Glossary of Terms
Alternating Current (AC) – Is the flow of electrons in a conductor that reverses polarity (direction) repeatedly at some interval of time. AC is the form in which electric power is delivered to businesses and residences
Ampere (Amp [A]) –Is the International System of Units (SI) of electric current. Ampere is defined as the measure of electrons passing a point in an electric circuit in 1 second.
[Circuit] Breakers –A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. The breaker’s basic function is to detect a fault condition and interrupt current flow. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.
Capacitance (C) –Capacitance is the measure of a substance’s ability to store an electrical charge.
Capacitors –A capacitor is an electrical component used to store energy. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, a capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.
Current (I) –An electric current is a flow of electric charge. In electric circuits moving electrons in a wire often carries this charge. The International System of Units (SI) for measuring an electric current is the ampere (A).
Demand – Utility companies describe Demand as a period of highest consumption rate in a billing period. For an electric utility company, the actual point of peak demand is a single half hour or hourly period which represents the highest point of customer consumption of electricity. Some utilities will charge customers based on their individual peak demand.
Energy – Energy (forms) include the kinetic energy of a moving object, the radiant energy carried by light and other electromagnetic radiation, and various types of potential energy such as gravitational. Energy is measured in the International System (SI) of units of joules (J).
ETL –Specializes in electrical product safety testing and benchmark performance testing. ETL operates more than 30 offices and laboratories on six continents.
Frequency (f) – Frequency is the number of occurrences of a repeating event per unit time. The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency.
Harmonics –Harmonics are electric voltages and currents that appear on the electric power system as a result of non-linear electric loads. Harmonic frequencies in the power grid are a frequent cause of power quality problems. Harmonic components should be reduced as much as possible.
Impedance (L) – A measure of the extent to which a circuit opposes the flow of electricity. All materials have some degree of electrical resistance, which causes some energy to be lost as heat, and reduces the flow of current.
Inductor –An inductor, also called a coil or reactor, has magnetic properties. When an electric current is passed through it, a magnetic field is created, which helps store the electric current for a short amount of time even if the supply is removed
Kilo (k) –Is the International System of Units (SI) prefix designating sets of 1000 (103). The Kilo prefix can preface any unit of measure including energy, work, and power such as kilowatts (kW) is 1000 watts, kilovolts (kV) is 1000 volts, etc.
Magnetizing Current –Magnetizing current establishes the magnetic field so the motor will spin. This current is constant, and the amount of current that a motor draws depends on how the motor was made.
Mega (M) –Is the International System of Units (SI) prefix designating sets of 1,000,000 (106). The Mega prefix can preface any units of energy, work, or power such as megawatts is 106 watts, kilovolts is 106 volts, etc.
Phase (φ), Single –In electrical engineering, single-phase electric power refers to the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors.
Polyphase (φ) –A polyphase system is a means of distributing alternating-current electrical power. Polyphase systems have three or more energized electrical conductors carrying alternating currents with a definite time offset between the voltage waves in each conductor. Polyphase systems are particularly useful for transmitting power to electric motors. The most common example is the three-phase power system used for industrial applications and for power transmission.
Power (P) – Electric power is the rate at which electric energy is transferred by an electric circuit. The International System of Units (SI) unit of power is the watt, one joule per second.
Power Factor –The power factor of an AC electrical power system is defined as the ratio of the real power flowing to the load, to the apparent or total power in the circuit, and is a dimensionless number between 0 and 1. For example, a business with poor or lower power factor is less efficient than a location with a power factor closer to 1.
Power Factor Correction (PFC) –Power factor correction brings the power factor of an AC power circuit closer to 1 by supplying reactive power of opposite sign, adding capacitors or inductors that act to cancel the inductive or capacitive effects of the load, respectively. For example, if a business has poor power factor and they install a power factor correction system, their motors will become more efficient and they will use less energy.
Reactive (current/power/energy) –Reactive power flow is needed in an alternating-current transmission system to support the transfer of real power over the network. In alternating current circuits, energy is stored temporarily in inductive and capacitive elements, which can result in the periodic reversal of the direction of energy flow.
Resistor –A passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits.
Resistance (R) – Is the opposition to the passage of an electric current through a conductor.
RoHS –The Restriction of Hazardous Substances Directive insists that substances of very high concern – including cadmium, lead and mercury – not be used in the manufacture of electronics and electronic devices.
Smart Meter – An electronic device that records consumption of electric energy in intervals of an hour or less and communicates that information at least daily back to the utility for monitoring and billing purposes. Unlike home energy monitors, smart meters can gather data for remote reporting.
Spike – (in electrical engineering) is a fast, short duration, electrical transients in voltage (voltage spikes), current (current spikes), or transferred energy (energy spikes) in an electrical circuit. Fast, short duration electrical transients (over-voltages) in the electric potential of a circuit are typically caused by:
- Lightning strikes
- Power outages
- Tripped circuit breakers
- Short circuits
- Electromagnetic pulses (EMP).
- Inductive spikes
- Power transitions in other large equipment on the same power line
- Malfunctions caused by the power company
Surge Protector –An appliance designed to protect electrical devices from voltage spikes. A surge protector attempts to limit the voltage supplied to an electric device by either blocking or by shorting to ground any unwanted voltages above a safe threshold.
Transformer –A transformer is an electrical device that takes electricity of one voltage and changes it into another voltage. Basically, a transformer changes electricity from high to low voltage using two properties of electricity.
UL 810 – Is the US National safety standard that applies to enclosed capacitors with integral protection intended to reduce the risk of rupture and venting of the capacitor enclosure under internal fault conditions.
Underwriter’s Laboratories (UL) – is a safety consulting and certification company headquartered in Northbrook, Illinois. It maintains offices in 46 countries. UL provides safety-related certification, validation, testing, inspection, auditing, advising and training services to a wide range of clients, including manufacturers, retailers, policymakers, regulators, service companies, and consumers.
Volt (V) –is the International System of Units (SI) for electric potential (voltage), electric potential difference, and electromotive force. A single volt is defined as the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points.
Volt-Ampere (VA) –is the International System of Units (SI) used for the apparent power in an electrical circuit, equal to the product of root-mean-square (RMS) voltage and RMS current. In direct current (DC) circuits, this product is equal to the real power (active power) in watts.
Volt-Ampere Reactive (VAr) –a unit used to measure reactive power in an AC electric power system.
Watt (W) –in the International System of Units (SI) for power, the ‘watt’ is defined as one joule per second and it measures the rate of energy conversion or transfer. Watts are basically the miles-per-hour measurement of the electrical world–they tell you how fast the electrons are speeding down the highway.
Watt-Hour (Wh) –is International System of Units (SI) for energy equal to 1000 watt-hours or 3.6 megajoules. The kilowatt-hour (kWh) is most commonly known as a billing unit for energy delivered to consumers by electric utilities. The kilowatt-hour is a unit of energy equivalent to one kilowatt (1 kW) of power expended continuously for one hour.
Work –There are three key ingredients to work: (1) force; (2) displacement; and (3) cause. In order for a force to qualify as having done work on an object, there must be a displacement and the force must cause the displacement. [Work = Force*distance].