Functionality - ABB RELION REX640 Technical Manual

Section 6
Supervision functions
6.2.3
6.2.4
1206

Functionality

The current circuit supervision function CCSPVC is used for monitoring current
transformer secondary circuits.
CCSPVC calculates internally the sum of phase currents (I_A, I_B and I_C) and
compares the sum against the measured single reference current (I_REF). The
reference current must originate from other three-phase CT cores than the phase
currents (I_A, I_B and I_C) and it is to be externally summated, that is, outside the
protection relay.
CCSPVC detects a fault in the measurement circuit and issues an alarm or blocks the
protection functions to avoid unwanted tripping.
It must be remembered that the blocking of protection functions at an occurring open
CT circuit means that the situation remains unchanged and extremely high voltages
stress the secondary circuit.
Analog channel configuration
CCSPVC has two analog group inputs which must be properly configured.
Table 1128: Analog inputs
Input
I3P
IRES
See the preprocessing function blocks in this document for the
possible signal sources.
There are a few special conditions which must be noted with the configuration.
Table 1129: Special conditions
Condition
IRES measured
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings. For
troubleshooting, check the contents of this chapter and also the preprocessing blocks
in this document. The configuration can be written to the protection relay once the
mismatch is corrected.
Description
Three-phase currents
Residual current (measured)
Description
In case IRES needs to be derived, the function
requires that all CT cores, except for the one used
for phase current measurement, must be used and
summed externally.
1MRS759142 C
REX640
Technical Manual