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Q4. A. Describe a brush less alternator with a.c. exciter static A.V.R.;

B. State the output voltage characteristics for this type of machine.

Q4. A. In a.c. generators, voltage dip occurs in two stages.

I. Sketch a voltage-time graph showing the pattern of voltage dip.

II. Referring to this graph, state with reasons the effect on the electrical system of a small power installation when a large load is suddenly switched on.

B. Explain EACH of the following categories of voltage control:

(i) Error operated; (ii) Functional.

Q2. A. Describe a brush less alternator with a.c. exciter static A.V.R. (8)
B. State the output voltage characteristics for this type of machine. (8)

Q3. a) Sketch a circuit diagram for an automatic voltage regulator illustrating how the A.V.R. utilizes a Silicon-controlled rectifier to control the excitation system for an alternator. (8)

b) Describe how the A.V.R. monitors output and controls the excitation system. (8)

Q3. a) What precautions must be taken when testing the insulation of generator cables and wiring connected to an AVR unit? (6)

b) If synchroscope is malfunctioning, which instrument is the most essential to parallel an alternator with the busbar? Justify your answer (6)

c) How the air gap of an alternator is measured and why the air gap of an alternator to be checked periodically? (4)