JPH0792219A - Optical balance detector for partial discharge - Google Patents

Abstract

PURPOSE:To provide an optical balance detector for a partial discharge,which can measure even the partial discharge having a short rise time under an impulse impression voltage, has a wide frequency band and is hardly affected by external noise. CONSTITUTION:When a supply voltage is impressed on a coupling capacitor 25 generating no corona and on a capacitor 27 to be tested which has a defective part such as a void, light-emitting diodes 28 and 31 are made to emit light by a charging current flowing into the capacitors 25 and 27 and by external noise. Emission outputs from these diodes are received by a coupling-side phototransistor 36 and a tested side phototransistor 42 respectively and balanced by regulation means such as variable resistors 38 and 44 and thereby a difference between the two reception outputs is made zero. When a partial discharge is generated in the capacitor 27 to be tested, a partial discharge pulse is superposed on the output of the tested-side phototransistor 42 and, therefore, the partial discharge pulse is detected as the difference between the two reception outputs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention When the partial discharge generated in a power device is detected by using a balanced detection circuit, the present invention expands the measurable frequency band of the partial discharge pulse.
The present invention relates to a partial discharge optical balance detection device capable of detecting partial discharge which has not been easy so far.

[0002]

2. Description of the Related Art Various applied voltages (in order to clarify the characteristics of partial discharge deterioration generated in voids (hereinafter, referred to as voids) existing in an electric insulating material in an electric power device or at an interface between the electric insulating material and a metal) AC, DC, impulse, etc.) are used.

In particular, if there are defects (voids, flakes, foreign matters, interface irregularities, etc.) in the electrically insulating material, partial discharge will occur from the beginning of voltage application or during operation. Due to the occurrence of this partial discharge, deterioration over time of the insulating material progresses, and finally dielectric breakdown occurs.

Conventionally, a method using balanced detection is known as a method for detecting a partial discharge generated in a void of an insulating material in a power device.

FIG. 10 is an example of a circuit showing a conventional partial discharge balance detection device. In FIG. 10, reference numeral 1 is a power supply of an applied voltage, for example, a commercial frequency AC power supply is used. The AC power supply voltage is applied to the input terminal 2 of the partial discharge balance detection device. The voltage applied to the input terminal 2 is supplied to the corona-free (here, meaning that partial discharge does not occur) coupling capacitor 3, and is also supplied to the test capacitor 4 as a test body. The coupling capacitor 3 is a capacitor that does not generate partial discharge at the working voltage, and the test capacitor 4 has defective portions (voids, chippings, foreign matter, interface irregularities, etc.), and partial discharge occurs at a certain voltage or higher. It is a thing. One end A of coupling capacitor 3
Is connected to ground through a detection impedance 6, and one end B of the capacitor under test 4 is connected to ground through a detection impedance 7. The primary coil 5a of the transformer 5 is connected between one end A of the coupling capacitor 3 and one end B of the sample capacitor 4, and the output of the secondary coil 5b of the transformer 5 is amplified by the amplifier 8. The image is supplied to the image display device 9 such as an oscilloscope.

In such a structure, when the power source 1 is turned on, the coupling capacitor 3 is passed from the power source 1 through the input terminal 2.
While the charging current flows into the sample capacitor 4, external noise enters through the power supply line connecting the power supply 1 and the input terminal 2. Therefore, the same external noise is superimposed on each charging current of the capacitors 3 and 4. The charging current flowing into the coupling capacitor 3 and the external noise superimposed on the charging current flow from the one end A to the other end B of the primary coil 5a of the transformer 5, and the charging current flowing into the test capacitor 4 and the charging current. The superposed external noise flows from one end B to the other end A of the primary coil 5a of the transformer 5, so that the charging currents and external noises from the capacitors 3 and 4 are in opposite directions, and the difference between them is zero, that is, the balance. Becomes Therefore, the charging current and external noise are not output to the secondary side of the transformer 5. However, when a partial discharge occurs in the capacitor under test 4, this partial discharge current pulse is not balanced, so that only a partial discharge current pulse is generated on the secondary side of the transformer 5. Since this pulse is weak, it is amplified by the amplifier 8 and displayed on the image display device 9 for detection.

As another conventional example, a partial discharge balance detecting device as shown in FIG. 11 is also known. In FIG. 11, the transformer 5 and the detection impedances 6 and 7 in FIG. 10 are removed, and instead the signal line at one end A of the coupling capacitor 3 is connected to ground, while the signal line at one end B of the sample capacitor 4 is connected. The signal lines extending from the points A and B are connected to the ground, the detection coil 10 is arranged so as to surround the intersection, and the output induced in the detection coil 10 is amplified by the amplifier 8. After that, it is displayed on the image display device 9 and detected.

According to the configuration of FIG. 11, the coupling capacitor 3
Also, the charging currents flowing into the sample capacitor 4 and the external noise mixed in the power supply line are in opposite directions at the cross portion, and the difference therebetween is zero, that is, the balance. Therefore, the charging current and external noise are not induced in the detection coil 10,
When a partial discharge pulse is generated in the test capacitor 4, only the partial discharge current pulse is led to the detection coil 10,
After amplification, it is displayed on the image display device 9 and detected.

By the way, when an impulse voltage (lightning impulse, square wave pulse, etc.) having a short rise time (on the order of μs) is applied, the transformer and the detection coil are used in front of the detector in the above-mentioned conventional example. There is a problem in that the frequency band is limited because it cannot respond sufficiently to a pulse with a short rise time due to a decrease in inductance, stray capacitance, coupling coefficient, etc.

[0010]

Therefore, in view of the above problems, the present invention can broaden the frequency band, can measure even partial discharge having a short rise time under an impulse applied voltage, and can reduce external noise. An object of the present invention is to provide a partial discharge optical balance detection device that is not easily affected.

[0011]

According to a first aspect of the present invention, there is provided a partial discharge optical equilibrium detection apparatus comprising: a power supply for supplying an applied voltage; a test piece to which the voltage from the power supply is applied; and a voltage from the power supply. A corona-free coupling capacitor to be added, a first light-emitting unit that is provided between the sample and a ground, and includes a first light-emitting element that emits light by a current flowing from the power source into the sample, and the coupling capacitor. A second light emitting element which is provided between grounds and includes a second light emitting element which emits light by a current flowing from the power source into the coupling capacitor;
A light emitting section, a first light receiving element for receiving a light output from the first light emitting element, and a first signal detecting section including a first detecting section for detecting a current photoelectrically converted by the element. A second signal detecting section including a second light receiving element for receiving a light output from the second light emitting element and a second detecting section for detecting a current photoelectrically converted by the element; The amplitude and phase of the first detection voltage of the signal detection unit and the second detection voltage of the second signal detection unit are adjusted to have the same amplitude, the same phase, or the same for the first and second detection voltages. Adjusting means for balancing so that the amplitude and the opposite phase may be obtained; subtracting or adding the first detection voltage of the first signal detection section and the second detection voltage of the second signal detection section A means for detecting the partial discharge pulse generated in the specimen by taking the difference between the first and second detection voltages. It is obtained by Bei.

According to a second aspect of the present invention, the first signal detecting section and the second signal detecting section according to the first aspect are:
The first detection voltage and the second detection voltage are respectively driven by two DC power supplies having polarities different from each other, and the first detection voltage and the second detection voltage are voltages having opposite phases having polarities different from each other.

According to a third aspect of the present invention, each of the first light emitting element and the second light emitting element according to the first aspect is formed by connecting two light emitting diodes in parallel so that their polarities are opposite to each other. However, it is characterized in that it can emit light regardless of the positive and negative polarities of the applied power source.

According to a fourth aspect of the present invention, the adjusting means in the first aspect is constituted by variable resistors respectively connected to the first and second light receiving elements.

According to a fifth aspect of the present invention, the adjusting means in the first aspect is constituted by a circuit of a variable resistance and a variable capacitance respectively connected to the first and second light receiving elements. .

According to a sixth aspect of the invention, there is provided a variable resistance and variable capacitance circuit in which the adjusting means according to the first aspect is connected to the first and second light receiving elements, respectively, and the first and second circuits. It is characterized in that it is configured by a variable DC power source for driving each light receiving element.

[0017]

In the present invention, when the power supply voltage is applied to the specimen having the defective portion such as void, peeling, foreign matter and interface irregularity and the corona-free coupling capacitor (the partial discharge does not occur at the working voltage) , The first light-emitting element on the test side and the second light-emitting element on the coupling side emit light due to the charging current and the external noise flowing into the test piece and the coupling capacitor, respectively. Received by the light receiving element and the second light receiving element on the coupling side, and balanced by the adjusting means, so that the difference between the two light receiving outputs is zero.
When partial discharge occurs in the test piece, the first side of the test side
Since the partial discharge pulse is superimposed only on the output of the light receiving element, the partial discharge pulse is detected as the difference between the two light receiving outputs.

Since optical coupling is used, it can respond to an applied voltage with a short rise time such as an impulse voltage, and since it is optical transmission, it is not affected by external noise such as a magnetic field. Furthermore, even if the DUT, which is the DUT, is located away from the partial discharge optical balance detection device main body, the partial discharge pulse generated in the DUT can be transmitted over a wide frequency band and over a long distance by an optical cable, etc. Moreover, it has an advantage that it is less likely to be affected by external noise.

[0019]

EXAMPLES Examples will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a partial discharge optical balance detection device according to an embodiment of the present invention.

In FIG. 1, reference numeral 21 is a power source for an applied voltage, and for example, a commercial AC power source is used. The AC power supply voltage is applied to the input terminal 23 of the partial discharge optical balance detection device via the current limiting resistor 22.
The voltage applied to the input terminal 23 is supplied to the corona-free coupling capacitor 25 (where partial discharge does not occur) via the fuse 24, and is also supplied to the test capacitor 27 via the fuse 26. The coupling capacitor 25 is a capacitor that does not generate partial discharge at the working voltage, and the test capacitor 27 has a defect (void, chipping, foreign matter, interface irregularity, etc.), and partial discharge occurs at a certain voltage or higher. It is a thing. One end of the coupling capacitor 25 is connected to the ground through the light emitting diode 28 and the resistor 30, and one end of the test capacitor 27 is connected to the ground through the light emitting diode 31 and the resistor 33.

On the other hand, the light output from the light emitting diode 28 is transmitted through the optical path 34 such as an optical fiber to the phototransistor 3.
The light is incident on the light receiving surface of No. 6. The phototransistor 36 has its collector connected to the ground through both ends of the variable resistor 38, and its emitter connected to a positive DC power source 39 with a variable voltage. Similarly, the light output from the light emitting diode 31 enters the light receiving surface of the phototransistor 42 via the optical path 40 such as an optical fiber. The phototransistor 42 has its emitter connected to ground through both ends of the variable resistor 44, and its collector connected to a negative DC power supply 45 whose voltage is variable. Although the optical paths 34 and 40 such as optical fibers are provided to reliably transmit the optical output, when the distance between the light emitting diode and the phototransistor is short, the optical paths 3 such as optical fibers 3 are provided.
4, 40 need not be provided in particular.

A current according to the amount of light received flows between the emitter and collector of the phototransistor 36, and the variable resistor 3
A positive voltage V1 is generated at the sliding terminal of No. 8, a current corresponding to the amount of light received flows between the emitter and collector of the phototransistor 42, and a negative voltage V1 is applied to the sliding terminal of the variable resistor 44.
Yields 2. The voltages V1 and V2 are added through an amplifier 48, the difference between the two voltages is taken out as an output, and is supplied to an image display device 49 such as an oscilloscope.

The variable resistors 38 and 44 are connected to the voltage V1,
It is possible to adjust the peak value (amplitude) of V2.
Further, here, since it is assumed that the capacitance values of the coupling capacitor 25 and the test capacitor 27 are the same, a phase adjusting capacitor is not used.

In such a structure, when the power supply 21 is turned on, the charging current and the external noise flow from the input terminal 23 into the partial discharge optical balance detecting device, and the coupling capacitor 2
5 and the sample condenser 27. Here, power supply 21
May be an AC power supply or an impulse voltage generation source, but each of the light emitting diodes 28 and 31 emits light only when the polarity of the output voltage of the power supply 21 is positive, and the light is emitted from the optical path 34 such as an optical cable. Each phototransistor 3 through 40
6,42. The operating resistance of the phototransistor receiving the light output from the light emitting diode is instantaneous (μs to ns
The photo-transistors 36 and 42 that have received light and the detection resistor 3 connected to these photo-transistors 36 and 42
A current corresponding to the amount of received light flows into 8 and 44 instantly. As a result, the voltage V1 is applied to the sliding terminals of the detection resistors 38 and 44,
V2 is generated. V1 is a positive voltage waveform and V2 is a negative voltage waveform.

Crest value (amplitude) of these voltages V1 and V2
Is adjusted by moving the sliding terminals of resistors 38 and 44, and V1
And adjust so that the peak value of V2 is the same. In addition,
Adjustment can also be performed by changing the voltages of the DC power supplies 39 and 45. When this adjusted voltage is added to the amplifier 48 and added, V1 and V2 at the output of the amplifier 48 have the same magnitude and become zero. Therefore, when partial discharge does not occur in the capacitor to be tested 27, the charging current and the external noise do not appear in the image display device 49 located after the amplifier 48.

However, when partial discharge occurs in the test capacitor 27, this partial discharge current pulse is superimposed on the charge current and external noise on the test piece side. Due to this superimposed current, the light emitting diode 31 emits light, and a voltage V2 is generated at the sliding terminal of the resistor 44 along the same path as described above. In this case, the voltage V1 in the path from the coupling capacitor 25 is not superposed with a partial discharge current pulse. Therefore, when the detected voltages V1 and V2 are added by the amplifier 48, the charging current and the external noise become zero because of opposite polarities.
Image display device 4 in which only partial discharge current pulses are detected and amplified
9 appears and is detected.

FIG. 2 shows the voltage waveform of each part when a commercial AC power source is used as the power source 21.

In FIG. 2, V0 is a voltage waveform applied to the input terminal 23, and this waveform shows a state in which the external noise that has entered from the power supply line is superimposed in a positive polarity. V
Reference numeral 1 is a positive voltage waveform appearing at the sliding terminal of the detection resistor 38, which is superposed with external noise. V2 is a negative voltage waveform in which the polarity of the positive polarity of the power source appearing at the sliding terminal of the detection resistor 44 is inverted, external noise is also superimposed, and the partial discharge pulse generated in the test capacitor 27 is also superimposed. Has become. V3 indicates a partial discharge pulse waveform extracted by adding V1 and V2 in the amplifier 48.

In this embodiment, since a photocoupler (optical coupling) having a quick response by a light emitting diode and a phototransistor is used, a standard lightning impulse voltage (rise) as shown in FIG. Time 1.2
.mu.s, pulse width 50 .mu.s), it is possible to detect a partial discharge pulse having a short rise time generated at the time of application. On the other hand, the conventional example (Fig. 10)
Also, in FIG. 11), since the transformer and the detection coil are used, the frequency band is limited, and the partial discharge pulse having a short rise time cannot be detected.

FIG. 4 shows the voltage waveform of each part in FIG. 1 when the standard lightning impulse voltage generating source is used as the power source 21. Here, it is described that the voltage generation source generates a positive polarity pulse.

In FIG. 4, V0 is an impulse voltage waveform applied to the input terminal 23, which is periodically generated at the illustrated application time intervals. V1 is a positive voltage waveform appearing at the sliding terminal of the detection resistor 38. V2 is the detection resistor 44
Is a negative voltage waveform in which the polarity of the positive polarity of the power source appearing at the sliding terminal is inverted, and is a waveform in which the partial discharge pulse generated in the sample capacitor 27 is superimposed. V3 is the amplifier 4
8 shows a partial discharge pulse waveform extracted by adding V1 and V2 at 8.

In the embodiment shown in FIG. 1, the detection resistors 38, 4
The voltages of the sliding terminals of No. 4 are opposite in phase to each other and added by the amplifier 48, but the voltages of the sliding terminals of the detection resistors 38 and 44 are in phase with each other and subtracted by the amplifier 48. Can be obtained.

FIG. 5 shows a configuration example in which the subtraction is performed by the amplifier 48. In the embodiment shown in FIG. 5, the polarity of the DC power supply 45 of the light receiving side circuit is positive, which is opposite to that of FIG. 1, the emitter of the phototransistor 42 is connected to the positive side of the DC power supply 45, and its collector is variable. It is connected to the ground through both ends of the resistor 44. Further, a differential amplifier is used as the amplifier 48, and the sliding terminal of the variable resistor 44 is connected to the differential amplifier 48.
The non-inverting terminal (+) is connected to the sliding terminal of the variable resistor 38. With this configuration, the voltages V1 and V2 obtained at the sliding terminals of the detection resistors 38 and 44 are in phase with each other, and the in-phase voltages V1 and V2 are obtained.
Is subtracted by the differential amplifier 48, the partial discharge pulse generated in the sample capacitor 27 can be extracted.

FIG. 6 is a circuit diagram showing a partial discharge optical balance detecting device according to another embodiment of the present invention. The embodiment shown in FIG.
A light emitting diode 29 is connected in parallel with the light emitting diode 28 in the embodiment of FIG. 1 so as to have a reverse polarity to this diode 28, and another phototransistor 37 is connected in parallel with the phototransistor 36. ,
The optical signal from the light emitting diode 29 is configured to enter the phototransistor 37 via the optical path 35 such as an optical fiber, while it is emitted in parallel with the light emitting diode 31 so as to have a polarity opposite to that of the diode 31. The diode 32 is connected, and another phototransistor 43 is connected in parallel with the phototransistor 42 so that the optical signal from the light emitting diode 32 is incident on the phototransistor 43 through the optical path 41 such as an optical fiber. In addition, a phase adjusting capacitor 46 is connected between the sliding terminal of the detection resistor 38 and the ground, and a phase adjusting capacitor 4 is connected between the sliding terminal of the detection resistor 44 and the ground.
7 is connected. Other configurations are the same as those in FIG.

With this configuration, the power source 21
When an AC power supply is used as the light source, light is emitted due to the charging current and external noise flowing into the coupling capacitor 25 and the test capacitor 27, respectively, in the half cycle in which the voltage V0 applied to the input terminal 23 is a positive polarity voltage. Diode 28
In the half cycle in which the light emitting diode 31 emits light and the voltage V0 has a negative polarity voltage, the light emitting diode 29 and the light emitting diode 3 are caused by the charging current and the external noise flowing into the coupling capacitor 25 and the test capacitor 27, respectively.
2 emits light. The light of the light emitting diode (28, 31) or the light emitting diode (29, 32) which emits light according to the positive or negative polarity of the voltage V0 is supplied to the phototransistor (3
6, 42) or the phototransistor (37, 43), the operating resistance of the phototransistor that receives light is instantly reduced. Electric current flows in. As a result, voltages V1 and V2 are generated at the sliding terminals of the detection resistors 38 and 44. The voltages V1 and V2 are supplied to the power source 2
Regardless of the positive or negative polarity of 1, V1 has a positive voltage waveform and V2 has a negative voltage waveform.

The peak values and phases of these voltages V1 and V2 are adjusted by the movement of the sliding terminals of the variable resistors 38 and 44 and the capacitors 46 and 47 so that the peak values and phases of V1 and V2 become the same. Adjust to. In addition, DC power supply 39, 4
It can be adjusted by changing the voltage of 5. When this adjusted voltage is added to the amplifier 48 and added, the amplifier 48
Since V1 and V2 at the output of the same have the same magnitude and phase, they are zero. Therefore, when partial discharge does not occur in the capacitor to be tested 27, the charging current and the external noise do not appear in the image display device 49 located after the amplifier 48.

However, when partial discharge occurs in the capacitor 27 under test, this partial discharge current pulse is superposed on the charging current and external noise on the sample side. Due to this superimposed current, the light emitting diode 31 emits light, and a voltage V2 is generated at the sliding terminal of the resistor 44 along the same path as described above.
In this case, the voltage V1 in the path from the coupling capacitor 25 is not superposed with a partial discharge current pulse. Therefore, when the detected voltages V1 and V2 are added by the amplifier 48,
Although the charging current and the external noise become zero due to the opposite polarities, only the partial discharge current pulse is detected and amplified, appears on the image display device 49, and is detected.

In the embodiment shown in FIG. 6, the voltages V1 and V2 are
The circuit of the variable resistor 38 and the variable capacitor 46 and the circuit of the variable resistor 44 and the variable capacitor 47 are provided on the phototransistor side in order to adjust the peak value and the phase of the variable resistance. Three
8 and the circuit of the variable capacitor 46 are only fixed value detection resistors, the resistor 30 on the light emitting diode side is composed of the circuit of the variable resistor and the variable capacitor, and the circuit of the variable resistor 44 and variable capacitor 47 on the phototransistor side is fixed Only the value detection resistor may be used, and the resistor 33 on the light emitting diode side may be configured by a circuit of a variable resistor and a variable capacitor.

FIG. 7 shows the voltage waveform of each part when a commercial AC power source is used as the power source 21.

In FIG. 7, V0 is a voltage waveform applied to the input terminal 23, and this waveform shows a state in which external noise that has entered from the power supply line is on it. V1 is a positive voltage waveform appearing at the sliding terminal of the detection resistor 38, and external noise is also superimposed. The voltage waveform V1 is a waveform obtained by full-wave rectifying the voltage V0 of the power supply 21 to the positive side.
V2 is a negative voltage waveform that appears at the sliding terminal of the detection resistor 44, and external noise is also superimposed. This voltage waveform V2 is
The waveform is such that the voltage V0 of the power source 21 is full-wave rectified to the negative side, and the partial discharge pulse generated in the sample capacitor 27 is superimposed. V3 indicates a partial discharge pulse waveform extracted by adding V1 and V2 in the amplifier 48.

In this embodiment, even when a standard lightning impulse voltage and its reverse polarity lightning impulse voltage as shown in FIG. 3 are applied, a partial discharge pulse having a short rise time generated at the time of application is applied. Can be detected.

Further, in the embodiment of FIG. 6, two phototransistors (36, 37) and (42, 43) connected in parallel to the coupling side and the test side in the light receiving side circuit, respectively.
Can be configured with one phototransistor 36 and 42 on the coupling side and the test side, respectively.

FIG. 8 shows an example in which one phototransistor 36 and 42 is provided on each of the coupling side and the test side.

In FIG. 8, the phototransistors 37 and 43 on the light receiving side in FIG. 6 are deleted, and one phototransistor 36 and 42 is provided on each of the coupling side and the test side, and two light emitting diodes 28 and 29 on the coupling side. Light from the two light-emitting diodes 31 and 32 on the test side is guided to the light receiving portion of one phototransistor 36 through the branch type optical path 34A.
It is configured to lead to the light receiving portion of one phototransistor 42 through 0A. With this structure, the number of phototransistors can be reduced and the circuit structure can be simplified.

FIG. 9 shows an example of the branch type optical path used in FIG. The optical path shown in FIG. 2 shows a branched optical fiber in which the light input side is bifurcated and the light output side is one.

In the embodiment shown in FIGS. 6 and 8, the voltages at the sliding terminals of the detection resistors 38 and 44 are opposite in phase to each other and added by the amplifier 48. However, as in the case of FIG. The voltages at the sliding terminals of the detection resistors 38 and 44 are in phase with each other,
The subtraction may be performed by the amplifier 48.

In the above-described embodiments, the case where the capacitor 27 is used as the test piece has been described, but it goes without saying that a power device such as a power cable may be used as the test piece. Also, the case where a corona-free capacitor (a partial discharge does not occur at the working voltage) is used as the coupling capacitor 25 has been described, but instead of the coupling capacitor, a corona-free power device (transformer, power capacitor, rotating machine). Etc.) is also possible.

In the above-described embodiment of the present invention, the light emitting diode and the phototransistor are connected using the optical cable, so that even if the optical cable is lengthened, there is no risk of being affected by external noise during this period. On the other hand, in the conventional example (FIGS. 10 and 11), when the distance between the test piece and the transformer or the detection coil is increased, the conductor between them receives external noise and only lowers the detection sensitivity. There was a drawback that it could not be balanced. Further, in the present invention,
Since no transformer is used, the frequency band is widened (GH
It can be up to the z band.

[0049]

As described above, according to the present invention, since optical transmission is used, it is possible to respond to a partial discharge having a short rise time under an impulse voltage, and since it is optical transmission, a magnetic field is applied. It is not affected by external noise such as.
Furthermore, even if the DUT, which is the DUT, is located away from the partial discharge optical balance detection device main body, the partial discharge pulse generated in the DUT can be transmitted over a wide frequency band and over a long distance by an optical cable, etc. Moreover, it has an advantage that it is less likely to be affected by external noise.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a partial discharge optical balance detection device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating the operation of FIG.

FIG. 3 is a waveform diagram showing a standard lightning impulse voltage.

FIG. 4 is a waveform diagram illustrating the operation of FIG.

FIG. 5 is a circuit diagram showing another embodiment of the present invention.

FIG. 6 is a circuit diagram showing another embodiment of the present invention.

FIG. 7 is a waveform diagram illustrating the operation of FIG.

FIG. 8 is a circuit diagram showing another embodiment of the present invention.

9 is a diagram showing a branch type optical path used in FIG. 8;

FIG. 10 is a circuit diagram showing a conventional partial discharge balance detection device.

FIG. 11 is a circuit diagram showing another conventional partial discharge balance detection device.

[Explanation of symbols]

21 ... Power source 23 ... Power source input terminal 25 ... Coupling capacitor 27 ... Test capacitor (test sample) 28, 29, 31, 32 ... Light emitting diode (light emitting element) 34, 34A, 35, 40, 40A, 41 ... Optical path 36, 37, 42, 42A, 43 ... Phototransistor (light receiving element) 38, 44 ... Variable resistance (detection resistance) 39, 45, 45A ... Variable DC power supply 46, 47 ... Variable capacitor (variable capacity) 48 ... Amplifier (adding means) 49 ... Image display device

Claims (6)

[Claims] 1. A power supply for supplying an applied voltage, a test piece to which a voltage from the power supply is applied, a corona-free coupling capacitor to which a voltage from the power supply is applied, and a test piece provided between the test piece and ground, A first light emitting unit including a first light emitting element that emits light by a current flowing from the power source into the sample, and is provided between the coupling capacitor and the ground, and emits light by a current flowing from the power source into the coupling capacitor. A second light emitting section including a second light emitting element, a first light receiving element for receiving the light output from the first light emitting element, and a first for detecting a current photoelectrically converted by this element
A first signal detecting section including a detecting section, a second light receiving element for receiving an optical output from the second light emitting element, and a second detecting a current photoelectrically converted by this element.
A second signal detecting section including a detecting section, and adjusting the amplitude and phase of the first detection voltage of the first signal detecting section and the second detection voltage of the second signal detecting section,
Adjusting means for balancing the first and second detection voltages so that they have the same amplitude and the same phase, or the same amplitude and the opposite phase; the first detection voltage of the first signal detection section and the second signal. The second detection voltage of the detection unit is subtracted or added, the difference between the first and second detection voltages is obtained, and the means for detecting the partial discharge pulse generated in the sample is provided. Partial discharge optical balance detector. 2. The first signal detection section and the second signal detection section are respectively driven by two DC power supplies having different polarities, and the first detection voltage and the second detection voltage have mutually polarities. The partial discharge optical balance detection device according to claim 1, wherein the voltages have different opposite phases. 3. The first light-emitting element and the second light-emitting element are respectively configured by connecting two light-emitting diodes in parallel so that their polarities are opposite to each other, and are independent of positive or negative polarities of an applied power source. The device is capable of emitting light.
Partial discharge optical balance detection device described. 4. The partial discharge optical balance detecting device according to claim 1, wherein the adjusting means is composed of a variable resistor connected to each of the first and second light receiving elements. 5. The partial discharge optical balance detection according to claim 1, wherein the adjusting means is composed of a variable resistance circuit and a variable capacitance circuit respectively connected to the first and second light receiving elements. apparatus. 6. The adjusting means includes a circuit of a variable resistance and a variable capacitance respectively connected to the first and second light receiving elements,
2. The partial discharge optical balance detection device according to claim 1, wherein the partial discharge optical balance detection device is configured by a variable DC power source that drives each of the first and second light receiving elements.