Single-Phase Transformer Operation and Polarity…

Q: What is the primary function of a transformer?

To change the voltage level of an AC supply — Transformers primarily alter voltage levels, stepping them up or down.

Q: The turns ratio of a transformer is defined as:

Np/Ns — Turns ratio is the ratio of primary turns (Np) to secondary turns (Ns).

Q: A step-up transformer has:

More turns on the secondary than the primary — Step-up transformers increase voltage, requiring more secondary turns.

Q: In an ideal transformer, what is the relationship between input and output power (neglecting losses)?

Input power is equal to output power — Ideal transformers have no losses; input power equals output power.

Q: What is the polarity marking used for on a transformer?

To ensure proper phasing when connecting multiple transformers. — Polarity markings ensure correct phase relationships when paralleling transformers.

Q: If the primary voltage is 240V and the secondary voltage is 120V, the transformer is a:

Step-down transformer — Step-down transformers reduce voltage levels.

Q: What is the core material typically used in transformers?

Iron — Iron cores enhance magnetic flux linkage between the windings.

Q: What is the relationship between primary and secondary currents in an ideal transformer?

They are inversely proportional to the turns ratio. — Currents are inversely proportional to the turns ratio because power must be conserved.

Q: What does a 'dot' on a transformer winding indicate?

The polarity of the winding — Dots indicate the instantaneous polarity of the induced voltages.

Q: Which of the following is NOT a common application of a transformer?

Converting DC to AC — Transformers work with AC. DC-to-AC conversion requires an inverter.

Question 1 of 10

What is the primary function of a transformer?

Transformers primarily alter voltage levels, stepping them up or down.

Question 2 of 10

The turns ratio of a transformer is defined as:

Turns ratio is the ratio of primary turns (Np) to secondary turns (Ns).

Question 3 of 10

A step-up transformer has:

Step-up transformers increase voltage, requiring more secondary turns.

Question 4 of 10

In an ideal transformer, what is the relationship between input and output power (neglecting losses)?

Ideal transformers have no losses; input power equals output power.

Question 5 of 10

What is the polarity marking used for on a transformer?

Polarity markings ensure correct phase relationships when paralleling transformers.

Question 6 of 10

If the primary voltage is 240V and the secondary voltage is 120V, the transformer is a:

Step-down transformers reduce voltage levels.

Question 7 of 10

What is the core material typically used in transformers?

Iron cores enhance magnetic flux linkage between the windings.

Question 8 of 10

What is the relationship between primary and secondary currents in an ideal transformer?

Currents are inversely proportional to the turns ratio because power must be conserved.

Question 9 of 10

What does a 'dot' on a transformer winding indicate?

Dots indicate the instantaneous polarity of the induced voltages.

Question 10 of 10

Which of the following is NOT a common application of a transformer?

Transformers work with AC. DC-to-AC conversion requires an inverter.

Single-Phase Transformer Operation and Polarity Quiz