NCEES Electrical Engineering PE Exam 2 — Questions and Answers
Question 1: On the NCEES PE Electrical exam, what is the 'skin effect' in AC conductors?
- Corrosion of the conductor surface over time
- The tendency for AC current to concentrate near the conductor surface, increasing effective resistance (Correct answer)
- The insulation breakdown at high voltages
- The magnetic saturation of steel conduit
Correct answer: The tendency for AC current to concentrate near the conductor surface, increasing effective resistance
At high frequencies, electromagnetic effects force AC current to flow near the conductor surface, reducing the effective cross-sectional area and increasing resistance above its DC value.
Question 2: In the NCEES PE Electrical exam, what does 'voltage regulation' of a transformer measure?
- The ratio of primary to secondary turns
- The percentage change in secondary voltage from no-load to full-load (Correct answer)
- The efficiency of the transformer at rated load
- The harmonic distortion in the secondary voltage
Correct answer: The percentage change in secondary voltage from no-load to full-load
Voltage regulation = (VNL - VFL)/VFL × 100%, measuring how much the secondary terminal voltage drops from no-load to full-load condition.
Question 3: For the NCEES PE Electrical exam, which NEC article governs the installation of electrical wiring in commercial and industrial facilities?
- Article 100 (Definitions)
- Article 230 (Services)
- Article 300 (Wiring Methods and Materials) (Correct answer)
- Article 700 (Emergency Systems)
Correct answer: Article 300 (Wiring Methods and Materials)
NEC Article 300 establishes general requirements for wiring methods and materials, covering conductor installation, raceway fill, and physical protection for commercial/industrial wiring.
Question 4: On the NCEES PE Electrical exam, what is the purpose of 'protective relaying' in a power system?
- To regulate voltage within ±5% of nominal
- To detect abnormal conditions and rapidly isolate faulted equipment to limit damage (Correct answer)
- To provide reactive power compensation
- To measure energy consumption for billing
Correct answer: To detect abnormal conditions and rapidly isolate faulted equipment to limit damage
Protective relays detect faults (overcurrent, undervoltage, differential currents) and send trip signals to circuit breakers to quickly isolate the faulted section and protect equipment.
Question 5: In the NCEES PE Electrical exam, what does the 'grounding electrode system' required by NEC Article 250 accomplish?
- Provides a low-impedance path for fault current to return to the source, enabling overcurrent device operation (Correct answer)
- Increases the efficiency of three-phase motors
- Reduces harmonic distortion in distribution systems
- Provides standby power during utility outages
Correct answer: Provides a low-impedance path for fault current to return to the source, enabling overcurrent device operation
The grounding electrode system stabilizes voltage during normal operation and provides a fault-return path that enables overcurrent devices to operate and clear ground faults safely.
Question 6: For the NCEES PE Electrical exam, which motor type has speed directly proportional to supply frequency and number of poles?
- DC shunt motor
- Wound-rotor induction motor at no load
- Synchronous motor (Correct answer)
- Universal motor
Correct answer: Synchronous motor
Synchronous motors run exactly at synchronous speed (Ns = 120f/P), directly proportional to supply frequency and inversely proportional to the number of poles.
NCEES Electrical Engineering PE Exam 2
On the NCEES PE Electrical exam, what is the 'skin effect' in AC conductors?