a) Increasing the field current
b) Increasing its speed
c) Increasing the armature resistance
d) All of these

Ans: (b)

a) Short-circuited terminals
b) Reversed terminal of field winding
c) Reversed terminal of armature winding
d) Disconnected load

Ans: (a)

a) 85 – 95 %
b) 75 – 85 %
c) 65 – 75 %
d) 55 – 65 %

Ans: (a)

a) Interpoles additionally supply mmf for counter acting the reactance voltage induced in the coil under going commutalion
b) Action of interpoles is localized
c) Interpoles also helps in equalizing distribution of current in brushes
d) (Both (a) and b)

Ans: (d)

a) High resistance of the brushes
b) Reactance voltage
c) Armature reaction
d) Quick reversal of current in the coil

Ans: (b)

a) Cross magnetizes it
b) Demagnetizes it
c) Strengthens the main flux
d) Both (a) and (b)

Ans: (d)

a) Rated voltage is less than no load voltage
b) Series field AT produces same voltage at rated and no load
c) Series field AT produces rated voltage grated then and no load
d) Series field AT produces rated voltage less than no load

Ans: (b)

a) Increasing the resistance of the brushes
b) Reducing the number of turns in armature coil
c) Neutralizing reactance voltage
d) All of these

Ans: (d)

a) To increase the series flux
b) Because both will pass equal currents to the load
c) To reduce combined effect of armature reaction of both
d) To increase speed and hence generated emf.

Ans: (b)

a) Not develop voltage at all
b) Generate maximum power
c) Generate maximum voltage
d) None of these

Ans: (a)

a) Polarities must be same
b) Phase sequence must be same
c) Polarities and voltage must be same
d) Both (b) and (c)

Ans: (d)

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