1. Exercise
101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal
[1] A 3φ, 50 Hz, 6 pole induction motor has a no load slip of
1 % and a full load slip of 3 %. Determine (a)
synchronous speed (b) no load speed (c) full load speed
(d) frequency of rotor current at standstill (d) frequency
of rotor current at full load

2. Exercise
101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal
[2] A 3φ, 50 Hz, 4 pole induction motor has a star connected
rotor. The per phase rotor resistance is 0.1 Ω and per
phase standstill reactance is 2 Ω. If the induced emf
between the slip rings is 100 V, full load speed is 1460
rpm, determine (a) slip (b) rotor induced emf (c) per
phase rotor reactance (d) rotor current. Assume the slip
rings are short circuited.

3. Exercise
101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal
[3] A 3φ, induction motor has a star connected rotor. The
rotor emf between the slip rings at standstill is 50 V. The
rotor resistance and standstill rotor reactance are 0.5 Ω
and 3 Ω respectively. Determine (a) per phase rotor
current at starting if a star connected rheostat of 6 Ω per
phase is connected across the slip rings (b) full load rotor
current and rotor power factor for a full load slip of 4 %
(c) per phase rotor emf under full load condition

4. Exercise
101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal 3
[4] A A 3φ, 50 Hz, 4 pole star connected induction motor
on full load develops a useful torque of 300 Nm. If the
rotor emf is 120 cycles per minute and torque lost in
friction is 50 Nm, determine (a) slip (b) operating speed
(c) net power output (d) gross torque (e) power lost due
to friction & windage (f) gross power output (g) total
power input if total losses are 10 kW (h) efficiency

5. Exercise
101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal 3
[5] A 3φ, 50 Hz, 36 kW, 4 pole induction motor has a full
load efficiency of 84 %. The friction & windage losses
are one-third of no load losses and rotor copper losses
equal the iron loss at full load. Determine (a) Total
Losses (b) Stator Core Loss (c) Rotor Copper Loss (d)
Friction & Windage Loss (e) Gross Power Output (f)
Rotor Input

6. Exercise
101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal 3
[5] A 3φ, 50 Hz, 36 kW, 4 pole induction motor has a full
load efficiency of 84 %. The friction & windage losses
are one-third of no load losses and rotor copper losses
equal the iron loss at full load. Determine (a) Total
Losses (b) Stator Core Loss (c) Rotor Copper Loss (d)
Friction & Windage Loss (e) Gross Power Output (f)
Rotor Input