Define circuit breakers
A device designed to open and close by non-automatic means, and to open the circuit automatically on a pre-determined condition
What is another name for indicating pilot devices that come in different colors?
Pilot or Indicator lamp
In the case of magnetically opened contacts, the normal state occurs when the operating coil is ______.
deenergized
A common use of a latching relay is in the rotor circuit of a wound rotor motor.
False
OSHA does not require that a person whose work requires them to work on energized equipment to have specialized training.
False
Name three types of fuses
- Standard one time fuse
- Time delay or dual element
- Current limiting
Name three types of circuit breakers
- Non automatic
- Magnetic
- Thermal
- Thermal-magnetic
- Ratings molded case
What does ambient temperature affect?
the trip setting of the device
List three types of operators in oil tight push button units.
- Standard flush head
- Extended head
- Mushroom head
- Key lock
Why is a low voltage indicating light bulb preferred?
due to vibration normally present in machines
What is the difference between a drum switch and a selector switch?
The drum switch is bigger in size, number of contacts and positions.
What is basically a communication carrier that is also used as a power amplifier?
A relay
The ______ is really nothing but a memory relay.
latching relay
The ______ has a distinct advantage when changing relays without disturbing the circuit wiring.
plug-in relay
What is generally constructed in a similar fashion to a relay?
a contactor
The coil of the contactor is generally what voltage?
120 V
What is the difference between a motor contactor and a motor starter?
A motor contactor has a separate overload protection provided.
What device has a timing function after the timer has been energized or de-energized?
A time delay relay
What is this symbol for?
Air Circuit Breaker
