3 PROTECTION FUNCTIONS
3.1 PHASE CURRENT DIFFERENTIAL PROTECTION
Accuracy
Pick-up Formula +/- 10%
Drop-off 0.75 x Formula +/- 10%
IDMT characteristic shape +/- 5% or 40 ms, whichever is greater
DT operation +/- 2% or 20 ms, whichever is greater
Typical instantaneous operation with default settings,
back
-to-back propagation delay included
up to 4 terminals
5 or 6 terminals
<1 cycle*
<1.25 cycles*
Reset time <60 ms
Repeatability +/- 2.5%
Characteristic
UK curves IEC 60255-3 – 1998
US curves IEEE C37.112 – 1996
Current transformer ratio compensation No affect on accuracy
High set characteristic setting No affect on accuracy
*with HSHB contact and direct fibre.
3.2 FIBRE TELEPROTECTION TRANSFER TIMES
The table below shows the minimum and maximum transfer time for InterMiCOM64 (IM64). The times are
measur
ed from opto initialization (with no opto filtering) to relay standard output and include a small propagation
delay for back-back test (2.7 ms for 64 kbits/s and 3.2 ms for 56 kbits/s).
IDiff IM64 indicates InterMiCOM64 signals working in conjunction with the differential protection fibre optic
communications channel. IM64 indicates InterMiCOM64 signals working as a standalone feature.
Configuration Permissive op times (ms) Direct op times (ms)
IM64 at 64 k 13 - 18 17 - 20
IM64 at 56 k 15 - 20 19 - 22
IDiff IM64 at 64 k 22 - 24 23 - 25
IDiff IM64 at 56 k 24 - 26 25 - 27
3.3 AUTORECLOSE AND CHECK SYNYCHRONISM
Accuracy
Timers +/- 20 ms or 2%, whichever is greater
3.4 PHASE OVERCURRENT PROTECTION
Accuracy
IDMT pick-up 1.05 x Setting +/-5%
DT pick-up Setting +/-5%
Drop-off (IDMT and DT) 0.98 x setting +/-5%
Chapter 22 - Technical Specifications P54A/B/C/E
512 P54xMED-TM-EN-1
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