ABB REG670 - Page 142

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Differential function
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Trafo
Data
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Instantaneous (sample based)
Differential current, phase L1
Instantaneous (sample based)
Differential current, phase L2
Instantaneous (sample based)
Differential current, phase L3
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
Negative sequence diff current
& NS current contribution from
individual windings
en06000554-3-en.vsd
MAX
Settings for Zer. Seq.
Current Reduction
IDL1MAG
IDL2MAG
IDL3MAG
IDNSMAG
IDL2
IDL1
IDL3
IBIAS
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IEC06000544 V3 EN
Figure 38: Treatment of measured currents within IED for transformer differential function
Figure 38 shows how internal treatment of measured currents is done in case of a two-
winding transformer.
The following currents are inputs used in the power transformer differential protection
function. They must all be expressed in power system (primary) A.
Section 6 1MRK502052-UEN B
Differential protection
136
Technical manual