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Electric Motor Control Q/A
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Electric Motor Control Q/A
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Electric Motor Control Q/AEquipment Grounding ✔️ connecting all metal parts of an electrical
system that do not normally carry current to earth ground
Examples of parts that you might ground. ✔️ 1. metal conduit
2. raceways
3. enclosures
4. transformer cases
Fatal current can be as low as ___ __. ✔️ 100 mA
You need to know ___ _________ ___ _____ that apply to your application before
you do any electrical work. ✔️ all standards and codes
NEC ✔️ national electric code
The ___ is the accepted guide in the US for safely installing and maintaining
electrical systems and equipment. ✔️ NEC
NEMA ✔️ National Electrical Manufacturers Association
____ publishes standards for a wide range of motor control equipment. ✔️
NEMA
NEMA standards are ___ commonly observed outside the US. ✔️ not
IEC ✔️ International Electrotechnical Commission
The ___ is the accepted standard in most other countries. ✔️ IEC
UL ✔️ Underwriters Laboratories
OSHA ✔️ Occupational Safety and Health Administration
Observing electrical safety rules will help you _____ a situation that could result
in a shock. ✔️ avoid
,Electrical Safety: ______ all metal jewelry. ✔️ remove
Electrical Safety: Be aware of condition ______ working on a piece of
equipment. ✔️ before
Electrical Safety: Do not rely on ______ _______ to protect you. ✔️ safety
devices
Electrical Safety: Never remove the _________ _____ on an AC plug. ✔️
grounding plug
Electrical Safety: Always keep your tools and test equipment _________. ✔️
organized
Electrical Safety: Do not work on ___ floors. ✔️ wet
Electrical Safety: Work with ___ hand. ✔️ one
Electrical Safety: ______ move slowly and deliberately. ✔️ always
Electrical Safety: Do not work _____. ✔️ alone
Electrical Safety: Avoid ____________. ✔️ distractions
OSHA requires the locking out of all _____ _______ that can be locked out to
prevent the possible dangers during servicing or maintenance. ✔️
power sources
Lockout ✔️ process of blocking the energy flow from a power source to
a piece of equipment and assuring that it remains
3 examples of lockout devices ✔️ lock, block, or chain
______ involves placing a tag on the power source that warns others not to
restore power. ✔️ tagout
What must tags must clearly state? ✔️ do not operate
,The only person who should remove a lockout / tagout is? ✔️ the
person who installed it
Equipment grounding involves connecting to earth ground all _____ parts of an
electrical system that do not carry current under normal conditions. ✔️
metal
A current as small as ___ __ can be fatal. ✔️ 100 mA
NEC stands for _____ _____ _____. ✔️ national electrical code
You cannot count on devices such as fuses, relays and interlocks to _______ you
from shock. ✔️ protect
Standing on a wet floor _________ the resistance between you and ground,
increasing the possibility of severe shock. ✔️ decreases
_______ is the process of blocking the energy flow from a power source to a
piece of equipment and assuring it remains blocked. ✔️ lockout
Three Phase Power ✔️ electrical power transmitted in three separate
phases
An __________ that had three main windings operating 120 degrees apart
creates the three phases.
Therefore, the electrical energy produced as the rotor rotates is also in three
phases that are 120 degrees ___ __ _____ with each other. ✔️ alternator
out of phase
_____ _____ _____ is very versatile because a variety of single phase and three
phase voltages are available with distribution and control transformers.
✔️ three phase power
Power companies transmit three phase power at a ____ ____ _______ to minimize
power losses. ✔️ very high voltage
Two basic three phase systems for power distribution are? ✔️ Wye and
Delta
, ___ configured distribution system has one end of each windings connected
together. ✔️ Wye
208 VAC is a common voltage between any two of the phases on a
________________ ______. ✔️ wye-configured system
the 208 vac on a wye system is known as? ✔️ phase to phase or high
voltage
Other common phase to phase voltages that can be supplied from this type of
___________ system include 480 VAC or 600 VAC. ✔️ distribution
Typical ________________ distribution system has each phase connected end to
end to form a loop. ✔️ delta configured
Neutral ✔️ conductor that provides a common return path to the source
for the conductors that carry current in a system
Where is a 4-wire wye distribution system neutral conductor connected to?
✔️ common point where the three phase windings meet
On a 4 wire wye configuration single phase voltages are available between any
of the ______ and the _______. ✔️ phases, neutral
In many cases in a 4 wire wye configuration the neutral conductor is
connected to ______ ( as required by the NEC ) ✔️ ground
Grounded wye configurations are _____ than delta configurations ✔️
safer
Grounded neutral wire should ___ be used as an equipment ground. ✔️
not
Center tapping and grounding one of the coils on a delta configured systems
allows several _______ options. ✔️ voltage
Bastard Voltage ✔️ unreliable voltage source that runs from phase b to
neutral on a grounded delta system that has 190 vac approximately.
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