Which of the following pair is used for frequency converter?
Right Answer is:
Squirrel cage induction motor and Wound rotor induction motor
SOLUTION
Frequency converter
Squirrel cage induction motor and Wound rotor induction motor pair is used for frequency converter.
A conventional wound-rotor motor along with a squirrel cage induction motor may be used as a frequency converter to generate a frequency different from that of the utility company. The stator of the wound-rotor machine is connected to the utility line, and the rotor is driven at an appropriate speed by a motor i.e Squirrel Cage Induction motor. The rotor supplies power to the 3-phase load at a voltage E2 and frequency f2 both of which depend upon the slip.
f2 = sf
In general, the desired frequency is two or three times that of the utility company. According to the above equation in order to attain this frequency, the slip must be positive and greater than 1. As a result, the shaft must be rotated against the direction of the revolving flux.
The operation of the frequency converter b then identical to that of an induction motor operating as a brake. However, the power P usually dissipated as heat in the rotor is now available to supply power to the load. The converter acts as a generator.