Electrical Glossary
Megavolt - Your source for electrical information in Israel





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Alternating Current (AC) a flow of electricity which reaches maximum in one direction, decreases to zero, then reverses itself and reaches maximum in the opposite direction. The cycle is repeated continuously. The number of cycles per second is equal to the frequency.
Alternator a generator that produces alternating electric current.
Ammeter an instrument that measures electric current.
Ampere or amp; A unit that measures the strength/rate of flow of electrical current.
Ampere Hour (Ah) is the amount of energy charge in a battery that will allow one ampere of current to flow for one hour.

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Ballast a device used to provide the starting voltage or to stabilize the current in a circuit. Commonly used for florescent and CFL type bulbs.
Battery a device that produces electric current as a result of chemical reaction.
Buss Bar (also Bus Bar) separate, metallic strips that extend through the service panel. Breakers slide onto the "hot" busses. Neutral and ground wires screw down in their respective busses.

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Capacitor (condenser) a device consisting of two conducting surfaces separated by an insulator and having the ability of storing electric energy.
Circuit Breaker the most common type of "over current protection." A breaker trips when a circuit becomes overloaded or shorts out.
Color Rendering Index (CRI) an international system used to rate a lamp's ability to render object colors. The higher the CRI (based upon a 0-100 scale) the richer colors generally appear.
Corona Discharge a luminous discharge which occurs when the applied voltage is high enough (5000 volts or more) to cause partial ionization of the surrounding gas
Current a flow of electrons through a conductor.

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Direct current (DC) an electric current that flows in one direction only.

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Earth see "Grounding"
Electric Arc a discharge of electricity between two electrodes; in effect a continuous electric spark.
Electricity the flow of electrons.
Electromagnet a temporary magnet consisting of a set of coils wound on an iron core. The device becomes magnetic when electricity is passed through the coils.
ElectroMagnetic Interference (EMI) an electromagnetic disturbance that degrades or limits the effective performance of electronic or electrical equipment.

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Field the region around a body where a certain influence is felt, such as an electric or magnetic field.
Floating Ground  when common connections providing a return grounding path exist, but are not actually connected to an earth ground.
Fluoresce exhibit or undergo fluorescence - which is light emitted during absorption of radiation of some other (invisible) wavelength.
Frequency the number of cycles of alternating voltage or current which occur during a particular amount of time, usually one second
Fuses removable devices that link a circuit at the fuse box. Fuse connections blow apart and break the circuit if an overload or short occurs.

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Generator an engine that converts mechanical energy into electrical energy by electromagnetic induction
Ground A conducting connection between an electrical circuit, or equipment, and the earth, or to some
conducting body that serves in place of the earth.
Ground Fault current misdirected from the hot (or neutral) lead to a ground wire, or any other conducting material.
Ground Fault Circuit Interrupter (GFCI or GFI) measures the current flowing through the live wire and the neutral wire. If they differ by more than a few milliamps, the GFI trips, breaking the circuit. Also called RCD or ELCD. Called a “Mimsar P’hat" in Hebrew.

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Hertz (Hz) expression of AC frequency in cycles per second, e.g., 50 Hz
"Hot" Wire slang term used for a live wire.

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Insulator a material that does not conduct electricity
Inverter a device used to convert direct current into alternating current.

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Joule  A unit of electrical energy equal to the work done when a current of one ampere is passed through a resistance of one ohm for one second.

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KW kilowatts.
Kilowatt-hour (kWh) a unit of energy equivalent to one kilowatt of power operating for one hour.

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LED Light Emitting Diode
"Live" Wire a wire connected to a power source, having a voltage potential
Lumens this is a measure of light output from a source, measured in candlepower. Each lumen represents the brightness of one candle.
Lux a unit of illumination equal to 1 lumen per square meter. This is actually measurement of light from a distance.

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Magnetic Field the region around a magnet in which the magnetic forces act.

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Neutral (O) Wire the conductor that is intended to have a ground potential.

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Ohm a unit that measures the resistance a conductor has to electricity.

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Photon an elementary particle composing light and other forms of electromagnetic radiation, sometimes called light quantum.
Phase a factional part of the period of a sinusoidal wave, usually expressed in electrical degrees.
Photoelectric Cell a cell whose electrical properties change when light falls on it. Such cells are used in camera light meters, television camera tubes, and automatic detection devices.
Photovoltaic (PV) Solar Energy The word photovoltaic comes from the words photo, meaning light, and voltaic, meaning electricity. Photovoltaic solar energy uses the optical light emitted by the sun to produce electricity.
Power Factor the ratio of true power (watts) to apparent  power (volt amps). When these two are identical (seldom found in an AC circuit) the power factor is 1.0. The power factor is expressed in decimal or percentage.

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Rectifier an electrical device that converts alternating current to direct current.
Resistance the resistance in a substance to the flow of electric current.

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Sine-Wave A uniform wave that is generated by a single frequency.
Single-Phase an alternating-current circuit consisting of two intentionally interrelated input terminals, if it’s a load, or two output terminals, if it’s a source.
Solar Cell a cell that converts the energy in sunlight into electricity.
Spike Same as a surge but for a very short period of time (millisecond), but can measure in the thousands of volts
SSL Solid State Lighting
Star Connection see Wye Connection
Static Electricity the electricity associated with electric charges, which tends to stay ‘static’ rather than flowing away
Surge (electrical) surges are an increase in "normal" electrical line voltage. Usually not more than 500-600 volts.
Surge Protector a device that shields computer and other electronic devices from surges in electrical power

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Three-Phase A circuit consisting of three different sine wave current flows, different in phase by 120 degrees from each other
Transformer an electrical device used to alter the voltage of alternating electric current

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Uninterruptible Power Supply (UPS) a device which maintains a continuous supply of electric power to connected equipment by supplying power from a separate source when utility power is not available.

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Volt the unit of electrical voltage, or "pressure"
Volt-ampere (VA) a measurement of electrical power in an electrical circuit. In DC current, 1VA is equivalent of one 1W (watt). When used with AC current this equation is less precise, because it represents apparent power, which often differs from true power.
Voltage Regulator An electrical device that keeps voltage at a constant level regardless of load fluctuations
Voltmeter an instrument for measuring the voltage

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Watt a unit that measures the amount of electrical power
Wye Connection A three-phase winding connection, formed by joining together similar ends of each phase winding. This point forms the electrical neutral. Also known as "star connection".

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XLPE Cross-Linked Polyethylene. A thermoset plastic compound that is used for insulation of wire and cable.

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Zero Crossing The point at which a sinusoidal voltage or current waveform crosses the zero reference axis.

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