Question: In a separately excited generator supplying rated load the armature reaction.

• 1. is always present
• 2. is always absent
• 3. may be sometimes present
• 4. none of the above

Question: The series field of a short-shunt D.C. generator is excited by_______________?

• 1. external current
• 2. armature current
• 3. shunt current
• 4. load current

Question: The critical resistance of the D.C. generator is the resistance of_____________?

• 1. field
• 2. brushes
• 3. armature
• 4. load

Question: As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately______________?

• 1. 40 percent
• 2. 25 percent
• 3. 10 percent
• 4. 5 percent

Question: Shunt generators are most suited for stable parallel operation because of their______________?

• 1. rising voltage characteristics
• 2. identical voltage characteristics
• 3. drooping voltage characteristics
• 4. linear voltage characteristics

Question: When two D.C. series generators are running in parallel, an equilizer bar is used________________?

• 1. to increase the speed and hence generated e.m.f.
• 2. to increase the series flux
• 3. so that two similar machines will pass approximately equal currents to the load
• 4. to reduce the combined effect of ar-mature reaction of both machines

Question: The main factor which leads to unstable parallel operation of flat and over compounded generators is_____________?

• 1. their rising voltage characteristics
• 2. unequal number of turns in their series field windings
• 3. unequal speed regulation of their primemovers
• 4. unequal series field resistances

Question: 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______________?

• 1. reverse the field connections
• 2. increase the field resistance
• 3. increase the speed of primemover
• 4. check armature insulation resistance

Question: Which of the following generating machine will offer constant voltage on all loads?

• 1. Self-excited generator
• 2. Separately excited generator
• 3. Level compounded generator
• 4. All of the above

Question: Which of the following generators will be preferred if they are required to be run in parallel?

• 1. Shunt generators
• 2. Series generators
• 3. Compound generators
• 4. None of the above