Principles of Operation of the Induction Rotor

It can be said that the high starting currents can cause undesirable factors, since they require certain dimensioning of cables with diameters much larger than necessary. Thus, it may be that there are momentary drops in the power factor, which must always be controlled by the electric utility, causing an increase in energy bills. To avoid these high starting currents, there are several electric motor drive methods which offer a reduction weg electric 00536os1dcd56h-s in the starting current value of these machines, for example star-delta start, series-parallel start and sine-start start.

Induction motors can be found in different ways, with three, six, nine or twelve external terminals. In the case of the induction machine with six terminals, there are two types of connection. The triangle with a nominal phase winding voltage equal to 220 V and the star which has the star-connected winding the line voltage becomes √3 times the winding voltage in Δ, that is, √3 times 220 which is equal to 380V. When the motor is energized, it starts to function as a transformer with the secondary being shorted, thus requiring a higher than nominal current from the mains.