Texas High-Voltage Electrical Systems Technician
Certification Exam Prep 2026 – Practice
Questions, Answers & Detailed Rationales
1. What is the primary purpose of a circuit breaker in a high-voltage
system?
A. Increase voltage stability
B. Interrupt fault current safely
C. Store electrical energy
D. Convert AC to DC
Rationale: Circuit breakers are designed to automatically interrupt
current flow during fault conditions to protect equipment and
personnel from damage.
2. Which gas is commonly used in high-voltage circuit breakers for
arc quenching?
A. Oxygen
B. Sulfur hexafluoride (SF₆)
C. Nitrogen
D. Hydrogen
Rationale: SF₆ is widely used due to its excellent dielectric strength
and arc-extinguishing properties.
3. The standard unit of electrical potential difference is:
A. Ampere
B. Volt
C. Ohm
,D. Watt
Rationale: Voltage (potential difference) is measured in volts.
4. What is the function of a potential transformer (PT)?
A. Increase current
B. Step down high voltage for measurement
C. Store energy
D. Convert DC to AC
Rationale: PTs safely reduce high voltages to measurable levels for
instruments.
5. What is the primary hazard of arc flash incidents?
A. Noise pollution
B. Magnetic interference
C. Extreme heat and thermal energy release
D. Voltage drop
Rationale: Arc flash releases intense heat that can cause severe burns
and equipment damage.
6. Which PPE rating is used for arc flash protection?
A. IP rating
B. Cal/cm² rating
C. PSI rating
D. BTU rating
Rationale: Arc-rated clothing is measured in calories per square
centimeter.
7. What is the function of a ground grid in substations?
, A. Increase voltage
B. Equalize potential and improve safety
C. Store energy
D. Reduce frequency
Rationale: Ground grids distribute fault currents safely and reduce
step/touch voltage.
8. What device protects transformers from internal faults?
A. Capacitor bank
B. Voltage regulator
C. Differential relay
D. Surge arrester
Rationale: Differential relays detect imbalance indicating internal
transformer faults.
9. Which frequency is standard in Texas power systems?
A. 25 Hz
B. 50 Hz
C. 60 Hz
D. 400 Hz
Rationale: The U.S. grid operates at 60 Hz standard frequency.
10. What does a surge arrester protect against?
A. Overcurrent
B. Transient overvoltage (lightning/switching surges)
C. Low voltage
D. Frequency variation
Rationale: Surge arresters divert high-voltage spikes safely to ground.
Certification Exam Prep 2026 – Practice
Questions, Answers & Detailed Rationales
1. What is the primary purpose of a circuit breaker in a high-voltage
system?
A. Increase voltage stability
B. Interrupt fault current safely
C. Store electrical energy
D. Convert AC to DC
Rationale: Circuit breakers are designed to automatically interrupt
current flow during fault conditions to protect equipment and
personnel from damage.
2. Which gas is commonly used in high-voltage circuit breakers for
arc quenching?
A. Oxygen
B. Sulfur hexafluoride (SF₆)
C. Nitrogen
D. Hydrogen
Rationale: SF₆ is widely used due to its excellent dielectric strength
and arc-extinguishing properties.
3. The standard unit of electrical potential difference is:
A. Ampere
B. Volt
C. Ohm
,D. Watt
Rationale: Voltage (potential difference) is measured in volts.
4. What is the function of a potential transformer (PT)?
A. Increase current
B. Step down high voltage for measurement
C. Store energy
D. Convert DC to AC
Rationale: PTs safely reduce high voltages to measurable levels for
instruments.
5. What is the primary hazard of arc flash incidents?
A. Noise pollution
B. Magnetic interference
C. Extreme heat and thermal energy release
D. Voltage drop
Rationale: Arc flash releases intense heat that can cause severe burns
and equipment damage.
6. Which PPE rating is used for arc flash protection?
A. IP rating
B. Cal/cm² rating
C. PSI rating
D. BTU rating
Rationale: Arc-rated clothing is measured in calories per square
centimeter.
7. What is the function of a ground grid in substations?
, A. Increase voltage
B. Equalize potential and improve safety
C. Store energy
D. Reduce frequency
Rationale: Ground grids distribute fault currents safely and reduce
step/touch voltage.
8. What device protects transformers from internal faults?
A. Capacitor bank
B. Voltage regulator
C. Differential relay
D. Surge arrester
Rationale: Differential relays detect imbalance indicating internal
transformer faults.
9. Which frequency is standard in Texas power systems?
A. 25 Hz
B. 50 Hz
C. 60 Hz
D. 400 Hz
Rationale: The U.S. grid operates at 60 Hz standard frequency.
10. What does a surge arrester protect against?
A. Overcurrent
B. Transient overvoltage (lightning/switching surges)
C. Low voltage
D. Frequency variation
Rationale: Surge arresters divert high-voltage spikes safely to ground.
