Reactive Curr
ent
Real Current (% of C.T. Primary)
Forward Operation =
0 OT
OT=Operating Threshold, FC 57, 1-5%
Tap changing
inhibited and
band edge
indicators are
turned off.
Reverse Operation =
OT
Normal Reverse
Operation FC 51-55
Normal Forward
Operation FC 1-5
Figure 27 . Bi-directional mode operation
OPERATION: See
. When the control is set to the
Bi-directional mode, it will regulate in the forward direction
(from source bushing to load bushing) when the real
component of system load current in the forward direction
exceeds a threshold value determined using the Reverse
Current Sense Threshold setting (FC 57).
The control will regulate in the reverse direction (from load
bushing to source bushing) when the real component of
system load current in the reverse direction exceeds the
threshold value.
When the the real component of system load current falls
between the forward and reverse threshold values:
●
●
Auto operation will be inhibited and the control will
idle on the tap position held before the threshold was
crossed.
●
●
The band-edge indicator LEDs will not illuminate, even
when the compensated voltage is out of band.
●
●
The operational timer (time delay) will reset.
●
●
As the current flow again exceeds the threshold in either
direction, auto operation will resume in that direction.
Neutral idle mode
The Neutral Idle setting is recommended for applications
where reverse power is possible but the source bushing
voltage cannot be determined and reverse power regulation
is not required. When the control is set for Neutral Idle, a
measured or calculated source voltage would be needed for
metering only.
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.
OPERATION: See
. When the control is set to the
Neutral Idle mode, the control will regulate in the forward
direction (from source bushing to load bushing) when the
real component of system load current, in the forward
direction, exceeds the current threshold value determined
using the Reverse Current Sense Threshold setting (FC 57).
When the real component of system load current, in the
reverse direction, exceeds the current threshold value for 10
continuous seconds, the control will tap to neutral. Neutral
position is determined using control tap position. If the tap
position is not valid, neutral is determined using percent
regulation (buck and boost).
When the real component of current is in the region
between the forward and reverse thresholds, the control
idles on the tap position held before the forward threshold
was crossed. While tapping to the neutral position, if
the current falls below the reverse threshold, the control
continues to tap until neutral position is reached.
On any excursion below the forward threshold, the
operational timer (time delay) is reset and the band edge
indicators turn off.
Reactive Curr
ent
Real Current (% of C.T. Primary)
Forward Operation =
0 OT
OT=Operating Threshold, FC 57, 1-5%
Band edge indicators are
turned off and tap changing
is inhibited when real
component of current is at or
below the operation threshold,
FC 57, in either direction.
Tap-to-Neutral =
OT
Figure 28 . Neutral idle mode* operation
* Band edge indicators are turned off.
128
INSTALLATION, OPERATION, AND MAINTENANCE INSTRUCTIONS
MN225003EN April 2018
CL-7 Voltage Regulator Control