Daily review: Transformers | Circuit Breakers Quiz…

Q: What is the primary function of the conservator tank in a power transformer?

To allow for the expansion and contraction of transformer oil due to temperature variations — The conservator provides space for oil expansion and contraction, preventing air contact with the main tank oil.

Q: In a transformer, what does the 'Buchholz relay' specifically detect?

Internal faults accompanied by gas generation — The Buchholz relay is a gas-actuated protective device installed between the main tank and the conservator.

Q: Which of the following is an advantage of SF6 circuit breakers?

Excellent arc quenching and dielectric properties — SF6 (Sulfur Hexafluoride) has high electronegativity, making it an excellent arc extinguishing medium.

Q: What is the phenomenon responsible for the 'humm' sound in a transformer?

Magnetostriction — Magnetostriction causes the iron core to physically expand and contract with the alternating magnetic field.

Q: What is the 'breaking capacity' of a circuit breaker?

The highest current it can successfully interrupt under specified conditions — Breaking capacity is the highest fault current that the breaker can safely interrupt without damage.

Q: Which transformer test is performed to determine the core losses?

Open-circuit test — The open-circuit test is conducted at rated voltage to measure core losses (iron losses).

Q: Why is transformer oil filtered and dehydrated?

To maintain high dielectric strength and prevent internal arcing — Moisture and impurities significantly lower the dielectric strength of transformer oil, risking insulation failure.

Q: Which type of circuit breaker is most commonly used in high-voltage DC (HVDC) transmission?

Specialized hybrid/solid-state DC breakers — DC has no natural zero-crossing, making conventional AC breakers ineffective; specialized breakers are required.

Q: In a transformer, the 'all-day efficiency' is primarily affected by:

Constant iron losses throughout the day — All-day efficiency depends more on constant iron losses than copper losses, especially in distribution transformers.

Q: What is the purpose of the 'arc chute' in an air-break circuit breaker?

To split and lengthen the arc to aid extinction — Arc chutes use plates to split, cool, and lengthen the arc, increasing its resistance to aid extinction.

Question 1 of 10

What is the primary function of the conservator tank in a power transformer?

The conservator provides space for oil expansion and contraction, preventing air contact with the main tank oil.

Question 2 of 10

In a transformer, what does the 'Buchholz relay' specifically detect?

The Buchholz relay is a gas-actuated protective device installed between the main tank and the conservator.

Question 3 of 10

Which of the following is an advantage of SF6 circuit breakers?

SF6 (Sulfur Hexafluoride) has high electronegativity, making it an excellent arc extinguishing medium.

Question 4 of 10

What is the phenomenon responsible for the 'humm' sound in a transformer?

Magnetostriction causes the iron core to physically expand and contract with the alternating magnetic field.

Question 5 of 10

What is the 'breaking capacity' of a circuit breaker?

Breaking capacity is the highest fault current that the breaker can safely interrupt without damage.

Question 6 of 10

Which transformer test is performed to determine the core losses?

The open-circuit test is conducted at rated voltage to measure core losses (iron losses).

Question 7 of 10

Why is transformer oil filtered and dehydrated?

Moisture and impurities significantly lower the dielectric strength of transformer oil, risking insulation failure.

Question 8 of 10

Which type of circuit breaker is most commonly used in high-voltage DC (HVDC) transmission?

DC has no natural zero-crossing, making conventional AC breakers ineffective; specialized breakers are required.

Question 9 of 10

In a transformer, the 'all-day efficiency' is primarily affected by:

All-day efficiency depends more on constant iron losses than copper losses, especially in distribution transformers.

Question 10 of 10

What is the purpose of the 'arc chute' in an air-break circuit breaker?

Arc chutes use plates to split, cool, and lengthen the arc, increasing its resistance to aid extinction.

Daily review: Transformers | Circuit Breakers Quiz