Insulation monitoring device, insulation monitoring system, and insulation monitoring method

Abstract

To determine a leaking current from an R-phase and a leaking current from a T-phase separately in an insulation monitoring device.SOLUTION: The phase of a test current of an effective leaking current is switched to a reverse phase and an effective leaking current is separated into an R-phase leaking current and a T-phase leaking current.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an insulation monitoring device, an insulation monitoring system, and an insulation monitoring method.

Background Art

[0002] There is a fundamental wave effective component method (Ior method) for an insulation monitoring device. The calculation method of the fundamental wave effective component method (Ior method) measures the leakage current using a zero-phase current transformer (hereinafter referred to as ZCT), and performs the calculation of the fundamental wave leakage current Io and the calculation of the effective component leakage current Ior. The effective component leakage current Ior obtained by this calculation is a value obtained by synthesizing the leakage currents of the R phase and the T phase.

[0003] Some insulation monitoring devices also have a function of flowing a test current of the effective component leakage current Ior. The test current flowing here is a vector current that becomes the leakage current from the R phase. As related technology, for example, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the calculation method of the fundamental wave effective component method (Ior method), although the synthesized value of the leakage currents of the R phase and the T phase can be obtained, the leakage current from the R phase and the leakage current from the T phase cannot be separated and obtained.

[0006] An object of the present invention is to separately obtain the leakage current from the R phase and the leakage current from the T phase in an insulation monitoring device.

Means for Solving the Problems

[0007] An insulation monitoring device according to one aspect of the present invention is characterized by comprising: a control unit that outputs a control signal; a test current phase switching unit that switches the phase of a test current of the effective leakage current based on the control signal; a test current output unit that outputs the test current to a zero-phase current transformer; and an amplification unit that amplifies the effective leakage current output from the zero-phase current transformer and sends it to the control unit. [Effects of the Invention]

[0008] According to one aspect of the present invention, in an insulation monitoring device, leakage current from the R phase and leakage current from the T phase can be determined separately. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows the configuration of the insulation monitoring device system of the present invention. [Figure 2] The vector diagram of the test current is shown. [Figure 3] The vector diagrams for each current are shown to help derive the calculation method. [Figure 4] A vector diagram is shown to illustrate the minimum value of the test current. [Figure 5] A vector diagram is shown to illustrate the maximum value of the test current. [Figure 6] These figures show the waveforms of the test current; (a) shows the waveform of the test current in positive phase, and (b) shows the waveform of the test current in positive phase. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [Examples]

[0011] Example 1 of the present invention will be described with reference to Figure 1.

[0012] A ZCT (zero-phase current transformer) 101 is connected to the insulation monitoring device 100.

[0013] The insulation monitoring device 100 includes a CPU (control unit) 105 that outputs a control signal, an Ior test current phase switching unit 104 that switches the phase of the Ior test current of the effective leakage current Ior based on the control signal, an Ior test current output unit 103 that outputs the Ior test current to a ZCT (zero-phase current transformer) 101, and an amplification unit 102 that amplifies the effective leakage current output from the ZCT 101 and sends it to the control unit 105.

[0014] The control unit 105 controls the ON / OFF of the Ior test current and calculates the effective leakage current Ior when the Ior test current is not flowing.

[0015] The control unit determines whether to perform a device inspection test for device inspection or an abnormal location identification test for identifying the location where an abnormality has occurred in the device.

[0016] When performing a device inspection test, the Ior test current phase switching unit 104 switches the phase of the Ior test current to the positive phase. When performing an abnormal location identification test, the Ior test current phase switching unit 104 switches the phase of the Ior test current to the reverse phase.

[0017] Here, FIG. 6 shows the waveform of the positive phase of the test current and the waveform (b) of the positive phase of the test current, respectively.

[0018] When the Ior test current phase switching unit 104 switches the phase of the Ior test current to the reverse phase, the control unit 105 separates the effective leakage current Ior into the R-phase leakage current and the T-phase leakage current.

[0019] When the Ior test current phase switching unit 104 switches the phase of the Ior test current to the reverse phase, the control unit 105 calculates the total value of the effective leakage current Ior and the Ior test current, and separates the leakage current into the R-phase leakage current and the T-phase leakage current based on the total value.

[0020] By separating the effective leakage current Ior into the R-phase leakage current and the T-phase leakage current, the control unit 105 identifies the phase in which an abnormality has occurred in the device.

[0021] The control unit 105 separates the active leakage current Ior into R-phase leakage current and T-phase leakage current by applying an Ior test current in opposite phase and performing a predetermined vector operation from the value at which the active leakage current Ior becomes the minimum value.

[0022] The insulation monitoring device 100 can output an Ior test current of the effective leakage current Ior from the Ior test current output unit 103. The test current is output at a phase that corresponds to the leakage current 200 from the R phase, as shown in Figure 2.

[0023] Since the value of this arbitrary Ior test current is determined by the insulation monitoring device 100, the insulation monitoring device 100 recognizes the arbitrary test current value. The wiring for the Ior test current passes through the ZCT101 and is energized. When the Ior test current is applied, the ZCT101 measures the normal leakage current plus the Ior test current.

[0024] In a normal test, an Ior test current is applied, but in this embodiment, the phase is controlled from the CPU 105, and the phase of the test current is reversed in the Ior test current phase switching unit 104. This results in the vector (reverse vector) of the Ior test current 201 shown in Figure 2. This Ior test current 201 is used to determine the effective leakage current Ior.

[0025] First, measure the active leakage current Ior as usual (without applying a test current). After determining the active leakage current Ior, apply the Ior test current 201 (a reverse-sequence test current) and recalculate the active leakage current Ior. Using the normal value of the active leakage current Ior and the value obtained when applying test current 201 (a reverse-sequence test current), separate the leakage current from the R phase and the leakage current from the T phase. This process is always repeated.

[0026] Here, the Ior test current is not constantly flowing. The control unit 105 controls the ON / OFF state of the Ior test current.

[0027] When no Ior test current is applied, the active leakage current Ior is calculated. When an Ior test current is applied, the sum of the active leakage current Ior and the Ior test current is calculated. The calculated sum of the active leakage current Ior and the Ior test current is then separated into the R-phase and T-phase active leakage current Ior.

[0028] By separating the R phase and the T phase, it becomes possible to identify the phase experiencing abnormalities, making it easier to pinpoint the cause of the abnormality on-site.

[0029] Furthermore, standard testing (a function used by customers to inspect equipment on-site) is performed by applying an Ior test current of 200 (a positive-phase test current with a positive vector).

[0030] To easily identify the location of the abnormality on-site, the R phase and T phase are separated by applying an Ior test current 201 (a test current with opposite phase and reverse vector).

[0031] Figure 3 shows the vector diagrams of each current used to derive the calculation method.

[0032] Taking the voltage of phase S 301 as the reference, the voltages of phase R 300 and phase T 302 are at an angle of 60°, as shown by 310. If we consider the leakage current from phase R as 303 and the leakage current from phase T as 304, the combined leakage current is I or 305. In normal calculations, the value of I or 305 can be determined. If a normal positive-phase test current is passed through I or 305, the vector shifts in the direction of 306.

[0033] In this embodiment of the present invention, the test current is deliberately applied in the reverse direction to 307. By varying this 307, the value that minimizes the combined Ior is determined. Ior is minimized when it reaches 308. This minimum value of Ior is 311.

[0034] In the insulation monitoring device 100, the test current flowing in the direction of 307 is the current value it itself supplied, and the minimum value Ior311 is the current value it measured; therefore, it recognizes both values. The angle 309 between the minimum value Ior311 and the leakage current 304 from the T phase is 30°. From this angle 309 and the minimum value Ior311, the leakage current 304 from the T phase can be determined using the law of cosines.

[0035] The calculation formula is as follows:

[0036] Leakage current from phase T: 304 = minimum value I or 311 ÷ Cos 30° Next, we determine the leakage current 303 from the R phase. This can be calculated by subtracting the unnecessary test current 312 from the test current flowing in the 307 direction when the minimum value I or 311 is reached. Therefore, the calculation formula is as follows.

[0037] Leakage current from phase R 303 = Test current flowing in the direction of 307 - Minimum value I or 311 × tan30° The above two processes allow for the separation of leakage current from the R phase and the T phase.

[0038] The range in which the reverse-phase test current 307 is applied is explained in Figures 4 and 5. By defining this range, it is possible to shorten the time required to determine the leakage current values ​​for each phase.

[0039] Figure 4 shows the minimum value of the test current.

[0040] For the test current to be minimized, the leakage current from the R phase is 0, and the only leakage current is 400 from the T phase. In this case, the minimum value of the test current 403 is 401, calculated as I or (leakage current from the T phase) 400 × sin30°.

[0041] Figure 5 shows the maximum value of the test current.

[0042] The maximum current occurs when the leakage current from the T phase is 0 and only the leakage current from the R phase (500) is present. Therefore, the maximum value is the combined I or 500. From these, the current-enhancing range can be defined as follows.

[0043] Ior × sin30° ≤ Test current ≤ Ior Thus, the control unit 105 predetermines the output range of the reverse-phase test current and flows the reverse-phase Ior test current within the output range.

[0044] The control unit 105 predetermines the minimum value and the maximum value of the Ior test current in the opposite phase as the output range.

[0045] The control unit 105 determines the minimum value when the R-phase leakage current is 0 and only the T-phase leakage current is present. It also determines the maximum value when the T-phase leakage current is 0 and only the R-phase leakage current is present. [Examples]

[0046] It is not necessary to constantly process and separate the leakage currents of the R phase and T phase. Normally, the combined active leakage current Ior can be measured, and the R phase and T phase can be separated when the insulation monitoring device 100 is operated.

[0047] According to Example 2, it is not necessary to constantly apply a test current value (inverse phase), and the power consumption of the insulation monitoring device 100 can be reduced. [Examples]

[0048] When collecting data from a higher-level control device 106 (see Figure 1), such as a personal computer, a process to separate the leakage currents of the R phase and T phase may be performed. Normally, the combined active leakage current Ior is measured, and this process is performed when a request communication is received from the higher-level control device 106. In this way, the higher-level control device 106 instructs the insulation monitoring device 100 on the timing to apply an Ior test current with the opposite phase.

[0049] According to Example 3, it is not necessary to constantly apply a test current value (inverse phase), and the power consumption of the insulation monitoring device 100 can be reduced.

[0050] In the above embodiment, a test current of an arbitrary effective leakage current Ior is applied from the insulation monitoring device, and calculations are performed using the value when energized (when a test current with the opposite phase is applied) and the value when not energized (when no test current with the opposite phase is applied). According to the above embodiment, the leakage current from the R phase and the leakage current from the T phase can be calculated. Furthermore, the test current has absolutely no effect on the circuit and does not have any effect on the field. [Explanation of Symbols]

[0051] 100 Insulation monitoring device 101 ZCT 102 Amplifier 103 Ior Test Current Output Section 104 Ior Test Current Phase Switching Section 105 CPU 106 Higher-level control unit

Claims

1. An insulation monitoring device having a function to supply a test current for effective leakage current, wherein a zero-phase current transformer is connected externally via wiring, A control unit that outputs a control signal, A test current phase switching unit connected to the control unit, which switches the phase of the test current based on the control signal, A test current output unit connected to the test current phase switching unit outputs the test current to the zero-phase current transformer, An amplification unit connected to the control unit amplifies the effective leakage current output from the zero-phase current transformer and sends it to the control unit, It has, The effective leakage current output from the zero-sequence current transformer to the amplification unit is the current with the test current added to it. The control unit, When the test current phase switching unit switches the phase of the test current to the opposite phase, The aforementioned effective leakage current is separated into R-phase leakage current and T-phase leakage current. The insulation monitoring device is characterized by performing inspections of equipment installed on-site by separating the effective leakage current into R-phase leakage current and T-phase leakage current.

2. The control unit, The insulation monitoring device according to claim 1, characterized in that the output range of the reverse-phase test current is determined in advance, and the reverse-phase test current is flowed within the output range.

3. The insulation monitoring device according to claim 1, The zero-phase current transformer connected to the insulation monitoring device, An insulation monitoring system comprising a higher-level control device connected to the insulation monitoring device, The aforementioned higher-level control device is An insulation monitoring system characterized by instructing the insulation monitoring device on the timing to apply the test current in the opposite phase.

4. An insulation monitoring method for an insulation monitoring device having a function to supply a test current for effective leakage current, wherein a zero-phase current transformer is connected to the outside via wiring, A control step in which the control unit outputs a control signal, A test current phase switching step in which the phase of the test current of the effective leakage current is switched based on the control signal by the test current phase switching unit, A test current output step in which the test current output unit outputs the test current to the zero-sequence current transformer, An amplification step in which the amplification unit amplifies the effective leakage current output from the zero-sequence current transformer and sends it to the control unit, It has, The effective leakage current output from the zero-sequence current transformer to the amplification unit is the current with the test current added to it. The control step is, When the test current phase switching step switches the phase of the test current to the opposite phase, The aforementioned effective leakage current is separated into R-phase leakage current and T-phase leakage current. The insulation monitoring device is characterized by performing an inspection of equipment installed on-site by separating the effective leakage current into R-phase leakage current and T-phase leakage current.

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