Power / Energy technology glossary 

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

AC - Alternating Current. Electrical energy which reverses its direction at regular intervals.

Ampere (Amp) - Electric current measurement unit.

Amp hours - Number of amps used/produced in a given hour.

Array module - A group of solar electric modules connected in series in a solar power system.

B

Battery bank - A group of batteries wired in a fashion that allows power storage in a solar power system.

Breakdown voltage - The voltage at which the insulation of an insulator fails and current flows through or across the surface as a discharge.

C

Controller - A regulator of electric current drawn from the solar charger into the battery bank.

Current - The rate of flow of electric charges and is measured in units of amp.

D

DC - Direct Current. Electric energy of constant value and flowing in one direction.

Duty factor - The ratio of the pulse duration to the pulse period. Also, the ratio of the average pulse power to the peak pulse power.

E

Effeciency - The ratio expressed as a percentage of the output power to the input power.

Energy consumption - Energy consumption and population data by continents.

Electricity generator - It consists of variuos components : A rotor, a geerbox and a

F

Fuse - A protective device which heats and melts so interupting a circuit when the current exceeds a certain value.

G

Glitch - Distortion of a pulse waveform in the form of a short-distortion distribution.

H

H - Henry, The unit of self-inductance or mutual inductance.

Hz - Hertz, The frequency of electrical current is described in cycles per seconds. Appliances in the US use 60 Hz, elsewhere it is 50 Hz.

Hum - An unwanted low-frequency noise originating from mains driven equipment and comprising harmonics of the mans frequency.

I

Insertion gain (loss) - The gain (loss) resulating from the inseration of a network between a generator and its load.

Instability - Generation of unwanted and sustained oscillations.

Inverter - An device that is used to convert DC power (eg. from a battery) into AC current to power household appliances. When comparing inverters check the continuous wattage rating, surge power, and efficiency for each.

J

Johnson noise - (also thermal noise) Arises from the thermal agitation of electrons in a conductor.

Joule effects - The heating effect generated by an electric current in a conductor by virture of its resistance.

K

Kenotron - A hot-cathode high vacuum diode used for high voltage low current rectification in industrial applications such as X-ray equipment.

L

Line loss - A voltage drop over the length of electric line wire.

Load - The amount of lighting and number of electric appliances need be supported by your local power supply system.

M

MTBF (Mean Time Between Failure) - A measure of the reliability of an equipment, ie. the time to the first failure.

Module - Used interchangeably with solar power panel.

N

Nuclear energy - The generation of energy by nuclear fission of fissionable nuclei.

O

Offset voltage - For a differential amplifier the output voltage arising from inherent DC unbalance of the amplifier.

Overloading - Conditions of a source of electrical power when more poer is drawn from it than the source can supply continously without overheating or damage.

Overshoot - Form of transient distortion of a step or pulse signal in which the respone temporarily exceeds the final value.

P

Parallel wiring - A method of connecting solar electric modules / batteries in order to increase current output (i.e., amperage).

Pilot lamp - A lamp used to indicate the condition of an associated circuit.

Power factor - In a AC circuit the ratio of the real power to the apparent power.

Power supply circuits - These are alternative options to batteries as af power source (regulated DC ) used nowadays in most electronic equipments.

Photoelectric effect - The formation and liberation of electrons in materials when irradiated by light or other e-m waves.

Photovoltaic - A process by which light power is converted directly into electric power and is often referred to as PV for short. Crystalline silicon or gallium arsenide or other semi-conductor materials are used in such as process. 

Pre-shoot - A form of transient distortion of a step or pulse signal in which the reproduced step is preceeded by oscillations.

Proximity effect - In a conductor caryying an alternating current a concentration of the curent towards the edges of the cross section caused by interaction between the conductor and the EM field setup by neighbouring conductors carrying the same current.

Q

Quiescent point - of an active device is the position of the operating point when no input signal is applied. It indicates the mean current and the mean voltage in the output circuit and so measures the dissipation within the active device in the absence of an input signal.

R

Rectifications - A process of converting electric AC current into DC current.

Return current (voltage) - In a transmission line the current (voltage) which is setup at any impedence discotinuity and travels back to the source.

Rise time - A measure of the steepness of the loading edge of a pulse, ie. it is the time taken for the instantaneuous amplitude to change from 10% to 90% of the peak value.

S

Sag - A form of distortion of a pulse signal in which the instantaneous amplitude falls during the period of the pulse.

Sawtooth signal - A periodic signal in which each cycle consists of a lnear change followed by a rapid return to the value at the begining of the linear change.

Self-regulating - Certain solar electric modules have an optional circuit that prevents the battery from overcharging. In this case, no regulator is required if such a circuit ensures battery storage capacity matching.

Shot noise (Schotky noise) - Noise arising from random variations in the emission of electrons from a cathode.

Single-Crystal silicon - Pure silicon is grown into crystalline only to be cut into very thin slices in order to make efficient state-of-the-art solar solar  cells.

Solar cell - The device which generates electric power when exposed to sunlight through what is known as the photovoltaic process.

Solar collectors - The direct collection of solar energy which is then fed into one of three processes : Thermal heating , photoelectric, and photovoltaic. They are available as flat-plate collectors or concentrating collectors.

Solar constant - The strength of the solar radiation at the Earth atmosphere, at average distance from the sun, and is equivalent to 1.37 x 10⁶ ergs/s cm²

Solar cooling - The utilization of solar energy as a heat source in a absorption cooling cycle (refrigeration).

Solar electric - The common term for the technical term photovoltaic.

Solar energy - The radiant energy produced in the sun as a result of nuclear (H and He) fusion reactions.

Solar furnaces - High temperature (~ 4000 C^o and contaminants-free application of solar collectors array used usually in materials research. 

T

Thin-Film silicon - A tiny solar charges found in many hand-held wrist watches and calculators.

Tilt - see sag.

Time constant - of a quantity that vary exponentially with time, the time taken for a quantity to vary by 63% of the full extent of the charge.

Transient - The signal which persists for a brief period following a sudden disturbance to the steady state condition.

Transient response - The ability of a circuit or device to reproduce transients without distortion.

Transformer - An electric device consisting of two coils that can be used to raise (step-up) or reduce (step-down) voltage through the use of induction between the coils. There are two types : Single-phase (residential) and three-phase (industrial) transformers.

U

Undershoot - A form of transient distortion of a step or pulse signal in which the response makes a temporarily excursion before the main transtion and in the opposite direction.

Unilateral impedence - A mutual impedence through which power can be transmitted in one direction only.

V

Voltage - The amount of electrical pressure that forces electricity to flow in power lines. 110 V in the USA and Japan, and 220 V in most other countries. Three-phase voltage is 380 V.

Voltage amplifier - A circuit incorporating one or more active devices and designed to amplify voltage waveforms.

Voltage feedback - A system in which the negative feedback signal is directly proportional to the voltage across the load.

Voltage - Multipier rectifier - A combination of rectifiers and capacitors which produces an output voltage approximately equal to an exact multiple of the peak value of the AC input voltage.

W

Watts - A unit for measuring total electric power. A KiloWatt (kW) is 1000 Watts.

Watt-hour - The quantity of electrical energy used/produced when on Watt of electric power is used/produced for one hour.

Windmill - A machine that converts wind into useful energy (usually regulated electricity or water pumping, pressing oil from seeds and irrigations). There are two types : horizontal-axis and vertical-axis towers. Typical machines starts operating at about 20 km/h with optimum performance at about 50 km/h.

Wind farms - An array of windmills capable of producing some 50 kW. The largest of such farms is in California, USA with an output of about 1000 MW . In Europe, Denmark and the Netherlands are leading with about 2 % share of total electricity production.

X

Y

Z

Zener breakdown - In a reverse-biased pn junction, a rapid increase in the current which occurs at a particular reverse voltage as a result of the Zener effect.

Zener effect - Condition through a reverse-biased pn junction caused by spntaneous generation of the hole-electron pairs within the inner electron shelss of atoms in the junction region.