2. !

4. Determine the slip of a four-pole induction
motor running at 1440 r/min when connected to
a 50 Hz supply.
!
Ns = 120 x 50 = 1500 r/min
4

5. Slip speed = synchronous speed – rotor speed
Slip speed = 1500 – 1440 = 60 r/min

6. !
Percentage slip = 1500 – 1440 x 100 = 4 %
1500
Note: At standstill (when starting) the slip is
100% but IF the machine could reach
synchronous speed the slip would be zero.