With the rapid development of power electronic technology, switching power supply is gradually replacing linear power supply been widely used. The proposed is a laboratory with a switch power supply a double way based on single-chip microcomputer control the development of digital switch power output. Switching power supply used in motor test bench for experimental Bi with dc motor and synchronous generators provide controllable dc current field winding. According to two different motor capacity, switching power supply is designed for double lk converter module output, one for all converter module capacity, the highest output voltage, maximum output Current capacity for all the other, the maximum output voltage, maximum output current. Two ways of output are independent output. To protect the motor excitation winding use safety, switch power design have over current protection, for maximum output current protection current value. At the same time, because only the test environment ac power, switch power plus an isolation transformer and not accused of single-phase rectifier bridge to get step-down chopper module input dc voltage.

The characterized by the fact that the control mechanism comprises a lever for opening the contacts that pivots from an on position corresponding to the closing of the contacts to a position corresponding to the opening of the contacts, this opening lever being associated with a pivoting cocking mechanism, able to bring back and hold said opening lever in the "on" position of the contacts, and by the fact that the trip means are able to control the mechanical separation of the opening lever and of the cocking mechanism so as to free this opening lever.