ABB RER670 Applications Manual page 336

Section 12
Control
330
DU is the deadband setting in percent.
•
• n denotes the desired number of difference in tap position between the
transformers, that shall give a voltage deviation U
dead-band setting.
• p is the tap step (in percent of transformer nominal voltage).
• a is a safety margin that shall cover component tolerances and other non-linear
measurements at different tap positions (for example, transformer reactances
changes from rated value at the ends of the regulation range). In most cases a
value of a = 1.25 serves well.
This calculation gives a setting of Comp that will always initiate an action (start
timer) when the transformers have n tap positions difference.
OperSimTap: Enabling/disabling the functionality to allow only one transformer at
a time to execute a Lower/Raise command. This setting is applicable only to the
circulating current method, and when enabled, consecutive tap changes of the next
transformer (if required) will be separated with the time delay t2.
OperUsetPar: Enables/disables the use of a common setting for the target voltage
USet. This setting is applicable only to the circulating current method, and when
enabled, a mean value of the USet values for the transformers in the same parallel
group will be calculated and used.
OperHoming: Enables/disables the homing function. Applicable for parallel control
with the circulating current method, as well for parallel control with the master-
follower method.
VTmismatch: Setting of the level for activation of the output VTALARM in case
the voltage measurement in one transformer bay deviates to the mean value of all
voltage measurements in the parallel group.
tVTmismatch: Time delay for activation of the output VTALARM.
T1RXOP.......T8RXOP: This setting is set On for every transformer that can
participate in a parallel group with the transformer in case. For this transformer
(own transformer), the setting must always be Off.
TapPosOffs: This setting gives the tap position offset in relation to the master so
that the follower can follow the master's tap position including this offset.
Applicable when regulating in the follow tap command mode.
MFPosDiffLim: When the difference (including a possible offset according to
TapPosOffs) between a follower and the master reaches the value in this setting,
then the output OUTOFPOS in the Automatic voltage control for tap changer,
parallel control TR8ATCC function block of the follower will be activated after the
time delay tMFPosDiff.
1MRK 506 375-UEN A
which corresponds to the
di
Railway application RER670 2.2 IEC
Application manual