Ans. Incandescent Lamp
The incandescent lamp is the oldest electric light source still in general use.The incandescent
lamp produces its light by the electrical heating of a wire (the filament), usually tungsten filament
to such a high temperature that radiation in the visible region of the spectrum is emitted.
Performance characteristics
Energy balance
Fig. 1 shows the energy balance in an incandescent Lamp. An incandescent lamp operates at
about 2800K and emits radiation throughout the visible spectrum with a bias towards the higher
wavelengths. The outer glass envelope is filled typically with a mixture of nitrogen and argon
whose function is to limit the evaporation of tungsten and also to prevent arcing across the
filament. The luminous efficacy of practical tungsten incandescent lamps is always considerably
low since most of the radiation is in the infra red range of wavelengths. For example, for modern
GLS lamps with a rated operating life of 1000 hours it varies between 8 and 21.5 Lm/W.
b. T5 Tube light
The latest development in the fluorescent lamp is the T5 lamp. This lamp has a diameter of only
5/8 “(15 mm) and has an inbuilt electronic ballast of high quality. The main advantage of T5
lamps are very high luminous efficacy between 85 to 90 lumens/watt for the 2’T5 tube and up to
104 Lumens/watt for the 28 W 4’ T5 tube. The T5 lamp also a very high power factor greater
than 0.85 and colour rendering index Ra of 90.
The T5 uses less quantity of mercury vapour in the tube. A coating of calcium nitrate on
the inside surface prevents absorption of mercury by the walls of the tube thereby prolonging the
life of the lamp. The narrow tube along with the powerful electronic ballast substantially
improves the luminous efficacies to the range of 90 to 104 Lumens/watt. The life of T5 lamp
is between 15000 to 18000 burning hours.
C. Ceiling fan
Ceiling fans shall be installed at a height of 2.75 m or more from floor. The fan rod shall be
preferably one piece. The suspension hook for ceiling fans should be fixed in roofs during
construction stage. All ceiling fans should be wired to ceiling-roses or to a special connector
boxes. The fan including its suspension, should confirm to IS:374 (Specification for ceiling fan
and regulator).
e. Window type AC System
Air conditioners of the window type, are completely self-contained units, with the compressor,
condenser, evaporator, refrigerant piping and air filter, all assembled in a very compact assembly. The
window units are usually of 1/2 to 2 tons capacity and fitted with 230 V motor upto 3 HP. Modern
tendency is to employ sealed type motor-compressor units with the refrigerant piping system sealed-in
with brazed joints, so that the leakage of gas is virtually eliminated and the unit may serve for long periods with hardly any attention. In these units expansion valve and liquid receiver are not provided.
The refrigerant is controlled with the capillary system. The unit is so designed that it can be mounted on
the window with small bracket from outside. Window units are particularly adopted when only few
rooms are to be air-conditioned and they are widely separated.
f. Electric iron
An electric iron consist of basically a heating coil and heat control circuit viz thermostat.
Thermostat act as a switch. When we switch on the electric iron current flows through the heating
coil. The heat in the heating coil causes expansion in the thermostat which gradually disconnects
the supply.