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Free PE Electrical and Computer Power Practice Questions

10 free, exam-style PE Electrical and Computer Power (PE Electrical and Computer Power) practice questions with answers and explanations. No signup required. Work through them below, then take the full free PE Electrical and Computer Power practice test to study every exam domain.

These 10 free PE Electrical and Computer Power questions are organized by exam domain, so you can see how each part of the PE Electrical and Computer Power blueprint is tested. Reveal the answer and explanation under each question.

Domain 2: General Applications (8-12 questions, ~13%)

Question 1

A 750 kW load operates at 0.78 power factor lagging. The reactive power required from capacitors to correct the power factor to 0.95 lagging is closest to:

  1. 602 kVAR
  2. 238 kVAR
  3. 470 kVAR
  4. 355 kVAR
Show answer & explanation

Correct answer: D - 355 kVAR

Domain 3: Electrical Safety (10-15 questions, ~16%)

Question 2

A 3/0 AWG THWN copper conductor is installed in a raceway with five other current-carrying conductors at an ambient temperature of 40°C. Using NEC Table 310.16 (75°C column = 200 A), with a temperature correction factor of 0.88 and an adjustment factor of 0.80, the adjusted ampacity is closest to:

  1. 176 A
  2. 141 A
  3. 160 A
  4. 123 A
Show answer & explanation

Correct answer: B - 141 A

Question 3

Per NFPA 70E Table 130.7(C)(15)(c), arc-rated PPE with a minimum rating of 8 cal/cm² corresponds to PPE Category:

  1. 1
  2. 2
  3. 3
  4. 4
Show answer & explanation

Correct answer: B - 2

Domain 4: Circuit Analysis (10-15 questions, ~16%)

Question 4

A 50 MVA, 138/13.8 kV transformer has an impedance of 8% on its own base. When referred to a 100 MVA system base, the per-unit impedance of the transformer is closest to:

  1. 0.04 pu
  2. 0.08 pu
  3. 0.16 pu
  4. 0.32 pu
Show answer & explanation

Correct answer: C - 0.16 pu

Question 5

A single-line-to-ground fault occurs on an unloaded, solidly grounded generator with sequence impedances Z₁ = j0.15 pu, Z₂ = j0.15 pu, and Z₀ = j0.05 pu. The total fault current is closest to:

  1. 2.86 pu
  2. 10.00 pu
  3. 6.67 pu
  4. 8.57 pu
Show answer & explanation

Correct answer: D - 8.57 pu

Domain 5: Power Electronic Circuits and Control Devices (5-8 questions, ~8%)

Question 6

A variable frequency drive operates a 460 V, 60 Hz induction motor at 45 Hz using constant volts-per-hertz control. The voltage applied to the motor is closest to:

  1. 390 V
  2. 460 V
  3. 307 V
  4. 345 V
Show answer & explanation

Correct answer: D - 345 V

Domain 6: Rotating Machines (5-8 questions, ~8%)

Question 7

A 6-pole, 60 Hz, NEMA Design B induction motor operates at a full-load speed of 1,160 rpm. The percent slip at full load is closest to:

  1. 5.6%
  2. 6.7%
  3. 2.2%
  4. 3.3%
Show answer & explanation

Correct answer: D - 3.3%

Domain 7: Electric Power Devices (8-12 questions, ~13%)

Question 8

A transformer has a percent resistance (%R) of 1.5% and a percent reactance (%X) of 5.0%. When supplying a load at 0.80 power factor lagging, the approximate voltage regulation is closest to:

  1. 6.5%
  2. 2.2%
  3. 4.2%
  4. 4.9%
Show answer & explanation

Correct answer: C - 4.2%

Domain 9: Protection (10-15 questions, ~16%)

Question 9

A transformer differential relay uses second-harmonic restraint primarily to prevent the relay from:

  1. tripping on magnetizing inrush current
  2. operating during external through-faults
  3. operating during transformer overexcitation
  4. misoperating due to CT saturation
Show answer & explanation

Correct answer: A - tripping on magnetizing inrush current

Question 10

On a time-current characteristic (TCC) coordination study, the minimum coordination time interval (CTI) between two series electromechanical overcurrent relays is typically:

  1. 0.10 to 0.15 seconds
  2. 0.20 to 0.25 seconds
  3. 0.30 to 0.40 seconds
  4. 0.50 to 0.60 seconds
Show answer & explanation

Correct answer: C - 0.30 to 0.40 seconds

The rest of the PE Electrical and Computer Power blueprint

The PE Electrical and Computer Power exam also covers these domains. Drill them in the full free practice test:

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