ingineria iluminatului - Journal of Lighting Engineering - Prof. Florin ...

the same. If an armature is purchased, any
fluorescent lamp can be used. An exception
is represented by compact fluorescent
lamps, where the ballast is attached to the
lamp in witch case a special lamp in dc
voltage is required.
a)
b)
Figure 4 a) 10 – 50 W halogen lamps and
b) 15 – 30 W fluorescent lamps [4]
4.1 Light emitting diodes
A light-emitting diode (LED) is a
semiconductor diode that emits light in
direct polarization of the p-n junction. The
effect is a form of electroluminescence. The
color of light emitted depends on the
composition and the semiconductor
material used, and may be in the range of
infrared, visible or ultraviolet. A lightemitting
diode is small light source, most
often accompanied by an electrical circuit
that allows the modulation of the light
radiation shape. They are used as indicators
within the electronic devices, but
increasingly more often are used in power
applications, such as lighting sources.
Compared with other sources presented,
they are three times more efficient than
halogen lamps and one of the most efficient
ways of transforming energy into light. Lightemitting
diodes are a good choice for local
applications and with a low illumination
level. Due to low consumption, they are
viable and economic applications, especially
in lighting systems using photovoltaic
modules.
DC Voltage lighting systems
Figure 5 DC Lighting System using LED’s [5]
5 Baterries [6]
Batteries are electrochemical cells that store
energy in chemical bonds. If the battery is
connected to an electrical load and
discharged, the chemical energy is converted
to electrical energy. By reversing the flow of
current, the battery is restored to its initial
state corresponding to the charged condition.
The following is a presentation of some
types of batteries that are applicable in the
lighting systems using dc voltage produced
by photovoltaic modules.
There are different types of flooded
lead-acid batteries: lead-antimony batteries,
lead-calcium batteries, lead-antimonycalcium
hybrid batteries.
The structure of a lead-acid battery is
presented in Figure 6.
In these types of applications are also
used Captive electrolytic Lead-acid and
nickel-cadmium batteries. Captive
electrolytic Lead-acid batteries are lead-acid
batteries with "captive" electrolyte, which are
similar to lead-acid batteries; the difference
consists in the semi-solid electrolyte structure
(using silica gel). The electrolyte
immobilization may also be achieved by its
Ingineria Iluminatului 2009; 11, 1: 27-34 31