Hello
What is the difference between synchronizing & sychro-check relays & where are they used?
Here is an example of a sync check relay:
http://www.crompton-instruments.com/installation_docs/DIN%20and%20ANSI%20Synchroscopes.pdf
It also has a dead bus verification and a syncscope. One would use the sync check part in the CB close circuit to prevent an operator or a broken automatic synchronizer from closing the paralleling CB when the two systems are too far out-of-phase.
Here is an example of a Synchronizer:
http://megaglobalsolution.com/WOODWARD_SALESCD/WOODWARD_PDFfiles/SPM_DSynchronizerPS03241a.pdf
This has outputs to the generator voltage regulator, and governeror. It adjusts the generator coming on-line to match the frequency, phase, voltage of the on-line generation. When they match close enough, it then issues a CB close signal.
That signal is usually in series with the sync check relay.
Often there is a third sync check in the CB protective relay.
As you likely knew, out-of-phase closing really can stress the generation.
cf
