Glossary LED Lighting

Glossary LED Lighting

Ambient Temperature
The temperature of the air surrounding the device.

A measure of electrical current. Amps = Watts/Voltage

Average Rated Life
An average rating, in hours, indicating when a large group of lamps have failed, when operated at nominal lamp voltage and current. The life of an LED is defined as the operating time in hours for the lamp to reach L70 which designates 70% lumen maintenance (or 30% reduction in initial lumen output).

The systematic dividing and distribution of LED chip performance parameters (Flux, Wavelength or CCT, and Vf) in to a small selection of finite groupings to optimize assembly performance.

Color Corrected
Refers to a lamp, such as an LED, with a special phosphor or coating to give it a color rendering profile similar to natural daylight.

Color Rendering Index ( CRI)
A lamp’s ability to render an object’s true colors based on a scale of 100.

Color Temperature
A numerical measurement of the color appearance of a light source measured in degrees Kelvin (K). It also refers to the way color groups are perceived (psychological impact of lighting) with “warm” colors at the red/orange/yellow end of the spectrum and “cool” colors at the blue end.

Chromaticity is the quality of a colour or light in reference to its purity and its dominant wavelength, or in simple terms, its departure from white light. The CIE Chromaticity Chart is a standard color space. In 1931, CIE defined a human color standard, based on measurements of the color-matching abilities of the average human eye. Using data from laboratory measurements, a system of three primaries, XYZ, was developed in which all visible colors can be represented using only positive values of X, Y and Z. The Y primary is identical to Luminance, X and Z give color (chroma) information.

A measure of the rate of flow of electricity, expressed in amperes (Amps).

A two-terminal semiconductor device having a positive-negative (p-n) junction which mainly allows energy to travel in one direction.

An LED driver is a self-contained power supply that has outputs which match the electrical characteristics of the LEDs.

Electrolytic Capacitor
An electrolytic capacitor is a type of capacitor that uses an electrolyte, an ionic conducting liquid, as one of its plates, to achieve a larger capacitance per unit volume than other types. Electrolytic capacitors produce excessive amounts of heat that often lead to failures in most LED lamps. They are used in relatively high-current and low-frequency electrical circuits, particularly in power supply filters, where they store charge needed to moderate output voltage and current fluctuations in rectifier output. They are also widely used as coupling capacitors in circuits where AC should be conducted but DC should not. There are two types of electrolytics: aluminum and tantalum.

Foot Candle
A unit of illuminance or light falling onto a surface measured as the light level on a surface one foot from a standard candle.

Heat Sink
A heat sink is an object that absorbs and dissipates the heat generated by the operation of an LED lamp. Generally it is made of Aluminum or Magnesium Alloy

Light falling on a surface, expressed in lumens per unit area; 1 lumen per square foot equals 1 footcandle, while 1 lumen per square meter equals 1 lux.

IK Rating
IK ratings are defined as protection provided by electrical enclosures (including luminaires) against external mechanical impacts. The IK rating scale identifies the ability of an enclosure to resist impact energy levels measured in joules (J). The rating varies from 00 to 10.

Initial Lumens
The measured luminous output of a new LED light source.

Integrated Circuit ( IC)
IC-based CFLs operate by controlling the voltage and current by adjusting the output frequency which provides stable operation of the CFL. Controlling the current produces less stress on the cathode and the electronic components, which results in long life, smoother dimming, and less noise.

IP Rating
IP (or "Ingress Protection") ratings are defined in international standard EN 60529 (British BS EN 60529:1992, European IEC 60509:1989). They are used to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies (tools, dirt etc) and moisture.

Kelvin Temperature
Light temperature term – using the symbol (K) – to indicate the comparative color appearance of a light source when compared absolute black. Warm incandescent lamps are 2700K. Halogen and other light sources range from 3000K to 7500K and higher.

Short for light-emitting diode. An LED is an electronic semiconductor device that emits light when an electric current passes through it. LEDs are considerably more efficient than incandescent and halogen bulbs, and rarely burn out. There are many types of LED like SMD LED, COB LED, MCOB LED, Power LED etc.

LED Driver
An electronic circuit that converts input power into a current source — current should remain constant despite fluctuations in voltage. Most LED drivers use an Electrolytic Capacitor to achieve constant surrent. The LED driver protects LEDs from normal voltage fluctuations, over voltages, and voltage spikes.

A lens is an optical device that refracts light, converging or diverging the beam.

Luminous Flux
A measure of luminous flux or quantity of light emitted by a LED lamp.

Lumen Depreciation
The gradual decline in light output from a solid state light source over time due to LED darkening. This is governed by standard LM-80

Lumen Maintenance
A measurement of how a lamp maintains its light output over time. Generally, lumen maintenance is a comparison of the amount of light produced from an LED lamp when it is brand new to the amount of light output at a specific time in the future.

Lumens per Watt ( LPW)
A measure of the efficacy (efficiency) of a light source. The number is achieved by dividing lumens produced by watts consumed.

Luminous Efficacy
The light output (lumens) of a light source divided by the total power input (watts) to that source. It is expressed in lumens per watt.

A unit of illuminance or light falling onto a surface. One lux is equal to one lumen per square meter.

An inorganic chemical compound processed into a powder and deposited on the inner glass surface of fluorescent tubes, CFL’s, LED’s and some mercury and metal-halide lamp bulbs.

Power Factor
The ratio of the actual electrical power dissipated by an AC circuit to the product of the r.m.s. values of current and voltage. The difference between the two is caused by reactance in the circuit and represents power that does no useful work.

Rated Lamp Life
The length of time of a statistically large sample between first use and the point when 70% of the LEDs on a lamp have failed.

Solid State Lighting
Lighting devices that do not rely on chemical reactions to produce light.  Most SSL lamps do not contain filaments or parts that can break, rupture, shatter, leak or contaminate the environment.

Surge Protection Device
A surge protection Device attempts to limit the voltage supplied to an electric device by either blocking or shorting current to reduce the voltage below a safe threshold. Blocking is done by using inductors which inhibit a sudden change in current.

Thermal Management
The method of controlling the operating temperature of the product by designing a path for heat to leave the body of the lamp using heat sinks and improved airflow.

Total Harmonic Distortion
The total harmonic distortion (THD) is a measurement of the harmonic distortion present in a signal and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency

A measurement of the electromotive force in an electrical circuit or device expressed in volts.

A unit of electrical power. Lamps are rated in watts to indicate the rate at which they consume energy.




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