GT200-B20J系列（常规型）电动机保护器（以下简称保护器）与交流接触器组成电动机保护控制电路。主要用于交流50Hz/60Hz、额定电压400V~690V、额定电流至20A及以下的三相异步电动机在常规负载、无特殊要求情况下运行中可能出现的断相、过载、堵转、阻塞、三相不平衡等故障进行保护。它具有抗干扰能力强，工作稳定可靠、精度高、安装调试简单方便等特点，是热继电器理想的更新换代产品.

GT200-B20J series (conventional) motor protector (hereinafter referred to as protector) and AC contactor form motor protection and control circuit. Mainly used in AC 50Hz/60Hz, rated voltage 400V~690V, rated current to 20A and below the three-phase asynchronous motor in the conventional load, may have no special requirements under the operation of the phase failure, overload, blocking, blocking and unbalance fault protection. The utility model has the advantages of strong anti-interference ability, stable and reliable work, high precision, simple and convenient installation and debugging, etc., and is an ideal replacement product of the thermal relay