Synchronization procedure of alternators

[samieee]

could you please explain how to synchronize an incoming alternator with running system.I heard about ''dark lamp" or 'bright' method.But what actually the process is?

 

[dlgoff]

Now days microprocessor are used to sense the line voltage, frequency, phase sequence, phase angle and waveform to determine when to make the connection to the grid and does it automatically. In the early days, lamps were used to get a visual indication when to manually switch the generator to the grid.

...three light bulbs were connected between the generator terminals and the system terminals (or more generally, to the terminals of instrument transformers connected to generator and system). As the generator speed changes, the lights will rise and fall in intensity at a rate proportional to the difference between generator frequency and system frequency.

http://en.wikipedia.org/wiki/Alternator_synchronization"