Introduction to Electrical Power and Power Electronics

96 Introduction to Electrical Power and Power Electronics

although the exact speed regulation is determined by Equation 3.15, which applies to

any source of mechanical power. Therefore, in the rst approximation, motor speed

regulation = slip at rated load. Furthermore, since the rotor sees the stator ux rotat-

ing at slip speed, the rotor current frequency is

f

r

= s × f, where f = frequency of the stator supply power (main lines). (4.7)

The motor with load on the shaft, no matter how small, cannot run at synchronous

speed. At synchronous speed, s = 0, and there would be no rotor current induced and

no torque produced on the motor shaft. At a ...