1. The term power quality refers to:
(A) The characteristics of electrical power that affect the performance of equipment
(B) The total power output of a system
(C) The mechanical strength of a generator
(D) The size of a power plant
2. The main factors affecting power quality are:
(A) Voltage, current, and frequency variations
(B) Load torque and inertia
(C) Transformer design
(D) Line insulation
3. A voltage sag (dip) is defined as:
(A) A short-duration decrease in RMS voltage
(B) A permanent voltage drop
(C) A sudden voltage rise
(D) A drop in current only
4. A voltage swell is:
(A) A short-duration increase in RMS voltage
(B) A reduction in current
(C) A steady-state voltage drop
(D) A phase shift in voltage
5. The most common cause of voltage sags is:
(A) Short circuits or motor starting
(B) Open circuits
(C) Frequency variation
(D) Power factor correction
6. Harmonics in a power system are caused by:
(A) Non-linear loads
(B) Inductive loads only
(C) Overvoltage
(D) Frequency drift
7. The Total Harmonic Distortion (THD) measures:
(A) The percentage of harmonic distortion in voltage or current
(B) The power factor of a system
(C) The load efficiency
(D) The system frequency
8. Voltage flicker is caused by:
(A) Rapid, repetitive changes in load current
(B) Constant voltage supply
(C) Frequency variation
(D) Capacitor switching
9. Transients in power systems are:
(A) Very short-duration high-frequency disturbances
(B) Long-duration voltage dips
(C) Steady-state voltage drops
(D) Frequency deviations
10. The main impact of harmonics is:
(A) Overheating of transformers and capacitors
(B) Reduced voltage
(C) Increased frequency
(D) Improved power factor
11. Voltage unbalance is caused by:
(A) Unequal loading on three phases
(B) Harmonic distortion
(C) Voltage regulation
(D) Power factor correction
12. The acceptable limit of voltage unbalance in a power system is generally:
(A) Less than 2–3%
(B) 5–10%
(C) 10–15%
(D) 20%
13. Power factor correction capacitors can worsen power quality when:
(A) Resonance occurs with system inductance
(B) Installed in balanced systems
(C) Operated at unity power factor
(D) Used with resistive loads
14. Flicker is a problem mainly associated with:
(A) Lighting systems
(B) Transformers
(C) Motors
(D) Generators
15. Notching in voltage waveform is typically caused by:
(A) Power electronic converters
(B) Overloaded transformers
(C) Induction motors
(D) Lighting systems
16. Interharmonics are frequencies:
(A) That are not integer multiples of the fundamental frequency
(B) Exactly equal to the fundamental frequency
(C) Always above the 50th harmonic
(D) Below DC
17. The main effect of voltage transients is:
(A) Damage to sensitive electronic devices
(B) Improved voltage regulation
(C) Increased efficiency
(D) Reduced harmonic levels
18. Frequency deviation in a power system occurs mainly due to:
(A) Imbalance between generation and load
(B) Voltage sag
(C) Harmonics
(D) Ground faults
19. The ideal power quality means:
(A) Constant voltage, frequency, and sinusoidal waveform
(B) High voltage only
(C) Low power factor
(D) Constant current only
20. Reactive power compensation improves power quality by:
(A) Maintaining voltage stability
(B) Increasing current harmonics
(C) Reducing efficiency
(D) Increasing losses
21. Surge protectors are used to protect equipment from:
(A) Voltage transients and spikes
(B) Harmonic distortion
(C) Voltage sags
(D) Frequency changes
22. The most sensitive equipment to power quality problems is:
(A) Computers and electronic devices
(B) Induction motors
(C) Transformers
(D) Heaters
23. Harmonic filters are used to:
(A) Eliminate unwanted frequency components
(B) Increase harmonics
(C) Store reactive energy
(D) Change power factor
24. Static VAR Compensators (SVCs) improve power quality by:
(A) Controlling reactive power dynamically
(B) Increasing harmonics
(C) Reducing load torque
(D) Changing supply frequency
25. UPS (Uninterruptible Power Supply) systems help improve power quality by:
(A) Providing continuous, clean power during disturbances
(B) Reducing power factor
(C) Increasing load fluctuations
(D) Adding voltage dips
26. Power Quality Monitoring Equipment (PQMs) measure:
(A) Voltage, current, harmonics, and transients
(B) Temperature only
(C) Load torque
(D) Magnetic flux
27. Voltage distortion mainly affects:
(A) Sensitive electronic devices
(B) Rotating machines only
(C) Heating loads
(D) Resistive circuits
28. IEEE Standard 519 is related to:
(A) Harmonic control in power systems
(B) Transformer insulation testing
(C) Transmission line design
(D) Grounding systems
29. The most effective way to maintain power quality in an industrial setup is:
(A) Use of active filters and proper grounding
(B) Reducing insulation
(C) Increasing motor loads
(D) Using smaller cables
30. The main objective of maintaining good power quality is to:
(A) Ensure reliable, efficient, and safe operation of electrical equipment
(B) Increase system impedance
(C) Reduce frequency
(D) Enhance current distortion