OPERATION: See
. When the control is set to the
Reverse Idle mode, the control will regulate in the forward
direction (from source bushing to load bushing) when the
real component of system load current exceeds a threshold
value determined using the Reverse Current Sense
Threshold setting (FC 57).
When the the real component of system load current falls
below the threshold, the control will go into an auto tap
blocking state and idle on the tap position held before the
threshold was crossed. The operational timer (time delay)
will reset on any excursion below this threshold. While
below the threshold, the control will display Rev Pwr Mode
on the Load Current Metering-PLUS screen. As the current
flow again exceeds the threshold, normal forward operation
resumes.
Reactive Curr
ent
Real Current (% of C.T. Primary)
Forward Operation =
0 0T
OT=Operating Threshold, FC 57, 1-5%
Tap changing is inhibited
when real component of
current is at or below the
operation threshold, FC 57.
Figure 25 . Reverse idle mode* operation
* Tap changing is inhibited and band edge indicators are turned off.
Bi-directional mode
The Bi-directional setting for Reverse Sensing Mode is
recommended for applications where forward and reverse
power are possible. The setting is not recommended
for applications in which the reverse power is due to a
co-generational facility. It is also not recommended for
applications with load currents in the forward or reverse
direction that do not meet the current sense threshold.
When the control is set for Bi-directional, a measured or
calculated voltage from the source bushing is required for
reverse power operation and metering.
Normal Forward
Metering
Rev Pwr
Off
Reverse Metering
Reverse Scaling
Rev Pwr
On
Current Level
1% 0 1%
Figure 26 . Bi-directional, neutral idle and reactive bi-direc-
tional metering
METERING: See
. A threshold level of 1% (.002
A) of the full load CT secondary current of .200 A is used
in setting the power direction. The metering will be forward
until the current exceeds the 1% threshold in the reverse
direction. At this time, the various parameters use the
reverse settings and the Reverse Power indicator turns on.
The control continues metering in reverse until the current
exceeds the 1% threshold in the forward direction, and
then the parameter scaling reverts back to normal and the
Reverse Power indicator turns off.
127
INSTALLATION, OPERATION, AND MAINTENANCE INSTRUCTIONS
MN225003EN April 2018
CL-7 Voltage Regulator Control