JPS61176873A - Breaking test circuit for dc breaker - Google Patents

Abstract

PURPOSE:To permit the use of a rectifier device having the capacity smaller than the capacity of an AC power source by inserting in series a discharge gap with a start electrode and resistor between the AC power source side terminals of the rectifier device and operating the discharge gap when the current flowing in a DC breaker exceeds a prescribed value. CONSTITUTION:The DC current flowing out of the rectifier device 41 flows through an impedance 49, the DC breaker 45 and a current measuring means 50 when a throwing switch 46 is thrown. A current detecting means 51 detects the prescribed current value IF when the breaker 45 fails in breaking and the current exceeds the prescribed cut-off current. Then the start pulse from a pulse generator 52 operates the discharge gap 54 with the start electrode inserted in series to the resistor 53 between the AC power source side terminals of the device 41. The increase in the current flowing in the breaker 45 slows down sharply and at the same time a protective breaker 44 starts a breaking operation so that the failure of the breaker 45 is suppressed. Thus the rectifier device 41 is just required to have the capacity corresponding to the current IF and is not required to have the capacity to deal with the final crest value of short circuit current.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to a DC circuit breaker used to protect DC circuits and DC equipment in DC electrical equipment such as electric railways, electrochemistry, and steel manufacturing. The present invention relates to a test circuit for verifying the breaking performance of a DC breaker that limits the short circuit current passing through the DC breaker before it reaches its final peak value.

[Prior art and its problems]

DC circuit breakers that interrupt short-circuit currents that flow due to short-circuit accidents in DC circuits or DC equipment in DC electrical equipment are usually
It is designed to limit and interrupt the short circuit current before it reaches its final peak value.

For example, in the conventional DC breaker shown in FIG.
When a short-circuit current flows from the
A part of the short-circuit current is shunted to the tripping coil 14, which is called a bucking coil, due to the voltage generated between the two terminals. 10
is a holding magnet, and a holding current is constantly supplied to its holding coil 13, and the armature 12 is attracted by the magnetic flux generated by this holding coil 3 against the force of the opening spring 6. When current flows through the tripping coil 14,
The magnetic flux created by this current cancels the magnetic flux created by the holding magnet 13 and passing through the armature 12, and the holding magnet loses its attractive force, driving the energizing lever 3 to the right. Since the movable contact 2 of the DC circuit breaker is attached to the tip of the energizing lever 3, an arc is generated between it and the solid contact 1. The magnetic flux created in the dark generates a force that drives the arc upward in Figure 1, and the arc is stretched out between the two insulating arc-extinguishing plates, rapidly increasing the arc voltage. This arc voltage waveform is shown in FIG. 4 as a voltage between electrodes. This arc voltage acts as a back electromotive force against the power supply voltage, so
The short circuit current rapidly attenuates from the current 1b at this point, leading to interruption. In the figure, 'ro is the point at which the short-circuit current reaches the scale current at which the DC breaker should start tripping, TI is the point at which the fixed contact and the movable contact are separated,
T2 is the point at which the arc is rapidly stretched, Tl
-Tz is the arc glue time.

Furthermore, in recent years, stationary type DC circuit breakers using semiconductors have begun to be put into practical use. This semiconductor DC breaker, like the mechanical DC breaker mentioned above, operates from the time when the current value of the short circuit current reaches the scale current value that starts the DC breaker until the contact opens. Since there is no time lag or arc stagnation time, and the process immediately enters the current-limiting circuit breaker, the size of the current-limiting value is almost equal to the scale current value that starts the fast breaker, and therefore, the current-limiting value of the mechanical DC circuit breaker A is relatively large, about the size of the final peak value of the short-circuit current. It is possible to rub it to a certain extent.

That is, for example, in a semiconductor DC breaker configured as shown in FIG. The current detecting means 26 inputted from the current measuring means 25 that measures the current determines that this scaled current value has been reached, and sends an ON signal to the gate of the auxiliary thyristor. The commutating capacitor 22 connected in series with this auxiliary thyristor through the reactor is smoothly charged from a separate power source, and when the gate of the auxiliary thyristor is turned on, the electric charge of the commutating capacitor 22 is transferred to the main thyristor 21. is discharged in the opposite direction, and from the point of discharge, the short circuit current begins to attenuate and is cut off. The speed of attenuation at this time is the circuit 22-24-23-21-29-2
It is determined by the frequency of natural vibration of 2.

In this way, the current value at which short-circuit current interruption begins, that is, the current limit value, is much smaller than the final peak value of the short-circuit current. However, as a test circuit for a DC circuit breaker, the test circuit conditions require an AC power supply that can supply the final peak value of the current in the event of a short circuit, and also to ensure that the test circuit will not be damaged even if the circuit breaker fails to shut off. Conventionally, a rectifier suitable for this power supply capacity is used, or instead of using a rectifier, the AC power supply, for example, a short-circuit generator, is operated at a low frequency of about 5 Hz, and the final wave of the short-circuit current is An equivalent interruption test is conducted in a flat current region near the peak value of the alternating current, which is equal to the high value. However, when using the former, that is, a rectifier, the rectifier, especially the rectifier, has a significantly large capacity, which requires a large amount of money to configure the test circuit, and when operating the AC power supply at a low frequency, In the event that the circuit breaker is unable to shut off,
Since it takes at least several tens of milliseconds for the alternating current to reach its zero point and be cut off, the test circuit was unstable.

[Purpose of the invention]

This invention provides a test circuit using a rectifier that does not have any drawbacks in the AC equivalence test, which does not cause problems such as damage when it cannot shut off even if a rectifier with a smaller capacity than a paradise power supply is used, and which does not cause problems such as damage to the circuit when it cannot shut off. It is an object of the present invention to provide a test circuit which can prevent the damage from spreading and which does not cause any trouble in verifying the breaking performance.

[Key points of the invention]

The present invention provides a test circuit for a DC breaker that verifies the current interrupting ability of the DC breaker by supplying a test current from an AC power supply through a rectifier to a series path between the DC breaker and a predetermined impedance. A discharge gap with a starting electrode and a resistor are inserted in series between the AC power supply side terminals of the rectifier,
The start occurs when the current flowing through the DC speed breaker exceeds a predetermined value that is slightly higher than a predetermined current limit value.

The object is to achieve the above object by operating a discharge gap with a moving electrode.

[Embodiments of the invention]

FIG. 1 shows an embodiment of a break test circuit based on the present invention. In this embodiment, the output voltage of the AC power button is high, and the rectifier 4
The case where 1 consists of a step-down transformer 42 and a rectifier section is shown. When the protective circuit breaker U of the AC side circuit A and the DC breaker 45 of the DC side circuit B are closed and the closing switch 46 is turned on, the DC current flowing out from the rectifier 41 is connected to the impedance 49 and the DC breaker 45. The current flows through the current measuring means 50, and attempts to draw a predetermined waveform 60 over time as shown in FIG. 2 by the resistor 47 and inductance that constitute the impedance 49. When this current reaches a predetermined scale current IO of the DC circuit breaker 45, the DC circuit breaker starts a circuit breaker operation, and performs circuit breaker by suppressing the current to a current limit value ratio scheduled for this circuit breaker. If circuit breaker 45
When the output current from the rectifier 41 attempts to rise beyond the expected current limit value due to failure of interruption, the current is detected to slightly exceed this current limit value ratio and reach a preset predetermined current value. Means 51 detects and activates pulse generator 52. The starting pulse output from the activated pulse generator 52 is guided to the starting electrode of the starting electrode-equipped discharge gap & inserted in series with the resistor between the AC power supply side terminals of the rectifier 41, and the starting electrode of the starting electrode-equipped discharge gap & Activate the gap. As a result, the current flowing out from the AC power button is shunted to the impedance 49 of the DC side circuit B via the resistor and the rectifier 41, so the current flowing through the DC WFR device 45 increases from this point T3. The current suddenly slows down, the speed begins to fall, and at the same time the protective circuit breaker 44 enters the breaking operation, so damage to the DC speed circuit breaker 45 is kept extremely small, and there is virtually no damage to the surrounding equipment. be able to. Moreover, the current value for starting the discharge gap with the starting electrode is set to a value that sufficiently covers the variation in the planned current-limiting value ratio.
This will not impede the judgment of the success or failure of the interruption in step 5. Therefore, the capacity of the rectifier 41 is sufficient to be large enough to correspond to the current difference, and does not need to be large enough to correspond to the final peak value In of the short-circuit current, making it possible to construct the test circuit extremely economically. Note that the current flowing out from the AC power supply 40 when the discharge gap & with a starting electrode is activated tends to become larger than before the discharge gap & is activated because the impedance of the entire circuit from the AC power supply 40 decreases. The impedance 55 is significantly larger than the impedance 49 and the resistance portion, and its change is extremely small, so the current flowing through the DC breaker 46 is extremely effectively reduced by the operation of the discharge gap 54 with starting electrode.

〔Effect of the invention〕

As described above, according to the present invention, a test current is supplied from an AC power supply through a rectifier to a series path between a DC breaker and a predetermined impedance to verify the current interrupting ability of the DC FI breaker. In a test circuit for a DC circuit breaker, a discharge gap with a starting electrode and a resistor, which are commonly used in continuous test sites, are inserted in series between the AC power supply side terminals of the rectifier, and the current flowing through the DC circuit breaker is Since the discharge gap with starting electrode is activated when the current value slightly exceeds the current limit value scheduled for this circuit breaker, the rectifier device can be operated without any additional cost. In addition, when the tested DC circuit breaker fails to shut off, it is possible to avoid damage to the internal body of the 4-rectifier device, damage to the test circuit breaker, and damage to peripheral equipment. Furthermore, it is possible to obtain the effect that the interruption performance can be verified without any problem.

[Brief explanation of drawings]

Fig. 1 is a test circuit configuration diagram showing one embodiment of the breaking test circuit based on the present invention, Fig. 2 is a diagram showing the waveform of the current passing through the DC breaker in the Oni diagram test circuit, and Fig. 3 is the mechanical diagram. An explanatory diagram showing an example of the configuration of a DC circuit breaker. Figure 4 is a diagram showing the voltage and current waveforms of each part of the circuit breaker when a short circuit current is interrupted by the DC speed circuit breaker in Figure 3. Figure 5 is a diagram showing the waveform of the voltage and current at each part of the circuit breaker when the short circuit current is interrupted by the DC circuit breaker in Figure 3. It is an explanatory view showing an example of a structure of a container.

Claims (1)

[Claims] 1) In a test circuit for a DC breaker that verifies the current interrupting ability of the DC breaker by supplying a test current from an AC power source to a series path between the DC breaker and a predetermined impedance through the rectifier, the rectifier A discharge gap with a starting electrode and a resistor are inserted in series between the AC power supply side terminals of the DC circuit breaker, and the discharge gap with a starting electrode is activated when the current flowing through the DC circuit breaker exceeds a predetermined value. Breaking test circuit for DC circuit breakers.