CHAPTER 12 — Contactors & Magnetic Motor Starters

Question 1

A _________ is a device used only periodically to remove electrical circuits from their supply source

Answer 1

Disconnect

Question 2

An advantage of silver alloy contacts is that the _______ (rust) that forms on the metal is an excellent conductor of electricity

Answer 2

Oxide

Question 3

A ___________ is the arrangement of contacts in such a way that both sets of contacts cannot be closed at the same time

Answer 3

Mechanical interlock

Question 4

A heater coil converts the excess current drawn by a motor into ______, which is used to determine whether the motor is in danger

Answer 4

Heat

Question 5

An ________ is a metal that has a fixed temperature at which it changes directly from a solid to a liquid state

Answer 5

Eutectic alloy

Question 6

_______________ are used to reduce the distance required and yet quench arcs quickly

Answer 6

Magnetic blowout coils

Question 7

_______________ are extremely quick to reset because they do not require a cooling-off period before being reset

Answer 7

Magnetic overload relays

Question 8

A ___________ is an overload relay that resets automatically

Answer 8

Bimetallic overload relay

Question 9

The ____ indicator on a trip indicator informs the operator or electrician why the unit is not operating and that it is potentially capable of restarting with an automatic reset

Answer 9

Red

Question 10

A ___________ is an overcurrent protection device with a mechanism that automatically opens the circuit when an overload condition or short circuit occurs

Answer 10

Circuit breaker

Question 11

Loose connections in the power circuit of contactors and motor starters cause _______

Answer 11

Overheating