JPS6247564A - Leading current cut-off testing circuit for switch - Google Patents

Abstract

PURPOSE:To realize a testing circuit which can verify a leading current cut-off performance by an actual working frequency, by connecting in series an auxiliary circuit-breaker between a sample switch and a test power source, and connecting an inductance and a capacitance in parallel to a lead capacitance between the circuit-breaker and the switch. CONSTITUTION:An auxiliary circuit-breaker 4 is connected in series between a sample switch 1 and a test power source 3, and an inductance 5 and a capacitance 6 are connected in parallel to a load capacitance 2 between the circuit- breaker 4 and the switch 1. In this state, when the power source 3 is detached by the circuit-breaker 4 as soon as the switch 1 cuts off a current at a current zero point, a difference of vibration voltages of a residual voltage (el) of a load side and a voltage (es) of the power source side, namely, the inductance 5 and the capacitance 6 which have been provided between the switch 1 and the circuit-breaker 4 is applied to the switch 1. A leading current cut-off test by a frequency which is used by the switch 1 actually can be executed by adjusting a value of said inductance 5 and capacitance 6, and varying optionally a frequency of the power source side voltage.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a lead current interruption test circuit for a switch, and in particular, a test circuit for applying a voltage of an arbitrary frequency between the poles of the switch after the switch interrupts the current. The present invention relates to a test circuit made as described above.

[Technical Background of the Invention and Problems Therewith] Generally, switches such as circuit breakers and contactors are responsible for switching on and off the charging current of power capacitors, no-load power transmission lines, power cables, and the like. The breaking of a capacitive circuit through which a current whose phase is π/2 ahead of this voltage flows is more specific than that of an inductive circuit, and as stipulated in standards such as JEC-181 (alternating current circuit breaker), This is one of the most important items in switch performance verification.

The phenomenon in which the switch advances and cuts off the current will be described below with reference to FIGS. 4 and 5.

FIG. 4 shows an example of a conventional leading current cutoff test circuit. In the figure, a capacitance 2 serving as a load (hereinafter referred to as load capacitance) 2 is connected in series with the test switch 1 on one side, and a test type #! 3 is connected.

Next, in this test circuit, the electrical phenomenon when the test switch 1 interrupts a lead current of 1° flowing through the load capacitance 2 is shown in FIG. In FIG. 5, voltage and current are plotted on the vertical axis, and time is plotted on the horizontal axis. In the figure, P-P'
When the test switch 1 is opened at the point in time, the current 1° is cut off at the first zero point Q-Q'. At this time, test switch 1
The voltage e5 on the power supply side changes according to the power supply frequency, but
The voltage eL of the capacitance 2 on the load side remains an instantaneous voltage when the current is zero, that is, a voltage corresponding to the voltage wave value. Therefore, the voltage applied between the contacts of the test switch 1 is the difference between the voltage e5 on the power supply side and the voltage eL remaining on the load side, and this value increases up to twice the N applied voltage peak value after 1/2 cycle. Rise.

By the way, the leading current interruption test verifies whether the switch can withstand current interruption and connection and the twice the voltage applied between the contacts. , the dielectric strength between the contacts breaks down and the current flows again (hereinafter, this phenomenon is referred to as restriking). When this restriking occurs, abnormal voltage is generated in the circuit, so when installed in a power grid. This could endanger the insulation of other equipment. A problem with this advanced current cutoff test is when the power supply frequency of the circuit to which the switch is applied differs from the test e number at the test site. For example, when a switch used in a 60Hz system is tested at 50H2, the time it takes for the voltage applied between the switch contacts to reach the peak value at 60Hz is 16.7ms, whereas at 60Hz it is 16.7ms. At 50Hz, it would be 20m5, which would be an easy test for the switch. In addition, in order to cover this, the test voltage of 50H2 is 1.2 times the value, and the test is also performed to include the time to the peak value of the 60Hz power supply voltage, but the 60H7 power supply is The waveform is the same as when I tested it, but when it exceeds 13m5, it is 608! A higher voltage is applied than when testing with a power supply, resulting in a harsher test for the switch. FIG. 6 shows a comparison of the voltage waveforms applied between the switch contacts when the 50H7 power supply and the 60Hz power supply are used.

[Object of the invention] The present invention was made in consideration of the above circumstances, and
Even if the purpose is a circuit with a certain test power frequency,
Provides a switch lead current cutoff test circuit that can arbitrarily change the frequency of the voltage applied between the switch contacts for current cutoff and verify lead current cutoff performance at the frequency actually used. It's about doing.

I Summary of the Invention 1 In order to achieve the above object, in the present invention, an auxiliary breaker is connected in series between the test circuit breaker and the test power supply in the test circuit described above, and the auxiliary breaker and the test switch A circuit is constructed in which inductance and capacitance are connected in parallel with the load capacitance between Apply the difference between the residual voltage on the load side and the voltage on the power supply side, that is, the oscillating voltage of the inductance and capacitance provided between the test switch and the auxiliary breaker, and adjust the values of this inductance and capacitance. Accordingly, the present invention is characterized in that the frequency of the power supply side voltage is arbitrarily changed to realize a leading current cutoff test at the frequency at which the switch is actually used.

Embodiment 1 An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows an example of the groove configuration of a lead current interruption test circuit for a switch according to the present invention, and the same parts as in FIG. 4 are denoted by the same reference numerals. In the figure, a test power source 3 is connected in series to the power source side of the test switch 1 via an auxiliary breaker 4, and a load capacitance 2 is connected in series to the load side thereof. In addition, test switch 1 and auxiliary breaker 4
An inductance 5 and a capacitance 6 are connected in parallel with the load capacitance 2 between them. The test switch 1 is designed to cut off the lead current that charges the load capacitance 2 from the test voltage 13.

Next, a lead current cutoff test in a test circuit having such a configuration will be explained with reference to FIG. In FIG. 2, voltage and current are shown on the vertical axis, and one hour is shown on the horizontal axis.

First, with the auxiliary breaker 4 and the test switch 1 closed,
With current 1c flowing through load capacitance 2, auxiliary breaker 4 and circuit breaker 1 are connected at point P-P'.
When simultaneously opened, the current 1o reaches the first zero point Q-Q'
It will be cut off. At the same time, the test switch 1, inductance 5, and capacitance 6 are disconnected from the test power source 3 by the auxiliary breaker 4.

Then, the power supply side voltage e5 of the test switch 1 is a voltage with a peak value remaining in the capacitance 6, and becomes a voltage that oscillates in the circuit with the inductance 5. The imaging frequency at this time is determined by the values of inductance 5 and capacitance 6. On the other hand, since the voltage peak value at the time of current interruption remains in the load side voltage eL of the test switch 1, there is a difference voltage between the power supply side voltage es and the load side voltage eL between the contacts of the test switch 1. It will be stamped. Since this voltage has a frequency determined by the values of the inductance 5 and capacitance 6, it is possible to perform a test at an arbitrary frequency by adjusting these values.

Note that since the inductance 5 includes a series resistance, the oscillating voltage generated between it and the capacitance 6 has an attenuating property, and the voltage applied to the test switch 1 is attenuated, but according to the breaker standard JEC By setting a large decay time constant (0.1 seconds or more) on the load side as specified in -181,
The voltage applied between the contacts of the test switch 1 can be made equivalent to that of the specified field, and this situation is shown in Figure 3 (a) (1).
).

[Effects of the Invention] As explained above, according to the present invention, an auxiliary breaker is connected in series between the test switch and the test power source, and an inductance is established between the auxiliary breaker and the test switch. The capacitance is connected in parallel with the load capacitance, so even in a circuit with a constant test power supply frequency, the frequency of the voltage applied between the switch contactors can be changed to any frequency for leading current cutoff. , it is possible to provide an extremely reliable lead current cutoff test circuit for a switch that can verify lead current cutoff at frequencies actually used.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, and FIG. 2 (
are waveform diagrams showing the voltage and current during the test in the same example, Figures 3 (a) and (b) are waveform diagrams to explain the case where the voltage is attenuated, and Figure 4 is a conventional leading current cutoff test circuit. Figure 5 is a waveform diagram showing the voltage and current when the current is cut off in Figure 4. Figure 6 is a comparison of the voltage applied between the switch contacts when using eight sources of 50H2 and 60Hz. FIG. 1... Test switch, 2... Load capacitance, 3
...Test power source, 4...Auxiliary breaker, 5...Inductance, 6...Capacitance. Applicant's representative Patent attorney Takehiko Suzue Figure 1 (a) (b) Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] In a test circuit in which a test power supply is connected in series to the amperage of the test switch, and a capacitance serving as a load is connected in series to the load side of the test switch, the connection between the test switch and the test power supply is An auxiliary breaker is connected in series between the auxiliary breaker and the test switch, and an inductance and a capacitance are connected in parallel with the breaker load capacitance between the auxiliary breaker and the test switch. Current cutoff test circuit.