Glossary of Terms Flashcards
What Is American Wire Gauge (AWG).
A standard wire gauge system for round, solid, electrically
conducting wire.
What Is The smallest AWG wire size
The smallest AWG wire size is #41 which is a 0.0028 inches
what is the largest wire size in AWG system?
pronounced “4 aught” which is 0.4600 inches in diameter.
What Is asperity.
As used in cable splicing, the unevenness or roughness of a surface. The many sharp,
rough projections from a surface are called asperities.
What Is backfeed
Occurs then power flows in the opposite direction from its usual flow. For example,
backfeed occurs when customer-generated power (PV panels, portable generators) are present.
Backfeed can occur in a de-energized phase of a three-phase transformer when one or more of
the other phases of that transformer are energized.
What Is BIL.
Basic insulation level. A measure of the ability of an insulation to withstand a specified
voltage. The point at which tracking will occur, leading to an arcing flashover. Also called basic
impulse insulation level.
What Is boiling out.
The process of pouring hot insulating oil over the insulation of a cable to rid the
area of contaminants and moisture.
What Is branch splice.
A type splice used to connect three connectors together. Also called a T splice.
What Is bunch stranding.
A collection of strands of conductors twisted together in the same direction
without regard to the geometrical arrangement.
What Is butyl rubber.
A synthetic rubber produced with the use of butylene, a gas. Butyl rubber offers a
large resistance to penetration by gases such as ozone.
who is cable splicer.
The person in whom confidence is placed to make a electrically reliable and
mechanically strong splice or termination, usually of a medium-voltage sable.
What Is capacitor.
Two conductors separated by an insulating dielectric. A conductor, its insulation, and
a shield form a capacitor.
What Is chamfering.
A technique used to remove sharp corners from an insulation layer, usually done
with a knife or special tool.
What Is CIC.
CIC. Cable in conduit.
What Is circular mil.
A measurement equal to the area of a circle with a diameter of one-thousandth of
an inch. Commonly used for the cross-sectional area of a conductor.
What Is Class termination.
**A Class 1 termination provides (1) electrical stress control at the end of the cable insulation shield, (2) external leakage insulation (tracking protection) between the cable conductor(s) and ground, and (3) a seal at the end of the cable to protect from entrance by the external environment. A Class 2 termination provides (1) and (2). A Class 3 termination provides only (3).**
What Is clearance (for working).
Specific permission to work on lines or equipment, including identification for specific persons(s) receiving permission and granting permission from the proper authority.
What Is CN.
Bare concentric neutral.
What Is cold shrink splice.
A type of splice in which a rubber tube is shrunk over a cable splice by pulling
a tab extending from the tube.
What Is compression connector.
- *A metal connector that can be secured to a cable by compressing or
crimping. **
What Is concentric wires.
A layer of spiral-wrapped wires used as a system neutral (on primary or
secondary cable) or to bleed off excessive static charges (on primary cable only).
What Is conductive breakout tube.
A heat-shrink tube used to electrically connect the conductive shields
of individual cables to the lead cover of PILC cable. Used when making a trifurcating transitional
splice.
What Is conductor.
A material which offers little opposition to current flow. Copper and aluminum are
commonly used conductors for medium voltage cable. Ozone is a gas conductor that can result
from air pockets in medium- and high-voltage cables.
What Is conductor shield.
shield. A layer of semi-conductive material directly around a conductor that gives a
stranded conductor a more uniformly round shape to reduce the concentration of voltage stress
at the high points of the round conductor strands.
What Is conductor strand sealant.
A material applied to a stranded conductor to impede longitudinal
water flow down the conductor.
What Is copper shielding tape
Tape applied to some primary tape splices over the insulation shield layer,
to provide added stress relief.
What Is corona.
The partial breakdown of the air around higher voltage conductors.
What Is corona cutting.
The damage resulting from corona discharge. Corona cutting appears as burnt
spots and pitting on the conductor jacket or in the conductor insulation. Corona cutting will
cut away sufficient cable jacket to cause failure of the insulation and eventual breakdown of the
cable.
What Is corona level.
The corona level is the AC voltage level that will sustain corona discharge.
What Is corona discharge.
A continuous electrical discharge that produces ozone which can lead to the
deterioration of insulation.
What Is creepage distance.
The distance between the end of a conductor and the insulation shield. Also
called leakage distance.
cross-linked polyethylene (XLP or XLPE).
A thermoset material used for cable insulation.
It can operate at high temperature, is light in weight, abrasion resistant, and not affected by
most chemicals. During the manufacturing process individual molecules in XLPE material
are joined together (cross-linked) to form an interconnected network that can operate at high
temperatures.
What Is dead.
Disconnected from any electrical source or supply, properly tagged, shorted, and
grounded. Normally used in reference to certain parts of the electrical system such as lines,
cables, or equipment.
What Is dead front.
Equipment or devices that have no exposed energized parts greater than 600 volts,
and cables and terminations have an effectively grounded metallic shield.
What Is deadbreak.
A termination or switching point that can be safely separated only when no current
is flowing through it. Also called non-loadbreak.
What Is dielectric.
An insulator which, when placed between two conductors, can be polarized. Electrons
in the material are attracted to one conductor and repelled from the other conductor, forming an
electric field. The term “dielectric” is from “dia-electric.”
What Is dielectric constant.
A measure of the ability of a material to store a charge. The dielectric
constant of air is 1, of polyethylene is 2.3, of butyl rubber is 3.7. See also K factor.
What Is disconnected
An electrical attachment removed from any electrical source.
double branch splice.
- *A variation of the branch splice used for multiple branching from a splice
point. **
What Is drain wire.
A small wire, usually #14 copper, that connects a cable accessory to ground to
prevent the buildup of static charge due to capacitive coupling. Note: This wire is not intended to
carry fault current.
drain wire tab.
A tab on a cable accessory which accepts a small wire, usually #14 AWG copper,
to prevent the buildup of static charge due to capacitive coupling.
effectively grounded.
Intentionally attached to earth through a ground connection or connec-tions of sufficiently low impedance. This connection has sufficient current-carrying capacity to prevent a buildup of voltage or fault current that could be hazardous to connected equipment or personnel.
What Is elastomer.
A rubber-based insulating material used with synthetic rubbers. Elastic or stretchy
dielectric with considerable bounce-back.
What Is electrostatic.
electrostatic. Electrical particles that are stationery or at rest.
What Is electrostatic field.
The region near or around an electrically charged object such as a conductor
charged with a voltage. The region around an electric charge is under strain in a manner similar
to that of the region around a magnetic pole. The field consists of electrostatic lines or paths,
that positive charges would take when moving toward a negatively charged object. As the voltage
increases, the strength of the electrostatic field increases.
What Is equipotential lines.
lines. Lines of equal voltage in the space between two conductors with different
voltages. In a shielded cable, the lines of equal voltage in the insulation between the center
conductor and the cable shield.
What Is erosion distance.
The ability of electrical insulation to resist erosion. Failure occurs by dielectric breakdown after the insulation is eroded
to a much reduced thickness. Erosion resistance is measured by its time-to-failure.
What Is ethylene propylene (EP) (EPR).
A rubber-based, thermoset material used for cable insulation. It
is able to withstand high temperatures. Used mostly within industrial sites.
What Is exposed.
Equipment, objects or devices not guarded, insulated or shielded to earth.
What Is fault.
In an electric power system, a fault is an unwanted flow of current. A short-circuit fault occurs when the current bypasses the load. A ground fault is a type of short-circuit fault where current flows directly into the neutral or earth. An open-circuit fault occurs when the normal flow of current is stopped by some failure. In a power system, protective devices detect faults and operate circuit breakers, fuses, and other devices to provide worker safety, and to limit the loss of
service to customers.
What Is floating shield
A cable shield which is not grounded. When there is no ground on the shield, the entire shield is floating and can be dangerous because the shield is not at ground potential. For
most installations, the shield is grounded at least at one end. The end that is not grounded is said
to be floating but the shield is at ground potential.
What Is flux lines.
lines. Lines that show the alignment of magnetic particles in the space between a positively charged material and a negatively charged material. Flux lines are formed whenever a conductor is energized. The strength of flux lines is proportional to the voltage between the materials.
What Is gradient, potential gradient.
Volts-per-unit-of-thickness across a dielectric. Example: 4,160 volts
across 10 mils of insulation is a potential gradient of 416 volts per mil.
What Is grounded.
A connection to earth, or other conductor taking the place of earth. The shield of medium voltage cable is grounded so the shield is at the same potential as the cable surface and its surrounding medium. The shield can be grounded at one end or both ends, as determined by specifications of the system being installed.
What Is grounding eye.
A connection point for a single concentric wire on a pre-molded slip-on primary
splice, to ensure contact between the concentric wire layer and the insulation shield layer of the
splice.
What Is heat shrink splice.
A type of splice in which a plastic tube is heated to shrink and adhere tightly
to the cable.