU 21 expands the program stored in the ROM (not shown) to the RAM (not shown) and executes it. The CPU 21 controls the two thyristors 23 in such a way that the temperature of the heating element 95 becomes a set temperature, for example. Specifically, the CPU 21 controls the power supply to the heating element 95 by applying a voltage to the gate terminal of the thyristor 23. The thyristor regulator 2 adopts a phase control method, and controls the thyristor 23 based on the timing of the voltage of the power supply 91 measured by the voltmeter 22 passing through 0V.

[0032] The CPU 21 can use various well-known methods to control the thyristor 23. For example, the CPU 21 obtains the output of a thermometer (not shown) provided near the heating element 95, and determines the phase range of the voltage applied to the gate terminal of the thyristor 23 based on the value obtained by multiplying the deviation from the target value by a predetermined gain. Furthermore, the CPU 21 sets the timing when the voltage of the power supply 91 exceeds 0 V and becomes positive to zero degrees, and applies the gate terminal voltage of the thyristor 23 within the previously determined phase range.

[0033] The insulation monitoring device 1 calculates a normalized leakage current based on the outputs of the primary voltmeter 92, the load current meter 93, and the leakage current detection device 94. The details will be described later.

[0034] Figure 2 1 is a hardware configuration diagram of the insulation monitoring device 1. The insulation monitoring device 1 includes a monitoring CPU 81 as a central processing unit, a monitoring ROM 82 as a read-only storage device, a monitoring RAM 83 as a readable and writable storage device, a sensor value acquisition unit 84 for acquiring a measurement value of a sensor, and an output unit 85.

[0035] The monitoring CPU 81 expands the program stored in the monitoring ROM 82 to the monitoring RAM 83 and executes it, thereby performing various operations described later. The insulation monitoring device 1 may also be implemented by replacing the combination of the monitoring CPU 81, the monitoring ROM 82, and the monitoring RAM 83 with a rewritable logic circuit, i.e., an FPGA (Field Programmable Gate Array) or an integrated circuit for a specific purpose, i.e., an ASIC (Application Specific Integrated Circuit). Furthermore, the insulation monitoring device 1 may also be implemented by a combination of different structures, for example, a combination of the monitoring CPU 81, the monitoring ROM 82, and the monitoring RAM 83 with an FPGA instead of the combination of the monitoring CPU 81, the monitoring ROM 82, and the monitoring RAM 83.

[0036] The sensor value acquisition unit 84 acquires the outputs of the primary voltmeter 92, the load current meter 93, and the leakage current detection device 94. The sensor value acquisition unit 84 has a hardware configuration corresponding to the communication method adopted by the primary voltmeter 92, the load current meter 93, and the leakage current detection device 94. For example, when the primary voltmeter 92 outputs the measured value as a 4-20mA analog signal, the sensor value acquisition unit 84 includes an AD converter. The output unit 85 outputs a signal to the notification device 96 based on the calculation result of the insulation monitoring device 1. The output unit 85 has a hardware configuration that outputs a signal that can be used by the notification device 96. For example, when the notification device 96 is a lamp, the output unit 85 is a DA converter that outputs an action signal to the lamp. For example, when the notification device 96 is a liquid crystal display, the output unit 85 is a display control device that outputs an image signal to the liquid crystal display.

[0037] Figure 31 is a functional block diagram showing the functions of the insulation monitoring device 1. The insulation monitoring device 1 includes a period determination unit 11, a leakage current acquisition unit 12, a primary side voltage acquisition unit 13, an estimation unit 14, and a notification unit 15. The period determination unit 11 determines the period during which the power supply to the heating element 95 is interrupted, that is, the shutdown period, based on the output of the load current meter 93. The period determination unit 11 is implemented by the calculation of the monitoring CPU 81 and the sensor value acquisition unit 84.

[0038] The leakage current acquisition unit 12 acquires the leakage current value measured by the leakage current detection device 94. The leakage current acquisition unit 12 is implemented by monitoring the operation of the CPU 81 and the sensor value acquisition unit 84. Among them, in the present embodiment, the leakage current is generated during the on-period when the heating element 95 is powered, and is not generated during the off-period when the heating element 95 is not powered. The on-period and the off-period are determined by the operation of the CPU 21 of the thyristor regulator 2, and at least the on-period and the off-period are not fixed. Therefore, the degree of insulation damage of the heating element 95 cannot be accurately estimated only by the size of the leakage current value acquired by the leakage current acquisition unit 12.

[0039] The primary side voltage acquisition unit 13 acquires the primary side voltage value measured by the primary voltmeter 92. The primary side voltage acquisition unit 13 is implemented by monitoring the calculation of the CPU 81 and the sensor value acquisition unit 84. The estimation unit 14 uses the leakage current value during the conduction period to calculate the normalized leakage current. The so-called normalized leakage current is the effective value of the leakage current that represents the original degree of insulation breakdown when the conduction period is 100%, for example, the effective value of the leakage current after the interpolation of the off period when the on period and the off period are 1:1, that is, 50% each, or the effective value of the leakage current when the on period is 100% and there is no off period. In the present embodiment, the effective value of the leakage current when the on period is 100% and there is no off period is defined as the normalized leakage current.

[0040] The notification unit 15 outputs the information of the normalized leakage current calculated by the estimation unit 14 to the notification device 96. The notification unit 15 may output the value of the normalized leakage current as it is, or may output the relationship with a preset threshold value. For example, the notification unit 15 may classify the leakage current into any one of the three levels of safety, caution, and danger based on the relationship between the two preset threshold values ​​and the normalized leakage current, and output the classification result in the form of sound, image, light, etc.

[0041] Figure 4 This is a diagram that explains the operation of the insulation monitoring system. Figure 44 time series changes are shown in FIG. 9 , which are, from the top, the primary voltage measured by the primary voltmeter 92, the load current measured by the load current meter 93, the off period and the on period determined by the period determination unit 11, and the leakage current measured by the leakage current detection device 94. Figure 4 The figure shows the situation where the voltage and current are in phase. And, Figure 4 The hatching in the figure is to emphasize the existence of the measured value. The +TH and -TH shown in the load current diagram are threshold values ​​described later.

[0042] The monitoring CPU 81 can sample the primary voltage at high speed and determine the timing when the primary voltage passes through 0V. Figure 4 In the example, the time when the primary voltage crosses 0 V and changes from negative to positive is defined as time t0. Then, the time when the primary voltage crosses 0 V and changes from positive to negative is defined as time t5. Furthermore, the time when the primary voltage crosses 0 V and changes from negative to positive is defined as time t10.

[0043] The load current shown in the second section is zero from time t0 to time t1. The load current is measured at a certain level at time t1, then increases, and after measuring a maximum value, it turns to decrease, and becomes zero at time t5. Thereafter, it is zero until time t6, and after being measured at time t6, it decreases, turns to increase through a minimum value, and becomes zero again at time t10.

[0044] The period determination unit 11 determines the period from when the absolute value of the load current exceeds the predetermined threshold value TH to when it becomes zero as the on period, and determines the period other than this, in other words, the period from when the absolute value of the load current is zero to when it is less than the predetermined threshold value, as the off period. In other words, the period determination unit 11 determines that the on period has started when the load current deviates from the range of +TH to -TH, and determines that the on period has ended when the load current becomes zero for the first time thereafter. Figure 4 In the example shown, the period determination unit 11 determines the time t0 to t1 and the time t5 to t6 as the off period, and determines the time t1 to t5 and the time t6 to t10 as the on period as shown in the third row.

[0045] The leakage current shown in the fourth paragraph is the leakage current measured by the leakage current detection device 94. Figure 4In the figure, the dotted lines represent the time t0-t1 and the time t5-t6, and the solid lines represent the time t1-t5 and the time t6-t10. In fact, the leakage current measured by the leakage current detection device 94 at the time t0-t1 and the time t5-t6 is the value obtained by adding noise to zero. Since the heating element 95 is not powered during the shutdown period, no leakage current is generated. However, in the present embodiment, in order to calculate the normalized leakage current, the leakage current during the shutdown period is estimated by the estimation unit 14 by the method described later. In addition, since the measured value is a current that does not appear as a true value, the effective value is calculated as described later. The leakage current estimated by the estimation unit 14 is the value shown by the dotted line.

[0046] (Processing of the Estimation Unit 14)

[0047] The estimation unit 14 performs Fourier transform on the leakage current value during the conduction period to determine the fundamental component. However, since the information on the leakage current value during the shutdown period is incomplete, a window function is used to reduce the weight during the shutdown period. In addition, in the Fourier transform, the vector of the primary side voltage is used as a reference for real numbers. The estimation unit 14 uses the magnitude and phase of the fundamental component obtained by the Fourier transform for subsequent processing. For example, consider the case where the leakage current value LI is obtained by Fourier transform as shown in Formula 1 below. In Formula 1, the DC component is omitted.

[0048] LI=A1 cos(ωt+φ1)+A2 cos(2ωt+φ2)+… (Formula 1)

[0049] In this case, the estimation unit 14 calculates the normalized effective leakage current NE according to the following equation 2, using the magnitude A1 of the apparent leakage current and the phase φ1.

[0050] NE=A1 cos(φ1) (Formula 2)

[0051] (flow chart)

[0052] Figure 5 1 is a flowchart showing the frequency determination process performed by the estimation unit 14. The estimation unit 14 performs the frequency determination process each time the power supply of the insulation monitoring device 1 is turned on. In the frequency determination process, the primary voltage outputted by the primary voltmeter 92 is read one by one to perform the determination. Figure 5 In the description, the process of reading the output of the primary voltmeter 92 is omitted. In addition, the frequency determination process described below is based on the premise that the power supply frequency is either 50 Hz or 60 Hz.

[0053] First, in step S311, the estimation unit 14 determines whether the primary side voltage changes from negative to positive. The estimation unit 14 stays at step S311 when it is determined that the primary side voltage has not changed from negative to positive, and proceeds to step S312 when it is determined that the primary side voltage has changed from negative to positive. The power supply 91 is an AC power supply, and the voltage changes in a short time cycle. However, since the phase of the voltage at the timing of starting the frequency determination process is uncertain, it waits in step S311 until the voltage value reaches a specific state.

[0054] In step S312, the calculation unit 14 starts time counting and proceeds to step S313. In step S313, the calculation unit 14 determines whether the primary side voltage changes from positive to negative. If the calculation unit 14 determines that it has not changed from positive to negative, it stays in step S313, and if it determines that it has changed from positive to negative, it proceeds to step S314. In step S314, the calculation unit 14 ends the time counting started in step S312.

[0055] In the subsequent step S315, the calculation unit 14 determines the value of the time count. When the calculation unit 14 determines that the time count is "10ms", the process proceeds to step S316, and the power supply frequency is determined to be "50Hz". When the calculation unit 14 determines that the time count is "8.3ms", the process proceeds to step S318, and the power supply frequency is determined to be "60Hz". When the calculation unit 14 determines that the time count is "other", that is, it is not any of "10ms" and "8.3ms", the process proceeds to step S317, and an error is output. End after executing any of steps S316 to S318 Figure 5 Processing shown.

[0056] Figure 6 1 is a flowchart showing the measurement process performed by the estimation unit 14. The estimation unit 14 does not record the leakage current value obtained by the leakage current acquisition unit 12 as it is, but only records the measured value during the conduction period as described below. The estimation unit 14 performs the measurement process when the power supply of the insulation monitoring device 1 is turned on. Since the estimation unit 14 continues the measurement process without interruption during the startup of the insulation monitoring device 1, Figure 6 There is no end.

[0057] In step S321, the estimation unit 14 obtains the sensor value, i.e., the primary side voltage value output by the primary voltmeter 92, the load current value obtained by the period determination unit 11, and the leakage current value obtained by the leakage current acquisition unit 12. In the subsequent step S322, the estimation unit 14 determines whether the primary side voltage is a zero crossing. Zero crossing means that the sign of the last measurement value is different from that of this measurement value. Zero crossing is equivalent to both a change from positive to negative and a change from negative to positive. In step S322, when the estimation unit 14 determines that the primary side voltage value is a zero crossing, it proceeds to step S323, and returns to step S321 when it is determined that it is not a zero crossing. Step S322 is to wait for the zero crossing point of the voltage, such as when starting the initial measurement. Figure 4 The state of the timing at time t0 in .

[0058] In step S323, the calculation unit 14 determines whether the absolute value of the load current value just obtained is greater than a predetermined threshold value. When the calculation unit 14 determines that the absolute value of the load current value is greater than the predetermined threshold value, the process proceeds to step S324, and when the calculation unit 14 determines that the absolute value of the load current value is less than the predetermined threshold value, the process proceeds to step S326. In step S324, the calculation unit 14 records the latest leakage current value as the measured value during the conduction period, and proceeds to step S325.

[0059] In step S325, the estimation unit 14 determines whether the latest acquired primary voltage is a zero crossing. If the estimation unit 14 determines that the primary voltage value is a zero crossing in step S325, the process returns to step S323 via a circle A. If it is determined that it is not a zero crossing, the process proceeds to step S327.

[0060] In step S326, the estimation unit 14 obtains the sensor value, that is, the primary side voltage value output by the primary voltmeter 92, the load current value obtained by the period determination unit 11, and the leakage current value obtained by the leakage current acquisition unit 12, and returns to step S323. The loop of step S323 and step S326 waits for the start of the conduction period, which is equivalent to Figure 4 The processing of time t0 to t1 or time t5 to t6 in the above process. Among them, the processing of step S323 and step S326 is accurately performed by the period determination unit 11.

[0061] In step S327, the estimation unit 14 obtains the sensor value, that is, the primary side voltage value output by the primary voltmeter 92, the load current value obtained by the period determination unit 11, and the leakage current value obtained by the leakage current acquisition unit 12, and returns to step S324. The loop of steps S323 and S326 continues to record until the conduction period ends, which is equivalent to Figure 4 The processing of time t1 to t5 or time t6 to t10 in step S325 is performed. Since the affirmative judgment in step S325 indicates the start of a new measurement cycle, Figure 4The state exceeds the time t0, so the loop of step S323 and step S326 is entered.

[0062] According to the above-mentioned first embodiment, the following effects can be obtained.

[0063] (1) The insulation monitoring device 1 monitors the leakage current of the thyristor regulator 2 that controls the supply of power from the power supply 91 to the heating element 95 as a load. The insulation monitoring device 1 includes: a leakage current acquisition unit 12 that acquires the leakage current value detected by the leakage current detection device 94 provided between the thyristor regulator 2 and the heating element 95, a primary side voltage acquisition unit 13 that acquires the voltage value of the power supply, and a period determination unit 11 that determines the period during which the thyristor regulator 2 supplies power to the load, that is, the conduction period. The period during which the heating element 95 of the thyristor regulator 2 is not supplied with power is regarded as the off period. The insulation monitoring device 1 includes an estimation unit 14 that estimates a normalized leakage current value as the effective value of the leakage current value when the conduction period is 100% based on the leakage current value during the conduction period and with reference to the voltage value of the power supply. Therefore, the insulation monitoring device 1 can accurately calculate the leakage current.

[0064] (2) The estimation unit 14 performs Fourier transform on the leakage current value during the on period to estimate the normalized leakage current value.

[0065] (3) The load to which the thyristor regulator 2 supplies power is the heating element 95. Since the heating element 95 switches on and off the power supply according to the target temperature, the leakage current is not generated uniformly, and it is difficult to estimate the degree of insulation breakdown. However, by using the method of this embodiment, the degree of insulation breakdown can be evaluated by normalizing the leakage current value.

[0066] (4) The period determination unit 11 determines the on-period based on the magnitude of the load current, which is the current passing through the thyristor regulator 2. Therefore, there is no need to perform special processing on the thyristor regulator 2.

[0067] (5) The notifying unit 15 that performs notification based on the normalized leakage current value is included. Therefore, the calculation result can be notified to the outside.

[0068] (Variation 1)

[0069] In the first embodiment described above, the estimation unit 14 performs Fourier transform using the leakage current value during the on period. However, the estimation unit 14 may estimate the leakage current value during the off period and perform Fourier transform using the estimated leakage current value during the off period and the measured leakage current value during the on period. The estimation unit 14 may use a linear approximation or a quadratic approximation to estimate the leakage current value during the off period, and may use mirror inversion when the on period is longer than the off period.

[0070] The estimation of the leakage current value by mirror inversion can focus on the excellent sine wave or cosine wave by focusing only on the fundamental wave, and can take advantage of the symmetry. For example, when the off period is 0 to 30 degrees and the fundamental wave is a cosine wave, a value of 360 to 330 degrees is used. In addition, since the frequency of the fundamental wave is determined by the above-mentioned frequency judgment process, as long as the timing of the leakage current value changing from negative to positive can be determined, the relationship between time and the phase of the fundamental wave can be determined.

[0071] According to this modification 1, the following effects can be obtained.

[0072] (6) The estimation unit 14 estimates the leakage current value during the OFF period, performs Fourier transform on the acquired leakage current value during the ON period and the estimated leakage current value during the OFF period, and estimates the normalized leakage current value.

[0073] (Variation 2)

[0074] In the first embodiment described above, the thyristor regulator 2 supplies power to the heating element 95. However, the object to which the thyristor regulator 2 supplies power is not limited to the heating element 95. The object to which the thyristor regulator 2 supplies power can be any device that consumes AC power, and various loads can be used as power supply targets. Furthermore, the thyristor regulator 2 can supply power to the load via a transformer for step-up or step-down. In this case, a leakage current detection device 94 can be provided between the transformer and the load to evaluate only the leakage current of the load, or a leakage current detection device 94 can be provided between the thyristor regulator 2 and the transformer to evaluate the leakage current of the transformer and the load.

[0075] (Variation 3)

[0076] In the first embodiment described above, the insulation monitoring device 1 is connected to the notification device 96, and the insulation monitoring device 1 includes the notification unit 15. However, the insulation monitoring device 1 may not include the notification unit 15. In this case, the insulation monitoring device 1 may record the normalized effective leakage current as the calculation result together with the time in a non-volatile storage medium (not shown) and read it later, or may output the calculation result through communication.

[0077] (Variation 4)

[0078] In the first embodiment described above, the load current meter 93 is arranged on the secondary side of the thyristor regulator 2, that is, on the heating element 95 side. However, the load current meter 93 may be arranged on the primary side of the thyristor regulator 2, that is, on the power supply 91 side.

[0079] (Variation 5)

[0080] In the first embodiment described above, the primary voltmeter 92 outputs the measured value to the insulation monitoring device 1. However, the primary voltmeter 92 does not need to output the measured value as it is to the insulation monitoring device 1, and may only output timing signals of the timing when the measured value changes from negative to positive and the timing when the measured value changes from positive to negative.

[0081] - Second Embodiment -

[0082] Reference Figure 7 , a second embodiment of the insulation monitoring system is described. In the following description, the same reference numerals are given to the same components as those in the first embodiment and the differences are mainly described. The points not specifically described are the same as those in the first embodiment. In this embodiment, the main difference from the first embodiment is that a control signal is obtained from a thyristor regulator.

[0083] Figure 7 This is a hardware configuration diagram of the insulation monitoring system of the second embodiment. The difference from the first embodiment is that the thyristor regulator 2 also outputs a control signal to the thyristor 23 to the insulation monitoring device 1. In addition, in this embodiment, the insulation monitoring system does not need to have the load current meter 93. The CPU 21 of the thyristor regulator 2 also outputs a signal to the insulation monitoring device 1 when starting and ending the application of the voltage to the gate terminal of the thyristor 23.

[0084] The period determination unit 11 of the insulation monitoring device 1 determines the on period and the off period based on the signal output by the CPU 21 of the thyristor regulator 2. Since the other configurations and operations are the same as those of the first embodiment, the description thereof will be omitted.

[0085] According to the above-mentioned second embodiment, the following effects can be obtained.

[0086] (7) The period determination unit 11 determines the on-period based on the control signal output from the thyristor regulator 2. Therefore, the load current meter 93 is not required, and the on-period can be accurately grasped.

[0087] -Third Embodiment-

[0088] Reference Figure 8 , the third embodiment of the insulation monitoring system is described. In the following description, the same reference numerals are given to the same components as those in the first embodiment and the differences are mainly described. The points not specifically described are the same as those in the first embodiment. In this embodiment, the position of the leakage current detection device 94 for measuring the leakage current is mainly different from that in the first embodiment.

[0089] Figure 8 FIG. 2 is a hardware configuration diagram of the insulation monitoring system according to the third embodiment. Figure 8In the embodiment, the leakage current detection device 94 is arranged on the primary side, that is, the power supply 91 side, of the thyristor regulator 2. Therefore, the leakage current detection device 94 of the present embodiment measures not only the leakage current of the heating element 95 but also the leakage current of the thyristor regulator 2. In the first embodiment, the leakage current is generated only during the conduction period when the heating element 95 is powered, and is not generated during the off period when the heating element 95 is not powered. However, in the present embodiment, the leakage current may also be generated during the off period when the heating element 95 is not powered. Furthermore, in the present embodiment, it is impossible to distinguish the leakage current generated by the heating element 95 from the leakage current generated by the thyristor regulator 2. Since the structure and operation of the insulation monitoring device 1 are the same as those of the first embodiment, the description is omitted.

[0090] According to the third embodiment described above, various hardware configurations can be adopted.

[0091] (Variation of the third embodiment)

[0092] Fig. 9 FIG. 2 is a hardware configuration diagram of an insulation monitoring system according to a variation of the third embodiment. Fig. 9 and Figure 8 For comparison, Figure 8 The first leakage current detection device 94A is arranged at the position of the leakage current detection device 94 in Figure 1 The second leakage current detection device 94B is arranged at the position of the leakage current detection device 94 in FIG. The first leakage current detection device 94A detects the total of the leakage current of the heating element 95 and the leakage current of the thyristor regulator 2 in the same manner as in the third embodiment. The second leakage current detection device 94B detects the leakage current of the heating element 95 .

[0093] The calculation unit 14 of the insulation monitoring device 1 calculates the normalized leakage current for each output of the first leakage current detection device 94A and the second leakage current detection device 94B. The calculation method is the same as that of the first embodiment. Furthermore, the notification unit 15 of the insulation monitoring device 1 notifies each output of the first leakage current detection device 94A and the second leakage current detection device 94B. Since the other configurations and operations are the same as those of the first embodiment, the description is omitted.

[0094] In this variation, the normalized leakage current value based on the measurement value of the second leakage current detection device 94B indicates the insulation degradation state of the heating element 95. Furthermore, the value obtained by subtracting the normalized leakage current value based on the measurement value of the second leakage current detection device 94B from the normalized leakage current value based on the measurement value of the first leakage current detection device 94A indicates the insulation degradation state of the thyristor regulator 2.

[0095] -Fourth embodiment-

[0096] Reference Fig.10, a fourth embodiment of the insulation monitoring system is described. In the following description, the same reference numerals are given to the same components as those in the first embodiment, and the differences are mainly described. The points not specifically described are the same as those in the first embodiment. In this embodiment, the main difference from the first embodiment is that the hardware constituting the insulation monitoring device is added.

[0097] Fig.10 This is a hardware configuration diagram of the insulation monitoring system of the fourth embodiment. The insulation monitoring device 1B includes: an insulation monitoring core device 1A equivalent to the insulation monitoring device 1 of the first embodiment, a primary voltmeter 92, a load current meter 93, and a leakage current detection device 94. The operation of the primary voltmeter 92, the load current meter 93, and the leakage current detection device 94 is the same as that of the first embodiment. The configuration and operation of the insulation monitoring core device 1A are the same as those of the insulation monitoring device 1 of the first embodiment.

[0098] According to the fourth embodiment described above, the following effects can be obtained.

[0099] (8) The insulation monitoring device 1B includes the leakage current detection device 94 , the primary voltmeter 92 for measuring a voltage value, and the load current meter 93 for measuring a load current. Therefore, insulation monitoring can be realized simply by providing the insulation monitoring device 1B to the existing thyristor regulator 2 .

[0100] (Variation of the Fourth Embodiment)

[0101] Fig.11 FIG. 4 is a hardware configuration diagram of an insulation monitoring system according to a variation of the fourth embodiment. Fig.11 and Fig.10 In comparison, the insulation monitoring device 1C includes a thyristor regulator 2 in addition to the configuration of the insulation monitoring device 1B. The configuration and operation of the thyristor regulator 2 are the same as those of the first embodiment.

[0102] According to this variation, the following effects can be obtained.

[0103] (9) The insulation monitoring device 1C includes the thyristor regulator 2. In other words, the insulation monitoring device 1C is a thyristor regulator having an insulation monitoring function.

[0104] In the above-mentioned embodiments and variations, the configuration of the functional blocks is only an example. Several functional structures to be represented as functional blocks may be integrally configured, or a structure represented by one functional block diagram may be divided into two or more functions. Alternatively, other functional blocks may have a portion of the functions possessed by each functional block.

[0105] In each of the above-mentioned embodiments and variations, the program is stored in a ROM (not shown), but the program may be stored in a rewritable non-volatile memory. In addition, the insulation monitoring device has an input / output interface (not shown), and when necessary, the program can be read from other devices via the input / output interface and a medium available to the insulation monitoring device. Here, the medium refers to, for example, a storage medium or communication medium that can be detached from the input / output interface, that is, a wired, wireless, optical network, or a carrier or digital signal propagated in the network. In addition, part or all of the functions implemented by the program may be implemented by a hardware circuit or FPGA.

[0106] The above-mentioned embodiments and variations can be combined respectively. Various embodiments and variations have been described above, but the present invention is not limited to these contents. Other methods that can be considered within the scope of the technical concept of the present invention are also included in the scope of the present invention. The applicable objects of the present invention are not limited to thyristor regulators, but can be applied to various switching devices that control load currents.

[0107] Description of Reference Numerals

[0108] 1, 1B, 1C…Insulation monitoring device

[0109] 2…Thyristor regulator

[0110] 11…Period determination department

[0111] 12…Leakage current acquisition unit

[0112] 13…Primary side voltage acquisition unit

[0113] 14…Estimation Department

[0114] 15…Notification Department

[0115] 94…Leakage current detection device

[0116] 95…heat generating element.

Claims

1. An insulation monitoring device for monitoring leakage current of a switching device for controlling power supply from a power source to a load, characterized in that: include: a leakage current acquisition unit that acquires a leakage current value detected by a leakage current detection unit provided at least one of between the switching device and the load and between the switching device and the primary side; A primary side voltage acquisition unit for acquiring a voltage value of the power supply, that is, a power supply voltage value; and a period determination unit for determining a period during which power is supplied to the load by the switching device, that is, an on-period, The period during which the load is not supplied with power by the switching device is defined as an off period. The insulation monitoring device further includes a calculation unit that estimates a normalized leakage current value that is an effective value of the leakage current value when the conduction period is 100% based on the leakage current value during the conduction period and with reference to the power supply voltage value.

2. The insulation monitoring device according to claim 1, characterized in that: The estimating unit performs Fourier transform on the leakage current value during the on-period to estimate the normalized leakage current value.

3. The insulation monitoring device according to claim 1, characterized in that: The estimating unit estimates the leakage current value during the OFF period, and estimates the normalized leakage current value by performing Fourier transform on the acquired leakage current value during the ON period and the estimated leakage current value during the OFF period.

4. The insulation monitoring device according to claim 1, characterized in that: The load is a heating element.

5. The insulation monitoring device according to claim 1, characterized in that: The period determination unit determines the on-period based on the magnitude of a current flowing through the switching device, ie, a load current.

6. The insulation monitoring device according to claim 1, characterized in that: The period determination unit determines the on-period based on a control signal output by the switching device.

7. The insulation monitoring device according to claim 5, characterized in that: The device further includes the leakage current detection unit, a voltmeter for measuring the voltage value, and a load current meter for measuring the load current.

8. The insulation monitoring device according to claim 6, characterized in that: The leakage current detection unit and a voltmeter for measuring the voltage value are also included.

9. The insulation monitoring device according to claim 7, characterized in that: Also included is the switching device.

10. The insulation monitoring device according to claim 1, characterized in that: The device further includes a notification unit configured to perform notification based on the normalized leakage current value.

11. An insulation monitoring method performed by an insulation monitoring device, wherein the insulation monitoring device monitors leakage current related to a switch device for controlling power supply from a power source to a load, the insulation monitoring method comprising: a leakage current detection step of acquiring a leakage current value detected by a leakage current detection unit provided at least one of between the switching device and the load and between the switching device and the primary side; A primary side voltage obtaining step of obtaining the voltage value of the power supply, that is, the power supply voltage value; and a period determination step of determining a period during which power is supplied to the load by the switching device, that is, a conduction period, The period during which the load is not supplied with power by the switching device is defined as an off period. The insulation monitoring method further includes a calculation step of calculating a normalized leakage current value that is an effective value of the leakage current value when the conduction period is 100% based on the leakage current value during the conduction period and with reference to the power supply voltage value.

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