Parallel operation of Alternators

Parallel operation of Alternators

Necessity of Operating the alternators in parallel

Continuity of service

•If power plant consists  only single unit

•In the event of breakdown of the prime mover or the

   Alternator

•Entire station will be

   shut down

•If several small units

   run in parallel

•If one unit fails the

   power is supplied by

   remaining units

To improve Efficiency

•Alternators operate most efficiently when delivering full load.

•Hence when load is light, single unit is used.

•When load increases, another unit can be run in

    parallel to share the load

Easy Maintenance

•When several alternators run in parallel one unit can be taken for maintenance.

 

•And the remaining units supply the load.

•

•If any unit get breakdown it can be separated

   and can be repaired.

Extention of Power Plant

•Now a days the load demand is increasing  day-

    by-day.

•Therefore if the alternators are connected in

    parallel extra units can be added without any

    difficulty to increase the capacity of the Plant.

•If single unit is used Extention of Power Plant is

   difficult.

Parallel Operation of Alternators

•   The process of connecting two or more

       alternators in parallel to share a common load  

        is called operation of alternators

Let us see the Conditions for parallel operation

of Alternators One by One.

Conditions

1) Equal terminal voltages

    

  This is obtained by

  adjustment of the incoming

  generator’s field strength.

2) Equal frequencies

          

  This is obtained by

     adjustment  the incoming

     generator’s prime-mover speed.

3) Same Phase sequence

        This is obtained by

   adjusting the connections of the alternators which connect in parallel.

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