Setting End X End Y End Z
Id High Set [p.u.] 3000/200 = 15 3000/200 = 15 3000/200 = 15
Id High Set (Primary) 15*500 = 7500A 15*800 = 12000A 15*200 = 300A
Id High Set (Secondary) 15*5 = 75A 15*5 = 75A 15*1 = 15A
In Diff Is1 [p.u.] 50/200 = 0.25 50/200 = 0.25 50/200 = 0.25
In Diff Is1 (Primary) 0.25*500 = 125A 0.25*800 = 200A 0.25*200 = 50A
In Diff Is2 (Secondary) 0.25*5 = 0.75A 0.25*5 = 0.75A 0.25*1 = 0.25A
In Diff Is1 [p.u.] 1000/200 = 5 1000/200 = 5 1000/200 = 5
In Diff Is1 (Primary) 5*500 = 2500A 5*800 = 4000A 5*200 = 100A
In Diff Is2 (Secondary) 5*5 = 25A 5*5 = 25A 5*1 = 5A
9.10 FEEDERS WITH SMALL TAPPED LOADS
Where transformer loads are tapped off the protected line, it is not always necessary to install CTs at this location.
If the tee-off load is light
, differential protection can be configured for the main line alone. The settings Phase
Char, Phase Time Delay and Phase TMS or Phase Time Dial allow the differential element to time grade with IDMT
overcurrent protection devices or fuses protecting the tap. This keeps stability of the differential protection for
external faults on the tee circuit.
Chapter 6 - Current Differential Protection P54A/B/C/E
122 P54xMED-TM-EN-1
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