In view of the high starting current value of the induction motors, the time taken to accelerate high inertia loads can result in a rapid rise in engine temperature. A starting with the electric motor heated, with the windings at regime temperature, simulating the case in which the first start of the motor is made, for example, by the shutdown of the protection, thus guaranteeing a second attempt.
The second starting condition occurs in the event of an accidental shutdown of the motor in normal operation, for example due to a lack of power in the mains, allowing to continue operation soon after the power is restored. DUTF-B
If the interval between consecutive starts is very small, this factor will cause a rise in temperature in the winding, which can damage or reduce its durability. The official standards lay down a minimum starting system (S1), which engines, regardless of their category, must be able to meet. Two continuous starts, the first one being made with the engine cold, that is, with its windings at room temperature, and the second starting immediately after the engine has decelerated until the moment of rest.