309A Transformers and Power Distribution 4

Question 1

What is the standard voltage for single-phase residential service in Canada?

Accepted Answer

120/240 V single-phase, three-wire

Answer

120 V only

Answer

120/208 V single-phase, three-wire

Answer

240 V only

Question 2

What is the purpose of a surge arrester on a transformer?

Accepted Answer

To protect the transformer from lightning strikes and switching surges

Answer

To regulate output voltage

Answer

To improve power factor

Answer

To prevent overloading

Question 3

What is a K-rated transformer designed to handle?

Accepted Answer

Harmonic loads from non-linear loads such as VFDs and computers

Answer

High ambient temperatures

Answer

Extremely cold environments

Answer

Frequent overload conditions

Question 4

In a three-phase, four-wire wye system at 208/120 V, what is the voltage between any two line conductors?

Accepted Answer

208 V

Answer

120 V

Answer

240 V

Answer

480 V

Question 5

What is the primary difference between a dry-type and liquid-filled transformer?

Accepted Answer

Dry-type uses air for cooling while liquid-filled uses oil or other fluids

Answer

Dry-type transformers are more efficient

Answer

Liquid-filled transformers are smaller

Answer

Dry-type transformers can handle higher voltages

Question 6

What is the purpose of the Buchholz relay on an oil-filled transformer?

Accepted Answer

To detect gas accumulation indicating internal faults

Answer

To regulate oil temperature

Answer

To control the cooling fans

Answer

To monitor oil level only