Section 6 Differential Protection; Transformer Differential Protection; Functionality - ABB REG650 Technical Manual

1MRK 502 048-UEN A
Section 6
6.1
6.1.1
Technical manual
Differential protection

Transformer differential protection

Functionality

Transformer differential protection, three-winding T3WPDIF is provided with
internal CT ratio matching and vector group compensation and settable zero sequence
current elimination.
The function can be provided with -phase sets of current inputs. All current inputs are
provided with percentage bias restraint features, making the IED suitable for two- or
three-winding transformer arrangements.
Three-winding applications
three-winding power
transformer with all
three windings
connected
xx05000052.vsd
IEC05000052 V1 EN
three-winding power
transformer with
unconnected delta
tertiary winding
xx05000049.vsd
IEC05000049 V1 EN
Figure 29: CT group arrangement
for differential
protection and other
protections
The setting facilities cover the application of the differential protection to all types of
power transformers and auto-transformers with or without load tap changer as well as
shunt reactors and local feeders within the station. An adaptive stabilizing feature is
included for heavy through-faults.
Stabilization is included for inrush and overexcitation currents respectively, cross-
blocking is also available. Adaptive stabilization is also included for system recovery
inrush and CT saturation during external faults. A high set unrestrained differential
current protection element is included for a very high speed tripping at a high internal
fault currents.
Section 6
Differential protection
81