JP3132250B2 - Transient recovery voltage measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a characteristic waveform of a transient recovery voltage which appears when a short-circuit current of a switching device such as a circuit breaker is cut off.

[0002]

2. Description of the Related Art There are the following six methods for determining a transient recovery voltage (TRV) characteristic waveform.

[0003] (1) Short-circuit short circuit method (2) Commercial frequency current injection method (3) Capacitance current injection method (4) Model network (5) Calculation from circuit constant (6) Test circuit including transformer No-load interruption Among the six determination methods, the direct interruption method of the short circuit of the item (1) is the most suitable method for evaluating the TRV characteristic waveform. That is, FIG. 4 shows a basic short-circuit test circuit showing a direct cut-off method. In FIG.
Is a protection circuit breaker, 2a is an A-phase contact of the protection circuit breaker 2, 2b is a B-phase contact, and 2c is a C-phase contact. 3a ~
3c is a current limiting reactor, 4 is a thrower, and contacts 4a,
4b and 4c. Reference numeral 5 denotes a test circuit breaker. The test circuit breaker 5 includes an A-phase contact 5a, a B-phase contact 5b, and a C-phase contact 5.
c. 6a to 6c are resistors for adjusting the transient recovery voltage, and 7a to 7c are capacitors for adjusting the transient recovery voltage.

FIG. 5 is an equivalent circuit of the short-circuit test circuit shown in FIG.
Ec is the output voltage of the short-circuit generator 1.

As shown in FIG. 5, when the phase A is the first phase cut-off, the phases B and C are energized and have the ground potential.
Accordingly, the voltage across the resistor 6a and the capacitor 7a is a transient recovery voltage (TRV) that is a voltage that is 1.5 times the A-phase voltage E _A × 1.5. The phase A is also at the ground potential until the current is cut off, and the voltage across the resistor 6a and the capacitor 7a is also zero.

[0006]

Although the direct breaking method of the short circuit is generally used, the waveform distortion due to the arc voltage, the post arc current, and the current chopping always occurs, and the transient obtained at the time of the ideal breaking. Recovery voltage (TR
V) It may be different from the unique waveform. Therefore, there are the following disadvantages.

(1a) It is difficult to measure a voltage zero point due to arc voltage generation.

(2a) The TRV waveform is reduced by the residual current (post-arc current).

(3a) In some cases, the arc voltage near the current zero point sharply rises, causing a current cutoff, resulting in a significantly different TRV waveform.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a transient recovery voltage measuring method capable of measuring a transient recovery voltage unique waveform without being affected by arc voltage or current interruption. It is to be.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a circuit configuration in which only one phase corresponding to the first phase cut-off phase is not connected to the short-circuit point. And after a lapse of a predetermined time, a voltage between the first phase and the ground is measured.

[0012]

Since no short-circuit current flows through the first phase, there is no distortion of the transient recovery voltage due to the arc voltage, reduction of the transient recovery voltage due to the residual current, and no significant deformation of the transient recovery voltage due to the current interruption.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a transient recovery voltage measuring circuit used in a transient recovery voltage measuring method according to an embodiment of the present invention.
The same or corresponding parts as those in FIG. 4 are denoted by the same reference numerals.

In the circuit of FIG. 1, the A-phase contact 2a, the B-phase contact 2b and the C-phase contact 2c of the protection circuit breaker 2 are connected to the short-circuit generator 1, and the contacts 2a, 2b,
The contacts 4a, 4b, 4c of the thrower 4 are connected to 2c via current limiting reactors 3a, 3b, 3c. Also,
The contacts 4a, 4b and 4c of the input device 4 are connected to the contacts 5a, 5b and 5c of the circuit breaker 5, and the contacts 5b and 5c of the circuit breaker 5 are grounded.

Each phase between the input device 4 and the circuit breaker 5 is grounded via a resistor and a capacitor. Therefore, only one phase (A phase) corresponding to the first phase cutoff phase has a circuit configuration in which the short-circuit point is not grounded.

FIG. 2 shows the first phase cutoff T in the circuit of FIG.
FIG. 3 is a waveform diagram of current I and voltage V of each phase at the time of TRV measurement. In FIG. 3, AGV is the output voltage of the short-circuit generator 1, C phase I is C phase current, and C phase V is C
Phase voltage, B phase I is B phase current, B phase V is B phase voltage, A phase I
Is an A-phase current, and A-phase V is an A-phase voltage.

In this embodiment, the measurement of the transient recovery voltage is performed in the following procedure.

(1A) The protective circuit breaker 2 and the test circuit breaker 5 are manually turned on, and the shutter 4 is turned off.

(2A) The short-circuit generator 1 is excited, and the generator output voltage AGV is raised to a predetermined supply voltage (the rated voltage of the circuit breaker 5) and held as shown in FIG.

(3A) As shown in FIG. 3, the B-phase contact 4b and the C-phase contact 4c of the thrower 4 are thrown by issuing a throwing command 90 degrees earlier than the A-phase by a timer.

(4A) Short-circuit currents (C-phase I and B-phase I) limited by the current limiting reactors 3b and 3c at the time when the injector 4 is turned on flow through the B-phase and the C-phase (B and C phases). Is set to 90 degrees or 270 degrees). At this time, the same phenomenon occurs as in the period from the completion of the first phase cutoff to the completion of the second and third phase cutoffs in FIG.

(5A) Next, the A-phase contact 4a of the thrower 4 is
It is turned on 90 degrees after the short-circuit current flows in the B and C phases.

(6A) As shown in FIG. 1, the A phase is not connected to the B and C phases and the circuit is cut off, so that no short-circuit current flows as shown in the A phase I of FIG. However, the A-phase is charged up to the power supply terminal voltage of the circuit breaker 5 under test.

(7A) By measuring the voltage between both terminals of the A-phase of the test circuit breaker 5, the same waveform as the transient recovery voltage (TRV) characteristic waveform at the time of the first-phase break in the three-phase short-circuit test can be measured. .

(8A) Thereafter, after the current is supplied for 10 to 20 ms, the B and C phases are cut off by the test circuit breaker or the protection circuit breaker 2.

As shown in FIG. 2, the B and C phases are first energized to produce the same phenomenon as in the case of the interruption of the second and third phases in FIG. Then applying a 1.5 voltage E _A × generated during the first phase interruption in Figure 4 the resistor 6a and the capacitor 7a by placing the insertion unit contacts 4a of the A phase. Since the A-phase contact 5a of the circuit breaker under test is not connected to the ground side, no short-circuit current flows. Therefore, no arc voltage is generated, so that no post-arc current flows and no current interruption occurs.

[0028]

As described above, the present invention has a circuit configuration in which only one phase corresponding to the first phase cut-off phase is not connected to the short-circuit point, and starts supplying a current flowing at the time of the second and third phase cut-offs. ,
Since the voltage between the first phase and the ground is measured after a lapse of a predetermined period of time, the transient recovery obtained at the time of the ideal interruption without being affected by the arc voltage, the residual current (post-arc current), and the current interruption. The voltage (TRV) characteristic waveform can be measured. A high-performance transient recovery voltage measurement method can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a transient recovery voltage measurement circuit for performing a transient recovery voltage measurement method according to an embodiment of the present invention.

FIG. 2 is a first phase cutoff transient recovery voltage generation circuit in the circuit of FIG. 1;

FIG. 3 is a waveform diagram of current and voltage of each phase when a transient recovery voltage is measured by the circuit of FIG. 1;

FIG. 4 is a block diagram of a conventional transient recovery voltage measurement circuit.

5 is a first phase cutoff transient recovery voltage generation circuit based on the circuit of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Short-circuit generator 2 ... Protective breaker 2a-2c ... Protective breaker contact 3a-3c ... Current limiting reactor 4 ... Input device 4a-4c ... Input device contact 5 ... Test circuit breaker 6a-6c ... Resistance 7a ~ 7c ... Capacitor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-142477 (JP, A) JP-A-63-75579 (JP, A) JP-A-49-56180 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) G01R 31/327 G01R 31/333

Claims (2)

(57) [Claims] 1. A circuit configuration in which only one phase corresponding to a first phase cut-off phase is not connected to a short-circuit point, an energizing current at the time of the second and third phase cut-offs starts to flow, and then the first phase after a predetermined time has elapsed. A method of measuring a transient recovery voltage, comprising measuring a voltage between a phase and a ground. 2. A test switchgear is connected to each phase output terminal of the short-circuit power supply via an input device, and only one phase corresponding to the first phase cutoff phase of the test switchgear is separated from the short-circuit point. A circuit configuration in which a transient recovery voltage adjusting circuit composed of a resistor and a capacitor is connected between each phase and the ground between the closing device and the switchgear, and the energizing current when the second and third phases are cut off is a phase without a DC component. A method of measuring a transient recovery voltage, comprising: starting to flow, then, after a predetermined time, closing a contact of a first phase of the thrower to measure a voltage across a transient recovery adjustment circuit of the first phase.