Starting torque



Starting torque, break away torque or locked-rotor torque - such a value of torque which allows an electric motor to accelerate the load, from the condition of stationary rotor.

The break away torque is significant especially for machines, which start with some load present, for instance motors driving mixers or pumps.

Some authors also refer to the torque curve, from stationary to nominal speed, as "starting torque curve".

Ordinary synchronous motors have zero starting torque. But with appropriate modification of the construction they might be designed to develop some starting torque, for instance by building in a squirrel cage into the rotor.

Wound-rotor motors can have higher starting torque than the nominal operating torque.