MC II: Lesson 5 - Motor Control Centers Flashcards
The ______ is an efficient method to mount, power, and organize electrical motor control, automation, and power distribution systems.
a. motor control center
b. panelboard
c. switchboard
a. motor control center
A typical motor control center section is ______ wide by 90 inches tall, and is 15 to 20 inches deep.
a. 16”
b. 20”
c. 24”
b. 20”
The ______ should be used to install, operate, or maintain an MCC.
a. manufacturer’s manuals
b. NEC
c. project specifications
a. manufacturer’s manuals
Identify the various parts of a motor control center.
Feeder power for an MCC enters the unit from ______.
a. overhead only
b. overhead or underneath
c. underneath only
b. overhead or underneath
The fault current withstand rating of an MCC is determined by the highest rated device within the MCC.
True or False
False
Type C, MCC Size ______ or smaller units or buckets, are factory-wired from unit-located terminal blocks to the master terminal blocks.
a. 2
b. 3
c. 4
b. 3
Power buses in MCCs are typically copper or aluminum.
True or False
True
What is the class and type of an MCC consisting of interconnecting units with Size 3 or smaller starters and terminations on terminal blocks mounted on the bottom of each vertical section?
a. Class 1 – Type A
b. Class 2 – Type B-D
c. Class 2 – Type C
c. Class 2 – Type C
What is the class and type of an MCC consisting of independent units with wiring connected directly to device terminals internal to the unit?
a. Class 1 – Type A
b. Class 2 – Type B-D
c. Class 2 – Type C
a. Class 1 – Type A
What is the class and type of an MCC consisting of interconnecting units with Size 3 or smaller starters and load wiring connected to factory-wired power terminals located immediately adjacent to and accessible from the vertical wireway?
a. Class 1 – Type A
b. Class 2 – Type B-D
c. Class 2 – Type C
b. Class 2 – Type B-D
MCC’s with ______ units or buckets use a sliding track and mechanical lever.
a. fixed
b. removable
b. removable
Metering compartments in MCCs often require the use of ______ and ______ transformers to condition voltage and current levels for metering devices.
a. control / current
b. differential / auto
c. potential / current
c. potential / current
Identify the motor control compartment components of a fixed MCC bucket.
In corrosive atmospheres, copper buses in MCCs are often coated with ______ to protect the bus from corrosion.
a. carbon
b. tin
c. zinc
b. tin
The defeater mechanism screw or interlock on the door of an MCC unit or bucket serves to prevent the door on the bucket from being opened when the disconnect switch or circuit breaker is on and the unit is energized.
True or False
True
The NEMA or IEC enclosure is the primary protection from the environmental elements.
True or False
True
If the manufacturer assembled the MCC on a level surface, then installing the MCC on a level surface is not necessary.
True or False
False
When performing maintenance on an MCC, what does the presence of ozone odor indicate?
a. Arcing
b. Open circuit
c. Overheating
a. Arcing
When performing maintenance on an MCC, what does discoloration of bolted electrical connections and insulation indicate?
a. Arcing
b. Open circuit
c. Overheating
c. Overheating
When performing annual MCC maintenance, buckets should be drawn out or removed from the MCC.
True or False
True
When performing annual MCC maintenance, it is not necessary to inspect, clean, or replace air filters.
True or False
False
