ETC ETC Electrical & Electronic Systems 2 — Questions and Answers
Question 1: What instrument is used to measure electrical resistance in a circuit?
- Ohmmeter (Correct answer)
- Voltmeter
- Ammeter
- Wattmeter
Correct answer: Ohmmeter
An ohmmeter measures electrical resistance in ohms and must be used on a de-energized circuit.
Question 2: In a three-phase power system, what is the phase angle between each phase?
- 120 degrees (Correct answer)
- 90 degrees
- 60 degrees
- 180 degrees
Correct answer: 120 degrees
In a balanced three-phase system, each of the three phases is separated by 120 electrical degrees.
Question 3: What does a power factor of 1.0 indicate about a circuit?
- Current and voltage are perfectly in phase (Correct answer)
- The circuit is purely inductive
- The circuit has high reactive power
- Power loss is maximized
Correct answer: Current and voltage are perfectly in phase
A power factor of 1.0 means current and voltage are in phase, indicating a purely resistive load with no reactive power.
Question 4: Which type of circuit protection device automatically resets after a fault is cleared?
- Circuit breaker (Correct answer)
- Fuse
- Disconnect switch
- Surge arrestor
Correct answer: Circuit breaker
A circuit breaker can be reset after tripping, while a fuse must be replaced because its element melts during a fault.
Question 5: What is the function of a transformer in an electrical distribution system?
- To change voltage levels between circuits (Correct answer)
- To store electrical energy
- To convert AC to DC
- To measure current flow
Correct answer: To change voltage levels between circuits
A transformer uses electromagnetic induction to step voltage up or down between two circuits without direct electrical connection.
Question 6: When working on energized electrical equipment, what NFPA 70E boundary requires rubber insulating gloves?
- Restricted Approach Boundary (Correct answer)
- Flash Protection Boundary
- Limited Approach Boundary
- Prohibited Zone
Correct answer: Restricted Approach Boundary
NFPA 70E defines the Restricted Approach Boundary where rubber insulating gloves and arc-rated PPE are mandatory.
ETC ETC Electrical & Electronic Systems 2
What instrument is used to measure electrical resistance in a circuit?