JPH06213978A - Test circuit for switch - Google Patents

Abstract

PURPOSE:To provide a circuit constitution in a test circuit for switches which has a capacitor as a power source charged with direct current, makes the capacitor discharge through the primary coil of a transformer and generates a test current with a specified frequency, and current value so that the statinary part in recovery voltage appearing between both terminals of the switch after the cutoff of the test current by the test switch in the secondary side of the transformer becomes alternating current with equal frequency to the test current frequency. CONSTITUTION:A possibility of the circuit is that a quick closing switch 92 having a short closing time, or a trigger cap or a trigger cap having in series a short circuit where closing operation is mechanically performed and a reactor 41 having nearly equal inductance to the leak inductance appearing in the primary side of transformer 5 are connected in series. Another possible constitution is a series circuit of a capacitor and a reactor having larger inductance than leak inductance of the primary side of the transformer are connected in parallel to the primary coil of the transformer 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a capacitor charged with direct current, a protective circuit breaker, a closing device, and a primary winding of a transformer connected in series. A switch for connecting a disconnection test switch to the secondary side and turning on the switch to discharge the capacitor charged with direct current to generate a test current of a predetermined frequency and a predetermined current value on the secondary side of the transformer. Test circuit.

[0002]

2. Description of the Related Art In recent years, in order to verify the current interruption performance of a switch, a test circuit using a capacitor charged with direct current as a power source and obtaining an alternating current with an LC resonance circuit utilizing the electrostatic capacitance of the capacitor is a generator. It has started to be widely used instead of a large-scale test circuit using. The basic circuit is shown in FIG. A closed circuit is formed by connecting a protective circuit breaker 2, a make-up device 3, a reactor 4 for adjusting a current frequency and a current value 12 to a test value, and a primary winding of a transformer 5 in series with a power supply capacitor 1. The test switch 6 is connected to the secondary side of the transformer 5 so that a predetermined test current 13 and a recovery voltage after the test current is cut off can be obtained.

FIG. 7 shows an explanatory diagram of the sequence of each device of the circuit of FIG. 6 and the waveforms during the interruption test. Prior to the start of the test, the protective circuit breaker 2 is closed and the test switch 6 is also closed. Next, the charging device 10 charges the power supply capacitor 1 to a predetermined DC voltage to complete the test preparation. When the test sequence is started and the injector 3 is closed, a current I21 (Fig. 7) flows through the primary circuit of the transformer. This current changes in size depending on the turns ratio of the transformer 5, and flows as a test current 13 into the test switch 6 on the secondary side. When the test switch 6 is opened as indicated by 61 in FIG. 7, the current reaches a zero value and is cut off in the arc time t1. Further, at this time point, as can be seen from the terminal voltage waveform 11 of the capacitor 1 shown in FIG. 7, the terminal voltage of the transformer secondary winding also has a predetermined recovery voltage, so that the breaking performance of the AC switch depends on the capacitor. It will be verified using a DC power supply.

[0004]

However, due to the interruption of the test current flowing through the secondary circuit of the transformer, the secondary circuit of the transformer is opened, and the stray capacitance 51 to the ground of the transformer secondary winding and the transformer. A recovery voltage accompanied by transient vibration due to the inductance of the secondary winding of the switch is applied between both terminals of the test switch. However, when the secondary circuit of the transformer is opened, the impedance of the primary winding of the transformer changes from leakage impedance (hereinafter also referred to as short-circuit impedance) to exciting impedance having an extremely large value. Therefore, the symbol 1 in FIG.
As shown in Fig. 4, the vibration recovery voltage (pseudo DC voltage) becomes extremely gentle, which is determined by the electrostatic capacity of the power supply capacitor and the excitation impedance of the transformer, and the recovery voltage at the commercial frequency as an AC switch cannot be obtained.

On the other hand, the withstand voltage of the main contact opening gap immediately after the breaking of the current of the switch is barely carried out because the time lapse differs depending on whether the breaking of the current is performed with margin or when it is barely carried out. In this case, the withstand voltage does not rise even after a lapse of time in the steady-state region following the transient oscillating portion of the recovery voltage, but it may level off from leveling off and then re-arc after a few cycles of the commercial frequency. is there. Therefore, in the breaking test of the switch,
After the current is cut off by the switch, the recovery voltage is required to hold at least several cycles of the commercial frequency.

On the other hand, the withstand voltage of the main contact opening gap has a polarity, and if only one polarity is applied as in the DC recovery voltage, the test becomes unnecessarily harsh or a relaxed test. Even if the test is performed with both polarities, the success or failure of the interruption will be judged from the result of the test on the severe side.As with the AC recovery voltage, the two polarities will appear alternately and the voltage between the two peak values will change. There is a problem that it is difficult to judge the equivalence with the case where the period is reduced and the period for insulation recovery is given.

An object of the present invention is to provide a test circuit of an AC switch, which has a basic circuit configuration described at the beginning and uses a capacitor charged with DC as a power source, as a test switch after the current is cut off on the secondary side of the transformer. It is to prevent the steady-state portion of the recovery voltage from becoming a DC voltage, and to provide a circuit that becomes an AC recovery voltage having the same frequency as the test current.

[0008]

In order to solve the above problems, in the present invention, a capacitor charged with direct current, a protective circuit breaker, an injector, and a primary winding of a transformer are connected in series. Is connected to the secondary side of the transformer, the switching test switch is connected to the secondary side of the transformer, the charging device is turned on to discharge the capacitor charged with direct current, and a predetermined frequency is applied to the secondary side of the transformer. Immediately after breaking the test current with the breaking test switch connected to the secondary side of the transformer between the two terminals of the breaking test switch, generate a test current of a specified current value. 1 of the transformer so that the steady-state part of the recovered recovery voltage becomes an alternating recovery voltage having a predetermined frequency and a predetermined peak value.
Equipped with a series circuit in parallel with the secondary winding, a mechanical high-speed injector with a short time from receiving the closing signal to closing the pole, and a reactor having an inductance almost equal to the leakage inductance seen from the primary side of the transformer. Circuit.

Here, a trigger cap may be used in place of the above-mentioned high speed injector. Also, instead of the high-speed thrower,
It is also possible to use a trigger cap with a short circuit, which is formed by connecting a trigger cap and a mechanical short circuit that is short-circuited by this trigger cap closing operation in parallel. Alternatively, in the test circuit having the above-mentioned basic circuit configuration which is the object of the present invention, immediately after the test current is cut off by the breaking test switch connected to the secondary side of the transformer, both terminals of the breaking test switch are connected. Leakage seen from the primary side of the transformer in parallel with the primary winding of the transformer so that the steady part of the recovery voltage appearing between them becomes an AC recovery voltage having a predetermined frequency and a predetermined peak value. It may be a circuit including a series circuit with a reactor having an inductance larger than the inductance.

[0010]

As described above, according to the present invention, it is difficult to theoretically prove the equivalence with the AC voltage having the frequency of the commercial frequency level when the DC voltage is the voltage of the recovery voltage steady portion. It focuses on the points. However, as described above, a test circuit is used in which a series circuit of a high-speed injector and a reactor having an inductance substantially equal to the leakage inductance seen from the primary side of the transformer is connected in parallel with the transformer primary winding. As a result, the steady-state part following the recovery voltage transient oscillating part immediately after the current is cut off on the secondary side of the transformer can be set to an AC recovery voltage having a frequency equal to the frequency of the test current. For this reason, as will be described in detail in the section of the embodiment, a current detection sensor is provided in the circuit on the primary side of the transformer, and a predetermined time point before the current zero value is detected from the current detected by the current detection sensor. The drive pulse generating means for outputting is provided in the control system of the test circuit, and the high speed injector is started by the signal at the predetermined time point before the final zero value of the test current on the secondary side of the transformer output by the drive pulse generating means to start the recovery voltage. The pole is closed in the vicinity of the end of vibration damping in the transient vibration part. As a result, a reactor having an inductance equal to the leakage inductance seen from the transformer primary side is connected in parallel with the transformer primary winding. However, since the leakage inductance is extremely smaller than the exciting inductance, the transformer 1 The current frequency of the secondary circuit maintains the same test current frequency as before the current interruption. Therefore, by adjusting the voltage of the power supply capacitor, the recovery voltage steady-state part applied to the test switch after the current is cut off on the secondary side of the transformer is changed to the AC recovery voltage having the frequency of the test current and the predetermined peak value. can do.

Here, in place of a mechanical high-speed injector that operates at high speed, a trigger cap that is generally widely used is used.
By using the (starting cap), the mechanical high-speed injector can be made mechanically and electrically robust because of its highly accurate operation time and the long life required based on its frequency of use. Therefore, the purpose can be achieved at a lower cost, while it is considerably expensive.

Further, instead of the mechanical high-speed injector, a trigger cap with a short circuit, which is formed by connecting in parallel a trigger cap and a mechanical short circuit which short-circuits the trigger cap by closing operation, is used. By doing so, the short-circuit device does not require a high-speed and highly accurate operation time unlike the above-mentioned high-speed injector, so the variation in the operation time is expected so that it will not be closed before the operation of the trigger cap. It is possible to suppress the consumption of the trigger cap due to the arc at low cost simply by setting the closing time with, and to control the transition time of the recovery voltage from the transient vibration part to the steady part at a long life and economically. It can be a high-speed charging means that can perform with high accuracy.

Further, in a test circuit in which a series circuit of a capacitor and a reactor having an inductance larger than the leakage inductance seen from the transformer primary side is connected in parallel with the transformer primary winding, a frequency equal to the test current frequency is obtained. In order to obtain the AC recovery voltage of, the current flowing in this series circuit after the test switch is opened is changed by the transformer 1 during the closing of the test switch in the conventional test circuit, as will be described in detail in the embodiment section. It can be made much smaller than the current flowing in the next winding,
As a result, the AC recovery voltage of the test current frequency including not only the recovery voltage steady-state part but also the vibration center of the transient vibration part can be obtained without increasing the size of circuit elements such as the power supply capacitor and without requiring time control. Can be

[0014]

FIG. 1 shows a first embodiment of the test circuit according to the present invention, and FIG. 2 shows the operation sequence of the circuit-constituting equipment and the voltage and current of each part during the interruption test by this test circuit. The test circuit consists of a power supply capacitor 1, a protective circuit breaker 2, a make-up device 3, a finely adjustable reactor 4 for matching a test current with a predetermined frequency and current value, and a primary winding of a transformer 5 in series. The test switch 6 is connected between the secondary winding terminals of the transformer 5. In addition, transformer 1
A current detection sensor 8 and a drive pulse generation circuit 7 that outputs a drive pulse by its output signal are arranged in the secondary side circuit, and the closing point of the injector 3 is used as the starting point of time, and the test opening / closing is performed according to the sequence of FIG. A drive signal is applied to the test switch 6 so that the device 6 is opened by a time control device (not shown). In FIG. 2, symbol 11 is the terminal voltage of the capacitor 1, 12 is the current waveform of the primary side circuit of the transformer 5, 31 is the closing operation of the injector 3, 61 is the opening operation of the test switch, Reference numeral 71 is a drive pulse for driving the high speed injector 92, which is arranged in parallel with the primary winding of the transformer 5. 9
20 is the closing operation of the high-speed injector 92, 13 is 2 of the transformer 5
The current waveform of the secondary circuit, and 14 are the voltage waveforms appearing between the terminals of the test switch 6.

The test of this circuit is carried out in the following procedure. The test switch 6 is the symbol 6 in the sequence of FIG.
It operates like ₁ and reaches the zero value of the test current at a predetermined arc time t ₁ and shuts off. At the same time that the test current 13 becomes zero, the stray capacitance 51 of FIG.
The recovery voltage 14 is generated by superimposing the transient vibration voltage determined by the inductance of the secondary winding of the transformer. In order to oscillate the steady part of this voltage waveform at the test current frequency, the drive pulse generation circuit 7 generates a drive pulse at Δt ₁ before the zero value of the current 12 flowing in the primary winding of the transformer 5, and the test current 13 becomes The high speed injector 92 is closed after a time Δt _{2 at} which the transient oscillation part of the recovery voltage 14 generated between the secondary winding terminals of the transformer 5 becomes zero and disappears. The time (Δt ₁ + Δt ₂ ) from the generation of the driving pulse to the closing of the high speed closing device 92 includes the closing operation time of the high speed closing device 92. In the current waveform 12 of the primary side circuit of the transformer 5, 121 is the transformer 1
122 is a current flowing through the next winding, and 122 is a current flowing through a series circuit of the high speed injector 92 and the reactor 41.

FIG. 3 shows an embodiment different from that of FIG. 1 in which a trigger cap 91 is used instead of the high speed injector 92 of FIG. Before the zero value Δt of the current waveform 12 of the primary side circuit of the transformer 5
Trigger cap 91 up to time Δt ₂ when the drive pulse is generated at ₁ and the transient vibration part of recovery voltage 14 (FIG. 2) disappears.
To adjust the operating time of the drive pulse generator circuit 7
This is accomplished by providing (not shown). Further, FIG. 3 (b) shows another embodiment of FIG. 3 (a), in which a short-circuiting device 94 for mechanically closing the pole is arranged in parallel with the trigger cap 91 to prevent the trigger cap 91 from being damaged. It shows that the trigger cap 91 is closed as soon as possible after its operation so that the arc of the trigger cap 91 is extinguished.

FIG. 4 shows a second embodiment of the present invention. Figure 1
In place of the series circuit of the high speed injector 92 and the reactor 42, a series circuit of a capacitor 93 (C ₁ ) and a reactor 42 (L ₂ ) is arranged, and the operation sequence is shown in FIG. When the test switch reaches the zero value of the test current 13 at a predetermined arc time t ₁ and is cut off, the secondary side of the transformer 5 is opened and the short-circuit impedance from the primary side of the transformer 5 is excited. Since it becomes impedance and all the DC voltage of the capacitor 1 is applied to the primary winding of the transformer 5, the primary side current 12 of FIG. 5 is added to the series circuit of the capacitor 93 and the reactor 42 which are connected in parallel. Of this, 123 current flows out, and the recovery voltage 1 is applied to the secondary side according to the transformation ratio of the transformer.
4 occurs.

Here, the condenser 93 and the reactor 42
And the primary winding current of the transformer 5 during the period when the test switch 6 is closed, assuming that the series circuit of is not connected in parallel to the transformer primary winding, The relationship between the current flowing in the series circuit of the capacitor 93 and the reactor 41 after the secondary side current is cut off by the test switch is as follows, and the secondary side of the transformer 5 is generated without any practical problem. The voltage can be an AC recovery voltage at the test current frequency.

That is, if the switch 6 is closed, the following equation holds.

[0020]

[Equation 1]

[0021] Here, I _121: transformer primary winding flows crest value V ₁ of the current: the charging voltage of the capacitor 1 L _1: Reactor inductance L _T: inductance C ₁ leakage viewed from the transformer primary side: Capacitance of capacitor 1

[0022]

[Number 2] _{I 13 = N · I 121 (} 2) where, I _13: peak value N of the current flowing through the transformer secondary winding: transformation ratio of the transformer

[0023]

## EQU3 ## ^{_{(2πf 0) 2 = C 1}} (L 1 + L T) (3) where, f _0: frequency of I _121, I ₁₃ In a state where the switchgear 6 is no current 13 is opened to flow The following equation holds. In this case, transformer 1
Since the excitation inductance seen from the secondary side is extremely large,
Considered as infinite in calculation.

[0024]

[Equation 4]

Where I ₁₂₃ is the peak value of the current flowing in the series circuit of the capacitor 93 and the reactor 42.

[0026]

[Equation 5]

Here, C ₀ : series capacitance of the capacitor 1 and the capacitor 93 C ₂ : capacitance of the capacitor 93 (<< C ₁ )

[0028]

[Equation 6]

From equation (3) and equation (6) above,

[0030]

## EQU7 ## C ₁ (L ₁ + L _T ) = C ₂ (L ₁ + L ₂ ) (7) Here, C ₁ >> C ₂ , and therefore L _T << L ₂ .

[0031]

[Equation 8]

[0032]

As described above, according to the present invention, the test circuit of the switch targeted by the present invention, that is, the capacitor charged with direct current, the protective breaker, the closing device, and the transformer. The primary winding of the transformer is connected in series, and a switch for breaking test is connected to the secondary side of the transformer, and the charger is turned on to discharge the capacitor charged with direct current to transform the transformer. In a test circuit of a switch that generates a test current of a specified frequency and a specified current value on the secondary side of the transformer, it appears between both terminals of the test switch immediately after the test current of the transformer secondary side is cut off by the test switch. Leakage seen from the primary side of the mechanical high speed injector and the transformer primary side in parallel with the primary winding of the transformer near the end of the vibration damping of the transient vibration part of the recovery voltage, with a short time from receiving the closing signal to closing the pole. A reactor with an inductance approximately equal to the inductance A series circuit of a Le was the high speed closing device triggers cap, a series circuit of said reactor,
Alternatively, a circuit in series with the reactor is connected as a trigger cap having a short-circuiting device in parallel with which a high-speed injector is mechanically operated to close a pole, or a leakage impedance seen from the primary side of a capacitor and a transformer. Since a series circuit with an impedance having a larger inductance is connected in parallel to the transformer primary winding, the recovery voltage steady-state part can be an AC recovery voltage having a frequency equal to the test current frequency. It has become possible to correctly evaluate the current interruption capability of the switch. As a result, when applying the rated breaking capacity of the switch that is normally set in stages,
Unnecessarily select a one-step higher rating, or mistake the difference in the severity of polarity when the recovery voltage steady-state part is a DC voltage and select a one-step lower rating. No longer happens, and when selecting a switch,
It has become possible to achieve both reliability and economy.

In the circuit of claim 1, the mechanical high-speed feeder can connect the reactor in parallel to the primary winding of the transformer with high accuracy at the closing time only by the closing signal.
It has the advantage that the control of the test circuit is simple and reliable. Further, in the circuit of claim 2, compared with the case of claim 1, although the life of the trigger cap as the high-speed closing means is short, there is an advantage that the object of the present invention can be achieved more economically.

Further, in the circuit of claim 3, the control of the test circuit is slightly complicated as compared with the case where the mechanical high-speed feeder is used, but it has a long life and is economical, and the time control accuracy is high. A high speed charging means can be obtained. The circuit of claim 4 has an advantage that the test can be performed without adding new control means to the conventional test circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a test circuit configuration according to the present invention.

FIG. 2 is an explanatory diagram showing an operation sequence of test circuit constituent devices and a voltage and current waveform of each part of the circuit during a breaking test by the test circuit shown in FIG.

3 is a diagram showing a modification of the test circuit configuration shown in FIG. 1, and FIG. 3 (a) is a circuit diagram showing the first modification thereof;
(b) is a circuit diagram of essential parts showing a second modification.

FIG. 4 is a circuit diagram showing a second embodiment of the test circuit configuration according to the present invention.

5 is an explanatory diagram showing the operation sequence of the test circuit constituent equipment and the voltage and current waveforms of each part of the circuit at the time of the interruption test by the test circuit shown in FIG.

FIG. 6 is a circuit diagram showing an example of a conventional test circuit configuration.

7 is an explanatory diagram showing an operation sequence of test circuit constituent devices and a voltage and current waveform of each part of the circuit at the time of the interruption test by the test circuit shown in FIG.

[Explanation of symbols]

 1 Capacitor 2 Protective Circuit Breaker 3 Charger 4 Reactor 5 Transformer 6 Switch (Switch for Breaking Test) 41 Reactor 42 Reactor 91 Trigger Cap 92 High-speed Charger 93 Capacitor 94 Short-circuiter

Claims (4)

[Claims] 1. A DC charging capacitor, a protective circuit breaker, a closing device, and a primary winding of a transformer are connected in series, and the secondary side of the transformer is used for a breaking test. In a test circuit of a switch for connecting a switch and turning on the switch to discharge the capacitor charged with direct current to generate a test current having a predetermined frequency and a predetermined current value on the secondary side of the transformer, Immediately after breaking the test current with the breaking test switch connected to the secondary side of the transformer, the steady part of the recovery voltage that appears between both terminals of the breaking test switch has a predetermined frequency and a predetermined peak value. 1 of the transformer so that the AC recovery voltage is obtained.
Equipped with a series circuit in parallel with the secondary winding consisting of a mechanical high-speed injector with a short time from receiving the closing signal to closing the pole, and a reactor with an inductance that is approximately equal to the leakage inductance seen from the primary side of the transformer. A switch test circuit characterized by 2. The test circuit according to claim 1, wherein:
A switch test circuit characterized by using a trigger cap in place of a high-speed injector. 3. The test circuit according to claim 1, wherein:
A switch test circuit characterized by using a trigger cap with a short-circuit device, which is formed by connecting in parallel a trigger cap and a mechanical short-circuit device that short-circuits this trigger cap by a closing operation in place of the high-speed injector. . 4. A capacitor charged by direct current, a protective circuit breaker, a closing device, and a primary winding of a transformer are connected in series, and a secondary side of the transformer is used for a breaking test. In a test circuit of a switch for connecting a switch and turning on the switch to discharge the capacitor charged with direct current to generate a test current having a predetermined frequency and a predetermined current value on the secondary side of the transformer, Immediately after breaking the test current with the breaking test switch connected to the secondary side of the transformer, the steady part of the recovery voltage that appears between both terminals of the breaking test switch has a predetermined frequency and a predetermined peak value. 1 of the transformer so that the AC recovery voltage is obtained.
A test circuit for a switch, which is provided with a series circuit of a capacitor and a reactor having an inductance larger than a leakage inductance seen from the primary side of a transformer in parallel with a secondary winding.