Logic Diagram - ABB REG650 Technical Manual

Section 5
Differential protection
5.1.3.13
IEC09000162 V1 EN
Figure 38: Treatment of measured currents within IED for transformer differential function
90
energized, the magnetic density in the iron core will be low and high sinusoidal
currents will flow from the very beginning. The waveform block algorithm will in
such a case remove all its three block signals in a very short interval of time. A
quick reset of the waveblock criterion will temporarily disable the second harmonic
blocking feature within the differential function. This consequently ensures fast
operation of the transformer differential function for a switch onto a fault
condition. It shall be noted that this feature is only active during initial power
transformer energizing, more exactly, under the first 50 ms. When the switch onto
fault feature is disabled by the setting parameter SOTFMode, the waveblock and
second harmonic blocking features work in parallel and are completely
independent from each other.

Logic diagram

The simplified internal logics, for transformer differential protection are shown in
the following figures.
ADM
Trafo
Data
Instantaneous (sample based)
Differential current, phase L1
Instantaneous (sample based)
Differential current, phase L2
Instantaneous (sample based)
Differential current, phase L3
Negative sequence diff current
& NS current contribution from
individual windings
Fundamental frequency (phasor
based) Diff current, phase L1 &
phase current contributions from
individual windings
Fundamental frequency (phasor
based) Diff current, phase L2 &
phase current contributions from
individual windings
Fundamental frequency (phasor
based) Diff current, phase L3 &
phase current contributions from
individual windings
Settings for Zer. Seq.
Current Reduction
1MRK 502 034-UEN -
Differential function
IDL1
IDL2
IDL3
IDNSMAG
IDL1MAG
IDL2MAG
IDL3MAG
IBIAS
MAX
IEC09000162_1_en.vsd
Technical Manual