1. This product applies to 50Hz、380V、14~190KW 3- phase asynchronous motors infrequently self-coupling step-down start; 2. Steel plate welded shell with plastic-sprayed surface; 3. Inside mounted auto-transformer, AC contactor thermal relay, time-relay, intermediate relay, fuser and indicator etc; 4. sessing the guarding function against overload、 under-voltage and phase failure; 5. Steelpipe and cable wiring; 6. Can be customized according to users requirements. 7. Suitable for GB3836-2000、IEC60079, GB12476.1-2000、 IEC61241 standard request.