Dear all,
Hope you can take my doubts out. First of all sorry for my english.
It's a fact that according to GEH-6421, VTUR requires generator "have been lagging for the last 10 consecutive cycles, and projected (anticipated) to be leading when the breaker actually reaches closure".
1. What this means? K25 will close leading after counting 20 cycles (200ms for 50Hz) plus Breaker Closing Time lagging. OR It doesn't matter since VTUR is counting Breaker Closing Time in between the 20 cycles lag period.
2. Why I am asking it?
The installation sync schematic includes and extra sync relay and this relay provides conditions in a [-12º, 12º] angle. I need to understand clearly VTUR calculations in order to calculate the minimum equivalent angle time to achieve conditions in both sync relays.
For instance, if i have angle window [-12,12º] equivalent to 480ms it may be impossible to sincronize since VTUR works in [-10,10º] which is equivalent to 400ms, and VTUR requires minimum of 20 cycles lag (200ms).
Thanks
Hope you can take my doubts out. First of all sorry for my english.
It's a fact that according to GEH-6421, VTUR requires generator "have been lagging for the last 10 consecutive cycles, and projected (anticipated) to be leading when the breaker actually reaches closure".
1. What this means? K25 will close leading after counting 20 cycles (200ms for 50Hz) plus Breaker Closing Time lagging. OR It doesn't matter since VTUR is counting Breaker Closing Time in between the 20 cycles lag period.
2. Why I am asking it?
The installation sync schematic includes and extra sync relay and this relay provides conditions in a [-12º, 12º] angle. I need to understand clearly VTUR calculations in order to calculate the minimum equivalent angle time to achieve conditions in both sync relays.
For instance, if i have angle window [-12,12º] equivalent to 480ms it may be impossible to sincronize since VTUR works in [-10,10º] which is equivalent to 400ms, and VTUR requires minimum of 20 cycles lag (200ms).
Thanks