SUB STATION

SUB STATION

 

What is Sub Station?

                       The assembly of apparatus used to change some characteristic (e.g. voltage, a.c. to d.c., frequency, p.f. etc.) of electric supply is called a sub-station.

Important points which must be kept in view while laying out a sub-station :

·        It should be located at a proper site.

·        It should provide safe and reliable arrangement. For safety, consideration must be given to the maintenance of regulation clearances, facilities for carrying out repairs and maintenance, abnormal occurrences such as possibility of explosion or fire etc.

·        It should be easily operated and maintained.

·        It should involve minimum capital cost.

CLASSIFICATION OF SUB-STATIONS

         1.According to service requirement]

·        Transformer Substation

·        Switching Substation

·        Power factor correction Substation 

·        Frequency changer substation

·        Industrial substation

     2. According to constructional features

(i)Indoor sub-station

(ii)Outdoor sub-station

          (iii) Underground sub-station

          (iv) Pole-mounted sub-station

Transformer sub-stations:

  Those sub-stations which change the voltage level of electric supply are called transformer sub-stations.   These sub-stations receive power at some voltage and deliver it at some other voltage. Obviously, transformer will be the main component in such substations.

  Most of the sub-stations in the power system are of this type.

Switching sub-stations:

These 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.

Power factor correction sub-stations:

Those sub-stations which improve the power factor of the system are called power factor correction sub-stations. Such sub-stations are generally located at the receiving end of transmission lines.

          These sub-stations generally use synchronous condensers as the power factor improvement equipment

Converting sub-stations:

 Those sub-stations which change a.c. power into d.c. power are called converting sub-stations. These sub-stations receive a.c. power and convert it into d.c. power with suitable apparatus (e.g. ignitron) to supply for such purposes as traction, electroplating, electric welding etc.

Industrial sub-stations:

          Those sub-stations which supply power to individual industrial concerns are known as industrial sub-stations

SUB STATION - EQUIPMENTS

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• Bus bar
• Power Transformer
• Lightning arrester
• Earth Switches
• Circuit breakers
• Current transformer
• Potential Transformer
• Shunt Capacitor
• Shunt Reactor
• Cables
• Insulators
• Isolaters