Synchronizing Method & Parameters for Alternators

When I was a student I study about alternator, so being a fresher & student I was willing to see how it works and synchronizing procedure. Fortunately I joined Utility Department purely electrical i.e. large machine including all Electrical costly & large machines by size and by cost too. 

The operation of paralleling two alternators is known as synchronizing, and certain conditions must be fulfilled before this can be affected. The incoming machine must have its voltage and frequency equal to that of the bus bars and, should be in same Phase with bus bar voltage.

A SYNCHRONIZING PANEL WITH ACESSARIES   

Synchronizing can be done with the help of

(i) Dark lamp method or 
(ii) By using synchro-scope.    

                                                                          

In Dark Lamp method we synchronize alternator with the dark and light glow of bulb. When in synchroscope method we synchronize alternator when frequency is matched in same direction. 
There are certain parameters are already feed in digital protection relay. Synchronizing process is completed after check synchronizing relay. It protects synchronizing circuit. These relays are used to verify that the voltages on either side of a circuit breaker are synchronized, and in the proper phase and magnitude relationship to allow automatic closing.

DOUBLE FREQUENCY METER 

DOUBLE VOLT METER

SYNCHROSCOPE

A Synchronizing panel have following mounting or auxiliary’s i.e.

Ø Double Frequency Meter

Ø Double Voltage Meter

Ø Synchroscope

Ø Master Trip Relay

Ø Check Synchronizing Relay

Ø DC Ampere meter

Ø DC Voltage meter

Ø Bulbs for Dark Lamp method

Ø Indication bulbs

Ø Equipment selector switch for selection

Ø Manual/Auto synchronizing selector switch

 Synchronizing Check Relay Settings

   df offset  = 0.20 Hz

   Max df    = 0.25 Hz (50.25Hz)

   Min df = 0.18 Hz (49.82Hz)

   dv Max = 3.00%  (10670 ~11330 Volt)

   Syn. Time Pulse = 0.20 Sec 

   Closing time pulse for CB = 80 mile sec

Note:- These all setting are for 3.9 MW Alternator, prime mover - gas engine