ABB RELION REX640 Technical Manual page 584

Protection functions
-
• Magnitude of true fault current is estimated without need on any pre-defined
information on the network topology.
• Also, the effect of fault resistance can be considered and compensated in the
estimated earth-fault current magnitude applying dedicated fault resistance
compensation method. This functionality allows acceleration of protection
operation speed during high(er) ohmic earth fault when actual fault current
magnitude is low.
IFPTOC includes also dedicated protection functionality for important practical
earth-fault scenarios such as switch onto fault (SOTF) condition, for intermittent
earth faults and for high current cross-country earth-faults. Each of such fault
condition can be tripped with individually defined operation criteria enabling high
application flexibility and reliability.
4.2.10.4 Analog channel configuration
IFPTOC has four analog group inputs which must be properly configured.
Table 625: Analog inputs
Input
I3P
IRES
U3P
URES
There are a few special conditions which must be noted with the configuration.
Table 626: Special conditions
Condition
U3P connected real meas-
urements
URES calculated
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings.
check the contents of this chapter and also the preprocessing blocks in this
584
fact that the phase angle difference between U
capacitive earth-fault current contribution increases. Phase angle difference
may become so high that correct operation of traditional protection functions
is endangered. This is not the case for IFPTOC, as fault current estimate is not
affected by the capacitive earth-fault current contribution of the protected
feeder itself.
In case earth fault occurs during abnormal network topologies, or when
fault current compensation is temporarily not effective or when network is
operated heavily over- or under-compensated.
See the preprocessing function blocks in this document for the possible
signal sources.
Description
Three phase currents
Residual current (measured or calculated)
Three phase voltages
Measured or calculated residual voltage
Description
Recommendation to connect all three phase-to-earth voltage
channels. Alternative is at least two phase-to-earth / phaseto-
phase voltages and measured residual voltage (URES).
Three phase-to-earth voltages must be connected for calcu-
lating the residual voltage. Setting
"Wye" in that particular UTVTR.
1MRS759142 F
and I increases as the
o o
VT connection must be
Technical Manual
REX640