Electrical PE Exam UPDATED ACTUAL
Exam Questions and CORRECT Answers
Inductor impedance equation - CORRECT ANSWER - Z = j*w*L
How can a transformer, motor, or generator be saturated? - CORRECT ANSWER - The
voltage/frequency ratio is altered. For example, this happens when excessive voltage is applied
to the primary side or the frequency is too low.
What are some sources of triplen harmonics? - CORRECT ANSWER - Electronics, CFL
lamps, electronics dimmers, etc.
What are the effects of triplen harmonics on an electrical system? - CORRECT
ANSWER - 1. Neutral over-loading
2. Electrical equipment (bus bars, transformers over-heating)
3. Eddy current losses (proportional to square of frequency)
How are triplen harmonics mitigated? - CORRECT ANSWER - Detuned filter or active
harmonic filter.
Capacitor impedance equation - CORRECT ANSWER - Z = (-j)/(w*C)
What is conductance? - CORRECT ANSWER - Inverse of resistance
RMS (root means square) equation - CORRECT ANSWER - RMS = Max/sqrt(2)
Parallel resistor Equation (only 2) - CORRECT ANSWER - (R1*R2)/(R1+R2)
Convert sin(wt) to cosine form - CORRECT ANSWER - cos(wt-90)
, Is a positive reactive power inductive or capacitive? - CORRECT ANSWER - Inductive
Is a negative reactive power inductive or capacitive? - CORRECT ANSWER - Capacitive
If the power factor is lagging, the _______ lags the _______ - CORRECT ANSWER -
current, voltage
If the power factor is leading, the _______ leads the _______ - CORRECT ANSWER -
current, voltage
Why is reactance required in a system? Why not have unity power factor? - CORRECT
ANSWER - Reactance is required for transformer action in transformers and generators
(inductive components consume reactive power) and to keep bus voltages at their required
values.
Power factor equation relating true power and apparent power - CORRECT ANSWER - pf
= P/S
Power factor equation relating the voltage and phase angles - CORRECT ANSWER - pf =
cos(theta_V-theta_I)
Equation for apparent power (S) based on real power (P) and reactive power (Q) - CORRECT
ANSWER - S^2 = P^2 + Q^2
A balanced 3-phase system has its phases spaced exactly ______ degrees apart - CORRECT
ANSWER - 120
Line-to-line to line-to-neutral ratio - CORRECT ANSWER - sqrt(3)
Exam Questions and CORRECT Answers
Inductor impedance equation - CORRECT ANSWER - Z = j*w*L
How can a transformer, motor, or generator be saturated? - CORRECT ANSWER - The
voltage/frequency ratio is altered. For example, this happens when excessive voltage is applied
to the primary side or the frequency is too low.
What are some sources of triplen harmonics? - CORRECT ANSWER - Electronics, CFL
lamps, electronics dimmers, etc.
What are the effects of triplen harmonics on an electrical system? - CORRECT
ANSWER - 1. Neutral over-loading
2. Electrical equipment (bus bars, transformers over-heating)
3. Eddy current losses (proportional to square of frequency)
How are triplen harmonics mitigated? - CORRECT ANSWER - Detuned filter or active
harmonic filter.
Capacitor impedance equation - CORRECT ANSWER - Z = (-j)/(w*C)
What is conductance? - CORRECT ANSWER - Inverse of resistance
RMS (root means square) equation - CORRECT ANSWER - RMS = Max/sqrt(2)
Parallel resistor Equation (only 2) - CORRECT ANSWER - (R1*R2)/(R1+R2)
Convert sin(wt) to cosine form - CORRECT ANSWER - cos(wt-90)
, Is a positive reactive power inductive or capacitive? - CORRECT ANSWER - Inductive
Is a negative reactive power inductive or capacitive? - CORRECT ANSWER - Capacitive
If the power factor is lagging, the _______ lags the _______ - CORRECT ANSWER -
current, voltage
If the power factor is leading, the _______ leads the _______ - CORRECT ANSWER -
current, voltage
Why is reactance required in a system? Why not have unity power factor? - CORRECT
ANSWER - Reactance is required for transformer action in transformers and generators
(inductive components consume reactive power) and to keep bus voltages at their required
values.
Power factor equation relating true power and apparent power - CORRECT ANSWER - pf
= P/S
Power factor equation relating the voltage and phase angles - CORRECT ANSWER - pf =
cos(theta_V-theta_I)
Equation for apparent power (S) based on real power (P) and reactive power (Q) - CORRECT
ANSWER - S^2 = P^2 + Q^2
A balanced 3-phase system has its phases spaced exactly ______ degrees apart - CORRECT
ANSWER - 120
Line-to-line to line-to-neutral ratio - CORRECT ANSWER - sqrt(3)
