Design of high speed transfer device for medium voltage motor bus supply transfer

In the paper the high speed motor bus transfer design and calculation algorithms are presented. The purpose of the presented algorithms is to achieve in phase circuit breakers commutation between main and auxiliary voltage power supply, taking into account the variable time delays of circuit breakers during turn on and turn off. Due to existence of the residual magnetic field within induction motors, connected to the motor bus, there is the stator voltage decay phenomenon. The detailed description of the algorithm implemented on the industrial grade PLC is presented as well as the experimental results. The possibility of algorithm improvements is discussed at last.