Regeneration of power with single-phase electric railway motors

The conditions necessary in order that an electric motor may operate successfully in regenerating or restoring power to the supply circuit are: 1. The counter pressure generated by the motor must be greater than the impressed pressure of the supply circuit. 2. The value of this excess counter pressure must be under control and maintained in suitable relation to the impressed pressure. 3. There must be at the time other power-consuming devices connected to the supply circuit.