| 摘要 |
A method for turning a three-phase alternating current motor on again, after it has been separated from a supply voltage, if a residual field voltage induced by a rotor residual field is present, and to an electrical circuit for implementing the method. The time progressions of the residual field voltage and the supply voltage are recorded, and the phase difference between the voltages is calculated in advance from the time progressions. A time point t s is determined, at which the phase difference goes below a predetermined maximum value .DELTA..phi.max.cndot. A switching command for applying voltage is triggered at a time interval that corresponds to a predetermined switching time delay .tau.s, before the time point t s is reached, so that the motor is connected to the supply voltage approximately at the time point t s. The electrical circuit has a measurement value detection device, a microcontroller and a direct current setting device.
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