Top 350+ Solved Electrical Machine 1 MCQ Questions Answer
Q. A shunt generator can self-excite
a. only if the resistance of the field circuit is less than critical value
b. only if the resistance of the field circuit is greater than critical value
c. irrespective of the value of the resis-tance in the field circuit
d. none
Q. The terminal voltage of a series generator is 150 V when the load current is 5 A. If the load current is increased to 10 A, the terminal voltage will be
a. 150 V
b. less than 150 V
c. greater than 150 V
d. none of the above
Q. The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage
a. will be less than 250 V
b. will always be 250 V
c. may be greater or less than 250 V
d. none of the above
Q. The essential condition for parallel operation of two D.C. generators is thatthey have '
a. same kW rating
b. the same operation r.p.m.
c. the same drooping voltage charac-teristics
d. same percentage regulation
Q. When two D.C. generators are running in parallel an equilizer bar is used
a. to increase the series flux
b. to increase the generated e.m.f.
c. to reduce the combined effect of ar-mature reaction of both the machines
d. so that the two identical machines will pass approximately equal currents to the load
Q. With a D.C. generator which of the following regulation is preferred ?
a. 100% regulation
b. infinite regulation
c. 50% regulation
d. 1% regulation
Q. Which generator would you prefer for feeding long D.C. transmission lines ?
a. Series generator
b. Shunt generator
c. Over compound generator
d. Flat compound generator
Q. In a D.C. generator the critical resistance can be increased by
a. increasing its field resistance
b. decreasing its field resistance
c. increasing its speed
d. decreasing its speed
Q. For both lap and wave windings, there are as many commutator bars as thenumberof
a. slots
b. armature conductors
c. winding elements
d. poles
Q. The series field of a short-shunt D.C. generator is excited by
a. external current
b. armature current
c. shunt current
d. load current
Q. As a result of armature reaction, the reduction in the total mutual air gap fluxin aD.C. generator is approximately
a. 40 percent
b. 25 percent
c. 10 percent
d. 5 percent
Q. Shunt generators are most suited for stable parallel operation because of their
a. rising voltage characteristics
b. identical voltage characteristics
c. drooping voltage characteristics
d. linear voltage characteristics
Q. The main factor which leads to unstable parallel operation of flat and over compounded generators is
a. their rising voltage characteristics
b. unequal number of turns in their series field windings
c. unequal speed regulation of their primemovers
d. unequal series field resistances