PLC and PC based monitoring and control system of the switchgear testing laboratory

The capacity and feature of a large-sized low-voltage switchgear laboratory are presented in this paper. A monitoring and control system is designed for the laboratory with industrial PC as upper computer and PLC as lower computer. The testing process and programming philosophy of switchgear testing are discussed in detail. WinCC configuration software with a human-machine interface (HMI) is used to configure the testing circuit and acting switches of switch apparatus flexibly, and monitor the dynamical testing process. Considering interlock and test circuit condition and fault protect etc., the PLC program has the capability in carrying out the three normal testing duties of closing tests, opening tests and closing-opening tests repeatedly for switchgear, the two special testing duties. The software of PLC is modularized and programmed as test duties of switch apparatus, so it is easy to be modified. The test result is also presented in this paper. It shows that the monitoring control system has high reliability, simple operation, friendly interface and stronger flexibility by running successfully in the field.