JP3034576B2 - Discharge charge calibration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of injecting a standard charge and measuring a magnitude of discharge in a partial discharge test (corona test) of an electric device such as a power cable or an electronic component. Regarding the method of calibrating discharge charge using a calibration pulse generator used for quantitative evaluation, in particular, calibration so that charge calibration of partial discharge can be performed even when high voltage is applied to the electrical equipment to be tested The present invention relates to a method of calibrating a discharge charge by a pulse generator for use in a computer.

[Prior art] In a case where an insulating weakness portion such as a void, a flaw, or an electric field concentration portion exists in an insulator of an electric device, the operation state of the device is as follows.
A partial discharge (corona) may be generated inside the void or the like, which may cause a problem such as deterioration of the insulation of the device and ultimately dielectric breakdown.

In order to foresee the insulation deterioration of the electrical equipment in order to prevent the above-mentioned dielectric breakdown accident and to manufacture the equipment reasonably and economically, it is necessary to efficiently detect the presence of the insulation weak point. Is required.

Therefore, a corona measuring device is used to detect the insulation weak point and the like. The corona measuring device, when a test voltage is applied to a test piece such as an electrical device or the like, measures a corona discharge generated in the insulator, so that the measurement information can be directly displayed on a display unit. It is configured.

For example, in a conventional partial discharge charge display device disclosed in Japanese Patent Publication No. 63-31056, etc., a measured value dB (Digibel) output from a corona measuring device is converted into a partial discharge charge amount (pC). The converted value can be displayed on the display unit as a digital signal.

By displaying the digital signal on the display unit, the efficiency of the partial discharge test on the specimen can be improved, and the labor of the test operation can be reduced.

The conventional partial discharge measuring device has a circuit configuration as shown in FIG. 10, and is performed by applying a high voltage to the specimen 12. In the circuit shown in FIG. 10, the circuit for injecting the charge from the pulse generator 2 of the calibration pulse generation circuit 1 and the circuit of the coupling capacitor 11 and the corona measuring device 10 are connected to the specimen 12. They are provided in parallel, and a high-voltage application circuit from the high-voltage transformer 18 is provided.

The high voltage application circuit includes a power supply 15, a switch 16, a sliding voltage regulator 17, a high voltage transformer 18, and a blocking coil.
19, the voltage of the power supply 15 is boosted to a high voltage of a predetermined value, and the voltage is applied to the specimen 12. Further, the pulse generator 2 has a circuit configuration as shown in FIG. 11, and includes a circuit including a battery-based power supply (quadrature wave voltage) 3, a charging resistor 4, and a pulse voltage value determining capacitor 5. The circuit comprises a mercury chopper 6 arranged in parallel with the circuit, and a pulse signal extracting capacitor 7 arranged in series on the output side circuit.

The purpose of injecting the standard charge into the specimen using the pulse generator 2 is that, during a test (corona discharge test), the detected partial discharge signal is governed by the capacitance value of the specimen,
The voltage value does not directly indicate the magnitude of the discharge. Therefore, for quantitative evaluation, charge calibration is performed in order to repeatedly inject a waveform approximating partial discharge as a standard charge and quantitatively evaluate the magnitude of discharge.

[Problems to be Solved by the Invention] However, in the conventional partial discharge test apparatus as described above, in a state where a voltage is applied to a test piece, that is, under a live state of an electric device (power cable), There is a problem that it cannot be used. That is, when a high voltage is applied to the specimen, a high voltage is applied to the calibration pulse generator 1 and the calibration pulse generator 1 is destroyed.

Therefore, when a conventional partial discharge test is performed, a known charge is injected from the calibration pulse generator 1 into a portion to which a high voltage is applied in a state where no voltage is applied to the test piece, and a measurement system is applied. After the calibration pulse generator 1 is removed from the specimen, a high voltage is applied to the specimen to compare the measured values of the two and detect the corona discharge occurrence state. Like that. That is, in the conventional apparatus, it is impossible to calibrate the discharge charge in a state where a high voltage is applied (charged state).

[Purpose of the Invention] The present invention solves the above-mentioned drawbacks of the conventionally used apparatus. Even when a high voltage is applied to the test piece, the circuit of the calibration pulse generator has a high voltage. It is an object of the present invention to provide a method of calibrating a discharge charge, which is provided with means for preventing the application of a voltage and improves the efficiency of an insulation test based on partial discharge measurement.

Means and Action for Solving the Problems The present invention provides a discharge charge using a calibration pulse generator for injecting a standard charge as a calibration for quantitative evaluation of a partial discharge during a partial discharge test of an electric device. In the calibration method, a choke coil for high voltage bypass and a capacitor for high voltage are provided in a circuit portion forming an output section of the calibration pulse generator, and a choke coil is arranged in parallel with the output circuit, and the capacitor is provided. The high voltage bypass choke coil and the high voltage capacitor are provided so as to be connected in series so that the high voltage applied to the electric device is not applied to the calibration pulse generator. It is characterized in that a standard charge is injected from a calibration pulse generator into an electrical device to be a test sample.

Therefore, in the discharge charge calibration method of the present invention, even when a high voltage is applied to the specimen, the high-voltage bypass choke coil and the high-voltage bypass choke coil disposed in the circuit portion of the output section of the calibration pulse generator are used. With the capacitor
The configuration is such that the high voltage applied to the specimen does not enter the circuit inside the calibration pulse generator, so that the calibration pulse generator may be destroyed by the high voltage applied to the specimen. Disappears. Then, by using the method for calibrating the discharge charge of the present invention, a partial discharge test can be performed at any time while a high voltage is applied to the specimen, and for example, in a live state of a high-voltage transformer, a power cable, or the like. Can be easily performed.

EXAMPLES Hereinafter, a method of calibrating a discharge charge according to the present invention will be described in detail with reference to the illustrated examples.

FIG. 1 is a circuit diagram showing the configuration of a calibration pulse generator used in the method for calibrating the discharge charge according to the present invention. The circuit of the calibration pulse generator includes a battery-based power supply (quadrature wave voltage) 3,
A circuit comprising a circuit including a charging resistor 4 and a pulse voltage value determining capacitor 5, a mercury chopper 6 arranged in parallel with the circuit, and a pulse signal extracting capacitor 7 arranged in series with the output side circuit. That is, in the circuit having the same configuration as the pulse generator of the conventional example shown in FIG. 11, further, in the circuit portion forming the output portion, a high-voltage bypass choke coil 20 and a high-voltage capacitor 22, Each output circuit has a configuration in which the choke coil 20 is additionally connected so as to be arranged in parallel and the capacitor 22 is arranged in series.

The relationship between the high-voltage capacitor 22 and the pulse signal extracting capacitor 7 is expressed by Cb of the pulse signal extracting capacitor 7.
1 is 0.01 μF, the high-voltage capacitor 22Cb2 is about 10 pF, and the capacitor of the high-voltage capacitor 22 is very small.

In the following description, Cb1, Cb2, L, Cb1, Cb2, L,... Are used without using a pulse signal extraction capacitor, a high-voltage capacitor, a high-voltage bypass choke coil, a rectangular wave voltage, a charging resistor,. The description will be made as E, R,.

In the following symbols, E: square wave voltage, R: charging resistor, Cb1: pulse signal extraction capacitor (conventional standard capacitor), Cb2: high voltage capacitor, L: high voltage bypass choke coil, respectively Shall be represented.

The circuit shown in FIG. 1 can be simplified to a circuit configuration as shown in FIG.

That is, as shown in FIG. 2, the circuit of the present invention comprises a means for outputting a quadrature wave voltage E and two capacitors Cb1 and Cb2.
And a high-voltage bypass choke coil L connected in series with E between the two capacitors.

Therefore, as shown in FIG. 3, the capacitances of the two capacitors Cb1 and Cb2 are Cb1≫Cb2, and Cb1≫CL (CL
Represents the stray capacitance of the choke coil L for high-voltage bypass). If E = Cb1 / (Cb1 + CL) = 1
Since the partial pressure of E by CL is negligible from the relationship, it can be shown as a circuit as shown in FIG.

Further, the circuit shown in FIG. 4 can be simplified as shown in FIGS. 5 and 6.

 Cb = (Cb1 · Cb2) / (Cb1 + Cb2), and Cb ≒ Cb2 Q = Cb · E (generated charge).

As shown in FIG. 5, the output current I1 from E flows, which is the same as that of the conventional device, as shown in FIG. In contrast, the seventh
As shown in the figure, the current I2 due to the high voltage HV applied to the specimen flows through the circuit including the high voltage capacitor Cb2 and the high voltage bypass choke coil L.

When the current flow path shown in FIG. 7 is replaced with an AC circuit using a commercial power supply, a circuit configuration as shown in FIG. 8 is obtained.

In other words, when Z1≫Z2, VZ1 = (Z1 / (Z1 + Z2) × HV) From the above equation, it is easy to reduce the Z1 terminal voltage, and to a value that does not affect Cb1 and the quadrature wave circuit at all. Can be reduced.

When the partial pressure is calculated for the above formula, for example, Cb1: 100 μF, L: 2.5 mH, f = 50 Hz, HV: 10 kV
Then, since VZ1 ≒ 2.5 × 10 ⁻⁸ , VZ1 = 0.25 mV.

As described above, in the calibration pulse generator used in the present invention, the choke coil 20 for the high-voltage bypass is added to the circuit forming the output section of the calibration pulse generator.
And the high-voltage capacitor 22 are connected to the output circuit such that the choke coil 20 is arranged in parallel and the capacitor 22 is arranged in series, whereby the calibration pulse from the pulse generator is supplied. It is output to the specimen, but the high voltage applied to the specimen does not enter the circuit in the pulse generator, and the circuit of the pulse generator is used even when performing the partial discharge measurement test in the live line. , And will be kept safe.

The method of calibrating the discharge charge of the present invention described above is actually
Calibration can be performed using a discharge charge calibration device as shown in FIG.

In FIG. 9, a discharge charge calibrating device 24 is provided with a handle 29 made of an arbitrary insulating member with respect to a main body 25 made of a transparent acrylic resin or the like. Terminal portions 27 and 28 to be brought into contact with the terminals are provided. Further, a high-voltage capacitor 22 is provided inside the main body 25, a calibration pulse generator 2 is connected to the circuit of the high-voltage capacitor 22, and a high-voltage bypass choke coil 20 is provided.

Then, the specimen connected to the circuit of the corona measuring instrument 10
By bringing the terminals 27 and 28 on both sides of the main body 25 into contact with the terminals on both sides of 12, the calibration pulse generator 2 is connected to a detection circuit using the corona measuring device. Therefore, the calibration pulse generator 2 of the present invention can inject a calibration pulse even in a state where a high voltage is applied to the specimen 2.

Note that, in addition to the above-described configuration, the discharge charge calibration device 24 may have any mechanism, and the capacitance values of the high-voltage bypass choke coil 20 and the high-voltage capacitor 22 provided in the device are as follows. It can be set arbitrarily according to the voltage applied to the specimen as the object.

[Effects of the Invention] As described in detail above, the method of calibrating the discharge charge of the present invention is characterized in that, when a standard charge for partial discharge quantitative evaluation is injected using a calibration pulse generator during a partial discharge test of electrical equipment, A high-voltage bypass choke coil and a high-voltage capacitor are connected to the circuit part forming the output part of the calibration pulse generator so that the choke coil is arranged in parallel with the output circuit and the capacitor is arranged in series. The calibration pulse generator has a configuration in which the high-voltage bypass choke coil and the high-voltage capacitor are configured so that the high voltage applied to the electric device is not applied to the calibration pulse generator. The standard electric charge is injected into the electrical equipment to be tested. Even when the voltage is applied, the standard charge can be injected into the specimen without damage to the calibration pulse generator, and the circuit configuration is the same as that of the conventional calibration pulse generator. It requires only a compact configuration in which the coil and the high-voltage capacitor are incorporated, and can be handled easily.

By using the discharge charge calibration method of the present invention, a partial discharge test in a state where a high voltage is applied to a specimen can be performed at any time. For example, insulation in a live state of a high-voltage transformer, a power cable, or the like can be performed. Testing and the like can be easily performed.

In particular, since the calibration method of the present invention can perform calibration while comparing the level with the partial discharge generated from the specimen during the measurement of the partial discharge, the measurement operation is further improved, and the specimen becomes the specimen. Along with the elimination of the time loss that there is no need to stop the operation of the electric equipment (power failure), there is an exceptional effect that the partial discharge test can be performed very economically.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing the configuration of a calibration pulse generator used in the method for calibrating discharge charge of the present invention, FIGS. 2 to 8 are explanatory diagrams of the circuit of the present invention, and FIG. Explanatory diagram showing the configuration of the discharge charge calibration device, FIG. 10 is an explanatory diagram of a calibration pulse generator in a general partial discharge measurement,
FIG. 11 is a circuit diagram showing a configuration of a conventional calibration pulse generator. Reference numeral 1 in the figure: a pulse generator for calibration; 2, a pulse generator;
...... Charging resistor, 5 ... Pulse voltage value determination capacitor, 6 ... Mercury chopper, 7 ... Pulse signal extraction capacitor, 10 ... Corona measuring instrument, 11 ... Coupling capacitor, 12 ... Test specimen , 20 ... High voltage bypass choke coil, 22 ... High voltage capacitor, 24 ... Discharge charge calibration device, 25 ... Main body, 27, 28 ... Terminal, 29 ... Handle.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Ado 1008 Shinbori, Kumagaya-shi, Saitama Mitsubishi Cable Industry Co., Ltd. Kumagaya Works (56) References JP-A-2-167483 (JP, A) JP-A-63 -233381 (JP, A) JP-B 63-31056 (JP, B2) JP-B 46-38207 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/12- 31/20

Claims (1)

(57) [Claims] 1. A method for calibrating a discharge charge using a calibration pulse generator for injecting a standard charge for use in calibrating quantitative evaluation of a partial discharge during a partial discharge test of an electric device. A choke coil for high voltage bypass and a capacitor for high voltage are connected to the circuit part forming the output part of the pulse generator by connecting the choke coil in parallel to the output circuit and the capacitor in series. The high-voltage bypass choke coil and the high-voltage capacitor serve as a specimen from the calibration pulse generator in a state in which the high voltage applied to the electric device is not applied to the calibration pulse generator. A method of calibrating a discharge charge, which comprises injecting a standard charge into an electric device.