4.30
SEL-751 Relay Instruction Manual Date Code 20170927
Protection and Logic Functions
Group Settings (SET Command)
NOTE: If setting SINGLEV:=Y then,
setting VNOM is set to OFF.
Figure 4.20 and Figure 4.21 give an overview of how these directional ele-
ments are enabled and routed to control the neutral ground and residual
ground overcurrent elements.
Note in Figure 4.20 and Figure 4.21 that setting ORDER enables the direc-
tional elements. Setting ORDER can be set with the elements listed and
defined in Table 4 . 19, subject to the setting combination constraints in
Table 4.20. Note that Table 4.19 and Tab le 4.20 also list the directional ele-
ment availability, per model (according to the neutral channel [IN] rating).
NOTE: When group settings
SINGLEV := Y and VSCONN = 3V0,
EDIR cannot be set to AUTO.
Table 4.21 details the availability of the ground directional elements for the
various combinations of the DELTA_Y, VSCONN, SINGLEV, and VNOM
settings. If none of the ground directional elements are available (per
Table 4.19 through Table 4 . 21), setting EDIR (directional control enable) can
only be set to N. Refer to Figure 2.20 and Figure 2.21 for information on
DELTA_Y, VSCONN, and SINGLEV settings and how they translate to phys-
ical connections.
NOTE: When VNOM = OFF, setting
VSCONN = VS and the relay has a
0.2 A nominal neutral rating, EDIR can
only be set to N.
Also, note that Table 4.19 through Table 4.21 (and lower left-hand corner of
Figure 4.20) detail the mutual exclusivity of ORDER setting choices I, S, P,
and U. If particular directional elements are not available (because of model
type) or are not listed in setting ORDER, these elements are defeated and non-
operational.
For example, suppose that setting choice S is listed in setting ORDER. By vir-
tue of not being available or not being listed in setting ORDER, the directional
elements corresponding to setting choices I, P, and U (see Table 4.19,
Figure 4.20, and Figure 4.21) are defeated and nonoperational. So, for
unavailable setting choice I, corresponding internal enable DIRIE = logical 0
and directional outputs FDIRI = logical 0 and RDIRI = logical 0. Similarly,
for the directional elements corresponding to unlisted setting choices P and U,
the logic outputs are at a logical 0 state.
The order in which these directional elements are listed in setting ORDER
determines the priority in which they operate to provide Best Choice Ground
Directional Element logic control. See the discussion on setting ORDER in
Directional Control Settings on page 4.53.
Table 4.21 Ground Directional Element Availability by Voltage Connection Settings
Element
Designation
in ORDER
Setting
Availability
a
When
VNOM OFF
VSCONN = VS
Availability
a
When
VNOM OFF
VSCONN = 3V0
Availability
a
When
VNOM = OFF
VSCONN = VS
Availability
a
When
VNOM = OFF
VSCONN = 3V0
DELTA_Y =
WYE
DELTA_Y =
DELTA
DELTA_Y = WYE or
DELTA_Y = DELTA
DELTA_Y = WYE,
DELTA_Y = DELTA, or
SINGLEV = Y
DELTA_Y = WYE,
DELTA_Y = DELTA, or
SINGLEV = Y
QYes Yes Yes No
b
No
b
VYes No Yes No
b
Yes
I Yes Yes Yes Yes Yes
SYes No Yes No
b
Yes
PYes No Yes No
b
Yes
UYes No Yes No
b
Yes
a
Subject to availability of elements by relay model shown in Table 4.19 and Table 4.20.
b
The displayed setting range for the ORDER setting may show these element choices, but the relay will not accept these choices when a
settings save is attempted.
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