JPH0361877A - Testing circuit for insulation recovery of switching apparatus - Google Patents

Abstract

PURPOSE:To achieve a compact configuration and low cost for a power source capacitor by constituting a circuit so that a parallel capacitor is directly charged with the electric charge from the power source capacitor through a series capacitor. CONSTITUTION:The resistance value of a series resistor (Rg) 11 is selected beforehand so that the electric charge which is charged in a series capacitor (Cg) 10 is discharged and made to disappear until a cutoff time t3. Then, the terminal voltage Eo of the series capacitor becomes approximately zero as shown in a voltage waveform 205 at the time t3. At this time, insulation between the electrodes of a breaker under test 1 is recovering. A current flowing through a starting gap 9 is only what flows across the capacity Co (including the capacitance C3 of a breaker under test 1) of a parallel capacitor (Co) 15 through a limiting resistor (Rv) 13 having the resistance Rv and a parallel resistor (Ro) 14 having the resistance Ro. Since the current is remarkably reduced, the discharging of the starting gap 9 is stopped. Then, the charging of the parallel capacitor 15 is performed through the series capacitor 10 and the series resistor 11.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is an insulation recovery method for verifying the insulation recovery characteristics between poles immediately after arc extinguishment in current interruption of switching equipment such as circuit breakers and switches. Regarding test circuits.

[Conventional technology]

Immediately after the current is cut off in switching equipment, high-temperature gas and plasma heated by the arc remain between the poles. Therefore, the dielectric strength between the electrodes is in a very low state immediately after the 7-ring disappears at the zero flow point. However, as time passes, the distance between the electrodes increases, the gas cools, and the plasma recombines, so the dielectric strength between the electrodes gradually recovers. The dielectric strength between the electrodes at this time is called dielectric recovery voltage. on the other hand,
A transient recovery voltage generated in the power system is applied between the poles after the interruption. If this transient recovery voltage is always less than the insulation recovery voltage between the electrodes, the interruption will be successful, but if it becomes higher than that, an arc will occur again between the electrodes due to insulation breakdown, and the interruption will become impossible. Therefore, insulation recovery characteristics are one of the important characteristics that indicate the breaking performance of switching equipment, and insulation recovery tests are performed to improve and confirm the performance of switching equipment.

Direct short-circuit testing using a circuit that supplies the breaking current and transient recovery voltage from the same power source as in a practical line is preferable for insulation recovery testing, but this is difficult because the scale of the testing equipment is large. As an alternative means,
A synthetic short-circuit test method is used in which circuits supply the interrupting current and transient recovery voltage from separate power supplies.

Figure 3 is an insulation recovery test circuit diagram using the conventional synthetic short-circuit test method.

Volume 108, No. 11, 1986. P541), and FIG. 4 is a waveform diagram showing temporal changes in voltage and current generated in the circuit of FIG. 3.

In FIG. 3, a series circuit breaker is connected to a high current power source 2 such as a short circuit t81. Circuit breaker 3 and current source circuit breaker 5. A current source circuit 6 supplies a breaking current 26 to the test circuit breaker 1 via a series reactor 4, a power supply capacitor 8 charged to a predetermined voltage by a DC power supply 7, and iI! a voltage source circuit 12 consisting of a starting gap 9 connected to the starting gap 9; and a resonant accelerator 2L rectifier 22 connected to the starting gap 9. Damping resistor 23. and a series resonant circuit 25 consisting of a series circuit of a resonant capacitor 24, a limiting resistor 13 connecting this series resonant circuit 25 and the circuit breaker under test 1, and the circuit breaker under test 1
A test circuit is constituted by a recovery voltage waveform adjustment circuit 16 consisting of a series circuit of a parallel resistor 14 and a parallel capacitor 15 connected in parallel.

The conventional test method will be explained based on the circuit diagram shown in FIG. 3 and the circuit diagram shown in FIG. 4. Before starting the test, the test circuit breaker 1 and 1i current source circuit breaker 5 are turned on, and the power supply capacitor 8 is also charged with a predetermined voltage.The voltage protection circuit breaker 3 is turned on to cut off the AC. The circuit breaker under test 1 issues an opening command to the circuit breaker under test 1 and the current source circuit breaker 5 while the current 26 is flowing through the current source circuit 6.
If the opening time of the current source circuit breaker 5 (i.e., the time when the arc starts to occur) is t, and the breaking time (i.e., the final current zero point at which the arc disappears) is t, then the breaking current 26
For example, the current waveform is as shown in the current waveform 201 in FIG. 2. The pinched portion corresponds to the arc occurrence period XJI, and after time t, the current supply from the current source circuit 6 is stopped, so the current becomes zero.

At time t2 immediately before the zero point t of the interrupting current 26, the starting pulse signal 2o is generated from the starting pulse generator 19 to discharge the starting gap 9, and the current capacitor 8 is charged! The load flows through the series resonant circuit 25 as an oscillating current, charging the resonant capacitor 24.

The terminal voltage of the resonant capacitor 24 is voltage waveform 2 in FIG.
When charged to the first peak value of the oscillating voltage as shown in 02,
The charging of the resonant capacitor 24 is interrupted because the rectifier 22 blocks the oscillating current of opposite polarity.

On the other hand, a part of the electric charge charged in the power supply capacitor 8 also flows to the recovery voltage waveform adjustment circuit 16 and the test circuit breaker 1. The voltage applied between the poles of the test circuit breaker 1 is as shown in the voltage waveform 203 in FIG. 4 at time t.

Until then, the voltage is zero because the arc between the electrodes causes a short circuit, but after time t3, the arc disappears, so the insulation between the electrodes is restored, and the time constant τ of the recovery voltage waveform adjustment circuit 16 increases.

stand up by However, when the voltage applied between the terminals of the test circuit breaker I rises to its own insulation recovery voltage between poles, it becomes zero due to dielectric breakdown, and then returns to the time constant τ.

After that, the same process repeats to form a voltage waveform 203. Therefore, in FIG. 4, a characteristic curve 204 connecting the dielectric breakdown points of the voltage waveform 203 shows the change over time in the dielectric recovery voltage of the test circuit breaker l.

[Problems to be Solved by the Invention] In the voltage source circuit 12 in FIG. The circuit is configured to discharge electricity again to the test circuit breaker 1 via the limiting resistor 13. When the power supply capacitor 8 is charged with a voltage Ev, the maximum value E0 of the voltage E generated in the resonance capacitor 24 is E*-/Ev = K-
A −−−−−−−−−−(1), where K −Cw / (Cv + C,) −・・・
-------・(2+Cv+Ca is the capacitance of the power supply capacitor 8, the resonant capacitor 24, Lv is the inductance of the resonant axle 21, and Ro is the voltage E of the resistance capacitor 24 of the attenuation resistor 23. However, If E is the voltage E after dielectric breakdown occurs n times and data on n dielectric recovery voltages are obtained, the following relational expression holds true.

C1 E,, /E,, -< ”)--
・−・−・−・−(4) C@ + Cm + Ce, where C0 is the capacitance of the parallel capacitor 15, and C3 is the capacitance of the test circuit breaker 1 including the stray capacitance 17. It is. Therefore, the voltage E charged to the test circuit breaker l
, and the voltage Ev charged in the power supply capacitor 8, from equations +1) and (4), C1 Ha-/By = K-A ・()''--(51C
m ” Cs ” C.

When conducting an insulation recovery test, E as the rated voltage of the test circuit breaker I increases. also requires high voltage. In order to make E-/EV in equation (5) as large as possible, make A as close to 2 as possible and Cv )C
m) It is necessary to set Cs + Go.

For example, if R11=IO, it becomes l A ” 2, so Cv -too Cm lC, -100(Cs
In the case of +Co Ln-5, from equation (5), it becomes 101 101 , and the voltage E is approximately twice the charging voltage Ev of the Kugen capacitor 8. However, the capacity of the power supply capacitor 8 is CW -10' -(cs +CO),
n1 of test circuit breaker l! The drawback is that it requires equipment that is four orders of magnitude larger than the capacity.

Furthermore, a rectifier 22 is required to maintain the first peak value of the vibration waveform and cut subsequent vibrations. This rectifier 22 needs to withstand high voltage and high frequency current specifications as the rated voltage of the test circuit breaker 1 becomes higher, and there is a drawback that a large rectifier 22 must be installed. In addition, a resonant axle 21 is also required to cause the voltage to resonate in series, which has the drawback of complicating the configuration of the test circuit and requiring a large amount of equipment cost.

An object of the present invention is to simplify the circuit configuration of an insulation recovery test circuit and reduce equipment costs.

[Means to solve the problem]

In order to solve the above problems, the present invention includes a current source circuit that supplies a breaking current to a test switchgear whose arc time is predetermined via a series circuit breaker and a reactor, and a current source circuit that is charged to a predetermined voltage by a DC power supply. A voltage source circuit that includes a power supply capacitor that is connected in series with this and a starting gap that is discharged by a starting pulse signal just before the zero point of the current that interrupts the arc of the switchgear under test, and a restriction that connects this voltage source circuit and the switchgear under test. It consists of a resistor and a recovery voltage waveform adjustment circuit consisting of a series circuit of a parallel resistor and a parallel capacitor connected in parallel between the poles of the switchgear under test, and the change over time in the insulation recovery voltage after current interruption of the switchgear under test. In the circuit for testing, the voltage source circuit includes a series circuit of a series resistor and a series capacitor connected in parallel to the starting gap and connected in series between the power supply capacitor and the limiting resistor. shall be taken as a thing.

[Effect]

In the above-mentioned means, by configuring so that the charged charge of the power supply capacitor is directly supplied to the test switchgear including stray capacitance and the parallel capacitor via the series capacitor,
The series resonant circuit, especially the resonant capacitor, which was conventionally required to obtain twice the charging voltage, is no longer required, and the capacity of the power supply capacitor can be reduced to several tens of times. is not necessary, and the voltage source circuit can be simplified. Also, by eliminating the resonant capacitor, the discharge current in the starting gap is reduced and the starting gap cannot sustainably supply charging current to its parallel capacitor. By providing a series circuit, the parallel capacitor is continuously charged via this. Power supply: I7 device and the capacitance of the series capacitor are connected to the test switchgear including stray capacitance and the parallel capacitor. By making the capacitance sufficiently larger than the sum of the capacitance and the capacitance, the voltage charged in the power supply capacitor can be transferred to the switchgear under test with almost no drop.

〔Example〕

The present invention will be explained below based on examples. FIG. 1 is an insulation recovery test circuit diagram showing an embodiment of the present invention, and FIG.
The figure is a waveform diagram showing changes over time in the voltage and current generated in the circuit of FIG.

The test circuit in FIG. 1 is a current source circuit that supplies a breaking current 26 from a large current power source 2 to a test circuit breaker 1 via a protective circuit breaker 3 which is a series circuit breaker, a current source circuit breaker 5, and a series reactor 4. 6, a power supply capacitor 8 charged to a predetermined voltage Ev by a DC power supply 7, a starting gap 9 connected in series to this, a series capacitor 10 and a series resistor 11 connected in parallel to the starting gear and gap 9. A voltage source circuit 12 consisting of a series circuit, a limiting resistor [3] connecting this voltage source circuit 12 and the circuit breaker under test 1, and a parallel resistor 14 and a parallel capacitor 15 connected in parallel to the circuit breaker under test 1. The recovery voltage waveform adjustment circuit 16 is composed of a series circuit.

The test method according to the example will be explained based on FIGS. 1 and 2. Before starting the test, the test circuit breaker 1 and the current source circuit breaker 5 are turned on in advance, and the power supply capacitor 8 is also charged to Ev by DC power #7.

At this time, since the test circuit breaker 1 is closed, the series resistor 11. The series capacitor 10 is also connected to E via the limiting resistor 13.
It is charged to v. With the protective circuit breaker 3 turned on and the AC breaking current 26 flowing through the current source circuit 6, an opening command is issued to the test circuit breaker 1 and the current source circuit breaker 5.

The opening time of the test circuit breaker 1 and the current B circuit breaker 5 is t.

Set the cutoff time to 1. Then, the breaking current 26 is, for example, the second
The current waveform becomes like the current waveform 201 in the figure. The hunted portion corresponds to the arc generation period, and from time 1 onward, the current supply from the current source circuit 6 ceases and the insulation of the test circuit breaker 1 begins to recover.

When the starting pulse signal 20 is generated from the starting pulse generator 19 at time 11 immediately before the zero point ts of the breaking current 26 and the starting gap 9 is discharged, the electric charge stored in the series capacitor 10 is transferred to the series resistor 11 and the starting pulse signal 20 is discharged. gap 9
The current flows through a closed circuit consisting of a series circuit with
If the resistance value of the series resistor 11 is selected in advance so that the electric charge stored in the series capacitor 10 is discharged and disappears, the terminal voltage E of the series capacitor at time t becomes the voltage shown in Fig. 2. As shown by waveform 205, it becomes almost zero.

At this time, the insulation between the poles of the test circuit breaker 1 is being restored, and the current flowing through the starting gap 9 passes through the resistance Rv of the limiting resistor 13 and the resistance R0 of the parallel resistor 14, and the electrostatic charge of the parallel capacitor 15 Capacity C, (including capacitance c of test circuit breaker 1
1 and the current decreases significantly, so that the starting gap 9 stops discharging and the parallel capacitor 15 is then charged via the series capacitor 10 and the series resistor 11.

When the insulation between the poles of the test circuit breaker 1 is restored, the voltage applied between the poles is equal to the circuit time constant τ. It is possible to obtain dielectric recovery characteristics. The voltage waveform 203 in FIG.
It shows the time change of the voltage E0 applied between the poles, and the characteristic curve &1
1204 indicates the insulation recovery characteristics of the test circuit breaker 1. In order to prevent the series capacitor 10 from bearing too much voltage, the capacitance NC1 of the series capacitor 10 is equal to the capacitance of the test circuit breaker 1 and the parallel capacitor 15. Choose a value that is sufficiently larger than the sum (CS+C,).

When the power supply capacitor 8 is charged with the voltage Ev, n@
If the voltage of the power supply capacitor 8 after dielectric breakdown is El, the following relationship holds true.

C.

Ev, l/Ev −()″ −−−−−f7+Cv
+ Cm + C.

For example, Cv"100 (Cs +Co)+n-
5, equation (7) becomes 01. In order to apply twice the voltage to the test circuit breaker 1 as in the case of the conventional method, T1. Charging of B capacitor 8 1
If we double the voltage, we get 0.951 x 2-1.90
The voltage generated in the conventional method in equation (6) is the same. However, the power supply capacitor 8 in this invention
Since the capacitance ICV of is two orders of magnitude smaller than that of the conventional method, the capacitance of the capacitor is 4/100 = 1/
25, which is smaller than the conventional method.

〔Effect of the invention〕

This invention comprises a series resistor and a series capacitor which are connected in parallel to the starting gap as a voltage source circuit (as described above) and which are connected in series between the 1i:a capacitor and the control resistor. Circuit so that it is directly charged by the charging charge of the power supply capacitor through the series capacitor! a.

As a result, the static t of the conventional method and 11.
′! The amount of ¥ is 1/100th. The voltage will be doubled, so
The capacitance is 25 minutes], and 1[the effect of making the capacitor smaller and lower in price can be obtained.

In addition, the large rectifier and resonant axle that were required in the conventional method are no longer necessary because they do not use a resonant circuit, resulting in a simplified insulation recovery test circuit, resulting in the insulation recovery of switching equipment. The effect is that the equipment cost of the test circuit is reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for an insulation recovery test of a circuit breaker showing an embodiment of the present invention, and FIG. 2 shows the voltage generated in the circuit of FIG.
FIG. 3 is a waveform diagram showing changes over time in IT current, etc., FIG. 3 is an insulation recovery test circuit diagram of a circuit breaker showing a conventional example, and FIG. 4 is a voltage generated in the circuit of FIG. 3. 3: Protective circuit breaker, 4: Series reactor, 5: Current 1lI
l Breaker, 6: Current source circuit, 7: DC power supply, 8: TsB
capacitor, 9: starting gap, IO = series capacitor, 11: I [column resistor, 12: voltage source circuit, 13: limiting resistor, 14: parallel resistor, 15: parallel capacitor, 1
6: Recovery voltage waveform adjustment circuit, 17: Stray vessel, 18: Grounding 1.19: Starting pulse generator, 20: Starting pulse signal, 21: Resonant axle, 22: Rectifier, 23: Damping resistor, 24: Resonance Capacitor, 25: Series name ■ Diagram

Claims (1)

[Claims] 1) A current source circuit that supplies a breaking current to the switching equipment under test whose arc time is predetermined via a series circuit breaker and reactor, a power supply capacitor that is charged to a predetermined voltage by a DC power source, and the switching equipment under test that is connected in series with this. A voltage source circuit that includes a starting gap that is discharged by a starting pulse signal just before the zero point of the current at which the equipment interrupts the arc, a limiting resistor that connects this voltage source circuit and the switching equipment under test, and a parallel circuit between the poles of the switching equipment under test. It consists of a recovery voltage waveform adjustment circuit consisting of a series circuit of connected parallel resistors and parallel capacitors,
In a circuit for testing changes over time in insulation recovery voltage after current interruption of a test switchgear, the voltage source circuit is connected in parallel to the starting gap and connected in series between the power supply capacitor and the limiting resistor. An insulation recovery test circuit for switching equipment characterized by comprising a series circuit of a series resistor and a series capacitor.