JPH04289623A - Thyristor switch - Google Patents

Abstract

PURPOSE:To resolve the trouble that a thyristor switch, constructed by thyristor switches and mechanical switch in series in every phase, is turned off by itself by reducing a load current during circuit closing operation. CONSTITUTION:Resistors 5 are connected between phase terminals U2, V2, W2 on the load side. So that a current in a thyristor switch 1, exceeding its holding current, can be kept during circuit closing operation in a thyristor switch, regardless of a load current.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thyristor switch used for the purpose of stationary operation of, for example, a sectional switch used in a power distribution system.

0002

[Prior Art] Figure 2 shows, for example, the Proceedings of the National Conference of the Institute of Electrical Engineers of Japan in 1989 [10] (Power Protection 10-106/107).
FIG. 2 is a circuit configuration diagram showing a conventional thyristor switch of this kind disclosed in JP-A-2006-102001. In the figure, 1 is a thyristor switch formed by connecting thyristor elements in antiparallel, 2 is a vacuum electromagnetic contactor as a mechanical switch, 3 is a zinc oxide type earth protector that protects the thyristor element from surge voltage, and 4 is a thyristor switch. 1 and vacuum electromagnetic contactor 2 from a low voltage level. The thyristor switch 1 and the vacuum electromagnetic contactor 2 are connected in series for each phase, and are connected between the input terminals U1, V1, W1 on the power supply side and the output terminals U2, V2, W2 on the load side. There is.

Next, the operation will be explained. The thyristor switch 1 and the vacuum electromagnetic contactor 2 are operated by the control device 4, but this device is configured with an electrical interlock, and the thyristor switch 1 is operated only when the vacuum electromagnetic contactor 2 is turned on. Turn on and also turn on the vacuum electromagnetic contactor 2.
can be opened only when the thyristor switch 1 is off.

Therefore, when the thyristor switch performs an opening operation, the thyristor switch 1 first turns off, and then the vacuum electromagnetic contactor 2 performs the opening operation. Further, when the thyristor switch performs a circuit closing operation, first the vacuum electromagnetic contactor 2 is closed, and then the thyristor switch 1 is turned on. Thyristor switch 1 in thyristor switch
Since the vacuum electromagnetic contactor 2 and the vacuum electromagnetic contactor 2 are configured based on the above-described operational coordination, the thyristor switch 1 has the current interrupting capacity for the steady current and fault current of the load.
Therefore, it is sufficient for the vacuum electromagnetic contactor 2 to have only a constant current carrying capacity.

[0005]

[Problems to be Solved by the Invention] Since the conventional thyristor switch is configured as described above, the impedance of the load is large (the load current is small), and the energizing current of the thyristor switch 1 is less than the holding current of the thyristor element. In this case, there is a problem in that the thyristor switch 1 is turned off even though the control device 4 has not issued a command to open the circuit, causing a problem in the operation of the power distribution system.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a thyristor switch which does not undergo abnormal opening operation even if the load current drops below the holding current of the thyristor switch. With the goal.

[0007]

[Means for Solving the Problems] A thyristor switch according to the present invention has a predetermined impedance element connected between each phase terminal on the load side.

[0008]

[Operation] When the thyristor switch is closed, the current flowing through the impedance element above also flows through the thyristor switch, and this current exceeds the holding current of the thyristor switch regardless of the load current, so the thyristor switch turns off by itself. Never.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram showing a thyristor switch according to an embodiment of the present invention. In the figure, the difference from the conventional one is that a resistor 5 as an impedance element is connected between the output terminals U2, V2, and W2 on the load side. Here, the resistance value of the resistor 5 is such that even when the load current is at the expected minimum value (for example, zero), the thyristor switch 1
The value is selected to be as large as possible within a range that can ensure a current that is greater than the holding current. Since the holding current varies depending on the rating of the thyristor element, it is necessary to select the resistor 5 having a resistance value that matches the circuit voltage and the rating of the thyristor switch 1.

As described above, since the resistor 5 is newly provided in the thyristor switch of this embodiment, a current greater than the holding current flows through the thyristor switch 1 during circuit closing operation, regardless of the magnitude of the load current. Therefore, the thyristor switch 1 will not be turned off unless an off command is issued from the control device 4, ensuring smooth operation in the power distribution system.

Although the resistor 5 is used as the impedance element in the above embodiment, an AC reactor or the like may also be used, and the same effect as in the above embodiment can be obtained. Further, in the above embodiment, the resistor 5 is connected between each output terminal in a so-called delta connection, but it may be connected in a so-called star connection. Moreover, in the case of UV 2-phase instead of 3-phase, the resistor 5 may be connected between the output terminals U2 and V2. Furthermore, depending on the operating method of the system in which the thyristor switch is inserted, the power supply side and the load side may change over time. In such a case, by connecting the impedance element between both the input and output terminals of the thyristor switch, the configuration of the present invention of connecting the impedance element between each phase terminal on the load side is always satisfied. The above effects can be obtained.

0012

[Effects of the Invention] As described above, this invention connects an impedance element between each phase terminal on the load side to ensure that the thyristor switch receives a current higher than its holding current, so that when the circuit is closed, the load current This solves the problem of the thyristor switch turning off by itself due to a decrease in .

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing a thyristor switch according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing a conventional thyristor switch.

[Explanation of symbols]

1 Thyristor switch

Claims (1)

[Claims] [Claim 1] In a thyristor switch inserted between the power supply side and the load side of a circuit and composed of a series body of a thyristor switch and a mechanical switch for each phase, a thyristor switch is inserted between each phase terminal on the load side. A thyristor switch, characterized in that an impedance element is connected to the thyristor switch so that when the thyristor switch is closed, a current greater than the holding current flows through the thyristor switch, regardless of the load current.