VAMP 59 - Line Differential Protection Ldi> (87 L)

2.12 Line differential protection
LdI> (87L)
2 Protection functions
Technical description
76
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VM59.EN001
Recorded values of the circuit breaker failure stage (8 latest
faults) CBFP (50BF)
Parameter
Value
Unit
Description
yyyy-mm-dd
Time stamp of the recording, date
hh:mm:ss.ms
Time stamp, time of day
EDly
%
Elapsed time of the operating time
setting. 100% = trip
2.12. Line differential protection LdI> (87L)
VAMP 59 relay is a differential protection device mainly
designed for sub-transmission overhead lines, medium voltage
cables and transformers. Two line ends may lie within the
protection zone.
Phase segregated protection is based on current (vector)
differential. Combination of both phase and magnitude
differential is used to determine operation. The differential
element takes a sampled version of the instantaneous current
waveform as its local input and compares it with a
corresponding current from the remote end. The signal is
converted to magnitude and angle information for comparison.
The threshold characteristics is biased for CT saturation as
presented in
dI
module
Phase current amplitude
Trip region
dI> pick-up
Basic setting
Slope
Start of slope (Basic limit)
.