Load Study
1 Introduction:-
The
loads are devices and equipment's which connected to the electrical network.
To
supply these loads with power, we should know the following.
1- Rated
power of the loads.
2-
Rated voltage
3-
P.f of each load.
And the current can be calculated form the
following relation ( for 3 phase circuits):-
This
information enables us to select:-
1- Transformers needed.
2- Cables.
3- C.B's.
2 Definition of loads:-
2.2.1
Industrial loads:-
Industrial
loads comprise all loads connected to the local network of the industrial
plant. The majority of industrial plants loads are function of the process
equipment and information about these loads will have to be obtained from process
designer. The rating of these loads will obtain from its name plate which is
related to its function in the process.
Other loads such as lighting, heating, air
condition can be fairly estimated with high degree of accuracy .this is due to
the fact that plant activity is known in advance.
In
general the following loads are commonly found in industrial plants and
factories.
1- Induction
Motor.
2- Synchronous
Motor.
3- Heating
Loads.
4- Welding
Machine.
5- Electric
Furnaces.
6- Lighting
Loads.
The following
items define the various requirements and characteristics of the loads and must
be determined and define in the planning process.
1- Peak load requirements in KVA.
2- Load variations expected during low load (non productive periods),
average loads, and peak load conditions.
3- Nature of load in terms of its occurrence (continuous- intermittent –
cyclical).
4- Expected power factor during low load, average load, and peak load
periods.
5- special or unusual loads such as:
a. Resistance welding.
b. Arc welding.
c. Induction melting.
d. Heat treating.
6- Harmonic generating loads.
7- Special power quality requirements for sensitive or critical loads such
as data processing operations and continuous processing load.
