The Electrical Life Test Technology of Relay with DC Motor Load

摘要

A specially designed relay, which is widely used in vehicles, used to control low-power DC motor. Such as: wipers, the window glasses and seats of movements. This specially designed relay is provided with two separate excitation coils S1 and S2, which control two groups of switch contact respectively. When the S1 close and S2 open, the motor power is forward rotation, otherwise the motor is reversal. In order to ensure the vehicle's overall performance, the quality of this special relay is also one of the important factors. To some extent, the electrical life of relay determines relay's life. At present, electrical life testing is an important means to obtain relay's life indicator. This article analyzed the changes in load current, on condition that the relay controlled the motor starting, normal stop, locked rotor and from forward rotation to inversion directly. Based on it, the text discussed the main circuit, a testing control logic and explained designing idea of test equipment of computer monitoring and controlling. Application of the principle of energy conservation I2t, we obtained that start testing current duration is 0.21 ～ 0.34 times of the actual motor starting time.The characteristics of the testing device are using simple, flexible, high automation and so on. And it's simulation of load current can reflect the actual using condition better.