Deck 23: Across-The-Line Starting

Question 1

Why is it that small DC motors can be started across-the-line?

Answer 1

Small DC motors can be started across-the-line because they have low inertia and the armature will rapidly gain enough speed to produce the counter EMF needed to limit current.

Question 2

Direct current motors require only one ____________________ contact to connect or disconnect them to the power line and one overload sensing device.

Answer 2

load

Question 3

The type of rotor is identified by a code letter on the ____________________ of a motor.

Answer 3

nameplate

Question 4

Direct current motors depend on inductive reactance to limit current flow.

Question 5

Some DC contactors contain two separate coils. Describe the two coils.

Question 6

In a DC contactor with two coils, the ____________________ coil is intended for momentary duty and not continuous operation.

Question 7

Across-the-line starting is the simplest of all starting methods.

Question 8

In direct current motors, by what is the initial in-rush current limited?

Question 9

What do direct current starters and contactors that do not utilize arc suppressors or magnetic blowout coils use to break the circuit?

Question 10

Contactors intended to connect direct current motors to the line often have arc suppression and magnetic blowout coils.

Question 11

Across-the-line starting is only used for alternating current.

Question 12

How is across-the-line starting accomplished?

Question 13

In a grounded system, the current sensing device must be in the ____________________ conductor.

Question 14

The type of bars used to construct the rotor has a great effect on the operating characteristics of the motor.

Question 15

In-rush current is referred to a(n) ____________________ current.