Characteristics Value
Operate time accuracy in definite
time mode
±1.0% of the set value or ±20 ms
Operate time accuracy in inverse
time mode
±5.0% of the set value or ±20 ms
4
Suppression of harmonics RMS: No suppression
DFT: -50 dB at f = n × fn, where n = 2, 3, 4, 5,…
Peak-to-Peak: No suppression
4.3.2 Stabilized and instantaneous differential protection for
two-winding transformers TR2PTDF (ANSI 87T)
4.3.2.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Stabilized and instantaneous differ-
ential protection for two-winding
transformers
TR2PTDF 3dI>T 87T
4.3.2.2 Function block
Figure 386: Function block
4.3.2.3 Functionality
The stabilized and instantaneous differential protection for two-winding
transformers 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.
4
Low operate value
multiples in the range of 1.5...20
Protection functions 1MRS759142 F
680 REX640
Technical Manual
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