Based on PLC in Automatic Put-in of Standby Power Source Abstract: with the increasing in power, the whole power production process, because all sorts of human factors or nature causes blackout fault, brings to the society of economic and political impact should not be negligible. Improve equipment quality and prolong the service life and increasing power reliability, ensure the safe operation of the power network is more and more important. Put forward by PLC control device consists of circuit breaker, due to internal have plenty of auxiliary PLC relay, can give full play to its interlock function, greatly improving the reliability of the control device, through the programming and changing external connection, can make the control device has a variety of functions, if properly equipped interface. With the PC communications, achieve power systems "four control".