CHAPTER 8: AUTOMATION AUTOMATION CONTROL
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 451
The voltages V
1
and V
2
are automatically matched so the corresponding voltages from the
two sources are used to measure conditions. A phase-to-phase voltage is used if available
in both sources. If one or both of the sources have only an auxiliary voltage, then this
voltage is used.
For example, if an auxiliary voltage is programmed to V
AG
, the synchrocheck element
automatically selects V
AG
from the other source. If the comparison is required on a specific
voltage, the user can externally connect that specific voltage to auxiliary voltage terminals
and then use this auxiliary voltage to check the synchronism conditions.
If using a single CT/VT module with both phase voltages and an auxiliary voltage, ensure
that only the auxiliary voltage is programmed in one of the sources used for synchrocheck.
NOTE:
Exception: synchronism cannot be checked between delta-connected phase VTs and a
wye-connected auxiliary voltage.
The D90
Plus
measures frequency and volts per hertz from an input on a given source with
priorities as established by the configuration of input channels to the source. The relay
uses the phase channel of a three-phase set of voltages if programmed as part of that
source. The relay uses the auxiliary voltage channel only if that channel is programmed as
part of the source and a three-phase set is not.
Synchrocheck settings
Select the Settings > Automation > Control > Synchrocheck menu to open the
synchrocheck configuration window.
Figure 383: Synchrocheck configuration settings
The following settings are available for each synchrocheck element. The default values
outlined are for the synchrocheck 1 element.
Phase VTs and
auxiliary VT
Phase VT Phase Phase V
AB
Phase VT Phase VT Phase Phase V
AB
Phase VT and
auxiliary VT
Auxiliary VT Phase Auxiliary V
aux
(as set for
source Z)
Auxiliary VT Auxiliary VT Auxiliary Auxiliary V
aux
(as set for
selected sources)
V
1
or V
2
(source Y) V
2
or V
1
(source Z) Auto-selected combination Auto-selected
voltage
Source Y Source Z
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