The essential condition for parallel operation of two D.C. generators is that they have ‘
same percentage regulation
the same operation r.p.m.
same kW rating
the same drooping voltage characteristics
the same drooping voltage characteristics
In D.C. generators on no-load the air gap flux distribution in space is
sinusoidal
triangular
flat topped
pulsating
flat topped
With a D.C. generator which of the following regulation is preferred ?
1% regulation
50% regulation
infinite regulation
100% regulation
1% regulation
Which generator would you prefer for feeding long D.C. transmission lines ?
Over compound generator
Shunt generator
Series generator
Flat compound generator
Over compound generator
The main factor which leads to unstable parallel operation of flat and over compounded generators is
unequal series field resistances
their rising voltage characteristics
unequal number of turns in their series field winding’s
unequal speed regulation of their prime movers
their rising voltage characteristics
If a self excited D.C. generator after being installed fails to build up on its first trial run the first thing to do is to
reverse the field connections
increase the field resistance
increase the speed of prime mover
check armature insulation resistance
reverse the field connections
In a D.C. generator the critical resistance can be increased by
decreasing its speed
decreasing its field resistance
increasing its field resistance
increasing its speed
increasing its speed
The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is
2
6
4
8
4
For both lap and wave winding’s there are as many commutator bars as the number of
winding elements
poles
armature conductors
slots
winding elements
The series field of a short-shunt D.C. generator is excited by
load current
armature current
external current
shunt current
load current
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