Synchronous Generator MCQ Part 1 – Alternator Multiple Choice Questions

Synchronous Generator MCQ Part 1.

Multiple choice questions on Synchronous Generator (Alternator)

Low speed alternators are driven by which of following turbines

Low speed alternators are driven by which of following turbines:

  1. Steam turbines
  2. Steam engines
  3. Hydraulic turbines
  4. None of these

Correct answer: 3. Hydraulic turbines

Low speed alternators are driven by hydraulic turbines.

Good to know:

  • Specific speed of hydraulic turbines is between 3 – 1200 RPM
  • Typical speed of steam turbines: 3600 rpm

Turbo-alternators have rotors that have

Turbo-alternators have rotors that have:

  1. Small diameter
  2. Medium diameter
  3. Large diameter

Correct answer: 1. Small diamter

Turbo-alternators have rotors that have small diameter

An under-excited alternator supplies

An under-excited alternator supplies:

  1. Lagging VAR
  2. Leading VAR
  3. No VAR
  4. None of above

Correct answer: 2. Leading VAR

Copper losses of an alternator can be measured by employing

Copper losses of an alternator can be measured by employing:

  1. Auto-transformer
  2. DC Motor
  3. Induction Generator
  4. Hydro-turbine

Correct answer: 2. DC Motor

For measurement of copper losses in alternator a calibrated DC motor is used.

Salient pole rotor construction is preferred for

Salient pole rotor construction is preferred for:

  1. High speeds
  2. Medium speeds
  3. Low speeds

Correct answer: 3. Low speed

Salient pole rotors are employed for four or higher number of poles. To obtain low speeds the pole number should be high. Speed = 120*f /P

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