1
GATE EE 2006
+2
-0.6
A $$3$$ phase, $$4$$ pole, $$400$$ $$V,$$ $$50$$ $$Hz,$$ star connected induction motor has following circuit parameters $${r_1} = 1.0\Omega ,\,{r_2} = 0.5\Omega ,$$ $${\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {x_1} = x{'_2} = 1.2\Omega ,{\mkern 1mu} {x_m} = 35\Omega$$
The starting torque when the motor is started direct-on-line is (use approximate equivalent circuit model)
A
$$63.6$$ $$Nm$$
B
$$74.3$$ $$Nm$$
C
$$190.8$$ $$Nm$$
D
$$222.9$$ $$Nm$$
2
GATE EE 2006
+2
-0.6
A $$3$$ phase, $$10$$ $$kW$$, $$400$$ $$V,$$ $$4$$ pole, $$50$$ $$Hz$$, star connected induction motor draws $$20$$ A on full load. Its no load and blocked rotor test data are given below.
No Load Test: $$400V$$ $$6A$$ $$1002W$$
Blocked Rotor Test: $$90V$$ $$15A$$ $$762W$$
Neglecting copper loss in No Load Test and core loss in Blocked Rotor Test, estimate motor's full load efficiency.
A
$$76\%$$
B
$$81\%$$
C
$$82.4\%$$
D
$$85\%$$
3
GATE EE 2005
+2
-0.6
Under no load condition, if the applied voltage to an induction motor is reduced from the rated voltage to half the rated value,
A
the speed decreases and the stator current increases
B
both the speed and the stator current decrease
C
the speed and the stator current remain practically constant
D
there is negligible change in the speed but the stator current decreases
4
GATE EE 2005
+2
-0.6
A three-phase cage induction motor is started by direct-on-line (DOL) switching at the rated voltage. If the starting current drawn is 6 times the full load current, and the full load slip is 4%, the ratio of the starting developed torque to the full load torque is approximately equal to
A
0.24
B
1.44
C
2.40
D
6.00
EXAM MAP
Medical
NEET