Classification of sub-station
There are several ways of classifying sub-station. However the two most important way of them are,
• According to service requirement
• According to constructional features
2.1.1 According to service requirement
According to service requirement sub-station may be classifying into:
(i) Transformer sub-stations: Those sub-stations witch change the voltage level of electric supply are called transformer sub-stations. Those sub-stations receive power at some voltage and deliver it at some voltage. Obviously, transformer will be the main component in such sub-stations. Most of the substations in the power system are of this type.
(ii) Switching sub-stations: Those sub-stations do not change the voltage level i.e. incoming and outgoing lines have the same voltage. However, they simply perform the switching operations of power lines.
(iii) Power factor correction sub-stations: Those sub-stations witch improve the power factor of the system are called Power factor correction sub-stations. Such sub-station are generally located at the receiving end of transmission lines. Those sub-stations generally use synchronous condensers as the Power factor improvement equipment.
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(iv) Frequency changer sub-stations: Those sub-stations witch change the Supply Frequency are known Frequency changer sub-stations. Such a frequency change may be required for industrial utilization.
(v) Converting sub-stations: Those sub-stations witch change the a.c. power into D.C. power are called Converting sub-stations. These sub-stations receive a.c. power and convert into D.C. power sub-stations witch suitable (e.g. ignitron) to supply for such purposes as traction, electroplating, electric winding etc
(vi) Industrial sub-stations: Those sub-stations witch Supply power in individual industrial concerns are known as Industrial sub-stations.
2.1.2 According to constructional features:
A sub-station has many...