-3U
0
=U
ref
Operate area
Instrument
transformer
angle error
3I
0
(prim)
3I
0
(to prot)
Characteristic after
angle compensation
RCAcomp
IEC06000651-3-en.vsd
RCADir = 0º
IEC06000651 V3 EN
Figure 179: Explanation of RCAComp
Directional residual power protection measuring 3I
0
· 3U
0
· cos φ
φ is defined as the angle between the residual current 3I
0
and the reference voltage
(U
ref
= -3U
0
e
-jRCA
) compensated with the set characteristic angle RCADir (|
φ=ang(3I
0
)—ang(U
ref
)|). The function operates when 3I
0
· 3U
0
· cos φ gets larger than
the set value SN>. Refer to the simplified logical diagram in Figure
181.
For trip, the residual power 3I
0
· 3U
0
· cos φ, the residual current 3I
0
and the release
voltage 3U
0
, shall be larger than the set levels (SN>, INRel> and UNRel>).
Trip from this function can be blocked from the binary input BLKTRDIR.
When the function picks up, binary output signals START and STDIRIN are
activated. If the output signals START and STDIRIN remain active for the set delay
tDef or after the inverse time delay (setting kSN) the binary output signals TRIP and
TRDIRIN get activated.
The function shall indicate forward/reverse direction to the fault. Reverse direction is
defined as 3I
0
· 3U
0
·cos (φ + 180°) ³ the set value.
Section 8 1MRK502052-UEN B
Current protection
396
Technical manual
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