This product is used for AC and DC load, its basic function can be used for AC and DC current and voltage indication; In addition, there are upper and lower limit setting mechanism and overrun warning light, which can be used as overrun alarm switch to protect emergency equipment. Therefore, it can be used as safety controller of emergency equipment to explain its application status: if the machine is in high load or low load condition, it will affect the normal operation of mechanical and electrical equipment and cause failure, in order to ensure the normal operation of mechanical and electrical facilities, It is necessary to install this controller, with its sensitive and accurate control of the load status function, play the role of monitoring and warning, widely used in military, chemical, metallurgical, mechanical, power distribution system.