Electric motor supply switch-over appts. - has contactors and start relay interconnected to form two separate reversible ring scalers

摘要

Appts. switching over the supply sources of an electric motor in an electric power station selects the optimum time during running down of the motor for switching the motor over to a reserve or standby supply source. The electric motor is separated from its supply source via power contacts and each supply source has a unit for controlling the phase at the supply source. To switch over the start relay and the associated contactors in the circuit connecting the electric motor to the supply source group, so that at the instant of failure or breakdown of the supply source, rapid automatic changeover of the motor onto the supply source in the group that is intact always takes place, the contactors and the start relay are connected together to form two separate reversible ring-scalers (counters) i.e. the start relay ring-scaler and the contactor ring scaler.