Stabilized And Instantaneous Differential Protection For Two-Winding Transformers Tr2Ptdf - ABB RELION 620 Series Technical Manual

1MRS757644 H
Characteristic
Reset time
Reset ratio
Retardation time
4.3.2 Stabilized and instantaneous differential protection for
two-winding transformers TR2PTDF
4.3.2.1 Identification
Function description
Stabilized and instantaneous differ-
ential protection for two-winding
transformers
4.3.2.2 Function block
Figure 266: Function block
4.3.2.3 Functionality
The stabilized and instantaneous differential protection function TR2PTDF is
designed to protect two-winding transformers and generator-transformer blocks.
TR2PTDF includes low biased and high instantaneous stages.
The biased low stage provides a fast clearance of faults while remaining stable
with high currents passing through the protected zone increasing errors on current
measuring. The second harmonic restraint, together with the 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 over-
excitation.
The instantaneous high stage provides a very fast clearance of severe faults with a
high differential current regardless of their harmonics.
The setting characteristic can be set more sensitive with the aid of tap changer
position compensation. The correction of transformation ratio due to the changes
in tap position is done automatically based on the tap changer status information.
3 High operate value
Ifault = 2 x
620 series
Technical Manual
Value
<40 ms
Typically 0.96
<20 ms
IEC 61850 IEC 60617
identification identification
TR2PTDF 3dI>T
Protection functions
ANSI/IEEE C37.2
device number
87T
519