Control circuit for alternating current contactor

Abstract

The invention discloses a control circuit for an alternating current contactor. The control circuit is used for controlling the alternating current contactor connected in a circuit between a power bus and a motor in series, and comprises an alternating current contactor drive circuit, a starting circuit, a retaining circuit and a buffer circuit, and the drive circuit is connected with the alternating current contactor. The starting circuit, the retaining circuit and the buffer circuit are connected with the drive circuit and the power bus respectively. The alternating current contactor is started in a direct-current mode, meanwhile, a direct-current retaining mode is adopted in the retaining circuit, the defect that the alternating current contactor cannot be pulled in or cannot be retained after pull-in due to low voltages is overcome, the alternating current contactor can work normally, the problem that electricity is hard to take under the low voltages is solved, and it is guaranteed that the alternating current contactor cannot be damaged under a high-voltage environment.

Description

technical field [0001] The invention relates to a contactor for controlling circuit breaking, in particular to an AC contactor control circuit. Background technique [0002] The AC contactor is mainly used to frequently connect or break the AC circuit. It has a large control capacity and can be operated from a long distance. It can realize timing operation, interlock control, and various quantitative control boxes. Voltage loss and undervoltage protection are widely used in Automatic Control System. [0003] In general, AC contactors are mostly used for switching on and off circuits in power systems, and can be combined with appropriate relays or electronic protection devices to form motor starters. [0004] The coil of the AC contactor needs to be supplied with alternating current to generate electromagnetic force. When an appropriate AC current passes through the coil, an inductive reactance will be generated, which forms a large reactance together with the DC resistance ...

AI Technical Summary

Problems solved by technology

In the field low-voltage environment, when the voltage value loaded on the AC contact coil fails to reach the minimum voltage value required to make the AC contactor pull in, the armature of the AC contactor will jump continuously, which is harmful to the AC contactor itself. and the entire power system will have a certain destructive effect, and even cause safety accidents

At the same time, even if the AC contactor normally pulls in at a small voltage, the voltage will be pulled down at the moment the motor starts, and the voltage value at this time is not enough to make the AC contactor enter the normal holding state, and the AC contactor will not Pull in again, causing the motor to fail to run normally

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