JPS6027865A - Impulse voltage testing circuit for electric appliance - Google Patents

Abstract

PURPOSE:To perform an impulse voltage testing between phases and poles avoiding the application of excessive voltage to a ground insulation part by using an impulse voltage generator with a voltage dividing means. CONSTITUTION:A metal body 4a of a sample appliance 4 used always grounded is insulated from the ground through an insulation device 10. The metal body 4a is connected to an intermediate potential tap (m) of a voltage dividing means 11 provided in parallel on an impulse voltage generator 1. Then, one of conductors intended for application of a voltage is connected to a high voltage terminal of the generator 1 and the other grounded. As a result, a specified impulse voltage is applied between the phases or poles of the appliance 4. At this point, a voltage reduced by a voltage supported by the insulation device 10 is applied to the ground insulation part of the appliance 4. Thus, by adjusting the position of the intermediate potential tap (m), an impulse voltage testing can be done between the phases and poles avoiding the application of excessive voltage to the ground insulation part.

Description

[Detailed Description of the Invention] [Field of contact to which the invention pertains] The present invention relates to a circuit breaker, an f! This invention relates to a test circuit for impulse voltage tests between conductors of different phases or between poles of the same phase, which are performed by applying a voltage that may exceed the withstand voltage of ground insulation in electrical equipment such as MM switchgears and high specific gravity S panels.

[Prior art and interlayer points]

In high-voltage electrical equipment, insulation sl to normal voltage)
In general, the dielectric strength between different phases (phase-to-phase insulation) or between poles of the same phase (inter-pole insulation) should be higher than the dielectric strength between the high-voltage conductor and a metal body such as a container (earth insulation). is necessary. For example, the phase-to-phase insulation is 1.6 of the ground insulation.
Normally, the insulation between poles is 115 times that of the ground insulation. When performing an impulse voltage test on electrical equipment installed according to these specificationsff), one terminal of the impulse voltage generator must be connected to '! i! ! Because it is at earth potential, other phases must be grounded during phase-to-phase insulation tests, for example.

In this case, a voltage is necessarily applied to the ground insulation side as well. To verify phase-to-phase insulation, it is necessary to apply a voltage 1.5 times higher than in the case of earth insulation, so unless the test circuit is devised, there is a risk that the earth insulation will not be able to withstand the correlation test. In addition, since it is not possible for the other phase or other pole to be grounded under actual operating conditions, there are drawbacks that make this method an ideal test method.

Also, when verifying insulation between poles of the same phase, 1.
Since a voltage 15 times higher is applied, a test circuit in which one conductor is grounded will have the same problem as in the 1 m electromotive correlation test.

Figures 1 and 2 are connection diagrams of a conventional impulse voltage test circuit that has improved the above-mentioned problems. Figure 1 is a correlation test circuit,
The figure shows an example of a pole-to-pole test circuit, and in both cases, the equipment under test is a Y-phase collective type circuit breaker. In the figure; 1 is an impulse voltage generator, 2 is a high voltage generator such as DC voltage, AC voltage, impulse voltage, etc., 4 is a test circuit breaker, 41 is a capacitive container (metallic body) used when grounded, 4b is each phase cutoff section.

4C is a high voltage conductor and B is a bushing. In the case of the correlation test circuit shown in Figure 1, 1!5 closed capacity 1t14m is 'M! Each phase cutoff s4b is in the closed state, one phase is connected to the impulse voltage generator 1, and the other two phases are connected to the high voltage generator 1112.
connected to. With such a test circuit, voltage is applied to the circuit breaker 4 by the two voltage generators 1 and 2, but the voltage generated by the impulse voltage generator 1 is applied to the circuit breaker 4 by the ground insulation (between Q and 4a). m below the voltage that can withstand
For the shortfall in the test voltage, a voltage of opposite polarity is supplied from the generator 2 at the other end.

In this way, by determining the voltages generated by the two high voltage generators 1 and 2 in consideration of the withstand voltage value of the ground insulating section, a phase impulse voltage test can be carried out without applying excessive voltage to the ground insulating section. In the inter-electrode test shown in Fig. 2, an inter-electrode impulse voltage test is carried out in the same manner as the inter-electrode test by opening the interrupter 4b and applying voltages of opposite polarity between the two generators 1 and 2 between the electrodes. can. However, this method requires two voltage generators and a synchronization circuit 8 that adjusts the voltage generation phases of both so that the polarities are opposite to each other. In addition, if the EUT 4 has dielectric breakdown, there is a risk that the breakdown current will flow into the other generator 2 and damage the generator 2, so in order to protect the generator 2, a discharge gap etc. Protection circuit 3
Requires.

Furthermore, since there are voltage generators on both sides, if you are not careful, depending on the circuit, the voltage generated by each generator may be divided by the correlation of the f14 under test or the capacitance between poles and the impedance of the other generator. When calculating the correlation between the test equipment 4 or the voltage applied between the poles, it may not be the simple sum of the voltages of the four generators.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned situation, and provides a test circuit that can perform mutual and interpole impulse voltage tests using a single impulse voltage generator without applying excessive voltage to the ground insulation part. The purpose is to

[Key points of the invention]

According to the present invention, the above-mentioned object is to ground metal bodies such as tanks, cases, supports, or iron cores of equipment under test that face live parts and are normally grounded using an insulating device such as an insulating frame. Connect one voltage-applying conductor of the equipment under test to the high-voltage terminal of the impulse voltage generator, connect the remaining voltage-applying conductor directly to the A metal body of the equipment under test is connected to the intermediate potential tap of the means, and a part of the voltage generated by the impulse voltage generator is borne by the insulating device such as the insulating frame to reduce the voltage burden on the ground line ll1IK of the equipment under test. This was achieved by configuring a test circuit so that a predetermined phase-to-plane or inter-electrode impulse test voltage is applied between the one and the other voltage-applied conductors.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

3.4 is a connection diagram of an impulse voltage test circuit showing an embodiment of the present invention, FIG. 3 is a correlation test circuit, and FIG. 4 is a gap test circuit. In the figure 7, test three-phase collective cutoff 81
The airtight container 4a of No. 4 is insulated from the earth by an insulating part ff1lO such as an insulating frame, and the voltage dividing means 11, such as a discharge resistor or a voltage dividing resistor, which is provided in parallel with the impulse voltage generator ni, is connected by an application line 12. Connected to intermediate potential tap appeal. On the other hand, the voltage applied conductor consisting of the interrupting part 4bt high voltage conductor 4c + bushing 6 etc. of the test device 4 is 8
In the correlation test shown in FIG. 3, for example, the A-phase conductor is connected to the high-voltage terminal of the impulse voltage generator @11 and the high-voltage terminal H of the voltage dividing means 11 by the application line 6, and the B-phase and C-phase conductors are directly grounded. In addition, in the inter-electrode test shown in Fig. 4, the interrupting portion 4b
is opened, one pole side is connected to the high voltage end of the impulse voltage generator in parallel for each phase, and the other pole side is grounded for each phase. In the test circuit connected in this way, the output voltage of the impulse voltage generator 1 is applied to the circuit breaker under test or between the poles, but the output voltage is applied to the closed vessel 4m at a predetermined voltage division ratio by the voltage dividing means 11. An intermediate potential is applied as a result of which the output voltage of the impulse voltage generator is
(for example, between 4a and 4b) and the insulating device 10
The share will be shared by a predetermined specific weight. Therefore, the voltage applied to the ground insulation part of the test circuit breaker 4 can be arbitrarily selected by changing the intermediate potential tap of the voltage dividing means 11 that connects the sealed container (metal body), etc. The purpose of the present invention, which is to perform phase-to-plane or pole-to-pole impulse voltage tests, can be achieved by the voltage generator 1 without applying excessive voltage to the ground insulation of the equipment under test.

6th=6*7 FIG. 7 is an equivalent circuit diagram of a test circuit for explaining the configuration of the voltage dividing means in the above-described embodiment. In the figure, Ct is the capacitance between phases or electrodes to which the test voltage of the equipment under test is applied, and CP is the capacitance between the conductor to which the impulse voltage is applied and a metal body such as a sealed container (ground insulation). , Ce% is the ground capacitance of the metal body insulated by the insulating device 10.

FIG. 6 shows an equivalent circuit when a resistive voltage divider 11 is used as a voltage dividing means, in which capacitances Cp and Cs are connected in parallel to a resistor 11a between m-H and a resistor 11b between TrL-B, respectively. Therefore, the potential of the intermediate potential tap is affected by the capacitances Cp and C・ of the equipment under test. Therefore, when determining the potential of the metal body 4a of the test device 114, the position of the intermediate potential tap door is determined in consideration of the influence of the capacitances C) and C.

In addition, if the discharge resistor of the impulse voltage generator is used as a resistive voltage divider, the resistance value is generally low, so C), C.
It is convenient because it can reduce the influence of

Figure 6 shows a modification of the pressure dividing means, in which the static SS amount C
If the ratio of the magnitudes of ν and C@ is significantly larger than the ratio of the magnitudes of resistance r%11maro and 11m, connect either capacitance Cz or Cm between H-111 or between the earthquake and the blade. By doing so, it is possible to prevent distortion of the applied voltage waveform and bring the potential of the intermediate potential tap close to the voltage division ratio of the resistor voltage division 1111.

FIG. 7 shows an example in which a capacitor type voltage divider 21 is used as the voltage dividing means. When a wavefront adjustment capacitor with a relatively large capacity is provided for adjusting the output voltage waveform of the impulse voltage generator 1, this Capacitors can be used as voltage dividing means.

〔Effect of the invention〕

According to the present invention, the voltage applied conductor is insulated from the ground by the insulating device 10 shown in FIG. One of the conductors was connected to the high voltage end of the impulse voltage generator, and the other conductor was connected to the ground. As a result, a predetermined impulse test voltage is applied between the phases or poles of the equipment under test, and this
Since a voltage reduced by the voltage applied to the insulating device 10 is applied to s, by adjusting the position of the intermediate potential tap of the voltage divider m11, it is possible to prevent excessive voltage from being applied to the ground insulation part. Impulse voltage tests between phases or poles can be carried out at any time. Also, the high voltage generator fi12 in the conventional test circuit. The synchronizer 18 + protection circuit 3, etc. are no longer necessary, and at the same time, a monovoltaic resistor or a wavefront adjustment capacitor attached to the impulse voltage generator can be used as the voltage dividing means. Therefore, there are advantages in that the test equipment is simplified and the test preparation work is also labor-saving. Further, the correlation or the ratio between the electrode-to-electrode voltage and the ground voltage can be determined arbitrarily and fI!
Im can be selected, and a highly reliable verification test can be performed because the voltage waveform applied to the correlation or between the poles and the voltage waveform applied to the ground insulation are almost equal.

[Brief explanation of the drawing]

Figure 81.2 is a connection diagram of a conventional impulse voltage test circuit, where Figure 1 is a connection diagram for an interpolation test, SIA diagram is a connection diagram for an interpolation test, and II! Figure 1.4 is a connection diagram of the impulse voltage test circuit showing the actual mW of the present invention,
Figure s is a connection diagram for a phase-to-phase test, Figure 4 is a connection diagram for a pole-to-electrode test, and Figures 6 and 7 are equivalent circuit diagrams showing details of the voltage dividing means in the test circuit of the embodiment of the present invention. Figure 6 shows a case where a resistor voltage divider is used as the voltage dividing means, Figure 6 shows a modification using a combination of a resistor voltage divider and a capacitor, and Figure 7 shows a case where a capacitor type voltage divider is also used. It is an equivalent circuit diagram. In the figure, 1...impulse voltage generator, 2...
High voltage generator 13... Protection circuit, 4... Equipment under test, 4--... Metal body (for example, constant weight container), 4b... Breaking part % 4c... High voltage conductor, 6... Bushing , 8
...Synchronizer, 11,21...-Voltage dividing means, depression...
Intermediate potential tap, Cz, Cs, Ca meeting $6 capacitor”
j, C*+C11*C@-1・The capacitance of each part of the equipment under test. Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1) Between conductors of different phases or between poles of the same phase of a high-voltage electric device that includes a plurality of S parts that are insulated from each other and a metal body that faces the xsia part and is normally grounded. In an impulse voltage test circuit between conductors, one voltage applied conductor is conductively connected to a high voltage terminal of an impulse voltage generator, the other voltage applied conductor is grounded, and the metal body is insulated from earth by an insulating device. and conductively connected to an intermediate potential tap of a voltage dividing means provided in parallel with the impulse voltage generator, and a predetermined voltage lower than the impulse voltage applied between the voltage applied conductors is applied to the metal body and one and the other. An impulse voltage test circuit for electrical equipment, characterized in that a voltage is applied between conductors. 2. Claim 11! An impulse voltage test circuit for electrical equipment, characterized in that the voltage dividing means comprises a resistor. 3) In the circuit described in claim 82, the voltage dividing means consisting of m@ device is connected between the intermediate potential tap and the ground or 6
An impulse voltage test circuit for electrical equipment, comprising a capacitor for a voltage division ratio mW & in parallel between high voltage terminals. 4) An impulse voltage testing circuit for electrical equipment as claimed in claim 11111!11, wherein the voltage dividing means is a capacitor provided for adjusting the wavefront of the impulse voltage.