Relay contact protection circuit for controlling inductive load

Abstract

The invention provides a relay contact protection circuit for controlling an inductive load, wherein the input end of a power-on delay driving module is connected with a first alternating current input end; the output end of the power-on delay driving module is connected with a relay RY1 coil; a relay RY1 contact and a starting instant protection module are connected in parallel; one end of the relay RY1 contact is connected with a second AC live wire; the other end of the relay RY1 contact is connected with one end of an AC load; the other end of the AC load is connected with a second AC zerowire; the starting instant protection module includes a thermistor NTC and a fuse F1 connected in series; and the thermistor NTC and the fuse F1 are in contact with each other. The relay contact protection circuit for controlling the inductive load provided by the invention achieves the purpose of protecting the relay at the moment of starting the AC load through the joint action of the power-ondelay driving module, the load working current path and the starting instant protection module.

Description

technical field [0001] The invention relates to the field of relay protection circuits, in particular to a relay contact protection circuit for controlling inductive loads. Background technique [0002] Inductive loads such as high-power industrial frequency transformers (1500W, etc.), motors, etc., all require the drive of the drive circuit to work normally. General conventional relay drive circuits for controlling inductive loads such as figure 1 As shown, the existing circuit has the following defects: the relay contact will be subjected to an instantaneous high current impact of 5-10 times the inductive load at the moment of pull-in. Because the high temperature brought by the sparks cannot dissipate heat for a short time, the contacts cannot be disconnected due to fusion. When the relay contacts need to be disconnected but cannot be disconnected normally, it will cause danger or even property loss; at the same time, this The instantaneous high current impact also shor...

AI Technical Summary

Problems solved by technology

General conventional relay drive circuits for controlling inductive loads such as figure 1 As shown, the existing circuit has the following defects: the relay contact will be subjected to an instantaneous high current impact of 5-10 times the inductive load at the moment of pull-in. Because the high temperature brought by the sparks cannot dissipate heat for a short time, the contacts cannot be disconnected due to fusion. When the relay contacts need to be disconnected but cannot be disconnected normally, it will cause danger or even property loss; at the same time, this The instantaneous high current impact also leads to the shortening of the life of the relay contacts

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