Auxiliary Summation Cts - ABB REB670 Applications Manual
Busbar protection 2.1 ansi, relion 670 series
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Also See for REB670:
- Applications manual (554 pages) ,
- Commissioning manual (196 pages) ,
- Operator's manual (116 pages)
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Section 6
Differential protection
6.1.5.2
152
•
Only one measuring circuit is utilized for all fault types (that is, no redundancy for
multi-phase faults)
•
Primary fault sensitivity varies depending on the type of fault and involved phase(s),
see table
24
•
The load currents in the healthy phases might produce the stabilizing current when an
internal, single phase to ground fault occurs. However, there is no problem for solidly
gounded systems with high ground-fault currents
•
No indication of faulty phase(s) in case of an internal fault
•
Not possible to fully utilize Open CT detection feature
Auxiliary summation CTs
Auxiliary Summation Current Transformer (that is, ASCT in further text) of the type
SLCE 8 is used with the summation principle of the IED. The principle drawing of one
such ASCT is shown in figure 74.
Auxiliary Summation CT
type SLCE 8; X/1A
P1
N1
S1
P2
P3
N4
N2
P4
P5
N3
S2
P6
en03000118_ansi.vsd
ANSI03000118 V1 EN
Figure 74:
Principle ASCT drawing
The ASCT has three primary windings and one secondary winding. In further text, turn
numbers of these windings will be marked with N1, N2, N3 & N4, respectively (see
figure
74
for more information).
There are three types of ASCT for REB670:
1MRK 505 337-UUS -
Application manual
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