Deck 25: Autotransformer Starting

Question 1

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

Answer 1

The CTs reduce the current to a level that common overload heaters can be used to protect the motor.

Question 2

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

Answer 2

inductive

Question 3

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

Answer 3

True

Question 4

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

Question 5

What is meant by open transition starting?

Question 6

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

Question 7

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

Question 8

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

Question 9

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

Question 10

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

Question 11

Figure 25-1

The accompanying figure shows transformers connected in open-____________________.

Question 12

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

Question 13

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

Question 14

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

Question 15

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