ABB Relion 670 Series Technical Reference Manual page 389

1MRK505222-UUS C
faultState
I3P
V3P
I3P
ANSI05000740 V1 EN
Figure 201: Functional overview of OC4PTOC (51/67)
Technical reference manual
Direction dirPhAFlt
Element
dirPhBFlt
dirPhCFlt
Harmonic
harmRestrBlock
Restraint
Element
enableDir
Mode Selection
enableStep1-4
DirectionalMode1-4
A common setting for all steps, NumPhSel, is used to specify the number of phase
currents to be high to enable operation. The settings can be chosen: 1 out of 3, 2 out of
3 or 3 out of 3.
The sampled analog phase currents are processed in a pre-processing function block.
Using a parameter setting MeasType within the general settings for the four step phase
overcurrent protection 3-phase output function OC4PTOC (51/67), it is possible to
select the type of the measurement used for all overcurrent stages. It is possible to
select either discrete Fourier filter (DFT) or true RMS filter (RMS).
If DFT option is selected then only the RMS value of the fundamental frequency
components of each phase current is derived. Influence of DC current component and
higher harmonic current components are almost completely suppressed. If RMS option
is selected then the true RMS values is used. The true RMS value in addition to the
fundamental frequency component includes the contribution from the current DC
Section 7
Current protection
4 step over current
element
faultState
One element for each
step
en05000740_ansi.vsd
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