4.3.2.2 Function block
GUID-134E8524-738D-4232-A6BD-4C9BD2A62F8D V1 EN
Figure 204: Function block
4.3.2.3 Functionality
The transformer differential protection 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.
4.3.2.4 Operation principle
The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of transformer differential protection can be described by using a
module diagram. All the modules in the diagram are explained in the next sections.
Section 4 1YHT530004D05 D
Protection functions
384 615 series
Technical Manual
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