I3P
I3PW1CT1
I3PW1CT2
C
B
A
52
52
52
52
52
52
ANSI05000214-2-en.vsd
REFPDIF (87N)
ANSI05000214 V2 EN-US
Figure 66:
Connection of Restricted earth fault, low impedance function REFPDIF
(87N) in multi-breaker arrangements
7.3.2.6
CT grounding direction
M13048-29 v13
To make the restricted earth fault protection REFPDIF (87N) operate correctly, the
main CTs are always supposed to be wye-connected. The main CT's neutral (star)
formation can be positioned in either way,
ToObject
or
FromObject
. However,
internally REFPDIF (87N) always uses reference directions towards the protected
transformers, as shown in Figure
. Thus the IED always measures the primary
currents on all sides and in the neutral of the power transformer with the same
reference direction towards the power transformer windings.
The grounding can be freely selected for each of the involved current transformers.
7.3.3
Setting guidelines
IP14942-1 v1
7.3.3.1
Setting and configuration
M13052-3 v3
Recommendation for analog inputs
M13052-8 v10
I3P: Neutral point current ( All analog inputs connected as 3Ph groups in ACT).
Section 7
1MRK 504 163-UUS A
Differential protection
182
Transformer protection RET670 2.2 ANSI
Application manual
Summary of Contents for RELION RET670
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