Types of Loads
A device which taps electrical energy from the electric power system is called a load on the system.
The load may be resistive (e.g., electric lamp), inductive (e.g., induction motor), capacitive or some
combination of them. The various types of loads on the power system are :
(i) Domestic load. Domestic load consists of lights, fans, refrigerators, heaters, television,
small motors for pumping water etc. Most of the residential load occurs only for some hours during
the day (i.e., 24 hours) e.g., lighting load occurs during night time and domestic appliance load occurs
for only a few hours. For this reason, the load factor is low (10% to 12%).
(ii) Commercial load. Commercial load consists of lighting for shops, fans and electric appli-
ances used in restaurants etc. This class of load occurs for more hours during the day as compared to
the domestic load. The commercial load has seasonal variations due to the extensive use of air-
conditioners and space heaters.
(iii) Industrial load. Industrial load consists of load demand by industries. The magnitude of
industrial load depends upon the type of industry. Thus small scale industry requires load upto
25 kW, medium scale industry between 25kW and 100 kW and large-scale industry requires load
above 500 kW. Industrial loads are generally not weather dependent.
(iv) Municipal load. Municipal load consists of street lighting, power required for water sup-
ply and drainage purposes. Street lighting load is practically constant throughout the hours of the
night. For water supply, water is pumped to overhead tanks by pumps driven by electric motors.
Pumping is carried out during the off-peak period, usually occurring during the night. This helps to
improve the load factor of the power system.
(v) Irrigation load. This type of load is the electric power needed for pumps driven by motors
to supply water to fields. Generally this type of load is supplied for 12 hours during night.
(vi) Traction load. This type of load includes tram cars, trolley buses, railways etc. This class
of load has wide variation. During the morning hour, it reaches peak value because people have to go
to their work place. After morning hours, the load starts decreasing and again rises during evening
since the people start coming to their homes
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