Synchronise 2 x 250KVA Gensets

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Thread Starter

Chris Serfontein

Hi,

I have a customer with 2 old Rolls Royce 250KVA 1978 model gensets which he want to use in sink maybe once or twice a year when the need arises. Both are still equipped with their original panels with breakers and then also a combiner panel when they are in sink. Controls are done manually and then hope for the best.

I suggest that we put VT's on say the red phase of each generator and connect that to an oscilloscope. Start genset1 and bring up to 50Hz and running stable. Start genset2 and sink the corresponding phases (red). Then close breakers on gensets and then close onto load.
As a second phase to take the VT output feed them onto a comparator and then vary the throttle control via a step motor to keep them in sink.

Do you think it can be done and how?
Awaiting your response. Thanking you in advance.

Friendly greetings.
Chris
 
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Bob Peterson

or you could just a panel designed to do this exact thing and not try and cobble up something.

one of the gensets will be throttle controlled to set the RPM and thus the Hertz. the other one will come up to speed and when they get into synch it will switch the tie contactor or breaker on so they are in parallel. the 2nd genset will have to be in droop mode where it is basically fed as much fuel as it takes to maintain the same speed and is locked into the speed indirectly by the grid (in this case the other generator).

there is no way to make them both run speed controlled.

--
Bob
http://ilbob.blogspot.com/
 
Use a lamp across the 2 red phases - when it extinguishes they are synchronised.

A sync check relay is a wise precaution!!!!!
 
Chris... presuming you are also interested in low cost, then I agree with Martiny’s lamp suggestion!

However, I don’t agree with his "Dark-Lamp-Method' of synchronizing! Instead I suggest a safer approach. Called the "Rotating-Lamp-Method", it uses three lamps; two-bright and one-dark... arranged horizontally in a row. Then, synchronization is reached when the ‘outer’ lamps are bright and the ‘center’ one is dark!

I can also provide you the circuit for a Phase-Sequence-Indicator using a few readily available components.

Caveat... if you use a lamp scheme, always connect two in series to prevent burnout at peak voltage.

Let us know if you need additional info!

Regards, Phil Corso
 
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