Sunday, July 3, 2016

CONFUSING QUESTIONS OF MACHINE



Q1:-Voltage regulation of an alternating may be negative where  
           1.       The load pf is lagging 
           2.       The load pf is leading
           3.       It is loaded beyond its full oad capacity
           4.       The m/c is run at very low load

ANSWER:-2




Q2:-Power t/f are designed such that max efficiency occurs at

1.       Half of the full load
2.       Near the full load
3.       1/4th of the full load
4.       3/4th of the full load(75%)

ANSWER:-4





Q3:- The brushes of a dc m/c should be physically placed on the

1.       Armature in the polar axis
2.       Armature in the interloper axis
3.       Commutation in the polar  axis
4.       Commutator in the interpoler axis

ANSWER:-3




Q4:-V curve for isolated 3-pahse synchronous motor show

1.       The variation of mechanical  power with field excitation at constant speed
2.       The variation of armature voltage with field excitation at constant mechanical power
3.       The variation of armature voltage with mechanical power
4.       The variation of armature current with field excitation at constant mechanical power

ANSWER:-4




Q5:-Which of the following is correct?

1.       Synchronous motor is supplied with dc voltage in the armature winding
2.       Synchronous motor is supplied with ac voltage in the field winding
3.       Synchronous  motor is supplied with rectified voltage in the field winding
4.       Synchronous motor is supplied with rectified voltage in the armature winding

ANSWER:-4




Q6:-During stating of 3-phase I.M. the m/c may refuse to start at all this phenomena is called

1.       Singe phase
2.       Cogging
3.       Staing
4.       Crawing

ANSWER:-2



Q7:- In arc welding the voltage required to maintain the arc is in range

1.       200-2501V
2.       1000-1200V
3.       3.2-5V
4.       20-30V

ANSWER:-4



Q8:-Which of the following equipments has the lowest pf

1.       Fully loaded I.M.
2.       Immersion heater
3.       Incandescent lamp
4.       Arc lamp


ANSWER:-4



Q9:-The mmf produced by interpole is proportional to

1.       Field current
2.       Armature current
3.       Armature current
4.       i/p field current

ANSWER:-2



Q10:- Lumen is the unit of

1.       candela
2.       amp
3.       fulorcent flux
4.       stater

ANSWER:-3


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