Setting Guidelines - ABB REL650 Applications Manual

Section 7
Current protection
7.8.3
226
functionality. A typical application for UC2PTUC (37) function is a line connected shunt
reactor, as shown in figure 114.
TRIP
X
~
source
Source
ANSI11000092 V1 EN
Figure 114: High voltage power line with solidly connected shunt reactor
Shunt reactors are generally protected by differential protection, which operates the local
line circuit breaker and sends a transfer trip command to the remote line end. The line
protection in the remote end is much less sensitive than the differential protection, and
operates only for low impedance reactor faults very close to the high voltage terminal. To
avoid line trips at the remote end due to false transfer trip signals, a local criterion can be
added at the remote end. Low current in at least two of the phases is, therefore, found to
be a very useful criterion to increase security.

Setting guidelines

The parameters for the undercurrent protection function are set via the local HMI or
PCM600.
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
Operation: operation of the entire undercurrent protection function has to be set to either
Enabled or Disabled.
I1Mode: number of phases involved for operation for step1.
I1<: low-set level of the current. If the current decreases below this limit, the function
picks up and issue start signals PU_ST1 and RI.
t1: time delay of I1< from pick-up to the issue of trip signals TRST1 and TRIP.
tReset1: instantaneous or time delayed reset of RI and PU_ST1 signals.
CR
LDD
VT1
Line
CT1
Line connected
1MRK 506 334-UUS A
CT2
TRIP
shunt reactor
37
CT3
ANSI11000092_1_en.vsd
Application manual
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CS