# MCQs on Electrical Machines

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01․ A load of 900 lbs is to be raised with a lift car weighting 855 lbs at a speed of 110 feet per minute, the over balance being 40 % and percentage efficiency 45 %. Find the horse power of the motor without counterweight
150.
160.
170.
180.

02․ Mechanical energy is supplied to DC generator at the rate of 4200 J / s. The generator delivers 32.2 Amp at 120 V. What is the percentage efficiency of the generator?
201.02 V.
205 V.
210 V.
212 V.

03․ If a shunt generator delivers 100 A at 200 V, and the resistances of the shunt field and armature are 100 ohms and 0.01 ohms respectively, the generator emf will be
series.
parallel.
any one of the connection.
no resistance is connected.

Source transformation is applied to a voltage source when an impedance is connected in series to it and it is applied to a current source when an impedance is connected in parallel to it.

04․ We can apply source transformation to voltage source when a resistance is connected to it in
10 HP.
13 HP.
14 HP.
15 HP.

05․ Universal motor have which of the following application?
Domestic pump.
Food mixer.
Traction.
Lift.

Universal motor is used in food mixer because of high speeds about 1500 - 15000 rpm .

06․ A 3 stack stepper motor has 12 teeth on stator as well as on rotor. Determine the step size when each stack excited?
10Ã‚Â°.
24Ã‚Â°.
30Ã‚Â°.
45Ã‚Â°.

07․ The field system of an alternator is usually excited
250 / 250 V DC.
110 / 220 V AC.
230 V AC.
3 - ÃŽÂ¦, 50 Hz and 400 V.

Under construction.

08․ Alternator operates on the principle of
self induction.
electromagnetic induction.
mutual induction.
self or mutual induction.

Under construction.

09․ In a synchronous machine, if the field flux axis is ahead of the armature field axis in the direction of rotation, the machine operating is
synchronous generator.
synchronous motor.
asynchronous motor.
asynchronous generator.

Under construction.

10․ In an alternator the voltage generated per phase is proportional to
flux per pole.
number of turns in coil.
frequency of waveform.
all of the above.

Under construction.

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