Homework Answers
Given,
Frequency of three phase induction motor, f=50Hz
Number of poles of the motor, P=6
Frequency of rotor current, f2=2.5Hz
Synchronous speed of motor, Ns=120f/P
Ns=120•50/6=1000rpm
Motor slip, s=f2/f
=2.5/50=0.05
s=0.05
Motor slip, s=(Ns-Nr) /Ns
sNs=Ns-Nr
Nr=Ns(1-s)
=1000(1-0.05) =950rpm
Therefore,
Slip of the three phase induction motor, s=0.05
Speed of the three phase induction motor, Nr=950rpm
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