Starting torque, break away torque or locked-rotor torque¹⁾ - such a value of torque which allows an electric motor to accelerate the load, from the condition of stationary rotor (locked rotor).²⁾

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

Starting, break away or locked-rotor torque³⁾

^{S. Zurek, E-Magnetica.pl, CC-BY-4.0}

Sometimes, the torque curve, from stationary to nominal speed, is referred to as starting torque curve.⁴⁾

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 an auxiliary squirrel cage into the rotor.

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

• Pull-in torque
• Pull-out torque
• Pull-up torque
• Stall torque