JP6128921B2 - Non-interruptible insulation diagnosis device and non-interruptible insulation diagnosis method - Google Patents

Description

  The present invention relates to an uninterruptible insulation diagnosis apparatus and an uninterruptible insulation diagnosis method that perform an insulation diagnosis of a transformer without an uninterruptible power.

  Devices for performing insulation diagnosis of transformers and cables without power failure are known.

  For example, in Patent Document 1, a clamp-type transformer that is magnetically set to a ground line of a diagnostic device connected to a bus, and a high-frequency current having a frequency sufficiently higher than the commercial frequency is supplied to the primary side of the clamp-type transformer. A high-frequency power supply and a current sensor that clamps the power supply cable that feeds power to the bus at once are magneto-dielectrically set to detect leakage current caused by the high-frequency current, and the insulation resistance and dielectric of the diagnostic device An apparatus for calculating a loss rate and a capacitance according to a detection result is disclosed.

  Further, in Patent Document 2, a conductive thin plate is provided on the inner surface of the clamp arm of a zero-phase current transformer that clamps a low-voltage single-phase circuit, to form a capacitance between the circuit conductor and a non-ground line, There has been disclosed a measuring instrument for obtaining a leakage resistance or a leakage resistance component current from a measurement current of a zero-phase current transformer using a capacitive current obtained from the conductive thin plate as a reference voltage vector.

  Patent Document 3 discloses a device including a dummy current transformer for canceling a dielectric current in the vicinity of a current transformer for detecting a ground line current of a cable to be measured.

  Patent Document 4 discloses a current transformer that is attached to a grounding wire that grounds a blocking layer of a cable line, a loss current component extracted from the output current of the current transformer, and a dielectric loss tangent of a cable insulator of the cable line. A bias tangent measuring unit that measures a bias current generating unit that supplies a preset bias current to the current transformer, and a bias current subtracting unit that subtracts the bias current from the output current of the current transformer. An apparatus comprising the same is disclosed.

Japanese Patent No. 2577825 JP 2009-25219 A Japanese Patent Publication No. 7-52205 No. 4-30487

  With respect to transformers, it is difficult to accurately perform insulation diagnosis as the capacitance decreases. There are two types of transformers: oil-filled transformers and molded transformers. Air, the main insulator in molded transformers, has a dielectric constant less than half that of oil, the main insulator of oil-filled transformers. As a result, the charging current is reduced, resulting in a smaller detected signal. In addition, there is a variation in noise level depending on the site where insulation diagnosis is performed, and the signal-to-noise ratio (S / N) may be deteriorated in a molded transformer. For example, in a molded transformer of less than 200 kVA, the capacitance is extremely small, and thus the capacitance may be below the lower limit level of the capacitance that can be measured by the diagnostic apparatus. In this case, the measured value is not stable, and it is difficult to accurately measure the dielectric loss tangent tan δ and the like. This is also true for oil-filled transformers. For oil-filled transformers, when the capacitance is small, the measured value is not stable, and it is difficult to accurately measure the dielectric loss tangent tan δ and the like. .

  An object of the present invention is to provide an uninterruptible insulation diagnosis device and an uninterruptible insulation diagnosis method capable of performing insulation diagnosis even on a transformer having a relatively small capacitance.

The invention according to claim 1 is provided with an auxiliary resistor and the auxiliary capacitor, wherein the auxiliary element high-voltage cable is connected to the connected transformer, and the transformer from the secondary side of the transformer to the primary side A test voltage applying means for applying a test voltage to the auxiliary element, and a clamp type for detecting a total leakage current of a leakage current flowing from the primary side of the transformer via the high-voltage cable and a leakage current flowing to the auxiliary element Current detection means, the test voltage and the total leakage current are used to obtain the capacitance and dielectric loss tangent of the entire system constituted by the transformer and the auxiliary element, and by using the electrostatic capacity and dielectric loss tangent, the capacitance of the transformer, possess a calculating means for calculating at least one of the dielectric loss tangent and insulation resistance, the ground lines on the secondary side of the transformer Is connected The test voltage application means applies a test voltage to the transformer via the ground line, and one end of the auxiliary element is connected to the ground line between the test voltage application means and the transformer, An auxiliary element cable is connected to the other end of the auxiliary element, a test voltage is applied to the auxiliary element by the test voltage applying means, and the current detecting means is configured to detect a leakage current flowing through the high voltage cable and the auxiliary current. A non-interruptible insulation diagnostic device characterized by detecting a total leakage current with a leakage current flowing through an element cable .

  The invention according to claim 2 is the non-interruptible insulation diagnosis apparatus according to claim 1, wherein the calculation means calculates the capacitance and dielectric loss tangent of the auxiliary element from the capacitance and dielectric loss tangent of the entire system. By subtracting, the capacitance and dielectric loss tangent of the transformer are obtained.

The invention according to claim 3 is the non-interruptible insulation diagnostic apparatus according to claim 1 or 2, wherein the first mode for measuring a transformer having a relatively large capacitance is relatively further comprising a switch for switching a second mode for measuring the transformer small capacitance, the auxiliary element, the mode by the switch is switched to the second mode, contact the transformer It is characterized by being continued.

The invention according to claim 4, the auxiliary device having an auxiliary resistor and the auxiliary capacitor, a step high-voltage cable is connected to the connected transformer on the primary side, by the test voltage applying means, said transformer two A step of applying a test voltage to the transformer and the auxiliary element from the secondary side, and a total leakage current of a leakage current flowing from the primary side of the transformer via the high-voltage cable and a leakage current flowing to the auxiliary element And detecting the electrostatic capacity and dielectric loss tangent of the entire system constituted by the transformer and the auxiliary element by using the test voltage and the total leakage current, by using the electrostatic capacity and dielectric loss tangent, the capacitance of the transformer, it viewed including the steps of obtaining at least one of the dielectric loss tangent and insulation resistance, the ground lines on the secondary side of the transformer Contact The test voltage applying means applies a test voltage to the transformer via the ground line, and one end of the auxiliary element is connected between the test voltage applying means and the transformer by the connecting step. In the meantime, the auxiliary element is connected to the ground line, and an auxiliary element cable is connected to the other end of the auxiliary element, and a test voltage is applied to the auxiliary element by the test voltage applying means. A non-interruptible insulation diagnosis method characterized by detecting a total leakage current of a leakage current flowing through a cable and a leakage current flowing through the auxiliary element cable .

  According to the present invention, the capacitance of the entire system can be increased to a measurable range by connecting an auxiliary element including an auxiliary resistor and an auxiliary capacitor in parallel to the transformer. Thereby, even when the capacitance of the transformer is relatively small, the dielectric loss tangent tan δ and the like of the transformer can be obtained based on the measured value, so that the insulation diagnosis of the transformer can be performed.

It is a block diagram which shows an example of the non-power failure insulation diagnostic apparatus which concerns on embodiment of this invention. It is a schematic diagram which shows an example of the non-interruption insulation diagnostic apparatus which concerns on embodiment of this invention. It is a schematic diagram which shows an example of the non-interruption insulation diagnostic apparatus which concerns on embodiment of this invention. It is a graph which shows typically the relation between electrostatic capacity and dielectric loss tangent tanδ. It is a schematic diagram which shows an example of the non-interruption insulation diagnostic apparatus which concerns on a modification.

  FIG. 1 to FIG. 3 show an example of the non-interruptible insulation diagnostic apparatus according to this embodiment. The uninterruptible insulation diagnostic apparatus according to this embodiment includes a test voltage generator 10, a voltage injection RT, a current detection CT, and a measuring device 20, and obtains the capacitance, dielectric loss tangent tan δ, and the like of the device to be diagnosed.

  As an example, the transformer 50 is a device to be diagnosed. The transformer 50 is used as a power receiving / transforming device, for example. The transformer 50 has a capacitance Cx and an insulation resistance Rx. A high voltage lead-in cable 60 is connected to the primary side of the transformer 50, and the transformer 50 is charged from the lead-in cable 60. The ground line 12 is connected to the secondary side of the transformer 50. The transformer 50 may be a molded transformer or an oil-filled transformer.

  The test voltage generator 10 generates an alternating test voltage Vsf. The voltage injection RT is a voltage injection transformer. The ground line 12 connected to the secondary side of the transformer 50 is inserted into the voltage injection RT, whereby the voltage injection RT applies the test voltage Vsf to the transformer 50. As shown in FIG. 2, one end of the Vs cable is connected to the ground line 12 between the voltage injection RT and the transformer 50, and the other end of the Vs cable is connected to the measuring device 20. As a result, the test voltage Vsf is input to the measuring instrument 20.

  The CT for current detection is a clamp-type current transformer for current detection, and detects leakage current flowing into the lead-in cable 60 and the auxiliary element cable 26 by clamping the lead-in cable 60 and the auxiliary element cable 26. .

  For example, when the capacitance Cx of the transformer 50 is relatively small, an insulation diagnosis of the transformer 50 is performed using an auxiliary element 24 described later. In this case, as shown in FIGS. 1 and 2, the auxiliary element cable 26 and the lead-in cable 60 connected to the auxiliary element 24 are inserted into the current detection CT, and the current detection CT passes through the transformer 50. The leakage current Isc, which is the sum of the leakage current flowing into the lead-in cable 60 and the leakage current flowing into the auxiliary element cable 26 via the auxiliary element 24, is detected.

  On the other hand, when the capacitance Cx of the transformer 50 is relatively large, the insulation diagnosis of the transformer 50 is performed without using the auxiliary element 24. In this case, as shown in FIG. 3, only the lead-in cable 60 is inserted into the current detection CT, and the current detection CT detects the leakage current Isc flowing into the lead-in cable 60 via the transformer 50.

  As shown in FIG. 1, the measuring device 20 includes a calibrator 22, an auxiliary element 24, a mode changeover switch 28, a calculation unit 30 and a display unit 32, receives the test voltage Vsf and the leakage current Isc, and sets the values. By using them, the capacitance Cx, the insulation resistance Rx, and the dielectric loss tangent tan δx of the transformer 50 are obtained. The measuring device 20 includes processing units such as a detection circuit, a filter, an A / D converter, and a D / A converter.

  The calibrator 22 includes a plurality of capacitors Ca having different capacitances, and the capacitor Ca can be switched by a switch Sb. As an example, the capacitance of the capacitor Ca is 0.5 nF, 1 nF, 10 nF, and 100 nF.

  The auxiliary element 24 includes a capacitor Ca and an auxiliary resistor Ra connected in parallel. In the following description, the capacitor Ca included in the auxiliary element 24 is referred to as “auxiliary capacitor Ca”. For example, when the mode changeover switch 28 is turned on, the switch Sa and the switch Sb are turned on, and the auxiliary element 24 is formed by the auxiliary capacitor Ca and the auxiliary resistor Ra. In the example shown in FIG. 1, the capacitor Ca included in the calibrator 22 is used as the auxiliary capacitor Ca. However, the present invention is not limited to this example, and a capacitor other than the calibrator 22 may be used as the auxiliary capacitor. In the present embodiment, as an example, a 0.5 nF capacitor Ca is selected as the auxiliary capacitor Ca.

  The auxiliary element 24 is connected in parallel to the transformer 50. Specifically, one end of the auxiliary element 24 is connected to the ground line 12 between the voltage injection RT and the transformer 50, and the auxiliary element cable 26 is connected to the other end, and the test is performed by the voltage injection RT. A voltage Vsf is applied to the auxiliary element 24. As described above, the auxiliary element cable 26 is inserted into the current detection CT.

  The mode switch 28 is a switch for switching the measurement mode. In the present embodiment, there are three measurement modes as an example. For example, when the mode switch 28 is off, the switches Sa and Sb are off. When the mode changeover switch 28 is in the first on state, the switch Sa is off and the switch Sb is on (0.5 nF, tan δ = 0% state). When the mode switch 28 is in the second on state, both the switches Sa and Sb are on (0.5 nF, tan δ = 1% state). That is, when the mode switch 28 is turned on, the switch Sb is turned on. For example, when the mode changeover switch 28 is set to the second on state, the switch Sa for the auxiliary resistor Ra and the switch Sb for the auxiliary capacitor Ca shown in FIG. 1 are turned on. The auxiliary element 24 is formed by the auxiliary capacitor Ca and the auxiliary resistor Ra. On the other hand, when the mode switch 28 is turned off, the switches Sa and Sb are turned off, and the auxiliary element 24 is not formed. For example, when the capacitance Cx of the transformer 50 is relatively small, the auxiliary element 24 is formed by turning on the mode changeover switch 28, and measurement is performed using the auxiliary element 24. On the other hand, when the electrostatic capacitance Cx of the transformer 50 is relatively large, the function of the auxiliary element 24 is canceled by turning off the mode switch 28, and measurement is performed without using the auxiliary element 24.

  The calculation unit 30 is a CPU as an example, and obtains the capacitance Cx, the insulation resistance Rx, and the dielectric loss tangent tan δx of the transformer 50 by using the test voltage Vsf and the leakage current Isc. For example, the calculation unit 30 calculates the dielectric loss tangent tan δ by performing a vector calculation.

  The display unit 32 displays the calculation result of the calculation unit 30. The display unit 32 displays, for example, capacitance, insulation resistance, tan δ, test voltage Vsf, leakage current Isc, and the like.

  Next, with reference to FIG.1 and FIG.2, the measuring method when the electrostatic capacitance Cx of the transformer 50 is comparatively small is demonstrated. For example, a transformer having a capacity of 50 to 200 kVA corresponds to a transformer having a relatively small capacitance Cx. First, the mode changeover switch 28 is turned on to turn on the switch Sa for the auxiliary resistor Ra and the switch Sb for the auxiliary capacitor Ca. Thereby, the auxiliary element 24 is formed by the auxiliary capacitor Ca and the auxiliary resistor Ra. Further, the auxiliary element cable 26 is connected to the other end of the auxiliary element 24, and the lead-in cable 60 and the auxiliary element cable 26 are clamped by the current detection CT. Further, the ground line 12 is inserted into the voltage injection RT. Then, the test voltage generator 10 generates the test voltage Vsf, and the test voltage Vsf is applied to the transformer 50 and the auxiliary element 24 via the ground line 12 by the voltage injection RT. As a result, the current detection CT uses the leakage current Isc that is the sum of the leakage current flowing into the lead-in cable 60 via the transformer 50 and the leakage current flowing into the auxiliary-element cable 26 via the auxiliary element 24. The leakage current Isc is detected and output to the measuring device 20. The calculation unit 30 of the measuring device 20 obtains the capacitance Cx and the like of the transformer 50 by using the test voltage Vsf and the leakage current Isc.

  Next, specific calculation processing in the calculation unit 30 will be described. First, the arithmetic unit 30 uses the test voltage Vsf and the leakage current Isc to perform a vector operation in the same manner as in the prior art, so that the dielectric tangent tan δm and static of the entire system constituted by the transformer 50 and the auxiliary element 24 are calculated. Obtain the capacitance Cm. Since the leakage current Isc is the sum of the leakage current flowing through the transformer 50 and the leakage current flowing through the auxiliary element 24, the transformer 50 and the auxiliary element are used by using the leakage current Isc and the test voltage Vsf. 24, the dielectric loss tangent tan δm and the electrostatic capacity Cm of the entire system constituted by. Further, the arithmetic unit 30 subtracts the capacitance Ca and the dielectric loss tangent tanδa of the auxiliary element 24, which are known values, from the dielectric loss tangent tanδm and the electrostatic capacitance Cm of the entire system, so Cx and dielectric loss tangent tan δx are obtained. Hereinafter, the arithmetic processing will be described in more detail.

Since the transformer 50 and the auxiliary element 24 are connected in parallel, the electrostatic capacity Cm of the entire system is expressed by the following (formula 1), and the combined resistance Rm of the entire system is expressed by the following (formula 2). Is done.
(Formula 1): Cm = Cx + Ca
(Formula 2): Rm = (Rx · Ra) / (Rx + Ra)
Here, since Ca is the capacitance of the auxiliary capacitor and Ra is the value of the auxiliary resistance, Ca and Ra are known values.

Further, the dielectric loss tangent tan δm of the entire system is expressed by the following (formula 3), and the dielectric loss tangent tan δx of the transformer 50 is expressed by the following (formula 4).
(Formula 3): tan δm = 1 / (2π · f · Cm · Rm)
(Formula 4): tan δx = 1 / (2π · f · Cx · Rx)
Here, f is the frequency of the test voltage Vsf.

Therefore, the capacitance Cx (= Cm−Ca) of the transformer 50 is obtained by substituting the measured system capacitance Cm of the entire system and the capacitance of the auxiliary capacitor Ca into (Equation 1). . That is, the capacitance Cx of the transformer 50 is obtained by subtracting (subtracting) the capacitance Ca of the auxiliary element 24 from the capacitance Cm of the entire system.
Further, the total resistance Rm of the entire system can be obtained by substituting the measured capacitance Cm and dielectric loss tangent tan δm into (Equation 3).
Furthermore, the insulation resistance Rx of the transformer 50 is calculated | required by substituting Ra and Rm which are resistance values for (Formula 2).
Then, the dielectric loss tangent tan δx of the transformer 50 is obtained by substituting the obtained Cx and Rx into (Equation 4).

Further, by substituting (Equation 1) and (Equation 2) into (Equation 4), tan δx is expressed by the following (Equation 5).
(Formula 5):
tan δx = 1 / {2π · f · (Cm−Ca) · (Ra · Rm) / (Ra−Rm)}
= (2π · f · Cm · Ra · tan δm-1) / (2π · f · (Cm-Ca) · Ra)
= (Cm · tan δm-Ca · tan δa) / (Cm-Ca)
Here, since Ca and tan δa are known values, and Cm and tan δm are measured values, tan δx is obtained from these values.
That is, the dielectric loss tangent tan δx of the transformer 50 is obtained by subtracting (subtracting) the electrostatic capacitance Ca and the dielectric loss tangent tan δa of the auxiliary element 24 from the electrostatic capacitance Cm and the dielectric loss tangent tan δm of the entire system.

  As described above, the capacitance measured by the measuring instrument 20 can be increased by connecting the auxiliary element 24 including the auxiliary resistor Ra and the auxiliary capacitor Ca in parallel to the transformer 50. Become. When the auxiliary element 24 is not used, the capacitance measured by the measuring instrument 20 is Cx. However, when the auxiliary element 24 is used, the capacitance measured by the measuring instrument 20 is Cm = Cx + Ca. Therefore, by using the auxiliary element 24, the capacitance measured by the measuring instrument 20 can be increased by the value of the auxiliary capacitor Ca. For example, as shown in FIG. 4, even when the capacitance Cx of the transformer 50 is small and originally included in a range that is difficult to diagnose (indicated by a black circle), the auxiliary element 24 is placed in the transformer 50. By connecting in parallel, the capacitance measured by the measuring instrument 20 can be increased to a diagnostic range (indicated by white circles). That is, by using the auxiliary capacitor Ca so that the capacitance Cm of the entire system is included in the range that can be measured by the measuring device 20, the capacitance can be increased to a range that can be diagnosed. Thus, since the measured capacitance increases, the number of detected signals increases and the signal-to-noise ratio (S / N) improves. As described above, since the capacitance can be increased to a range that can be measured by the measuring instrument 20, even if the capacitance Cx of the transformer 50 is less than a value that can be measured by the measuring instrument 20, the transformer 50 capacitance Cx, insulation resistance Rx and dielectric loss tangent tan δx can be obtained. Therefore, it is possible to accurately perform insulation diagnosis even with the transformer 50 having a small capacitance Cx. Further, since the insulation diagnosis of the transformer 50 having a small electrostatic capacity Cx can be performed only by switching the measurement mode by the mode changeover switch 28, the work load on the worker does not increase, and a simple method can be used in a non-power failure state. Insulation diagnosis can be performed.

  Next, with reference to FIG.1 and FIG.3, the measuring method when the electrostatic capacitance Cx of the transformer 50 is comparatively large is demonstrated. For example, a transformer having a capacity of 200 kVA or more corresponds to a transformer having a relatively large capacitance Cx. First, the mode changeover switch 28 is turned off to turn off the switch Sa for the auxiliary resistor Ra and the switch Sb for the auxiliary capacitor Ca. Thereby, the function of the auxiliary element 24 is released. As shown in FIG. 3, the grounding wire 12 is inserted into the voltage injection RT, and the auxiliary cable 26 is not used, and only the lead-in cable 60 is clamped by the current detection CT. Then, the test voltage generator 10 generates the test voltage Vsf, and the test voltage Vsf is applied to the transformer 50 via the ground line 12 by the voltage injection RT. As a result, the current detection CT detects the leakage current Isc flowing into the lead-in cable 60 via the transformer 50. The calculation unit 30 uses the test voltage Vsf and the leakage current Isc by the same method as in the conventional technique without considering the respective values of the auxiliary resistor Ra and the auxiliary capacitor Ca, so that the capacitance Cx of the transformer 50 is obtained. Insulation resistance Rx and dielectric loss tangent tan δx are obtained. Even when the capacitance Cx of the transformer 50 is relatively large, the capacitance Cx of the transformer 50 and the like may be obtained using the auxiliary element 24. In this case, the auxiliary element cable 26 connected to the auxiliary element 24 is inserted into the current detection CT, and the electrostatic capacity Cm and the dielectric loss tangent tan δm of the entire system are obtained, and according to the above (Expression 1) to (Expression 5). What is necessary is just to obtain | require the electrostatic capacitance Cx etc. of the transformer 50. FIG.

  As described above, the auxiliary element 24 is provided so that the function of the auxiliary element 24 can be switched, so that the measurement is performed for both cases where the capacitance Cx of the transformer 50 is relatively small and relatively large. It becomes possible to do.

  Next, specific examples will be described. The non-interruptible insulation diagnostic apparatus according to the above-described embodiment was verified using a 100 kVA mold transformer as a diagnosis target device. In this verification, a test voltage Vsf of 1035 Hz and 6 V was applied by the test voltage generator 10.

The known capacitance of the auxiliary capacitor Ca, the resistance value of the auxiliary resistor Ra, and the dielectric loss tangent tan δa are as follows.
Ca = 0.5nF
Ra = 30.75MΩ
tan δa = 1.0%

Then, the capacitance Cm and the dielectric loss tangent tan δm were measured using the non-interruptible insulation diagnostic apparatus according to the present embodiment, and the combined resistance Rm was obtained from (Equation 3) by using the capacitance Cm and the dielectric loss tangent tan δm. . The values of the capacitance Cm, the combined resistance Rm, and the dielectric loss tangent tan δm were as follows.
Cm = 0.78nF
Rm = 28.16MΩ
tan δm = 0.7%

Then, the capacitance Cx is obtained by substituting the known Ca and the measured capacitance Cm into (Equation 1), and the known resistance Ra and the obtained combined resistance Rm are substituted into (Equation 2). Thus, the insulation resistance Rx was obtained, and the dielectric loss tangent tan δx was obtained by (Expression 4) or (Expression 5). The values of the capacitance Cx, the insulation resistance Rx, and the dielectric loss tangent tan δx are as follows.
Cx = 0.28nF
Rx = 334.29MΩ
tan δx = 0.16%
In this way, tan δx (= 0.16%) of a 100 kVA mold transformer could be calculated.

  In order to check whether the values of the capacitance Cx and the dielectric loss tangent tan δx obtained by the above method are correct, the transformer 50 was subjected to a power failure and the capacitance Cx and the dielectric loss tangent tan δx were measured by the Schering bridge method. As a result, Cx = 0.28 nF and tan δx = 0.16% were obtained. Since the same value was obtained by this embodiment and another method, it turned out that the method of this embodiment is effective.

  Next, a modification will be described with reference to FIG. In the modification, the auxiliary element 24 is not provided in the measuring instrument 20, but the external auxiliary element 40 installed outside the measuring instrument 20 is used. For example, when the capacitance Cx of the transformer 50 is relatively small, measurement is performed using the external auxiliary element 40, and when the capacitance Cx of the transformer 50 is relatively large, measurement is performed without using the external auxiliary element 40. . Similarly to the auxiliary element 24, the external auxiliary element 40 includes an auxiliary capacitor Ca and an auxiliary resistor Ra connected in parallel. Similar to the embodiment described above, the values of Ca, Ra and tan δa are known.

  When the capacitance Cx of the transformer 50 is relatively small, the external auxiliary element 40 is connected to the transformer 50 in parallel. Specifically, one end of the external auxiliary element 40 is connected to the ground wire 12 between the voltage injection RT and the transformer 50, and the auxiliary element cable 26 is connected to the other end. Is connected to the ground line 12 between GND and the voltage injection RT. Further, the lead-in cable 60 and the auxiliary element cable 26 are inserted into the current detection CT. Then, the test voltage Vsf is applied to the transformer 50 and the external auxiliary element 40 via the ground line 12 by the voltage injection RT. Thus, the current detection CT is the sum of the leakage current flowing into the lead-in cable 60 via the transformer 50 and the leakage current flowing into the auxiliary element cable 26 via the external auxiliary element 40. Is detected. As in the above-described embodiment, the calculation unit 30 of the measuring instrument 20 obtains the capacitance Cx and the like of the transformer 50 by using the test voltage Vsf and the leakage current Isc.

  When the capacitance Cx of the transformer 50 is relatively large, the leakage current Isc flowing into the lead-in cable 60 is detected by the current detection CT without using the external auxiliary element 40 and the auxiliary element cable 26, and the transformer 50 Is obtained.

  As described above, when the external auxiliary element 40 is used without providing the auxiliary element 24 in the measuring instrument 20, the capacitance measured by the measuring instrument 20 can be increased as in the above embodiment. Therefore, even if the capacitance Cx of the transformer 50 is less than a value measurable by the measuring device 20, the capacitance Cx and the like of the transformer 50 can be obtained. Therefore, the insulation diagnosis of the transformer 50 can be accurately performed.

  10 Test voltage generator, 12 Ground wire, 20 Measuring instrument, 22 Calibrator, 24 Auxiliary element, 26 Auxiliary element cable, 28 Mode selector switch, 30 Arithmetic unit, 32 Display unit, 40 External auxiliary element, 50 Transformer, 60 Lead-in cable.

Claims (4)

Provided with an auxiliary resistor and the auxiliary capacitor, an auxiliary element which is connected to the transformer high voltage cable is connected to the primary side,
Test voltage application means for applying a test voltage to the transformer and the auxiliary element from the secondary side of the transformer;
A clamp-type current detection means for detecting a total leakage current of a leakage current flowing from the primary side of the transformer via the high-voltage cable and a leakage current flowing to the auxiliary element;
By using the test voltage and the total leakage current, the capacitance and dielectric loss tangent of the whole system constituted by the transformer and the auxiliary element are obtained, and the capacitance and dielectric loss tangent of the whole system are obtained. Calculating means for obtaining at least one of capacitance, dielectric loss tangent and insulation resistance of the transformer,
I have a,
A ground wire is connected to the secondary side of the transformer,
The test voltage application means applies a test voltage to the transformer via the ground line,
One end of the auxiliary element is connected to the ground line between the test voltage applying means and the transformer, and an auxiliary element cable is connected to the other end of the auxiliary element, and the test is applied by the test voltage applying means. A voltage is applied to the auxiliary element;
The current detection means detects a total leakage current of a leakage current flowing through the high-voltage cable and a leakage current flowing through the auxiliary element cable;
Non-interruptible insulation diagnostic device characterized by that. The uninterruptible insulation diagnostic device according to claim 1,
The arithmetic means obtains the capacitance and dielectric loss tangent of the transformer by subtracting the electrostatic capacitance and dielectric loss tangent of the auxiliary element from the capacitance and dielectric loss tangent of the entire system.
Non-interruptible insulation diagnostic device characterized by that. The uninterruptible insulation diagnosis device according to claim 1 or 2,
A switch for switching between a first mode for measuring a relatively large capacitance transformer and a second mode for measuring a relatively small capacitance transformer;
The auxiliary device includes a mode by the switch when switched to the second mode, is connected to the transformer,
Non-interruptible insulation diagnostic device characterized by that. An auxiliary device having a auxiliary resistor and the auxiliary capacitor, a step high-voltage cable is connected to the connected transformer on the primary side,
Applying a test voltage from the secondary side of the transformer to the transformer and the auxiliary element by a test voltage applying means ;
Detecting a total leakage current of a leakage current flowing from the primary side of the transformer via the high-voltage cable and a leakage current flowing to the auxiliary element;
By using the test voltage and the total leakage current, the capacitance and dielectric loss tangent of the whole system constituted by the transformer and the auxiliary element are obtained, and the capacitance and dielectric loss tangent of the whole system are obtained. Using to determine at least one of capacitance, dielectric loss tangent and insulation resistance of the transformer;
Only including,
A ground wire is connected to the secondary side of the transformer,
The test voltage application means applies a test voltage to the transformer via the ground line,
In the connecting step, one end of the auxiliary element is connected to the ground line between the test voltage applying means and the transformer, and an auxiliary element cable is connected to the other end of the auxiliary element, A test voltage is applied to the auxiliary element by a test voltage applying means,
In the detecting step, a total leakage current of a leakage current flowing through the high-voltage cable and a leakage current flowing through the auxiliary element cable is detected.
Non-interruptible insulation diagnostic method characterized by the above.

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