Deck 16: Single-Phase, Three-Wire Secondary System

Question 1

The ____________________ transformer is used as the source for three-wire secondary distribution.

Answer 1

double-wound

Question 2

The ____________________ is designed to carry no only the unbalanced current in the two 120-volt circuits, but also the entire load on any one side should the load on the other side be cut off completely.

Answer 2

neutral

Question 3

In a series circuit, the highest voltage appears across the highest value of resistance.

Answer 3

True

Question 4

The distribution transformers used in industrial plants or network substations for three-wire secondary systems are equipped with three low-voltage ____________________ and the series connection is made inside the tank.

Question 5

Why are the copper losses in the line considerably less for a three-wire system?

Question 6

The distribution transformers used in industrial plants or network substations for three-wire secondary systems are usually mounted on poles or in ____________________.

Question 7

Why is the junction N between the two secondary coils usually grounded?

Question 8

The three wires terminate in the residence at the load center panel so that most individual circuits carried through the house are at 240 volts.

Question 9

The copper losses in the line are of two types: (1) voltage drop (IR) and (2) ____________________ loss.

Question 10

Electric ranges and clothes dryers are designed for three-wire operation.

Question 11

Provide an example to illustrate why a three-wire system uses less copper than a two-wire system.

Question 12

What type of transformer is commonly used in residential installations?

Question 13

What are the advantages of using three-wire service in general distributions?

Question 14

Few homes are wired for three-wire service.

Question 15

The neutral is carried through the system as an unfused or switched conductor.