JP2000055975A - Layer corona testing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain the generation phase of partial discharge without shift from image display of corona measuring device. SOLUTION: Provided are a potential dividing capacitor 11 generating partial voltage of that impressed in the winding component 1 which is placed at a neutral point 3 of a testing winding component 1 or between a capacitor bushing 4 at the ends of the particular windings 2u, 2v or 2w and the earth a voltage detection resistor 12 converting the partial voltage into current which is placed in between the connection point of the potential dividing capacitor 11 and a corona measuring device 13, and an indication processing means detecting the phase zero point of the impressed voltage from the current flowing the voltage detection resistor 12 and adding the zero marker (e) of the synchronizing with the phase zero point to the screen indication of the measuring device 13 which is placed in the measuring device 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a layer corona test circuit used for verifying insulation between layers of a winding device such as a reactor or a transformer.

[0002]

2. Description of the Related Art Conventionally, a layer corona test circuit of this kind is formed as shown in FIG.

In FIG. 1, reference numeral 1 denotes a three-phase winding 2u, 2
v, 2w are star-connected reactors, transformers, etc.
Phase winding test equipment, neutral point 3 and winding 2 of each phase
A capacitor bushing 4 having a capacity of about 200 pF and having an equalizing capacitor is connected to each of the ends u, v, w of u, 2v, 2w.

FIG. 4 shows a winding 2u of the test winding device 1.
, And the end u of the winding 2u and the remaining two windings 2u
v, w shows a connection when a voltage is applied between the ends v, w, and a partial discharge (Layer corona) therebetween is measured and tested. The ends v, w are grounded, and the ends u, w A high frequency power supply 7 is connected between the grounded ends v and w via a blocking coil 5 and a resonance capacitor 6.

The high-frequency power supply 7 has a higher frequency than the system power supply (50 Hz or 60 Hz), for example, 800 Hz, and changes its voltage from 0 V to 3000 V, for example, by an operation of an operator.

The resonance capacitor 6 has a capacitance of several tens of μF, and forms a series resonance circuit with the winding device 1 to be tested.
The voltage is increased to 5000 V and applied to the test winding device 1.

When a partial discharge occurs between the end u and the ends v and w during the step-up change of the applied voltage, the discharge voltage superimposed on the applied voltage passes through the capacitor bushing 4 at the end u. The corona measuring device 8 detects the voltage waveform and displays the detected voltage waveform on a monitor screen such as a CRT screen of the corona measuring device 8.

At this time, the windings 2u, 2v, and 2w have the same impedance, and the voltage applied between the end u and the ends v and w is 2/3 of the voltage applied to the winding 2u. , 2
Since the remaining 1/3 is applied to the parallel circuit of w, the applied voltage is high in the target winding 2u, and partial discharge easily occurs.

The voltage waveform displayed on the screen of the corona measuring device 8 is, for example, as shown on a monitor screen 8 'of FIG. This is a waveform in which a voltage waveform b of a high-frequency minute voltage of partial discharge is superimposed on an annular voltage waveform a obtained by combining a half cycle waveform.

On the other hand, the blocking coil 5 has a sufficiently smaller impedance than the winding device 1 to be tested, and blocks the output of the partial discharge voltage to the power supply side without affecting the series resonance circuit.

In order to monitor the applied voltage at the end u, an ammeter 10 is connected to the end u via a capacitor 9 for measuring an applied voltage of about 500 pF.
Is applied indirectly to the applied voltage between the end u and the ends v and w.

This is because the above-mentioned 800 Hz, 27,5000
This is because it is difficult to directly detect a high-frequency high voltage of V as a voltage by a general voltage detector.

When the test in the connection state of FIG. 4 in which the winding 2u is the target winding is completed, for example, the windings 2u, 2
v, 2w are changed to the connection state where they are moved to the positions of the windings 2v, 2w, 2u shown in FIG. , And the same test as above is performed. Thereafter, the winding 2w is set as a target winding,
A test is performed by applying a high-frequency high voltage between the end w and the ends u and v.

That is, in the case of the three-phase test winding device 1,
As described above, the applied voltage of the target winding is twice the applied voltage of the remaining two windings, and the applied voltages of all the windings 2u, 2v, and 2w are not equal. The inspection is repeatedly performed based on the result.

[0015]

In the case of the conventional layer corona test circuit, only the partial discharge voltage waveform is displayed on the monitor screen 8 'of the corona measuring instrument 8 as shown in FIG. However, there is a problem that the generated phase based on the applied voltage of the test winding device 1 cannot be easily grasped.

Since the partial discharge occurs in synchronization with the actual applied voltage of the test winding device 1, the phase and pattern of the partial discharge vary depending on the location (position) of the partial discharge. If the generation phase can be ascertained, the location where the partial discharge occurs can be specified from the phase and the generation pattern.

However, in the conventional circuit, as described above, it is difficult to know the generation phase of the partial discharge from the monitor screen 8 ', and it is not possible to accurately identify the location where the partial discharge occurs, and the like. Insulation verification etc. cannot be performed with high accuracy.

Note that the phase zero of a low-frequency system power source forming the power source such as the high-frequency power source 7 can be easily detected by a general zero-cross point detection or the like. It is conceivable that the phase zero of the applied voltage of the test winding device 1 is indirectly detected and displayed on the monitor screen 8 ′. In this case, a phase shift due to series resonance occurs, so that the screen is displayed. Therefore, the phase zero point greatly deviates from the phase zero point of the high-frequency actual applied voltage of the test winding device 1, and the occurrence phase of the partial discharge cannot be accurately grasped.

According to the present invention, from the screen display of the corona measuring instrument,
It is an object of the present invention to enable the occurrence phase of partial discharge to be easily grasped without deviation.

[0020]

In order to solve the above-mentioned problems, in the layer corona test circuit of the present invention, a capacitor bushing at a neutral point of a test winding device or at an end of a target winding is connected to the ground. A voltage dividing capacitor, which is provided between the voltage dividing capacitor for dividing the voltage applied to the winding device under test, and a capacitor bushing, which is provided between a connection point of the voltage dividing capacitor and the corona measuring instrument, and which converts the voltage divided into a current. A phase zero of the applied voltage is detected from a detection resistor and a current flowing through the voltage detection resistor provided in the corona measuring device, and a zero marker synchronized with the phase zero is formed and added to a screen display of the corona measuring device. Display processing means.

Therefore, the divided voltage of the actual applied voltage of the test winding device is generated by the voltage dividing capacitor, and the divided voltage is converted into a current by the voltage detecting resistor and detected.

Then, the display processing means of the corona measuring instrument forms a zero marker in synchronization with the phase zero of the actual applied voltage of the winding device under test, and the zero marker is displayed on the screen together with the voltage waveform of the partial discharge. You.

For this reason, the zero point marker displayed on the screen of the corona measuring instrument allows the phase zero point of the applied voltage of the test winding device to be immediately known, and the occurrence phase of the partial discharge can be easily grasped based on the zero point without deviation. be able to.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a configuration in which a three-phase test winding device 1 is tested with its winding 2u as a target winding.

4, the same reference numerals as those in FIG. 4 denote the same or corresponding components, and a voltage dividing capacitor 11 is provided between the capacitor bushing 4 at the neutral point 3 and the ground.
Neutral point 3 based on applied voltage between end u and ends v, w
Is divided by the capacitor bushing 4 and the voltage dividing capacitor 11 to generate a voltage obtained by dividing the applied voltage at a connection point α between the capacitor bushing 4 at the neutral point 3 and the voltage dividing capacitor 11.

At this time, in order to sufficiently divide the applied voltage of 27,5000 V at the maximum, the voltage dividing capacitor 11 is set to, for example, a capacitance of 1 μF.

Further, a high impedance (several MΩ) voltage detection resistor 12 is provided between the connection point α and the corona measuring device 13, and the applied voltage is converted into a current by the resistance 12, and the voltage at the connection point α The current according to the voltage detection resistor 1
Flow through 2.

Next, a corona measuring device 13 provided in place of the corona measuring device 8 in FIG. 4 is formed, for example, as shown in FIG. 2, and a partial discharge taken in through the capacitor bushing 4 at the end u. Are detected and processed by the discharge voltage side processing circuit 15 of the display processing unit 14 forming the display processing means in the same manner as in the case of the conventional corona measuring device 8, and the voltage waveforms a and b in FIG. A display signal having the same voltage waveform as that shown in FIG.

Further, a voltmeter circuit 16 as an applied voltage side processing circuit provided between the other end of the voltage detection resistor 12 and the ground measures the applied voltage from the current of the voltage detection resistor 12 and determines the phase zero thereof. (Zero cross point) is detected, and a display signal of a zero point marker having a positive or negative single pulse waveform corresponding to, for example, a change in polarity of the applied voltage is formed.

Then, the display signals of the discharge voltage side processing circuit 15 and the voltmeter circuit 16 are added and combined by the adder 17, and the waveform of the combined signal is displayed on the CRT 18 on the screen.

At this time, the display screen of the CRT 18, that is, the monitor screen 18 'in FIG. 3 is a screen in which the zero-point marker e is added to the voltage waveforms c and d corresponding to the voltage waveforms a and b in FIG.

Then, the applied voltage between the end u and the ends v, w of the test winding device 1 is directly detected from the divided voltage at the connection point α, and based on this detection, the applied voltage is set to the phase zero point. Synchronously, a zero point marker e is formed.
8 'is displayed together with the voltage waveforms c and d of the partial discharge.

Therefore, the phase zero of the applied voltage of the test winding device 1 can be easily grasped from the display of the zero marker e without any deviation, and the applied voltage can be easily determined based on the interval between the zero marker e and the voltage waveform d. The occurrence phase of the partial discharge can be easily grasped without a shift based on the phase zero point.

The applied voltage is equal to the upper limit voltage (for example, 275
000V), the target winding is changed to the winding 2v, and the applied voltage is increased again from 0V to the upper limit voltage. Thereafter, the target winding is changed to the winding 2w, and the applied voltage is increased from 0V to the upper limit voltage. , Repeat the test.

Based on the phase and pattern of occurrence of the partial discharge obtained by these tests, the location (position) where the partial discharge occurs can be specified with high accuracy, and winding equipment such as a reactor and a winding transformer can be used. With this method, it is possible to perform high-precision insulation verification between layers and to specify the location of the occurrence of partial discharge.
The quality and reliability of this type of winding equipment can be significantly improved.

As is apparent from FIG. 1, when the test winding device 1 is a three-phase device, a voltage dividing capacitor 11 and a voltage detecting resistor 12 are connected to the capacitor bushing 4 at the neutral point 3.
Are connected, the target winding is changed from the winding 2u to the windings 2v and 2w.
When the test is repeated, the voltage dividing capacitor 11,
There is no need to change the connection of the voltage detection resistor 12, and there is an advantage that the layer corona test can be performed efficiently.

The voltage dividing capacitor 11 and the voltage detecting resistor 12 may be connected to the capacitor bushing 4 at the end u, v or w of the target winding instead of being connected to the capacitor bushing 4 at the neutral point 3. Also in this case, the detection phase of the partial discharge similar to the above can be detected.

Of course, the test winding equipment may be various winding equipment of single phase, three phase,....

Further, the present invention can be similarly applied even if the frequency, voltage, boosting amount due to series resonance, and the like of the high frequency power supply 7 are different from those of the above-described embodiment.

The internal configuration of the corona measuring device 13, the voltage waveform of the partial discharge on the monitor screen 18 ', and the display of the zero point marker are not limited to those of the above-described embodiment.

[0041]

The present invention has the following effects. A divided voltage of the actual applied voltage of the test winding device 1 is generated by a voltage dividing capacitor 11, and the divided voltage is divided by a voltage detecting resistor 12.
Thus, the current can be converted into current and detected.

Further, the display processing means (display processing unit 14) of the corona measuring device 13 forms a zero-point marker e in synchronization with the phase zero of the actually applied voltage of the test winding device 1, and the zero-point marker e Can be displayed on the screen together with the voltage waveform of the partial discharge.

Then, the zero point marker e displayed on the screen of the corona measuring device 13 makes it possible to immediately know the phase zero point of the applied voltage of the test winding device 1, and to determine the partial discharge generation phase based on this zero point. It can be easily grasped without any deviation, and from this result, the position (point) where partial discharge occurs in the test winding device 1 can be grasped accurately, and insulation verification between layers can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a connection diagram of one embodiment of the present invention.

FIG. 2 is a detailed circuit block diagram of the corona measuring device of FIG.

FIG. 3 is a front view of a monitor screen of the CRT in FIG. 2;

FIG. 4 is a connection diagram of a conventional circuit.

5 is a front view of a monitor screen of the corona measuring device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Test winding apparatus 2u, 2v, 2w winding 3 Neutral point 4 Capacitor bushing 6 Resonance capacitor 7 High frequency power supply 11 Voltage dividing capacitor 12 Voltage detection resistor 13 Corona measuring instrument 14 Display processing unit 18 CRT e Zero point marker

Claims (1)

[Claims] 1. An AC voltage having a frequency higher than a system frequency,
The voltage is boosted by the series resonance method and applied between the end of the target winding of the test winding device and the end of the remaining winding, and the voltage of the partial discharge generated in the test winding device is corona measured. In the layer corona test circuit which detects the voltage waveform of the partial discharge on the screen by the corona measuring device, the capacitor bushing at the neutral point of the test winding device or at the end of the winding of interest and the ground. A voltage dividing capacitor, which is provided between the capacitor bushing and the voltage dividing capacitor, and is provided between the connection point of the capacitor bushing and the voltage dividing capacitor and the corona measuring device; A voltage detection resistor for converting a pressure into a current, and a phase zero point of the applied voltage, which is provided in the corona measuring device and detects a phase zero of the applied voltage from a current flowing through the voltage detection resistor, and forms a zero point marker synchronized with the phase zero. Said Reyakorona test circuit, characterized in that a display processing means for adding to the surface display.