Transformer
Electrical device used to transform input and
output electrical power parameters (tension,
current intensity), maintaining constant electrical
power. The transformer is a device that can be
operated in alternate current, thanks to the
electromagnetic principles linked to variable
fluxes.
Tunable white
Light source able to create different tones
of white light, going from warm (2,500K)
to cold white (6,500K). It can be made
of white or coloured sources.
Neutral white: white light with neutral
colour temperature (3,500-5,000K).
Warm white: white light with warm colour
temperature (2,500-3,500K).
Cool white: white light with cold colour
temperature (5,000-10,000K).
UGR
Unigied Glare Ratio. Parameter expressing
the glare of a light fitting, through the evaluation
of its luminance.
Ultraviolet radiation
Optical radiation with wavelengths shorter
than those of visible radiation. In the range
between 100 and 400 nm, ultraviolet radiation
is generally indicated with the symbols
UVA between 315 and 400 nm, UVB between
280 and 315 nm and UVC between 100
and 280 nm.
Uni EN 12464 standard
UNI standard that establishes the lighting
technology parameters related to workstations.
The standard defines characteristics such as:
Minimum illumination, uniformity, colour
rendering of sources and UGR for various
workplaces. This standard also prescribes the
maximum permissible luminance of a device for
its use in places where there are video terminals.
Very Wide Flood
Term to identify a 2 ½ theta opening greater
than 30° in a projector.
Visible radiation
Optical radiation that directly causes a visual
sensation. Even if the range of wavelengths
concerned in vision depends on the individual
and on the illuminance on the retina, the lower
limit is normally indicated between 360 nm
and 400 nm and the upper limit between
760 nm and 830 nm.
Visual performance
Degree of effectiveness of the visual system,
measured for example by the speed and accuracy
with which a visual task is accomplished.
Visual task
Set of elements of the work performed.
U
W
V
Voltage drop
Voltage drop (Vf) is a synonym of the potential
difference. More specifically if a resistor of
resistance R is inserted between two points
A and B of an electrical circuit and traversed by
a current of intensity I, Ohm’s law states that the
electric potential at A is greater than at B in a
quantity equal to R·i. In other words, between
A and B there is a potential difference, or voltage
drop, equal to ΔV = R·I
Wall washer
Luminaire designed to illuminate the walls
of buildings, whether external or internal;
wall washers can be with white light or RGB,
they are very frequently used to create
spectacular effects outside.
Warm white
White colour of a light source with a colour
temperature between 2700 and 3500 Kelvin.
Wavelength (λ)
Distance between two successive points,
in the direction of propagation of a periodic
wave, in which the oscillation has the same
phase. Measured in metres (m) and nano
metres (nm).
Wide Flood
Term to identify a 2 ½ theta opening between
20 and 30° in a projector.
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