Use digitalized RDCPS(KB0) as main switch, adopt modularized structure, integrated the functions of fuse, circuit breaker, contactor, starter, isolator, thermal relay, overload (or over current, phase missing) protection relay, motor protector, intelligent leakage circuit breaker(relay) etc. low voltage appliance together, with suitable reversible contactor, timer relay and other necessary accessories, through electrical interlock to form new protection type delta-star voltage reduce starter, RDCPS-J or RDCPS-J2,self-coupling voltage reduce starter RDCPS-Z, resistivity voltage reduce starter RDCPS-R, to achieve integrated, internal coordinated voltage reduce start auto control and protection functions,suitable for start control and protection of below 50KW motors. Have panel indication and electromechanical signal alarm auxiliary contact module. The selected reversible contactor product inside have mechanical interlock and electrical interlock accessories, greatly improved the operating reliability. Product can install with electrical interlock as per request, have the advantages of high reliability, high breaking capacity, long working life, small size, small mounting space, less maintenance job etc.