Input Description
URES3
1
Residual voltage (measured or calculated)
URES4
1
Residual voltage (measured or calculated)
See the preprocessing function blocks in this document for the possible
signal sources. The GRPOFF signal is available in the function block called
Protection.
There are a few special conditions which must be noted with the configuration.
Table 260: Special conditions
Condition Description
U3P1/U3P2/U3P3/U3P4
connected to real measure-
ments
The function requires that at least one voltage channel is
connected. The function requires that all the U3Px that are
connected to real source must be capable of providing (at
least) the same data that the default source U3P1 is capable
of. E.g. if the source UTVTR conneted to U3P1 has two inputs
(e.g. UL1, UL2) connected then others need to also have at
least two inputs connected (e.g. UL1, UL2 or UL2, UL3 or
UL3, UL1).
URES1/URES2/URES3/URES4
calculated
The function requires that all three voltage channels are con-
nected to calculate the residual voltage. Setting
VT connec-
tion
must be "Wye" in that particular UTVTR.
3.20.16.5 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "on" and "off".
For this function, the setting is hidden and fixed to "on".
The switch logic depends on inputs SWITCH_TO2, SWITCH_TO3 and SWITCH_TO4.
Source 1 is selected as default and switching is done on increased priority.
GRPOFF signal must be connected to unused voltage inputs. GRPOFF
signal is available as output from the Protection function block.
Table 261: Switching operation
Control input signals Outputs
SWITCH_TO
2
SWITCH_TO
3
SWITCH_TO
4
SOURCE1 SOURCE2 SOURCE3 SOURCE4 Source for
U3P
Source for
URES
FALSE FALSE FALSE TRUE FALSE FALSE FALSE U3P1 URES1
TRUE FALSE FALSE FALSE TRUE FALSE FALSE U3P2 URES2
x
1
TRUE FALSE FALSE FALSE TRUE FALSE U3P3 URES3
x
1
x
1
TRUE FALSE FALSE FALSE TRUE U3P4 URES4
1
No difference
Basic functions 1MRS759142 F
276 REX640
Technical Manual
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