Question 1: Low speed synchronous machines are often driven by which of the following turbines?
- hydro - turbines
- steam turbines
- Gas turbines
Previous
DC Shunt Motor Practice Test Questions
Next
circuit breaker theory quiz question and answers
BASIC
NEC 2023
Synchronous Generator Practice Questions
Free online synchronous generator (alternator) practice test. 25 basic electrical questions on synchronous speed, excitation, synchronizing conditions, governor and AVR control, and voltage regulation. Good for electrician exam prep.
TOPICS COVERED
Electrical Practice Questions
How this test works
Read each question carefully
Look for absolute words like always / never — they often distinguish the right answer.
Manage your time
You have 38 min for 25 questions. Skip tough ones and come back.
Progress is auto-saved
Your answers are saved locally — a page refresh won't lose your work.
Review your answers
After submitting you'll see every explanation and your NEC references.
A synchronous generator (alternator) always runs at a fixed speed set by the supply frequency and the number of poles: Ns = 120f/P. Two separate controls run the machine: the governor on the prime mover controls real power (and frequency, when running alone), while the excitation (field current) controls reactive power and terminal voltage. Before connecting a generator to a live grid, it must be properly synchronized — matched in voltage, frequency, and phase sequence — otherwise a very large current can flow.
25
Questions
38 min
Time
70%
Pass
Timer starts immediately. Progress is auto-saved.
0
Correct0
Wrong0s
TimeSynchronous Generator Practice Questions — Question List
Question 2: In rotating armature synchronous machines ..............
- The armature winding is on rotor and field winding is on stator
- The armature winding is on stator and field winding is on rotor
- Both armature and field winding is on stator
- Both armature and field winding is on rotor
Question 3: EMF method is used to measure ................... of synchronous Generator.
- voltage regulation
- induced EMF
- Terminal Voltage
- Short Circuit current
Question 4: Which of the following is the speed of the 2 pole 60 Hz synchronous machine?
- 3600 rpm
- 7200 rpm
- 1800 rpm
- 1000 rpm
Question 5: Which of the following turbines are most efficient at higher generator speed?
- Steam Turbines
- Water Turbines
- Gas Turbines
Question 6: In synchronous generator the terminal voltage .......................
- lags the current by 90 degrees
- leads the current by 90 degrees
- lags the current by 45 degrees
- leads the current by 45 degrees
Question 7: When an inductive load is added to synchronous generator , which following will be observed?
- The phase voltage will increase slightly
- The phase voltage will decrease slightly
- The phase voltage will be constant
Question 8: A synchronous generator with a no-load frequency of 62 Hz with a droop of 2MW/Hz connected to a 2MW load with a power factor of 0.8. What is the operating frequency of synchronous generator?
- 62 Hz
- 61 Hz
- 60 Hz
- 59 Hz
Question 9: The governor of a synchronous machine controls ..............
- Operating frequency of machine
- No -Load Frequency of the machine
- Operating voltage of the machine
- No-Load Voltage of the machine
Question 10: When the synchronous generator is connected to grid without proper synchronization, then ............................ will flow in the system.
- Very large current
- very large reactive power
- very large real power
- very large voltage
Question 11: In synchronization the frequency of the incoming machine must be slightly lower than running machine (system).
- True
- False
Question 12: The slip of a synchronous machine ranges between zero and unity.
- True
- False
Question 13: What is the synchronous speed of a 6-pole synchronous generator connected to a 60 Hz system?
- 1200 rpm
- 1800 rpm
- 3600 rpm
- 600 rpm
Question 14: The Automatic Voltage Regulator (AVR) of a synchronous generator controls the:
- Field (excitation) current, to keep terminal voltage steady
- Speed of the prime mover directly
- Number of poles on the rotor
- Frequency of the grid supply
Question 15: Before connecting (synchronizing) a generator to a live grid, which conditions must be matched?
- Voltage magnitude, frequency, and phase sequence must all match
- Only the current needs to match
- Only the generator color coding needs to match
- No conditions are needed if the breaker is fast enough
Question 16: A synchroscope is used during generator synchronizing to show:
- The phase and frequency difference between the incoming generator and the system
- The oil pressure of the prime mover
- The insulation resistance of the stator winding
- The temperature of the cooling water
Question 17: Once a synchronous generator is connected to a large grid, increasing the governor (prime mover) power setting mainly:
- Increases the real power output, while grid frequency stays essentially fixed
- Increases the terminal voltage only
- Has no effect on the generator at all
- Reverses the direction of rotation
Question 18: Damper windings (amortisseur windings) fitted in the pole faces of a salient-pole synchronous generator are mainly used to:
- Reduce hunting (speed oscillation) and improve stability
- Increase the output voltage permanently
- Replace the need for field excitation
- Reverse the direction of rotation
Question 19: A "brushless excitation" system on a large synchronous generator supplies DC field current to the rotor without using:
- Slip rings and brushes
- A prime mover
- A stator winding
- A cooling system
Question 20: A synchronous generator with a HIGH short circuit ratio (SCR) generally has:
- Better voltage stability and reactive power capability, but larger size and cost
- Always a smaller and cheaper machine
- No relation to voltage stability at all
- Zero reactive power capability
Question 21: For a synchronous generator connected to a large grid at constant real power, increasing the field excitation (current) mainly:
- Increases the reactive power (VARs) delivered by the generator
- Increases the real power output directly
- Changes the number of poles
- Has no effect on the generator operation
Question 22: Besides the EMF (synchronous impedance) method, which other method is commonly used to estimate the voltage regulation of a synchronous generator?
- The MMF (Ampere-turn) method
- The hydrometer method
- The Wheatstone bridge method
- The megger insulation test method
Question 23: A synchronous generator has 8 poles and is driven at 750 rpm. What frequency does it generate?
- 40 Hz
- 50 Hz
- 60 Hz
- 75 Hz
Question 24: Reactive power sharing between parallel synchronous generators is controlled only by adjusting the governor (prime mover) setting.
- True
- False
Question 25: A stand-alone (islanded) synchronous generator, supplying a load with no grid connection, controls its output frequency mainly using the:
- Governor of the prime mover
- Field excitation (AVR) only
- Number of parallel armature paths
- Direction of rotation
Student Reviews
No reviews yet — be the first to share your experience!
Leave a Review