ABB RED650 Applications Manual

0 deg
180 deg
90 deg
270 deg
120 deg
IMinNegSeq
If one or the
other of
currents is too
low, then no
measurement
is done, and
120 degrees
is mapped
External
fault
region
Internal
fault
region
Internal/external
fault boundary
NegSeqROA
(Relay
Operate
Angle)
en05000188-3-en.vsd
IEC05000188 V3 EN-US
Figure 40: Negative sequence current function Relay Operate Angle (ROA)
IminNegSeq
M12541-223 v4
IminNegSeq is set as a multiple of IBase. The local, and the sum of all remote
negative sequence currents are compared separately if they are above the set
threshold value IminNegSeq. If either is below the threshold, no comparison is
made. Neither internal nor external fault is declared in this case. The default value
0.04 × IBase can be used if no special considerations, such as extremely week
sources, are taken into account. Observe that internally, whenever the bias current
is higher than 1.5 times IBase, the actual threshold is equal to the sum of
IminNegSeq + 0.1 Ibias. This is in order to prevent wrong decisions of the internal/
external fault discriminator under heavy three-phase external fault conditions with
severe CT saturation.
6.1.3.5 Power transformers in the protected zone
M12541-6 v7
One three-winding transformer or two two-winding transformers can be included in
the line protection zone. The alternative with one two-winding transformer in the
protected zone is shown in Figure
41 and Figure 42.
1MRK 505 393-UEN B Section 6
Differential protection
Line differential protection RED650 2.2 IEC 93
Application manual

ABB RED650 Specifications

General

Brand	ABB
Model	RED650
Category	Protection Device
Language	English