NCEES Electrical Engineering PE Exam 3

Question 1

On the NCEES PE Electrical exam, what is 'harmonic distortion' in a power system and why is it a concern?

Accepted Answer

Non-fundamental frequency currents generated by nonlinear loads that cause overheating, interference, and metering errors

Answer

Harmonics are multiples of the 60 Hz fundamental generated by nonlinear loads (VFDs, UPS systems); they cause extra heating in neutrals, transformers, and motors, and can cause metering and communication errors.

Question 2

In the NCEES PE Electrical exam, what is the 'demand factor' used for in electrical load calculations?

Accepted Answer

The ratio of maximum demand to installed load capacity, used to size service entrance conductors

Answer

Demand factor accounts for the fact that not all connected loads operate simultaneously at full capacity, allowing service conductors and switchgear to be sized more economically.

Question 3

For the NCEES PE Electrical exam, what is the significance of 'interrupting rating' on a circuit breaker?

Accepted Answer

The maximum fault current the breaker can safely interrupt without damage

Answer

The interrupting rating (in kA rms) is the maximum symmetrical fault current the breaker can safely clear; if fault current exceeds this rating, the breaker may explode or fail to interrupt.

Question 4

On the NCEES PE Electrical exam, what is 'load flow analysis' (power flow study) used to determine?

Accepted Answer

Bus voltages, phase angles, and real/reactive power flows throughout a power network under normal conditions

Answer

Load flow (power flow) analysis solves for steady-state bus voltages, angles, and branch power flows using Newton-Raphson or Gauss-Seidel iterative methods, used for system planning and operation.

Question 5

In the NCEES PE Electrical exam, what does 'capacitor bank power factor correction' achieve in an industrial facility?

Accepted Answer

Supplies reactive power locally, reducing reactive current drawn from the utility and lowering demand charges

Answer

Power factor correction capacitors supply leading reactive power (VAR) that offsets lagging reactive demand of inductive loads, reducing total current, line losses, and utility reactive demand charges.

NCEES National Council of Examiners for Engineering and Surveying Practice Practice Test

NCEES National Council of Examiners for Engineering and Surveying Practice Practice Test

NCEES Electrical Engineering PE Exam 3