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WorksheetsUnit 19 Review
Total questions: 22
Worksheet time: 12mins
Name
Class
Date
1.
A common practice in condensing units is to use a contactor with only one set of contacts opening only one side of the power to the unit. This is to ____.
a)
reduce the cost of the contactor
b)
make it easier to wire the unit
c)
teach the service technician not to put hands in the unit with the power on
d)
provide off-cycle heat to the compressor
2.
An inherent motor protector is a ____ .
a)
circuit breaker
b)
motor starter overload
c)
thermally activated device in the motor winding
d)
line fuse
3.
Beside maintaining pressure on the contacts for current carrying capacity, the pressure springs have a second important function. This is to ____.
a)
keep the contacts in line
b)
help obtain equal contacts against the stationary contacts
c)
slow down the pull of the armature into place to reduce the noise
d)
increase the power required to close the contacts
4.
Technician "A" says that if you take a voltage reading from terminal L1 to terminal T1 on a contactor whose coil is energized, you should read zero volts. Technician "B" says that contactors can only have normally open contacts. Which of the following statements is correct?
a)
Technician A is correct. Technician B is correct.
b)
Technician A is correct. Technician B is incorrect.
c)
Technician A is incorrect. Technician B is correct.
d)
Technician A is incorrect. Technician B is incorrect.
5.
The __ in a contactor keeps equal tension on all all contact surfaces
a)
stationary contacts
b)
holding coil
c)
springs
d)
movable contacts
6.
The motor starter has ____.
a)
a belt and pulley
b)
a start compacitor
c)
one or more overload protectors,magnetic coil, and electrical contacts
d)
been replaced by a potential relay
7.
The service factor of an electric motor is determined by ____.
a)
National Electrical Code
b)
National Electrical Manufacturers Association code
c)
motor's reserve capacity
d)
none of these
8.
When a contactor's coil is energized, how much resistance should be measured between terminal L1 and terminal T1?
a)
zero ohms
b)
50-3000 ohms
c)
5000-6000 ohms
d)
infinite
9.
Which of the following overload devices is not affected by ambient temperature?
a)
Which of the following overload devices is not affected by ambient temperature?
b)
magnetic
c)
bimetal
d)
none of these
10.
If a normally operating motor draws 75 amps on startup, it will most likely draw ___ amps when running.
a)
15
b)
25
c)
35
d)
12
11.
If a relay starts the indoor fan in the cooling mode of a central air-conditioning system, it must be able to withstand the ____________________ of the fan motor on start-up.
a)
Capacitance
b)
Rated Load Amps
c)
Running Load Amps
d)
inrush current
12.
The best way to repair a defective relay is by ____________________.
a)
replacement
b)
replacing worn parts
c)
cleaning contacts
d)
polishing it
13.
The best way to repair a large contactor is ____________________.
a)
replace component parts
b)
replace the whole contactor
c)
call a contractor
d)
tapping on it
14.
The most common material used on the surface of contacts is ____________________.
a)
silver
b)
gold
c)
platinum
d)
paladium
15.
A set of contacts are closed when the relay is energized. These contacts are classified as normally closed.
a)
true
b)
Could Be
c)
false
d)
On Friday after 4:00pm
16.
A sure sign of contact failure is discoloration on the contact surfaces.
a)
true
b)
Could Be
c)
false
d)
Never on a Sunday
17.
Auxiliary contacts are usually rated at a lower amperage than the contactor's primary contacts.
a)
true
b)
Could Be
c)
false
d)
Just another Manic Monday!
18.
Bimetal and solder pot overload devices are thermally operated.
a)
true
b)
Could Be
c)
false
d)
What Day Is It?
19.
Contactor contacts that are badly pitted can cause the motor to burn out.
a)
true
b)
Could Be
c)
false
20.
Magnetic overload devices are the most accurate type of device for electrical protection.
a)
true
b)
Could Be
c)
false
21.
The locked rotor amperage, LRA, of a motor is typically five times higher than the full load amperage, FLA, of the motor and can be as high as seven times the FLA.
a)
true
b)
Could Be
c)
false
22.
The sun shining on a distribution panel has no effect on the breakers in the panel.
a)
true
b)
Could Be
c)
false
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