VAMP 140 - Page 38

VAMP 140 Overcurrent and earth-fault relay
Technical description
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SCntr Start counter (Start) reading
TCntr Trip counter (Trip) reading
1-N, 2-N
3-N
Fault type/single-phase fault
e.g.: 1-N = fault on phase L1
1-2, 2-3
1-3
Fault type/two-phase fault
e.g.: 2-3 = fault between L2
and L3
Type
1-2-3 Fault type/three-phase fault
Flt pu
Max. value of fault current as
compared to In
Load pu
1 s mean value of pre-fault
phase currents IL1…IL3
Recorded
values
EDly %
Elapsed time as compared to
the set operate time, 100% =
tripping
The low-set stage (I>) of the overcurrent unit can be configured
for inverse time characteristic. Four sets of characteristic
curves according to IEC 60255-3 are available for the low-set
stage, i.e.: Normal Inverse (NI), Very Inverse (VI), Extremely
Inverse (EI) and Long Time Inverse (LTI). The mathematical
expressions and the curve sets are given in Figs. 2.2.1.-3, -4, -5
and -6.
Limitations:
1. The maximum measured current is 50 x I
n
. This limits the
scope of inverse curves when the setting is more than 2.5 x
I
n
. E.g. at setting 4 x I
n
the maximum setting relative
current is 12.5 x I
set
/I
n
although the curves are defined up to
20 x I
set
/I
n
2. The fastes possible operating time is about 60 ms at inverse
time characteristic according to curve types VI and EI.
Figure 2.2.1-2 Block diagram of the three-phase overcurrent stage I>>.