Control cct. for AC motor - returns control gradually back to normal after failed supply returns

摘要

The control circuit, for an a.c. motor, has a switch that opens when the supply fails. When the supply returns, the voltage regulator gradually returns to its normal state and thereby the voltage on the supply rectifier is only gradually increased. The frequency divider is controlled such that the static inverter has a load free interval after the supply has returned to normal. The switch is then closed after a given delay so that the frequency divider then receives an input. The control circuit monitors the phase of the motor's terminal voltage.