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About Cord Sets
Power cords and extension
cords are detachable means of supplying electricity from a main
power source to electrical equipment or appliances. The electrical
energy is in the form of alternating current (AC). A power cord
set consists of a flexible cord with plug attachments at each end,
one male and one female. The power cord is comprised of a conducting
medium, typically copper, the insulation surrounding the medium and
an outer jacket to protect and insulate the wire. Power supply cords,
which are permanently affixed to electrical equipment, and power cord
sets are utilized anywhere that electrical equipment and appliances
are in use, including industrial, office and domestic settings. Extension
cords, one type of cord
set, are used for electrical power tools, lighting and various
other private uses.
The female plug connects to the appliance or electrical equipment. The male plug
connects the electrical
outlet to the power supply. Power cord manufacturers can group molded male
plugs into North American types and International types, with currently fifteen
different types. The standards of a country will determine which plug is in common
use. A typical North American plug consists of two blades or prongs, a molded
plastic body holding the two blades apart and a blade/cord connection within
the plug body. Inserting the blades into an electric plug energizes the blades.
Electricity then flows through the blades, the blade-cord connection and the
power supply cord, providing electricity to the equipment.
When determining the appropriate power cords for different applications, many
factors are considered. Power cord manufacturers follow various specifications,
including length, wire shape and size, jacket material, hospital grade, maximum
cable temperature, rated current and rated voltage, as well as the type of molded
plug and female connector. The length of extension
cords is the length of the power cords plus connectors. The shape of the
wire is either flat or round. The electric
cord application determines the jacket material, which includes PVC, rubber,
polychloroprene (neoprene) and textile construction. The size of the wire is
determined by the amount of voltage that will be able to flow through the cord
and is given a designation in accordance with the American Wire Gauge (AWG) standards
for wire sizes.
The National Electrical Manufacturers Association (NEMA) sets the standards power
cord manufacturers follow for both male electric plugs and female electric plugs.
A male electric plug may be polarized or non-polarized. An electric plug is polarized
when the physical characteristics of the blades allow the plug to be connected
to the electrical outlet in only one way. Three-prong electrical plugs are inherently
polarized. Non-polarized plugs do not restrict the way the electrical plug is
connected to the electrical
outlet. Two-prong electrical plugs do not have a grounding pin but can be
polarized if one blade is larger than the other. Polarization and grounding is
especially important for certain parts of appliances and other electrical equipment
that could have a higher risk of electric shock when they become live. Polarization
of an electric plug ensures that the equipment is connected to the neutral, or
grounded, side of the circuit. Sensitive electrical equipment and products should
only be used with polarized or grounding type cord
sets.
Featured
Articles
Quail Electronics, Inc. (pdf)
http://www.kltannehill.com/Technical%20Documents/controlling_noise.htm
Types of Cord Sets
- conduct alternating current from
one point to another. AC power cords consist of a conducting medium,
typically copper, surrounded by insulation and a jacket.
- are used for computers and related electronic
equipment.
- consist of several wires or cables collected into
a single unit with connectors on at least one end.
- are power cords with a male electrical plug at one end and a female plug at the other.
- are conductive cables used to transfer AC power from a plug to an electrical device.
- are commonly known as outlets.
- are marked with necessary information pertaining
to their use, size and wattage rating. Extension cords are available
in
many lengths and are marked with a size, or gauge, which is based on
the American Wire Gauge (AWG) system.
- are
specially designed for rough, heavy-usage environments in industrial
or commercial applications. The head is constructed with
large flats having deeply contoured ridges that afford a non-slip grip,
and a heavy molded strain relief shroud protects the cord/plug union.
- are designed to meet the critical needs of medical
equipment applications. Heavy-duty solid brass blades and pins are
soldered or
welded to the conductors for added durability.
- have
one blade that is wider than the other, which helps reduce the potential
for shock. Three-prong plugs are automatically
polarized, since they can be inserted only one way.
- are
flexible lengths of cord that have an attachment plug molded to their
ends and are used to transmit electrical energy
from the main supply to an electrical device. A power supply cord,
which could also have terminations or a molded strain relief on the
opposite end of the plug, is permanently installed in the device being
powered, as opposed to a cord set, which is detachable.
- allow users to plug in electrical equipment
close to walls without bending or damaging power cords and are available
in both a two-conductor (polarized or non-polarized) or three-conductor
configuration. The three-conductor plug could have the grounding
pin in the top or bottom location.
- have two vertical blades and a grounding
pin. They are polarized by default, since they can be plugged in
just one way.
- consist of two vertical
blades, one if which is neutral and the other is referred to as hot.
Two-conductor plugs,
which
have no grounding pin, are polarized or non-polarized.
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