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
50 Hz, 1 p.u. ≤ relay current < 2 p.u.
60 Hz, 1 p.u. ≤ relay current < 2 p.u.
50 Hz, relay current ≥ 2 p.u.
60 Hz, relay current ≥ 2 p.u.
<35 ms
<30 ms
<30 ms
<25 ms
Reset time <60 ms
Repeatability +/- 2.5%
Characteristic
UK curves IEC 60255-3 – 1998
US curves IEEE C37.112 – 1996
Vector compensation No affect on accuracy
Current transformer ratio compensation No affect on accuracy
High set characteristic setting No affect on accuracy
Three ended scheme operation No affect on accuracy
3.2 NEUTRAL CURRENT DIFFERENTIAL PROTECTION
Accuracy
Pick-up Formula +/- 10%
Drop-off 0.75 x Formula +/- 10%
DT operation +/- 2% or 40 ms, whichever is greater
Typical instantaneous operation with default settings
and IN Differential > 50% above threshold
50 Hz
60 Hz
30-50 ms
25-42 ms
Repeatability +/- 2.5%
Current transformer ratio compensation No affect on accuracy
Three ended scheme operation No affect on accuracy
Chapter 27 - Technical Specifications P543i/P545i
722 P54x1i-TM-EN-1
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