Electrical Substations

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     Electrical Substations

An electrical substation forms an integral part of the power system. It is placed at the both ends of the long distant transmission line...

but why??!! Of-course to transform voltage!

 A substation at the beginning End or say generation side normally used to boost up the voltage to higher magnitude suitable for transmitting the generated power to long distant load with minimum losses.( Uses a step up transformer )!! Yes the other type is at the other end of the long distant transmission line nearer to load centre... here the high voltage is stepped down to a relevant magnitude which may be used for distribution purpose or another voltage level transmission for near by substations.

                   The heart of a substation is nothing but our transformer, depending upon the purpose transformer can be step up or step down!! Now we are considering a load end substation as an example. Here our hero is step down transformer 😎!! A substation has a fenced area called substation yard and our hero called transformer lies in it along with the protection devices, switching equipments, metering equipments more over a "control unit" simply a control room with all its controls😉.
Control room includes panel boards of every units in the yard and these panel boards is simply filled with controlling keys,switches,ammeter,voltmeter, energy meters,indication lights, semaphores, MW meters ,MVAR meters etc... Also there is relays etc... All these are for evaluating and monitoring the performance of the whole station!!

                                       
Above is single line diagram of a typical substation.

The incoming portion from the tower called as feeder( high voltage) the conductors from the tower is first connected to the lighting arrester(LA). Then it travels to Capacitive voltage transformer (CVT) after that it meets the isolator and current transformer (CT) finally to circuit breaker (CB). All equipments and structural unit will have adequate level of insulations since they are dealing with high voltages!!
Lighting Arrester

Isolators

Circuit breaker

CVT & CT 

The output of circuit breaker or say second terminal of the CB is connected to the busbars. The busbars contains parallel connected feeders and transformers ...!
                 
       Transformer

 As said above the transformer step downs voltage to a lower level according to need( design and rating of transformer is decided) of-course the transformers also have CT, Isolator,LA, circuit breakers and relays all these co-ordinate to protecting and operation of the transformer. It employs differential protection scheme😉 the secondary side or output of transformer is again connected to low voltage (w.r.t. primary) busbar and again the power is now ready for its further journey out side the substation!!!!!!😉😉😉


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