Daily review: Transformers | Circuit Breakers…

Q: Which component in a transformer is primarily responsible for minimizing eddy current losses?

Laminated core — Laminating the core increases resistance to eddy currents, reducing heat loss.

Q: What is the primary function of a Buchholz relay in a transformer?

Protection against internal faults — It is a gas-actuated relay used for detecting internal faults in oil-immersed transformers.

Q: In a circuit breaker, the 'arc' is formed when:

The contacts begin to separate — As contacts separate, current continues to flow through ionized air/gas, creating an arc.

Q: Which type of relay is most commonly used for the protection of long transmission lines?

Distance relay — Distance relays measure impedance to determine the location of a fault on a transmission line.

Q: What happens if a transformer is connected to a DC source?

The primary winding will likely burn out — DC has no frequency, resulting in zero inductive reactance; the low resistance causes excessive current.

Q: Which of the following circuit breakers is most suitable for Extra High Voltage (EHV) applications?

SF6 circuit breaker — SF6 gas has excellent arc-quenching and insulating properties, ideal for EHV.

Q: The 'Pick-up' value of a relay is defined as the:

Minimum current at which the relay trips — The pick-up value is the threshold current above which the relay contacts move to operate.

Q: What is the purpose of 'Transformer Oil'?

Insulation and cooling — Transformer oil acts as both an electrical insulator and a heat-transfer medium.

Q: A relay that operates when the current exceeds a preset value is known as:

Overcurrent relay — An overcurrent relay is triggered when the measured current exceeds the relay's setting.

Q: What is the function of the 'Conservator' tank in a large transformer?

To allow for oil expansion and contraction — The conservator provides space for oil volume changes due to temperature variations.

Question 1 of 10

Which component in a transformer is primarily responsible for minimizing eddy current losses?

Laminating the core increases resistance to eddy currents, reducing heat loss.

Question 2 of 10

What is the primary function of a Buchholz relay in a transformer?

It is a gas-actuated relay used for detecting internal faults in oil-immersed transformers.

Question 3 of 10

In a circuit breaker, the 'arc' is formed when:

As contacts separate, current continues to flow through ionized air/gas, creating an arc.

Question 4 of 10

Which type of relay is most commonly used for the protection of long transmission lines?

Distance relays measure impedance to determine the location of a fault on a transmission line.

Question 5 of 10

What happens if a transformer is connected to a DC source?

DC has no frequency, resulting in zero inductive reactance; the low resistance causes excessive current.

Question 6 of 10

Which of the following circuit breakers is most suitable for Extra High Voltage (EHV) applications?

SF6 gas has excellent arc-quenching and insulating properties, ideal for EHV.

Question 7 of 10

The 'Pick-up' value of a relay is defined as the:

The pick-up value is the threshold current above which the relay contacts move to operate.

Question 8 of 10

What is the purpose of 'Transformer Oil'?

Transformer oil acts as both an electrical insulator and a heat-transfer medium.

Question 9 of 10

A relay that operates when the current exceeds a preset value is known as:

An overcurrent relay is triggered when the measured current exceeds the relay's setting.

Question 10 of 10

What is the function of the 'Conservator' tank in a large transformer?

The conservator provides space for oil volume changes due to temperature variations.

Daily review: Transformers | Circuit Breakers | Relay Quiz