ABB RELION 620 Series Technical Manual page 811

1MRS757644 F
5.1.5
620 series
Technical Manual
It is recommended to use the second harmonic and the waveform
based inrush blocking from the TR2PTDF function, if available.
Application
Transformer protections require high stability to avoid tripping during magnetizing
inrush conditions. A typical example of an inrush detector application is doubling the
start value of an overcurrent protection during inrush detection.
The inrush detection function can be used to selectively block overcurrent and earth-
fault function stages when the ratio of second harmonic component over the
fundamental component exceeds the set value.
Other applications of this function include the detection of inrush in lines connected
to a transformer.
A070695 V4 EN
Figure 410: Inrush current in transformer
It is recommended to use the second harmonic and the waveform
based inrush blocking from the transformer differential protection
function TR2PTDF, if available.
Protection related functions
Section 5
805