Electrical Machines
Induction Machines
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Synchronous Machines
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1
GATE EE 2007
MCQ (Single Correct Answer)
+2
-0.6
A three phase squirrel cage induction motor has a starting current of seven times the full load current and full load slip of $$5\% $$

If a star-delta starter is used to start this induction motor, the per unit staring torque will be

A
$$0.607$$
B
$$0.816$$
C
$$1.225$$
D
$$1.616$$
2
GATE EE 2007
MCQ (Single Correct Answer)
+2
-0.6
A three phase squirrel cage induction motor has a starting current of seven times the full load current and full load slip of $$5\% $$

If an auto-transformer is used for reduced voltage starting to provide $$1.5$$ per unit starting torque, the auto-transformer ratio $$\left( \% \right)$$ should be

A
$$57.77\% $$
B
$$72.56\% $$
C
$$78.25\% $$
D
$$81.33\% $$
3
GATE EE 2007
MCQ (Single Correct Answer)
+2
-0.6
A three-phase squirrel cage induction motor has a starting torque of $$150\% $$ and a maximum torque of $$300\% $$ with respect to rated torque at rated voltage and rated frequency. Neglect the stator resistance and rotational losses. The value of slip for maximum torque is
A
$$13.48\% $$
B
$$16.42\% $$
C
$$18.92\% $$
D
$$26.79\% $$
4
GATE EE 2006
MCQ (Single Correct Answer)
+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
$$85\% $$
GATE EE Subjects
Electromagnetic Fields
Signals and Systems
Engineering Mathematics
General Aptitude
Power Electronics
Power System Analysis
Analog Electronics
Control Systems
Digital Electronics
Electrical Machines
Electric Circuits
Electrical and Electronics Measurement