Design And Research Of Self-Powered Switch Controller

The traditional switch can't be used alone to cut the general overload current because of many disadvantages,but after combining the thermal efficiency and the contactor,it is not the same.After repeated overload,the metal fatigue will be lowed,and the accuracy of the thermal effect-action will be gradually reduced.And if serious,the disoperation or failure to operate will appear,to cause more fault probability and risks to the safety in production due to the bending of the thermal-effect bimetallic strip caused by heating.And the traditional switch cannot be flexibly set according to the users' operation or time requirements on load current,short-circuit current and circuit breaker.Based on the design of controller switching power supply,the switch can separate accurate protection according to user set numerical judgments on the short-circuit current and promptly cut off,so as to ensure the long-term operation of the circuit is normal and stable.In the topic,according to the actual need of production,the self powered switch controller was studied to realize the current overload protection on the switch controller without the external power supply.The hardware design mainly included the self power supply,the current sampling circuit,the double range switching circuit,the setting circuit and the tripping circuit.The self power supply could be used for the power supply of the SCM,so that all energy to judge and control the loop were derived of the current signal from the transformer.The current sampling circuit could be used to detect the current in the main loop and convert it into the voltage signal.The double range switching circuit could be used to automatically select the appropriate range according to the size of the detected current,to ensure a relatively accurate signal.And,the setting circuit was the hardware circuit whose key value was set manually.It could be used to select the action current-inverse time curve according to the specific requirements.The software design mainly included the main program block diagram,the A/D conversion design,the dial encoder parameter read-in design and the three-section protection on the current.The SCM could be used to determine whether the tripping action was required through the interruption sampling of the current and the thermal simulation after the A/D conversion.The CM1 E self powered switch controller developed in the topic has been put into practice,and the switch function has achieved the expected design goal,and satisfactory results.