A A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Absorber: A material that readily absorbs photons to generate charge
carriers (free electrons or holes).
Absorbers: Dark-colored objects that soak up heat in solar collectors.
Absorption coefficient: The factor by which photons are absorbed as they
travel a unit distance through a material.
Acceptor: A dopant material, such as boron, which has fewer outer shell
electrons than required in an otherwise balanced crystal structure, providing a
hole, which can accept a free electron.
Accessible: (As applied to wiring methods) Capable
of being removed or exposed without damaging the building structure or finish,
or not permanently closed in by the structure or finish of the building.
Accessible: (as applied to equipment) Admitting
close approach: not guarded by locked doors, elevation, or other effective
means. (see Accessible, Readily)
Accessible, Readily: (Readily Accessible) Capable of
being reached quickly for operation, renewal, or inspections, without requiring
those to whom ready access is requisite to climb over or remove obstacles or to
resort to portable ladders, chairs, etc.
Actinide: an element with atomic number of
89 (actinium) or above.
Activation product: A radioactive isotope
of an element (e.g., in the steel of a reactor core) which has been created by
neutron bombardment.
Active solar heater: A solar water or space-heating system that moves heated
air or water using pumps or fans.
Affected employee: An employee whose job
requires him or her to operate or use a machine or equipment on which
servicing or maintenance is being performed under lockout or tagout, or
whose job requires him or her to work in an area in which such servicing or
maintenance is being performed.
 |
Air Circuit Breakers: These are used to interrupt circuits while current flows
through them. Compressed air is used to quench the arc when the connection is broken.
|
Air mass: The ratio of the mass of atmosphere in the actual observer-sun path
to the mass that would exist if the observer was at sea level, at standard
barometric pressure, and the sun was directly overhead. Note: (sometimes called
air mass ratio).
Air mass 1.5 (AM1.5) standard reference spectrum: The solar spectral
irradiance distribution (diffuse and direct) incident at sea level on a
sun-facing 37-degree tilted surface. The atmospheric conditions for AM1.5 are: precipitable water vapor, 14.2 mm; total ozone, 3.4 mm; turbidity (base e,
lambda=0.5 mm), 0.27. [ASTM E 892, Table 2]
Alternating current: Electric current in which the direction of flow is
reversed at frequent intervals: usually 100 or 120 times per second (50 or 60
cycles per second or 50//60 Hz).
ALARA: As Low As Reasonably Achievable, economic and social factors being
taken into account. This is the optimization principle of radiation protection.
Alpha particle: A positively-charged particle from the nucleus of an atom,
emitted during radioactive decay. Alpha particles are helium nuclei, with 2
protons and 2 neutrons.
Alternative fuels: Solid fuels such as municipal solid waste (MSW),
refuse derived fuel (RDF), biomass, rubber tires, and other combustibles that are used
instead of fossil fuels (gas, oil, or coal) in a boiler to produce steam for the generation
of electrical energy.
Ambient Temperature: The temperature of the air,
water, or surrounding earth. Conductor ampacity is corrected for changes in
ambient temperature including temperatures below 86°F. The cooling effect can
increase the current carrying capacity of the conductor. (Review Section 310-10
of the Electrical Code for more understanding)
Ammeter: An electric meter used to measure current,
calibrated in amperes.
Ampacity: The current-carrying capacity of
conductors or equipment, expressed in amperes.
Ampere (A) or amp: The basic SI unit measuring the quantity of electricity.
The unit for the electric current; the flow of electrons. One amp is 1 coulomb
passing in one second. One amp is produced by an electric force of 1 volt acting
across a resistance of 1 ohm.
Ampere-hour (Ah): Quantity of electricity or measure of charge. (1 Ah = 3600
C [Coulomb])
Amorphous semiconductor: A non-crystalline semiconductor material that has no
long-range order.
Annual solar savings: The annual solar savings of a solar building is the
energy savings attributable to a solar feature relative to the energy
requirements of a non-solar building.
Anthropogenic: Referring to alterations in the environment due to the
presence or activities of humans.
Antireflection coating: A thin coating of a material, which reduces the light
reflection and increases light transmission, applied to a photovoltaic cell
surface.
Armored Cable: A cable provided with a
wrapping of metal, usually steel wires or tapes, primarily for the purpose of
mechanical protection.
Arc-over Voltage: The minimum voltage
required to cause an arc between electrodes separated by a gas or liquid
insulation.
Array: Any number of photovoltaic modules connected together to provide a
single electrical output. Arrays are often designed to produce significant
amounts of electricity.
Atom: A particle of matter which cannot be
broken up by chemical means. Atoms have a nucleus consisting of
positively-charged protons and uncharged neutrons of the same mass. The positive
charges on the protons are balanced by a number of negatively-charged electrons
in motion around the nucleus.
Attendant: An employee assigned to remain
immediately outside the entrance to an enclosed or other space to render
assistance as needed to employees inside the space.
Attenuation: (l) The ratio of the input to
output power levels in a network (transmission line) when it is excited by a
matched source and terminated in a matched load. (2) Power loss in an electrical
system.
Authorized employee: An employee who locks out
or tags out machines or equipment in order to perform servicing or
maintenance on that machine or equipment. An affected employee becomes an
authorized employee when that employee's duties include performing servicing
or maintenance covered under this section.
Automatic circuit re-closer: A self-controlled
device for interrupting and re-closing an alternating current circuit with a
predetermined sequence of opening and re-closing followed by resetting,
hold-closed, or lockout operation.
Autonomous system: A stand-alone Photovoltaic system that has no back-up generating
source. May or may not include storage batteries.
Availability: Describes the reliability of power plants. It refers to the
number of hours the turbines are available to produce power divided by the total
hours in a year.
Avoided cost: The minimum amount an electric utility is required to pay an
independent power producer, under the PURPA regulations of 1978, equal to the
costs the utility calculates it avoids in not having to produce that power
(usually substantially less than the retail price charged by the utility for
power it sells to customers).
B A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Background radiation: The naturally-occurring ionizing
radiation
which every person is exposed to, arising from the earth's crust (including
radon) and from cosmic radiation.
Balance of system: Represents all components and costs other than the
Photovoltaic modules. It includes design costs, land, site preparation, system installation,
support structures, power conditioning, operation and maintenance costs,
indirect storage, and related costs.
Band gap: In a semiconductor, the energy difference between the highest
valence band and the lowest conduction band.
Band gap energy (EG): The amount of energy (in electron volts) required to
free an outer shell electron from its orbit about the nucleus to a free state
and, thus, to promote it from the valence level to the conduction level.
Band-to-band Auger recombination: Recombination of an electron and a hole
occurring between bands of the same energy in which no magnetic radiation is
emitted.
Bare Conductor: A conductor not covered with insulating material.
Barricade: A physical obstruction such as
tapes, cones, or A-frame type wood or metal structures intended to provide a
warning about and to limit access to a hazardous area.
Barrier: A physical obstruction which is
intended to prevent contact with energized lines or equipment or to prevent
unauthorized access to a work area.
Barrier energy: The energy given up by an electron in penetrating the cell
barrier; a measure of the electrostatic potential of the barrier.
Barrier, fire: A continuous membrane, either vertical or horizontal, such as
a wall or floor assembly, that is designed and constructed with specified
fire resistance rating to limit the spread of fire and that will also
restrict the movement of smoke. Such barriers can have protected openings.
Base load: That part of electricity demand which is continuous, and
does not vary over a 24-hour period. Approximately equivalent to the minimum
daily load.
Base power: Power generated by a utility unit that operates at a very high
capacity factor.
Baseline performance value: Initial values of
short-circuit current, open-circuit voltage,
and current at maximum power measured by
the accredited laboratory and corrected to Standard Test Conditions, used to
validate the manufacturer's performance measurements provided with the
qualification modules per IEEE 1262.
 |
Batteries: These are used in the substation control house as a backup to power the
control systems in case of a power blackout. |
Battery energy storage: The three main applications for battery energy
storage systems include spinning reserve at generating stations, load leveling
at substations, and peak shaving on the customer side of the meter. Battery
storage has also been suggested for holding down air emissions at the power
plant by shifting the time of day of the emission or shifting the location of
emissions.
Bayonet Coupling: A quick coupling device for plug and receptacle connectors,
accomplished by rotation of a cam operating device designed to bring the
connector halves together.
Becquerel: The SI unit of intrinsic radioactivity in a material. One
Bq measures one disintegration per second and is thus the activity of a quantity
of radioactive material which averages one decay per second. (In practice, GBq
or TBq are the common units.)
Beryllium Copper (BeCu): A relatively expensive contact material with properties superior to
brass and phosphor bronze. It is recommended for contact applications
requiring repeated extraction and reinsertion because of its resistance to
fatigue at high operating temperatures.
Beta particle: A particle emitted from an atom during radioactive
decay. Beta particles may be either electrons (with negative charge) or
positrons.
BIPV
(Building-Integrated Photovoltaic): A term for the design and integration of
Photovoltaic into the building envelope, typically replacing conventional building materials.
This integration may be in vertical facades, replacing view glass, spandrel
glass, or other facade material; into semitransparent skylight systems; into
roofing systems, replacing traditional roofing materials; into shading
"eyebrows" over windows; or other building envelope systems.
Biological shield: A mass of absorbing material
(e.g., thick concrete
walls) placed around a reactor or radioactive material to reduce the radiation
(especially neutrons and gamma rays respectively) to a level safe for humans.
Blocking diode: A diode used to restrict or block reverse current from
flowing backward through a module. [UL 1703] Alternatively, diode connected in
series to a Photovoltaic string; it protects its modules from a reverse power flow and,
thus, against the risk of thermal destruction of solar cells.
Boiling water reactor (BWR): A common type of light water reactor (LWR),
where water is allowed to boil in the core thus generating steam directly in the
reactor vessel. (cf PWR)
Bonding Jumper: A bare or insulated conductor used
to ensure the required electrical conductivity between metal parts required to
be electrically connected. Frequently used from a bonding bushing to the service
equipment enclosure to provide a path around concentric knockouts in an
enclosure wall - also used to bond one raceway to another.
Boron (B): A chemical element, atomic number 5, semi-metallic in nature, used
as a dopant to make p-semiconductor layers.
Boule: A sausage-shaped synthetic single-crystal mass grown in a special
furnace, pulled and turned at a rate necessary to maintain the single-crystal
structure during growth.
Breakdown Voltage: The voltage at which an insulator or dielectric ruptures, or at
which ionization and conduction take place in a gas or vapor.
Breed: To form fissile nuclei, usually as a result of neutron capture,
possibly followed by radioactive decay.
Breeder reactor: see Fast Breeder Reactor and Fast Neutron Reactor.
British thermal unit (Btu): The amount of heat energy required to raise the
temperature of one pound of water from 60 degrees F to 61 degrees F at one
atmosphere pressure.
Burnable poison: A neutron absorber included in the fuel which
progressively disappears and compensates for the loss of reactivity as the fuel
is consumed. Gadolinium is commonly used.
Burnup: Measure of thermal energy released by nuclear fuel relative to
its mass, typically Gigawatt days per tonne (GWd/tU).
Bushing: An insulating structure, including a
through conductor or providing a passageway for such a conductor, with
provision for mounting on a barrier, conducting or otherwise, for the
purposes of insulating the conductor from the barrier and conducting current
from one side of the barrier to the other.
 |
Bus Support Insulators: These are porcelain or fiberglass insulators that serve to
isolate the bus bar switches and other support structures and to prevent leakage current from flowing through the structure. These
insulators are similar in function of other insulators used in substations and transmission poles and towers. |
Bypass diode: A diode connected across one or more solar cells in a
photovoltaic module such that the diode will conduct if the cell(s) become
reverse biased. [UL 1703] Alternatively, diode connected anti-parallel across a
part of the solar cells of a Photovoltaic module. It protects these solar cells from
thermal destruction in case of total or partial shading of individual solar
cells while other cells are exposed to full light.
C A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Cable: A conductor with insulation, or a
stranded conductor with or without insulation and other coverings
(single-conductor cable), or a combination of conductors insulated from one
another (multiple-conductor cable).
Cable Assembly: A cable with plugs or connectors on each end.
Cable sheath: A conductive protective covering
applied to cables. Note: A cable sheath may consist of multiple layers of
which one or more is conductive.
Cadmium (Cd): A chemical element, atomic number 48, used in making certain
types of solar cells and batteries.
Cadmium telluride (CdTe): A polycrystalline thin-film photovoltaic material.
Calandria: (in a CANDU reactor) a cylindrical reactor vessel which
contains the heavy water moderator. It is penetrated from end to end by hundreds
of calandria tubes which accommodate the pressure tubes containing the fuel and
coolant.
CANDU: Canadian deuterium uranium reactor, moderated and (usually)
cooled by heavy water.
Capacitance: That property of a system of conductors and dielectrics that permits
the storage of electricity when potential difference exists between the
conductors. Its value is expressed as the ratio of quantity of electricity to
a potential difference. A capacitance value is always positive.
 |
Capacitor Bank:
An array of capacitors connected into a circuit. Capacitors are used to control voltages supplied to the customer by
eliminating the voltage drop in the system caused by inductive reactive loads. |
Capacity factor: The amount of energy that the system produces at a
particular site as a percentage of the total amount that it would produce if it
operated at rated capacity during the entire year. For example, the capacity
factor for a wind farm ranges from 20% to 35%. Thirty-five percent is close to
the technology potential.
Cathodic protection: A method of preventing oxidation (rusting) of exposed
metal structures, such as bridges and pipelines, by imposing between the
structure and the ground a small electrical voltage that opposes the flow of
electrons and that is greater than the voltage present during oxidation.
Cell: The basic unit of a photovoltaic system.
Cell barrier: A very thin region of static electric charge along the
interface of the positive and negative layers in a photovoltaic cell. The
barrier inhibits the movement of electrons from one layer to the other, so that
higher-energy electrons from one side diffuse preferentially through it in one
direction, creating a current and thus a voltage across the cell. Also called
depletion zone, cell junction, or space charge.
Cell junction: The area of immediate contact between two layers (positive and
negative) of a photovoltaic cell. The junction lies at the center of the cell
barrier or depletion zone.
Central power: The generation of electricity in large power plants with
distribution through a network of transmission lines (grid) for sale to a number
of users. Opposite of distributed power.
Chain reaction: A reaction that stimulates its own repetition, in
particular where the neutrons originating from nuclear fission cause an ongoing
series of fission reactions.
Charge carrier: A free and mobile conduction electron or hole in a
semiconductor.
Chemical vapor deposition (CVD): A method of depositing thin semiconductor
films. With this method, a substrate is exposed to one or more vaporized
compounds, one or more of which contain desirable constituents. A chemical
reaction is initiated, at or near the substrate surface, to produce the desired
material that will condense on the substrate.
Chlorofluorocarbon: A family of chemicals composed primarily of carbon,
hydrogen, chlorine, and fluorine whose principal applications are that of
refrigerants and industrial cleansers and whose principal drawback is the
tendency to destroy the Earth's protective ozone layer.
Circuit: A conductor or system of conductors
through which an electric current is intended to flow.
 |
Circuit Switchers:
Circuit switchers a a set of switches for redirecting current in a substation.
Circuit switchers provide equipment protection for
transformers, lines, cables, and capacitor banks. They also are used to energize and deenergize capacitor banks and other circuits. |
Cladding: The metal tubes containing oxide fuel pellets in a reactor
core.
Clearance (between objects): The clear
distance between two objects measured surface to surface.
Clearance (for work): Authorization to perform
specified work or permission to enter a restricted area.
Cleavage of lateral epitaxial films for transfer (CLEFT): A process for
making inexpensive GaAs photovoltaic cells in which a thin film of GaAs is grown
atop a thick, single-crystal GaAs (or other suitable material) substrate and
then is cleaved from the substrate and incorporated into a cell, allowing the
substrate to be reused to grow more thin-film GaAs.
Closed Entry Contact: A female contact designed to prevent the entry of a pin or probing
device having a cross-sectional dimension (diameter) greater than the mating
pin.
Coal: A black, solid fossil fuel found in the Earth. Coal is often burned to
make electricity.
Coaxial Cable: A high-band width cable consisting of two concentric cylindrical
conductors with a common axis that is used for high-speed data communication
and video signals.
Cogeneration: The process in which fuel is used to produce heat for a
boiler-steam turbine or gas for a turbine. The turbine drives a generator that
produces electricity, with the excess heat used for process steam.
Combined collector: A photovoltaic device or module that provides useful heat
energy in addition to electricity.
Compact fluorescent lights: Lights that use a lot less energy than regular
light bulbs. We can use compact fluorescent lights for reading lights and
ceiling lights.
Component Lead: The solid or stranded wire or formed conductor that extends from a
component and serves as a readily formable mechanical or electrical connection
or both.
Compressed-air energy storage (CAES): CAES plants use off-peak electrical
energy to compress air into underground storage reservoirs for storage until
times of peak or intermediate electricity demand. Wind power offers a good
opportunity for charging CAES storage. The storage is typically underground in
natural aquifers, depleted oil or gas fields, mined salt caverns, or excavated
or natural rock caverns. To generate power, the compressed air is first heated
by gas burners, then passed through a turbine.
Concentrator: A Photovoltaic module that uses optical elements to increase the amount
of sunlight incident on a Photovoltaic cell.
Concentrating: arrays must track the sun and use only the direct sunlight
because the diffuse portion cannot be focused onto the Photovoltaic cells.
Concentrate: See Uranium oxide concentrate (U3O8).
Concentrator (module, array, or collector): An arrangement of photovoltaic
cells that includes a lens to concentrate sunlight onto small-area cells.
Concentrators can increase the power flux of sunlight hundreds of times.
Concentricity: In a wire or cable, the measurement of the location of the center of
the conductor with respect to the geometric center of the surrounding
insulation.
 |
Concrete Foundations:
A platform made of concrete that provides a solid stable support for large
equipment. Concrete foundations or pads are laid for all
large equipment, support structures, and control buildings in a substation. |
Conductance: The reciprocal of resistance. It is the ratio of current passing
through a material to the potential difference at its ends.
Conduction band; Conduction level: Energy level at which electrons are not
bound to (orbiting) a specific atomic nucleus but are free to wander among the
atoms. An energy band in which electrons can move freely in a solid, producing a
net transport of charge.
Conductivity: The ability of a material to conduct electric current. It is
expressed in terms of the current per unit of applied voltage. It is the
reciprocal of resistivity.
Conductor: A wire or combination of wires not insulated from one another,
suitable for carrying electric current.
 |
Conduits: Conduits are hollow tubes running from manhole to manhole in an
underground transmission or distribution system. |
Connection: That part of a circuit that has negligible impedance and that joins
components, devices, etc., together.
Connector: A device providing electrical connection/disconnections. It consists
of a mating plug and receptacle. Various types of connectors include DIP, card
edge, two-piece, hermaphroditic and wire-wrapping configurations. Multiple
contact connectors join two or more conductors with others in one mechanical
assembly.
Connector Discontinuity: An ohmic change in contact resistance.
Connector Insert: For connectors with metal shells, the insert holds contacts in
proper arrangement while electrically insulating them from each other and from
the shell.
Connector Shell: The case that encloses the connector insert and contact assembly.
Shells of mating connectors can protect projecting contacts and provide proper
alignment.
Constant-speed wind turbines: Turbines that operate at a constant rotor
revolutions per minute (RPM) and are optimized for energy capture at a given
rotor diameter at a particular speed in the wind power curve.
Contact, Female: A contact located in an insert or body in such a manner that the
mating contact is inserted into the unit. It is similar in function to a
socket contact.
Contact, Male: A contact located in an insert or body in such a manner that the
mating portion extends into the female contact. It is similar in function to a
pin contact.
Contact Plating: Plated-on metal applied to the base contact metal to provide the
required contact resistance and/or wear resistance.
Contact Resistance: Maximum permitted electrical resistance of pin and socket contacts
when assembled in a connector under typical service use.
Contact Retainer: A device either on the contact or in the insert to retain the
contact.
Contact Size: Defines the largest size wire that can be used with the specific
contact. By specification dimensioning, it also defines the diameter of the
engagement end of the pin.
Contact resistance: The resistance between metallic contacts and the
semiconductor.
Continuity: The state of being whole, unbroken.
Continuous Load: A load where the maximum current is
expected to continue for three hours or more. Rating of the branch circuit
protection device shall not be less tan 125% of the continuous load.
 |
Control House: The substation control house contains switchboard panels,
batteries, battery chargers, supervisory control, power-line carrier, meters, and relays. The control house provides all
weather protection and security for the control equipment. It is also called a doghouse. |
 |
Control Panels:
Control panels contain meters, control
switches and recorders located in the control building, also called a doghouse. These are used to control the substation
equipment, to send power from one circuit to another or to open or shut down circuits when needed. |
Control rods: Devices to absorb neutrons so that the chain reaction in
a reactor core may be slowed or stopped by inserting them further, or
accelerated by withdrawing them.
 |
Control Wires: Control wires are installed connecting the control house
control panels to all the equipment in the substation. A typical substation control house contains several thousand feet of conduit
and miles of control wire. |
Conversion: Chemical process turning U3O8 into
UF6 preparatory to enrichment.
Conversion efficiency (cell or module): The ratio of the electric energy
produced by a photovoltaic device (under one-sun conditions) to the energy from
sunlight incident upon the cell.
 |
Converter Stations: Converter stations are located at the terminals of a DC
transmission line. Converter stations change alternating current into direct current and invert direct current to alternating current. |
Coolant: The liquid or gas used to transfer heat from the reactor core
to the steam generators or directly to the turbines.
Copper indium diselenide (CuInSe2, or CIS): A polycrystalline
thin-film photovoltaic material (sometimes incorporating gallium (CIGS) and/or
sulfur).
Core: The central part of a nuclear reactor containing the fuel
elements and control devices.
 |
Coupling Capacitors: Coupling capacitors are used to transmit
communication signals to transmission lines. Some are used to measure the voltage in transmission lines. |
Critical mass: The smallest mass of fissile material that will support
a self-sustaining chain reaction under specified conditions.
Criticality: Condition of being able to sustain a nuclear chain
reaction.
Current at maximum power (Imp): The current at which maximum power is
available from a module. [UL 1703]
 |
Current Transformers: Current transformers can be used to supply information
for measuring power flows and the electrical inputs for the operation of protective relays associated with the transmission and
distribution circuits or for power transformers. |
Cycle life: Number of discharge-charge cycles that a battery can tolerate
under specified conditions before it fails to meet specified criteria as to
performance (e.g., capacity decreases to 80-percent of the nominal capacity).
Czochralski process: A method of growing large size, high quality
semiconductor crystal by slowly lifting a seed crystal from a molten bath of the
material under careful cooling conditions.
D A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Dangling bonds: A chemical bond associated with an atom on the surface layer
of a crystal. The bond does not join with another atom of the crystal, but
extends in the direction of exterior of the surface.
dc to DC converter: Electronic circuit to convert DC voltages (e.g.,
Photovoltaic module voltage) into other levels (e.g., load voltage). Can be part of a maximum
power point tracker (MPPT).
Decay: Disintegration of atomic nuclei resulting in the emission of
alpha or beta particles (usually with gamma radiation). Also the exponential
decrease in radioactivity of a material as nuclear disintegrations take place
and more stable nuclei are formed.
Decommissioning: Removal of a facility (e.g., reactor) from service, also
the subsequent actions of safe storage, dismantling and making the site
available for unrestricted use.
De-energized: Free from any electrical
connection to a source of potential difference and from electric charge; not
having a potential different from that of the earth. Note: The term is used only with reference to
current-carrying parts, which are sometimes energized (alive).
Deep discharge: Discharging a battery to 20-percent or less of its full
charge.
Deflagration: Propagation of a combustion zone through a
fuel-oxidizer mixture at a rate that is less than the speed of sound in the
un-reacted medium and capable of producing a significant increase in
pressure.
Demand Factor: For an electrical system or feeder circuit, this is a ratio of the amount of connected
load (in kva or amperes) that will be operating at the same time to the total
amount of connected load on the circuit. An 80% demand factor, for instance,
indicates that only 80% of the connected load on a circuit will ever be
operating at the same time. Conductor capacity can be based on that amount of
load.
Dendrite: A slender threadlike spike of pure crystalline material, such as
silicon.
Dendritic web technique: A method for making sheets of polycrystalline
silicon in which silicon dendrites are slowly withdrawn from a melt of silicon
whereupon a web of silicon forms between the dendrites and solidifies as it
rises from the melt and cools.
Depletion zone: Same as cell barrier. The term derives from the fact that
this microscopically thin region is depleted of charge carriers (free electrons
and holes).
Depleted uranium: Uranium having less than the natural 0.7% U-235. As
a by-product of enrichment in the fuel cycle it generally has 0.25-0.30% U-235,
the rest being U-238. Can be blended with highly-enriched uranium (e.g., from
weapons) to make reactor fuel.
Designated employee (designated person): An
employee (or person) who is designated by the employer to perform specific
duties under the terms of this section and who is knowledgeable in the
construction and operation of the equipment and the hazards involved.
Detachment: The locating of a combustible particulate solid process in the
open air or in a separate building.
Deuterium: "Heavy hydrogen", a stable isotope having one proton and
one neutron in the nucleus. It occurs in nature as 1 atom to 6500 atoms of
normal hydrogen, (Hydrogen atoms contain one proton and no neutrons).
Diallyl Phthalate (DAP): A thermosetting plastic that offers outstanding dimensional
stability and resistance to most chemicals and chemical compounds. It is used
in the production of connector housings.
Dielectric: (l) Any insulating medium that intervenes between two conductors.
(2) A material that, having the property required to establish an electric
field, is recoverable in whole or in part as electric energy.
Dielectric Constant: That property of a dielectric that determines the electrostatic
energy stored per unit volume for a unit potential gradient. Permittivity is
the preferred term.
Dielectric Strength: The maximum voltage that a dielectric material can withstand, under
specified conditions, without rupturing. It is usually expressed as volts/unit
thickness. Also called Disruptive Gradient or Electric Strength.
Dielectric Withstanding Voltage: Maximum potential gradient that a dielectric material can withstand
without failure.
Diffuse insulation: Sunlight received indirectly as a result of scattering
due to clouds, fog, haze, dust, or other obstructions in the atmosphere.
Opposite of direct insulation.
Diffusion furnace: Furnace used to make junctions in semiconductors by
diffusing dopant atoms into the surface of the material.
Diffusion length: The mean distance a free electron or hole moves before
recombining with another hole or electron.
Direct current (dc): Electric current in which electrons flow in one
direction only. Opposite of alternating current.
Direct gain: In direct-gain buildings, sunlight directly enters the home
through the windows and is absorbed and stored in massive floors or walls. These
buildings are elongated in the east-west direction, and most of their windows
are on the south side. The area devoted to south windows varies throughout the
country. It could be as much as 20% of the floor area in sunny cold climates,
where advanced glazings or moveable insulation are recommended to prevent heat
loss at night. These buildings have high insulation levels and added thermal
mass for heat storage.
Direct insulation: Sunlight falling directly upon a collector. Opposite of
diffuse insulation.
Discharge rate: The rate, usually expressed in amperes or time, at which
electrical current is taken from the battery.
|
|
Disconnect Switches: Disconnect switches or circuit breakers are
used to isolate equipment or to redirect current in a substation. |
Distributed power: Generic term for any power supply located near the point
where the power is used. Opposite of central power. See 'stand-alone'; 'remote
site.'
Distributed systems: Systems that are installed at or near the location where
the electricity is used, as opposed to central systems that supply electricity
to grids. A residential photovoltaic system is a distributed system.
 |
Distribution Bus: A distribution bus is a steel structure array of switches
used to route power out of a substation. |
 |
Distribution Feeder Circuits: These are the connections between the
output terminals of a distribution substation and the input terminals of primary circuits. The distribution feeder circuit
conductors leave the substation from a circuit breaker or circuit recloser via underground cables, called substation exit cables. |
 |
Distribution Transformers: Distribution transformers reduce the voltage of the primary
circuit to the voltage required by customers.
|
DOD: 'Depth of Discharge,' from 100-percent state of charge (SOC), in a
battery or battery system.
Donor: An n-type dopant that puts an additional electron into an energy level
very near the conduction band; this electron is easily exited into the
conduction band where it increases the electrical conductivity over than of an
undoped semiconductor.
Donor level: The level that donates conduction electrons to the system.
Dopant: A chemical element (impurity) added in small amounts to an otherwise
pure semiconductor material to modify the electrical properties of the material.
An n-dopant introduces more electrons. A p-dopant creates electron vacancies
(holes).
Doping: The addition of dopants to a semiconductor.
 |
Duct Runs: Ducts are hollow tubes running from manhole to manhole inside a
conduit in an underground system. They are of various sizes usually from 2 to 6 inches in diameter. |
Dustproof: Constructed or protected so that dust
will not interfere with its successful operation.
Dusttight: Constructed so that dust will not enter
the enclosing case under specified test conditions.
Duty, continuous: A service requirement that demands
operation at a substantially constant load for an indefinitely long time.
Duty, intermittent: A service requirement that
demands operation for alternate intervals of load and no load, load and rest, or
load, no load, and rest.
Duty, periodic: A type of intermittent duty in which
the load conditions regularly reoccur.
Duty, short time: A requirement of service that
demands operations at a substantially constant load for a short and definitely
specified time.
Duty, varying: A requirement of of service that
demands operation at loads, and for intervals of time, both of which may be
subject to wide variation.
E A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Edge-defined film-fed growth (EFG): A method for making sheets of
polycrystalline silicon in which molten silicon is drawn upward by capillary
action through a mold.
Elastomer: A material that at room temperature stretches under low stress to at
least twice its length and snaps back to original length upon release of
stress.
Electric circuit: Path followed by electrons from a power source (generator
or battery) through an external line (including devices that use the
electricity) and returning through another line to the source.
Electric current: A flow of electrons; electricity.
Electrical grid: An integrated system of electricity distribution, usually
covering a large area.
Electric line truck: A truck used to transport personnel, tools, and material for electric supply line work.
Electric Strength: The maximum potential gradient that a material can withstand without
rupture. Also called Dielectric Strength and Disruptive Gradient.
Electric supply: Conductors used to
transmit electric energy and their necessary supporting or containing
structures. Signal lines of more than 400 volts are always supply lines
within this section, and those of less than 400 volts are considered as
supply lines, if so run and operated throughout.
Electric supply equipment: Equipment that produces, modifies, regulates, controls, or safeguards a supply of electric
energy.
Electric utility: An organization responsible for the installation, operation, or maintenance of an electric supply
system.
Electrodeposition: Electrolytic process in which a metal is deposited at the
cathode from a solution of its ions.
Electrolyte: A liquid conductor of electricity.
Electron volt: An energy unit equal to the energy an electron acquires when
it passes through a potential difference of one volt; it is equal to 1.602 x 10-19 volt.
Element: A chemical substance that cannot be divided into simple
substances by chemical means; atomic species with same number of protons.
Emc: Electromagnetic compatibility.
Emi: Electromagnetic interference.
Enclosed space: A working space, such as a
manhole, vault, tunnel, or shaft, that has a limited means of egress or
entry, that is designed for periodic employee entry under normal operating
conditions, and that under normal conditions does not contain a hazardous
atmosphere, but that may contain a hazardous atmosphere under abnormal
conditions.
Note: Spaces that are enclosed but not designed for
employee entry under normal operating conditions are not considered to be
enclosed spaces for the purposes of this definition. Similarly, spaces that are
enclosed and that are expected to contain a hazardous atmosphere are not
considered to be enclosed spaces for the purposes of this definition. Such
spaces meet the definition of permit spaces in 1910.146, and
entry into them must be performed in accordance with that standard.
Energized (alive, live): Electrically
connected to a source of potential difference, or electrically charged so as
to have a potential significantly different from that of earth in the
vicinity.
Energy audit: A survey that shows how much energy you use in your house or
apartment. It will help you find ways to use less energy.
Energy contribution potential: Recombination occurring in the emitter region
of a photovoltaic cell.
Energy density: The ratio of energy available from a battery to its volume (Wh/1)
or mass (Wh/kg).
Energy isolating device: A physical device
that prevents the transmission or release of energy, including, but not
limited to, the following: a manually operated electric circuit breaker, a
disconnect switch, a manually operated switch, a slide gate, a slip blind, a
line valve, blocks, and any similar device with a visible indication of the
position of the device. (Push buttons, selector switches, and other
control-circuit-type devices are not energy isolating devices.)
Energy levels: The energy represented by an electron in the band model of a
substance.
Energy source: Any electrical, mechanical,
hydraulic, pneumatic, chemical, nuclear, thermal, or other energy source
that could cause injury to personnel.
Enriched uranium: Uranium in which the proportion of U-235 (to U-238)
has been increased above the natural 0.7%. Reactor-grade uranium is usually
enriched to about 3.5% U-235, weapons-grade uranium is more than 90% U-235.
Enrichment: Physical process of increasing the proportion of U-235 to
U-238.
Environment: All the natural and living things around us. The earth, air,
weather, plants, and animals all make up our environment.
Epitaxial growth: The growth of one crystal on the surface of another
crystal. The growth of the deposited crystal is oriented by the lattice
structure of the original crystal.
Equipotential zone: A zone of equal potential used to protect workers from hazardous step
and touch potentials.
Extrinsic semiconductor: The product of doping a pure semiconductor.
Explosionproof: Designed and constructed to
withstand and internal explosion without creating an external explosion or fire.
Exposed: Not isolated or guarded.
F A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Fast breeder reactor (FBR): A fast neutron reactor
configured
to produce more fissile material than it consumes, using fertile material
such as depleted uranium in a blanket around the core.
Fast neutron reactor: A reactor with little or no moderator and hence utilizing fast neutrons. It normally burns plutonium while producing fissile
isotopes in fertile material such as depleted uranium (or thorium).
Feeder: A circuit, such as conductors in conduit or
a busway run, which carries a large block of power from the service equipment to
a sub-feeder panel or a branch circuit panel or to some point at which the block
power is broken into smaller circuits.
Fermi level: Energy level at which the probability of finding an electron is
one-half. In a metal, the Fermi level is very near the top of the filled levels
in the partially filled valance band. In a semiconductor, the Fermi level is in
the band gap.
Fertile (of an isotope): Capable of becoming fissile, by capturing
neutrons, possibly followed by radioactive decay; e.g., U-238, Pu-240.
Fill factor: The ratio of a photovoltaic cell's actual power to its power if
both current and voltage were at their maxima. A key characteristic in
evaluating cell performance.
Fire Barrier Wall: A wall separating buildings or subdividing a building to prevent the spread of
fire and having a fire resistance rating and structural stability.
Fire loading: The amount of combustibles present in a given area, expressed in Btu/ft2
(kJ/m2).
Fire point: The lowest temperature at which a liquid in an open container will give off sufficient
vapors to burn once ignited. It generally is slightly above the flash point.
Fire protection rating: The time,
in minutes or hours, that materials and assemblies used as opening protection have
withstood a fire exposure as established in accordance with test procedures of NFPA 252,
Standard Methods of Fire Tests of Door Assemblies, and NFPA 257, Standard on
Fire Test for Window and Glass Block assemblies, as applicable.
Fissile (of an isotope): Capable of capturing a slow (thermal) neutron
and undergoing nuclear fission, e.g., U-235, U-233, Pu-239.
Fissionable (of an isotope): Capable of undergoing fission: If
fissile, by slow neutrons; if fertile, by fast neutrons.
Fission: The splitting of a heavy nucleus into two, accompanied by the
release of a relatively large amount of energy and usually one or more neutrons.
It may be spontaneous but usually is due to a nucleus absorbing a neutron and
thus becoming unstable.
Fission products: Daughter nuclei resulting either from the fission of
heavy elements such as uranium, or the radioactive decay of those primary
daughters. Usually highly radioactive.
Flammable liquid: Any liquid having a flash point below 100°F
(37.8°C) and having a vapor pressure not exceeding an absolute pressure of
40 psi (276 kPa) at 100°F (37.8°C).
Flat-plate photovoltaic module: An arrangement of photovoltaic cells mounted
on a rigid flat surface with the cells exposed freely to incoming sunlight.
Flat-plate Photovoltaic: Refers to a
Photovoltaic array or module that consists of non-concentrating elements. Flat-plate arrays and modules use direct and diffuse
sunlight, but if the array is fixed in position, some portion of the direct
sunlight is lost because of oblique sun-angles in relation to the array.
Float charge: Float charge is the voltage required to counteract the
self-discharge of the battery at a certain temperature.
Float life: Number of years that a battery can keep its stated capacity when
it is kept at float charge (see float charge).
Float-zone process: A method of growing a large-size, high-quality crystal
whereby coils heat a polycrystalline ingot placed atop a single-crystal seed. As
the coils are slowly raised the molten interface beneath the coils becomes
single crystal.
Fossil fuel: A fuel based on carbon presumed to be originally from
living matter, e.g., coal, oil, gas. Burned with oxygen to yield energy,
used in a boiler to produce steam for the generation of electrical energy.
Fresnel lens: An optical device that focuses light like a magnifying glass;
concentric rings are faced at slightly different angles so that light falling on
any ring is focused to the same point. Fresnel lenses are flat rather than thick
in the center and can be stamped out in a mold.
 |
Frequency Changers: A frequency changer is a motor-generator set that
changes power of an alternating current system from one frequency to one or more different frequencies, with or without a change
in the number of phases, or in voltage. |
Fuel: Any material that can be burned to make energy.
Fuel assembly: Structured collection of fuel rods or elements, the
unit of fuel in a reactor.
Fuel cell: A device that converts the energy of a fuel directly to
electricity and heat, without combustion. Because there is no combustion, fuel
cells give off few emissions; because there are no moving parts, fuel cells are
quiet.
Fuel fabrication: Making reactor fuel assemblies, usually from
sintered UO2 pellets which are inserted into zircalloy tubes,
comprising the fuel rods or elements.
G A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Gallium (Ga): A chemical element, atomic number 31, metallic in nature, used
in making certain kinds of solar cells and semiconductor devices.
Gallium arsenide (GaAs): A crystalline high-efficiency
semiconductor/photovoltaic material.
Gamma rays: High energy electro-magnetic radiation from the atomic
nucleus, virtually identical to X-rays.
Gassing current: Portion of charge current that goes into
electrolytic
production of hydrogen and oxygen from the electrolytic liquid. This current
increases with increasing voltage and temperature.
Gel-type battery: Lead-acid battery in which the electrolyte is composed of a
silica gel matrix.
Genetic mutation: Sudden change in the chromosomal DNA of an
individual gene. It may produce inherited changes in descendants. Mutation in
some organisms can be made more frequent by irradiation (though this has never
been demonstrated in humans).
Gigawatt (GW): One billion watts. One million kilowatts. One thousand
megawatts.
Glazings: Clear materials (such as glass or plastic) that allow sunlight to
pass into solar collectors and solar buildings, trapping heat inside.
Grain boundaries: The boundaries where crystallites in a polycrystalline
material meet.
Graphite: Crystalline carbon used in very pure form as a moderator,
principally in gas-cooled reactors, but also in Soviet-designed RBMK reactors.
Gray: The SI unit of absorbed radiation dose, one joule per kilogram
of tissue.
Greenhouse effect: The effect of the Earth's atmosphere, due to certain
gases, in trapping heat from the sun; the atmosphere acts like a greenhouse.
Greenhouse gases: Gases that trap the heat of the sun in the Earth's
atmosphere, producing the greenhouse effect; the two major greenhouse gases are
water vapor and carbon dioxide; lesser greenhouse gases include methane, ozone,
chlorofluorocarbons, and nitrogen oxides.
Grid-connected (Photovoltaic
system): A Photovoltaic system in which the Photovoltaic
array acts like a
central generating plant, supplying power to the grid.
Grid-interactive (Photovoltaic
system): See 'Grid-connected (Photovoltaic system).'
Ground: A large conducting body (such as the earth) used
as a common return for an electric circuit and as an arbitrary zero of
potential.
Grounded, effectively: Intentionally connected to
earth through a ground connection or connections of sufficiently low impedance
and having sufficient current-carrying capacity to prevent the buildup of
voltages that may result in undue hazards to connect equipment or to persons.
Grounded Conductor: A system or circuit conductor
that is intentionally grounded, usually gray or white in color.
Grounding Conductor: A conductor used to connect
metal equipment enclosures and/or the system grounded conductor to a grounding
electrode, such as the ground wire run to the water pipe at a service; also may
be a bare or insulated conductor used to ground motor frames, panel boxes, and
other metal equipment enclosures used throughout electrical systems. In most
conduit systems, the conduit is used as the ground conductor.
Grounding Equipment Conductor: The conductor used to
connect the noncurrent-carrying metal parts of equipment, raceways, and other
enclosures to the system grounded conductor, the grounding electrode conductor,
or both, of the circuit at the service equipment or at the source of a
separately derived system.
Grounding Electrode: The conductor used to connect
the grounding electrode to the equipment grounding conductor, to the grounded
conductor, or to both, of the circuit at the service equipment or at the source
of a separately derived system.
 |
Grounding Resistors: Grounding Resistors are designed to provide added
safety to industrial distribution systems by limiting ground fault current to reasonable levels. |
 |
Grounding Transformers: A grounding transformer intended primarily
to provide a neutral point for grounding purposes. |
Ground Fault Circuit Interrupter: A device intended
for the protection of personal that functions to de-energize a circuit or
portion thereof within an established period of time when a current to ground
exceeds some predetermined value that is less than required to operate the
overcurrent protection device of the supply circuit.
Ground Fault Protection of Equipment: A system
intended to provide protection of equipment from damaging line to ground fault
currents by operating to cause a disconnecting means to open all ungrounded
conductors of the faulted circuit. This protection is provided at current levels
less than those required to protect conductors from damage through the
operations of a supply circuit overcurrent device.
Guarded: Covered, fenced, enclosed, or
otherwise protected, by means of suitable covers or casings, barrier rails
or screens, mats, or platforms, designed to minimize the possibility, under
normal conditions, of approach or accidental contact by persons or
objects. Note: Wires which are insulated, but not otherwise
protected, are not considered as guarded.
H A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Half-life: The period required for half of the atoms of a particular
radioactive isotope to decay and become an isotope of another element.
Hazardous atmosphere: An atmosphere that
may expose employees to the risk of death, incapacitation, impairment of
ability to self-rescue (that is, escape unaided from an enclosed space),
injury, or acute illness from one or more of the following causes:
-
Flammable gas, vapor, or mist in excess of 10 percent of
its lower flammable limit (LFL);
- Airborne combustible dust at a concentration that meets or
exceeds its LFL; Note: This concentration may be approximated as a
condition in which the dust obscures vision at a distance of 5 feet (1.52 m)
or less.
- Atmospheric oxygen concentration below 19.5 percent or
above 23.5 percent;
- Atmospheric concentration of any substance for which a
dose or a permissible exposure limit is published and which could
result in employee exposure in excess of its dose or permissible exposure
limit;
- Note: An atmospheric concentration of any substance that
is not capable of causing death, incapacitation, impairment of ability to
self-rescue, injury, or acute illness due to its health effects is not
covered by this definition.
- Any other atmospheric condition that is immediately
dangerous to life or health.
-
Note: For air contaminants for which OSHA has not
determined a dose or permissible exposure limit, other sources of
information, such as Material Safety Data Sheets that comply with the Hazard
Communication Standard, 1910.1200, published information, and
internal documents can provide guidance in establishing acceptable
atmospheric conditions.
Heat pump: Like an air conditioner or refrigerator, a heat pump moves
heat from one location to another. In the cooling mode, heat pumps reduce
indoor temperatures in the summer by transferring heat to the ground. Unlike
an air conditioning unit, however, a heat pump's cycle is reversible. In
winter, a heat pump can extract heat from the ground and transfer it inside.
The energy value of the heat thus moved can be more than three times the
cost of the electricity required to perform the transfer process.
Heavy water: Water containing an elevated concentration of molecules
with deuterium ("heavy hydrogen") atoms.
Heavy water reactor (HWR): A reactor which uses heavy water as its
moderator, e.g., Canadian CANDU (pressurized HWR or PHWR).
Heterojunction: A region of electrical contact between two different
semiconductor materials.
High-level wastes: Extremely radioactive fission products and
transuranic elements (usually other than plutonium) in spent nuclear fuel. They
may be separated by reprocessing the spent fuel, or the spent fuel containing
them may be regarded as high-level waste.
Highly (or High)-enriched uranium (HEU): Uranium enriched to at least
20% U-235. (In weapons it is about 90% U-235.)
High-power tests: Tests in which fault currents, load currents, magnetizing currents, and line-dropping currents
are used to test equipment, either at the equipment's rated voltage or at
lower voltages.
 |
High Voltage
Underground Cables: High voltage cables
are designed to carry high voltage current and are constructed in many different
ways, but are usually shielded cables. They are made with a conductor, conductor-strand shielding, insulation, semi-conducting insulation
shielding, metallic insulation shielding, and a sheath. |
High voltage direct current (HVDC) converter station: A facility that
functions as an electrical rectifier (ac-dc) to control and transmit power
in a high voltage network. There are two types of HVDC valves: the mercury
arc valve and the present-day technology solid state thyristor valve. Both
types of valves present a fire risk due to high voltage equipment that
consists of oil-filled converter transformers, wall bushings, and capacitors
in addition to various polymeric components.
 |
High Voltage Fuses: High voltage fuses are used to protect the electrical
system in a substation from power transformer faults. They are switched for maintenance and safety. |
High-voltage tests: Tests in which voltages of
approximately 1000 volts are used as a practical minimum and in which the
voltage source has sufficient energy to cause injury.
High wind: A wind of such velocity that the following hazards would be present:
- An employee would be exposed to being blown from elevated locations, or
- an employee or material handling equipment could lose control of material being handled, or
- an employee would be exposed to other hazards not controlled by the standard involved.
- Note: Winds exceeding 40 miles per hour (64.4 kilometers
per hour), or 30 miles per hour (48.3 kilometers per hour) if material
handling is involved, are normally considered as meeting this criteria
unless precautions are taken to protect employees from the hazardous effects
of the wind.
Hole: The vacancy where an electron would normally exist in a solid;
behaves like a positively charged particle.
Homojunction: The region between an n-layer and a p-layer in a single
material photovoltaic cell.
Hybrid system: A Photovoltaic system that includes other sources of electricity
generation, such as wind or diesel generators.
Hydrogenated amorphous silicon: Amorphous silicon with a small amount of
incorporated hydrogen. The hydrogen neutralizes dangling bonds in the amorphous
silicon, allowing charge carriers to flow more freely.
I A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Impedance: The total opposition that a circuit offers to the flow of
alternating current or any other varying current at a particular frequency.
Incident light: Light that shines onto the face of a solar cell or module.
Indium oxide: A wide band gap semiconductor that can be heavily doped with
tin to make a highly conductive, transparent thin film. Often used as a front
contact or one component of a heterojunction solar cell.
Inductive reactance: Electrical current produces heat and/or a
magnetic field (such as in the windings of a motor). We refer to the tendency
for current flow and changes in flow to be influenced by magnetic fields as
inductance. An AC circuit that contains only inductance, capacitance or a
combination of the two is defined by the total opposition to current flow
expressed in reactance. Inductance only affects current flow when the current is
changing. Inductance produces a self-induced voltage (called a counter emf) that
opposes changes in current. Obviously, the current changes constantly in an AC
circuit. Inductance in an AC circuit, therefore, causes a continual opposition.
This opposition to current flow is called inductive reactance.
Infrared radiation: Electromagnetic radiation whose wavelengths lie in the
range from 0.75 micrometer to 1000 micrometers.
Insertion Force: The effort, usually measured in ounces, required to engage mating
components.
Insulation: A material that offers high electric resistance making it suitable
for covering components, terminals and wires to prevent the possible future
contact of adjacent conductors resulting in a short circuit.
Insolation: Sunlight, direct or diffuse; from 'incident solar radiation.' Not
to be confused with insulation.
Insulation: Materials that prevent or slow down the movement of heat.
In situ leaching (ISL): The recovery by chemical leaching of minerals
from porous ore bodies without physical excavation. Also known as solution
mining.
In Sight From: (within sight from, within sight)
Where it is specified that one equipment shall be "in sight from",
"within sight from" or "within sight", etc. of another equipment, the specified
equipment is to be visible and not more that 50´ distant from
the other
Insulated: Separated from other conducting
surfaces by a dielectric (including air space) offering a high resistance to
the passage of current.
Note: When any object is said to be insulated, it is
understood to be insulated for the conditions to which it is normally
subjected. Otherwise, it is, within the purpose of this section, uninsulated.
Insulation (cable): That which is relied upon to insulate the conductor from other conductors or conducting parts or from
ground.
Interconnect: A conductor within a module or other means of connection
which provides an electrical interconnection between the solar cells. [UL
1703]
Interfacial Seal: Sealing of a two-piece, multiple contact connector over the whole
area of the interface to provide sealing around each contact.
Interrupter Rating: The highest current at rated
voltage that a device is intended to interrupt under standard test conditions.
Intrinsic semiconductor: An undoped semiconductor.
Inverters: Devices that convert DC electricity into AC electricity (single or
multiphase), either for stand-alone systems (not connected to the grid) or for
utility-interactive systems.
Ion: An atom that is electrically-charged because of loss or gain of
electrons.
Ionizing radiation: Radiation (including alpha particles) capable of
breaking chemical bonds, thus causing ionization of the matter through which it
passes and damage to living tissue.
Irradiate: Material subjected to ionizing radiation. Irradiated reactor
fuel and components have been subjected to neutron irradiation and hence become
radioactive themselves.
Isotope: An atomic form of an element having a particular number of
neutrons. Different isotopes of an element have the same number of protons but
different numbers of neutrons and hence different atomic mass, e.g.,. U-235, U-238.
Some isotopes are unstable and decay to form isotopes of other elements.
ISPRA guidelines: Guidelines for the assessment of
Photovoltaic Plants, published by
the Joint Research Centre of the Commission of the European Communities, Ispra,
Italy.
I-type semiconductor: Semiconductor material that is left intrinsic, or
undoped so that the concentration of charge carriers is characteristic of the
material itself rather than of added impurities.
I-V curve: A graphical presentation of the current versus the voltage from a
photovoltaic device as the load is increased from the short circuit (no load)
condition to the open circuit (maximum voltage) condition. The shape of the
curve characterized cell performance.
I-V data: The relationship between current and voltage of a photovoltaic
device in the power-producing quadrant, as a set of ordered pairs of current and
voltage readings in a table, or as a curve plotted in a suitable coordinate
system (e.g., Cartesian). [ASTM E 1036]
J A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Jacket: Outermost layer of insulating material of a cable or wire.
Junction: A region of transition between semiconductor layers, such as a p/n
junction, which goes from a region that has a high concentration of acceptors
(p-type) to one that has a high concentration of donors (n-type).
Junction box: A Photovoltaic generator junction box is an enclosure on the module where
Photovoltaic strings are electrically connected and where protection devices can be
located, if necessary.
Junction diode: A semiconductor device with a junction and a built-in
potential that passes current better in one direction than the other. All solar
cells are junction diodes.
K A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Kilowatt (kW): 1000 watts.
Kilowatt-hour (kWh): One thousand watts acting over a period of 1 hour. The
kWh is a unit of energy. 1 kWh=3600 kJ.
L A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Labeled: Items to which a label, trademark, or other
identifying mark of nationally recognized testing labs has been attached to identify the items as having been tested and meeting appropriate standards.
Lattice: The regular periodic arrangement of atoms or molecules in a crystal.
Light-induced defects: Defects, such as dangling bonds, induced in an
amorphous silicon semiconductor upon initial exposure to light.
 |
Lightning Arresters: Lightning arresters are
devices for protecting many different
pieces of equipment such as, power poles and towers, power transformers, circuit breakers, bus structures, and steel superstructures,
from damage from lightning strikes. |
Light trapping: The trapping of light inside a semiconductor material by
refracting and reflecting the light at critical angles; trapped light will
travel further in the material, greatly increasing the probability of absorption
and hence of producing charge carriers.
Light water: Ordinary water (H20) as distinct from
heavy water.
Light water reactor (LWR): A common nuclear reactor cooled and usually
moderated by ordinary water.
Lines, Communication: The conductors
and their supporting or containing structures which are used for public or
private signal or communication service, and which operate at potentials not
exceeding 400 volts to ground or 750 volts between any two points of the
circuit, and the transmitted power of which does not exceed 150 watts. If
the lines are operating at less than 150 volts, no limit is placed on the
transmitted power of the system. Under certain conditions, communication
cables may include communication circuits exceeding these limitations where
such circuits are also used to supply power solely to communication
equipment.
Note: Telephone, telegraph, railroad signal, data, clock,
fire, police alarm, cable television, and other systems conforming to this
definition are included. Lines used for signaling purposes, but not included
under this definition, are considered as electric supply lines of the same
voltage.
Line-commutated inverter: An inverter that is tied to a power grid or
line. The commutation of power (conversion from DC to AC) is controlled by
the power line, so that, if there is a failure in the power grid, the Photovoltaic
system cannot feed power into the line.
Listed: Equipment or materials included in a list
published by an organization acceptable to the authority having jurisdiction and
concerned with product evaluation, that maintains periodic inspection of
production of listed equipment or materials, and whose listing states either
that the equipment or material meets appropriate designated standards or has
been tested and found suitable for use in specified manner.
Load: Anything in an electrical circuit that, when the circuit is turned on,
draws power from that circuit.
Location, damp: A location subject to moderate
amount of moisture such as some basements, barns, cold storage, warehouse and
the like.
Location, dry: A location not normally subject to
dampness or wetness: a location classified as dry may be temporarily subject to
dampness or wetness, as in case of a building under construction.
Location, wet: A location subject to saturation with
water or other liquids.
Low-enriched uranium: Uranium enriched to less than 20% U-235. (That
in power reactors is usually 3.5: 5.0% U-235.)
Lower Flammable Limit (LFL): The lowest
concentration of material that will propagate a flame from an ignition source
through a mixture of flammable gas or combustible dust dispersion with a gaseous
oxidizer.
M A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z
Majority carrier: Current carriers (either free electrons or holes) that
are in excess in a specific layer of a semiconductor material (electrons in
the n-layer, holes in the p-layer) of a cell.
 |
Manholes: A manhole is the opening in the underground duct system which houses
cables plices and which cablemen enter to pull in cable and to make splices and tests. Also called a splicing chamber or cable vault. |
Marginal cost: The cost of one additional unit within a group of like units.
Maximum power point (MPP): The point on the current-voltage (I-V) curve of a
module under illumination, where the product of current and voltage is maximum.
[UL 1703] For a typical silicon cell, this is at about 0.45 V.
Maximum power point tracker (MPPT): Means of a power conditioning unit that
automatically operates the Photovoltaic-generator at its MPP under all conditions.
Megaohm: A unit of electrical resistance equal to
one million ohms.
Megaohmmeter: An instrument for measuring extremely
high resistance.
Megawatt (MW): A unit of power, = 106 watts. MWe
refers to electric output from a generator, MWt to thermal output from a reactor
or heat source (e.g., the gross heat output of a reactor itself, typically three
times the MWe figure).
Megger: A test instrument for measuring the
insulation resistance of conductors and other electrical equipment;
specifically, a megaohm (million ohms) meter; this is a registered trade mark
of the James Biddle Co.
 |
Metal-clad Switchgear: An outdoor
metal-clad switchgear is a weatherproof housing for circuit breakers,
protective relays, meters, current transformers, potential transformers, bus
conductors, and other equipment. An indoor switchgear must be protected from
the environment and contains the same types of equipment as the outdoor
type. |
Metal fuels: Natural uranium metal as used in a gas-cooled reactor.
 |
Meters: They are measuring devices and can be an indicating meter or a
recording meter. An indicating meter shows on a dial the quantity being measured. A recording meter makes a permanent record of
the quantity being measured, usually by tracing a line on a chart or graph. |
Micro: one millionth of a unit (e.g., microsievert is 10-6 Sv).
Microgroove: A small groove scribed into the surface of a cell which is
filled with metal for contacts.
 |
Microwave: Substations commonly use microwave communication equipment for
communication with local and regional electric power system control centers. This system allows for rapid communication and signaling
for controlling the routing of power. |
Milling: Process by which minerals are extracted from ore, usually at
the mine site.
Minority carrier: A current carrier, either an electron or a hole, that is in
the minority in a specific layer of a semiconductor material; the diffusion of
minority carriers under the action of the cell junction voltage is the current
in a photovoltaic device.
Minority carrier lifetime: The average time a minority carrier exists before
recombination.
Mixed oxide fuel (MOX): Reactor fuel which consists of both uranium
and plutonium oxides, usually about 5% Pu, which is the main fissile component.
Moderator: A material such as light or heavy water or graphite used in
a reactor to slow down fast neutrons by collision with lighter nuclei so as to
expedite further fission.
Module: See 'Photovoltaic Module.'
Monolithic: Fabricated as a single structure.
Multicrystalline: Material that is solidified at such as rate that many small
crystals (crystallites) form. The atoms within a single crystallite are
symmetrically arranged, whereas crystallites are jumbled together. These
numerous grain boundaries reduce the device efficiency. A material composed of
variously oriented, small individual crystals. (Sometimes referred to as
polycrystalline or semicrystalline).
Multijunction device: A photovoltaic device containing two or more cell
junctions, each of which is optimized for a particular part of the solar
spectrum, to achieve greater overall efficiency.
N |
