低压开关触头压降取样电路的设计

针对低压开关通断前后端电压相差很大,触头压降检测仪表难以兼顾精度与安全的问题,利用稳压二极管的稳压特性,提出一种检测触头压降的无源电路取样方案.在此基础上,对取样电路中限流电阻和稳压二极管的影响进行理论分析,确定选取规则.然后,通过直流特性测试,检测取样电路测量误差;通过频率特性测试,检测取样电路对不同频率谐波的衰减和失真情况;通过模拟工况测试,检测取样电路的实际应用情况.实验结果表明:低压开关触头压降取样电路有助于实现精确测量触头压降,并保证检测仪表安全.

Design of Sampling Circuit for Measuring ContactVoltage Drop of Low Voltage Switch

Aiming at the problem that the contact voltage difference of low voltage switch between making and breaking is so large that the instrumentation is difficult to balance the precision and safety issues, a new method of passive circuit sampling for measuring the contact voltage drop was proposed by using the steady voltage characteristics of the Zener diode. On this basis, the influence of the current-limiting resistor and the Zener diode in the contact voltage drop sampling circuit was analyzed theoretically and the selection rules were determined. The detection circuit characteristic test was used to detect the measurement error of the sampling circuit. Through the test of frequency characteristic, the attenuation and distortion of different frequency harmonics in the sampling circuit were detected. The practical application of the sampling circuit was tested by simulating the condition test. The experimental results show that the contact voltage drop sampling circuit of the low voltage switch can accurately measure the contact voltage drop and ensure the safety of the measuring instrument.