The Starting Current

It is important to note that in most cases it is essential to remove an electric motor at full voltage to take full advantage of the starting torque. If the full voltage starting of an electric motor causes a voltage drop greater than the maximum permissible, use a starter with reduced voltage, however, taking care to analyze if the torque is sufficient to drive the load.

In order for the link between motors and a public electricity grid to be made, some important guidelines for this purpose, which are set up by specific rules, must be followed. Thus, the two methods for reducing the starting voltage are:

– supply current to the normal voltage, forcing the motor to be temporarily connected to the grid, with the winding for a higher voltage, thus using the star-delta starting system;

– to cause current to voltage below normal, through resistors, inductors or autotransformer.

Thus, all the starting systems with reduced voltage have some drawbacks, considering that the starting torque decreases in proportion to the square of the voltage reduction supplied to the motor.