LADWP ELECTRICAL POWER QUALITY
PRACTICE EXAM WITH QUESTIONS AND
VERIFIED ANSWERS, PLUS DETAILED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. A commercial customer reports that sensitive electronic
equipment repeatedly resets whenever a large motor starts. During
investigation, the voltage at the service entrance briefly falls and
then returns to normal. Which power-quality phenomenon most
directly describes this event?
A. Harmonic distortion
B. Voltage sag
C. Voltage swell
D. Electrical noise
Answer: B. Voltage sag
Rationale: A voltage sag is a short-duration reduction in RMS voltage,
commonly associated with the starting of large motors or other sudden
increases in load current. The increased current flowing through
system impedance produces a temporary voltage drop. LADWP
specifically identifies load-related disturbances as an important power-
quality concern because sensitive equipment may malfunction even
though the interruption is extremely brief.
2. Which statement best describes the fundamental objective of
power-quality management on an electric distribution system?
A. To eliminate all reactive power from customer loads
B. To maintain every customer's voltage at exactly one fixed value
1
,regardless of system conditions
C. To ensure that supplied voltage and current characteristics remain
suitable for reliable operation of connected equipment
D. To prevent customers from using nonlinear electrical equipment
Answer: C. To ensure that supplied voltage and current
characteristics remain suitable for reliable operation of connected
equipment
Rationale: Power quality encompasses voltage and current
characteristics and their effects on customer equipment. The practical
objective is not to make the system perfectly static, but to maintain
voltage, frequency, waveform quality, and related characteristics
within appropriate operating ranges. LADWP describes power quality
in terms of clean sinusoidal waveforms at 60 Hz without objectionable
disturbances that would compromise reliable equipment operation.
3. A 480-V service is being evaluated against LADWP's published
service-voltage guidelines. Which voltage range represents the
desirable range?
A. 440–508 V
B. 456–504 V
C. 450–510 V
D. 480–520 V
Answer: B. 456–504 V
Rationale: LADWP's published table lists a nominal 480-V service
with a desirable range of 456–504 V and an acceptable range of 440–
508 V. The desirable range corresponds to approximately 95%–105%
of nominal voltage. A reading outside the desirable range does not
automatically mean the service is unacceptable; the acceptable range
is broader.
2
,4. A technician measures 448 V on a nominal 480-V service. Based
on LADWP's published voltage table, which conclusion is most
appropriate?
A. The voltage is inside the desirable range
B. The voltage is above the acceptable maximum
C. The voltage is below the desirable range but within the acceptable
range
D. The voltage necessarily represents an outage
Answer: C. The voltage is below the desirable range but within the
acceptable range
Rationale: For 480 V, LADWP lists 456–504 V as desirable and 440–
508 V as acceptable. Therefore, 448 V falls outside the desirable range
but remains within the acceptable range. A technician should consider
duration, frequency, loading conditions, equipment sensitivity, and
whether the voltage persists rather than automatically classifying the
condition as an outage.
5. Which condition is most characteristic of a voltage swell?
A. RMS voltage decreases below normal for a short duration
B. RMS voltage increases above normal for a short duration
C. Fundamental frequency decreases permanently
D. Current becomes perfectly sinusoidal
Answer: B. RMS voltage increases above normal for a short
duration
Rationale: A voltage swell is a temporary increase in RMS voltage.
LADWP describes short-duration voltage swells as increases to
approximately 1.1–1.8 per unit for durations from about one-half cycle
3
, to one minute. Single-line-to-ground faults are among the possible
causes, and sensitive equipment can experience overvoltage stress.
6. A customer reports that several programmable controllers
malfunction simultaneously during a switching event, while the
RMS voltage recording shows a very brief, high-frequency
disturbance. What is the most likely concern?
A. Transient
B. Long-duration undervoltage
C. Steady-state power factor
D. Frequency regulation
Answer: A. Transient
Rationale: Transients are very short-duration disturbances that can
contain high-frequency components and substantial voltage
magnitude changes. Switching operations, lightning, capacitor
operations, and protective-device actions can produce such
disturbances. Sensitive electronic equipment can react to these events
even when conventional RMS meters show little evidence of the event.
LADWP identifies switching and protective apparatus as potential
sources of power-quality disturbances.
7. Which customer-side condition can create power-quality
disturbances because of an improper connection between neutral
and ground?
A. Multiple neutral-to-ground bonds
B. Correct phase rotation
C. Proper equipment grounding
D. Balanced three-phase loading
Answer: A. Multiple neutral-to-ground bonds
4
PRACTICE EXAM WITH QUESTIONS AND
VERIFIED ANSWERS, PLUS DETAILED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. A commercial customer reports that sensitive electronic
equipment repeatedly resets whenever a large motor starts. During
investigation, the voltage at the service entrance briefly falls and
then returns to normal. Which power-quality phenomenon most
directly describes this event?
A. Harmonic distortion
B. Voltage sag
C. Voltage swell
D. Electrical noise
Answer: B. Voltage sag
Rationale: A voltage sag is a short-duration reduction in RMS voltage,
commonly associated with the starting of large motors or other sudden
increases in load current. The increased current flowing through
system impedance produces a temporary voltage drop. LADWP
specifically identifies load-related disturbances as an important power-
quality concern because sensitive equipment may malfunction even
though the interruption is extremely brief.
2. Which statement best describes the fundamental objective of
power-quality management on an electric distribution system?
A. To eliminate all reactive power from customer loads
B. To maintain every customer's voltage at exactly one fixed value
1
,regardless of system conditions
C. To ensure that supplied voltage and current characteristics remain
suitable for reliable operation of connected equipment
D. To prevent customers from using nonlinear electrical equipment
Answer: C. To ensure that supplied voltage and current
characteristics remain suitable for reliable operation of connected
equipment
Rationale: Power quality encompasses voltage and current
characteristics and their effects on customer equipment. The practical
objective is not to make the system perfectly static, but to maintain
voltage, frequency, waveform quality, and related characteristics
within appropriate operating ranges. LADWP describes power quality
in terms of clean sinusoidal waveforms at 60 Hz without objectionable
disturbances that would compromise reliable equipment operation.
3. A 480-V service is being evaluated against LADWP's published
service-voltage guidelines. Which voltage range represents the
desirable range?
A. 440–508 V
B. 456–504 V
C. 450–510 V
D. 480–520 V
Answer: B. 456–504 V
Rationale: LADWP's published table lists a nominal 480-V service
with a desirable range of 456–504 V and an acceptable range of 440–
508 V. The desirable range corresponds to approximately 95%–105%
of nominal voltage. A reading outside the desirable range does not
automatically mean the service is unacceptable; the acceptable range
is broader.
2
,4. A technician measures 448 V on a nominal 480-V service. Based
on LADWP's published voltage table, which conclusion is most
appropriate?
A. The voltage is inside the desirable range
B. The voltage is above the acceptable maximum
C. The voltage is below the desirable range but within the acceptable
range
D. The voltage necessarily represents an outage
Answer: C. The voltage is below the desirable range but within the
acceptable range
Rationale: For 480 V, LADWP lists 456–504 V as desirable and 440–
508 V as acceptable. Therefore, 448 V falls outside the desirable range
but remains within the acceptable range. A technician should consider
duration, frequency, loading conditions, equipment sensitivity, and
whether the voltage persists rather than automatically classifying the
condition as an outage.
5. Which condition is most characteristic of a voltage swell?
A. RMS voltage decreases below normal for a short duration
B. RMS voltage increases above normal for a short duration
C. Fundamental frequency decreases permanently
D. Current becomes perfectly sinusoidal
Answer: B. RMS voltage increases above normal for a short
duration
Rationale: A voltage swell is a temporary increase in RMS voltage.
LADWP describes short-duration voltage swells as increases to
approximately 1.1–1.8 per unit for durations from about one-half cycle
3
, to one minute. Single-line-to-ground faults are among the possible
causes, and sensitive equipment can experience overvoltage stress.
6. A customer reports that several programmable controllers
malfunction simultaneously during a switching event, while the
RMS voltage recording shows a very brief, high-frequency
disturbance. What is the most likely concern?
A. Transient
B. Long-duration undervoltage
C. Steady-state power factor
D. Frequency regulation
Answer: A. Transient
Rationale: Transients are very short-duration disturbances that can
contain high-frequency components and substantial voltage
magnitude changes. Switching operations, lightning, capacitor
operations, and protective-device actions can produce such
disturbances. Sensitive electronic equipment can react to these events
even when conventional RMS meters show little evidence of the event.
LADWP identifies switching and protective apparatus as potential
sources of power-quality disturbances.
7. Which customer-side condition can create power-quality
disturbances because of an improper connection between neutral
and ground?
A. Multiple neutral-to-ground bonds
B. Correct phase rotation
C. Proper equipment grounding
D. Balanced three-phase loading
Answer: A. Multiple neutral-to-ground bonds
4
