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Electric Motors Controls BOMA Pre-Quiz 2024/2025 Graded A+
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Electric Motors Controls BOMA Pre-Quiz 2024/2025 Graded A+
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Electric Motors Controls BOMA Pre-Quiz2024/2025 Graded A+
_____ converts between electrical and mechanical power. - ANSWER-Motor,
Generator, alternator.
________ have overloads and _________ do not? - ANSWER-Starters, contactors
"Cross firing " is? - ANSWER-Arcing across a double-brake contact
A "ladder rung" in a electrical diagram refers to? - ANSWER-A single line in the diagram
A 7200 rpm motor at 60hz has? - ANSWER-Two poles
A component that has high resistance in one direct and low in the other is a ? -
ANSWER-Diode
A contactor with two sets of contacts is? - ANSWER-2 pole contactor
A defective starter would likely not cause? - ANSWER-Damage bearings, excessive
vibrations, high voltages,
A device used to measure the rotating speed of a motor is called a? - ANSWER-
Tachometer
A double-break contacts function is to reduce the current of each arc. - ANSWER-True
A four-pole induction motor operates with a line frequency of 60 hz. What is the speed
at which the field is rotating in revolutions per minute? - ANSWER-1800
A fuses interrupting capacity is based on ? - ANSWER-The application it is used in
The maximum amperage it can interrupt without being damaged.
Manufacturers design
A latching circuit consists of? - ANSWER-Start and stop push buttons.
A magnetic field is created when? - ANSWER-Electricity flows
A magnetic field? - ANSWER-Is created when current flows,
Surround a magnet,
Is invisible
A motor - ANSWER-Converts electrical energy into mechanical energy.
, A soft start is used to? - ANSWER-Reduce starting current
A sticky armature in a contactor will most likely? - ANSWER-Burn out the coil
A tachogenerator? - ANSWER-Generates a voltage based on speed.
A temporary magnet is? - ANSWER-An electromagnet
A voltage monitor relay is used for? - ANSWER-Starting backup generators.
AC motor speed is determined by? - ANSWER-The number of poles.
an armature is - ANSWER-The movable portion of a contractor.
An electrical motors nameplate? - ANSWER-Must me on every motor in the plant
An induction motor will develop maximum torque at what speed? - ANSWER-70% to
80%
Arc chutes. - ANSWER-Help confine the arcs.
At a 60 hz frequency, a two-pole motor will operate at? - ANSWER-3600 rpms
Batteries energy capacity is measured in? - ANSWER-Amp-hours
Batteries have two rated values. - ANSWER-Voltage and amp-hours
Being wired across the line refers to? - ANSWER-A circuit that automatically restarts
after power failures.
Branch circuit conductors, must be rated at least _____ of the motors full load capacity.
- ANSWER-125%
Contacts excessively cycled: - ANSWER-Causes the contacts to overheat
DC arcs. - ANSWER-Are the most difficult to extinguish.
Drum switches reverse motors by swapping leads in a 3-please system. - ANSWER-
True
Fuel for diesel generators is often stored in a? - ANSWER-Day tank
How are normally closed contacts indicated on a ladder diagram? - ANSWER-An
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