ABB RELION REX640 Technical Manual page 717

1MRS759142 F
phase current sets either on the winding 1 or winding 2 side in case of two-
winding transformer protection. The function includes a biased low stage and an
instantaneous high stage.
The biased low stage provides fast fault clearing while remaining stable with the
high currents passing through the protected zone, which increase the errors in
current measuring. The second harmonic restraint, together with waveform-based
algorithms, ensures that the low stage does not operate due to the transformer
inrush currents. The fifth harmonic restraint ensures that the low stage does
not operate on apparent differential current caused by a harmless transformer
overexcitation.
The instantaneous high stage provides very fast clearing of severe faults with a high
differential current regardless of their harmonics.
The setting characteristic can be set more sensitive with tap changer position
compensation. The correction of the transformation ratio due to changes in
tap position is done automatically based on the tap changer status information
provided to the function through input.
4.3.3.4 Analog channel configuration
TR3PTDF has three analog group inputs which must be properly configured.
Table 664: Analog inputs
Input
I3P1
I3P2
I3P3
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.
4.3.3.5 Operation principle
The function can be enabled and disabled with the
corresponding parameter values are "on" and "off".
The operation of TR3PTDF can be described with a module diagram. All the modules
in the diagram are explained in the next sections.
1
Can be connected to GRPOFF if
REX640
Technical Manual
1
See the preprocessing function blocks in this document for the possible
signal sources. The GRPOFF signal is available in the function block called
Protection.
Current group 3 type is set to "Not in use"
Protection functions
Description
Three-phase currents
Three-phase currents
Three-phase currents Necessary when
rent group 3 type is other than "Not in use"
Operation setting. The
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