Deck 25: Autotransformer Starting

Question 1

If 50 percent of the normal voltage is connected to the motor, the in-rush current will drop to ____________________ percent.

Answer 1

50
fifty

Question 2

Open transition starting is generally used on starters of size ____________________ and smaller.

Answer 2

5
five

Question 3

Most autotransformer starters use two transformers to reduce the voltage applied to the motor during the period of acceleration.

Answer 3

True

Question 4

Many autotransformer starters contain taps that can be set for 50, 65, or 80 percent of the line voltage.

Question 5

What are the two effects of reducing the voltage applied to the motor?

Question 6

What is meant by open transition starting?

Question 7

For closed transition starting, four separate start contactors are used.

Question 8

____________________ starters are generally employed to start squirrel cage type motors.

Question 9

Autotransformer starters provide greater starting torque per ampere drawn from the line than any other type of reduced voltage starter.

Question 10

Wound rotor type motors and synchronous motors generally use autotransformer starters.

Question 11

In an autotransformer starter, what happens when the START button is pressed?

Question 12

Autotransformer starters are ____________________ type loads and will affect the power factor during the starting period.

Question 13

How do autotransformer starters reduce the amount of in-rush current?

Question 14

In closed transition starting, what is the role of three current transformers (CTs) being used in the circuit?

Question 15

Figure 25-1
The accompanying figure shows transformers connected in open-____________________.