For Regulate Reverse the source voltage is calculated by knowing the local voltage, the
load current, and the tap position using a presumed regulator impedance. That impedance
is a function of the tap position. The calculated source voltage is only valid with a 5/8 %
step-voltage regulator.
When Reverse power is detected and the Operation Mode is in "Regulate Reverse
Measured", the control will energize an internal contact that will switch the input to the VT
from Load side to Source side. After a 4 cycle delay, the source side voltage will be
measured, the load voltage at this instant will be displayed as zero. In forward power
direction, the control will switch the input back to the load side voltage.
With the control recognizing reverse power flow, the following occurs:
•
The REV PWR LED is illuminated.
•
Reverse power setpoints are used.
•
Source voltage is calculated in case of Regulate Reverse and measured in case of
Regulate Reverse Measured and motor output commands are reversed. For example,
when the voltage is high, the control raises the tap thereby lowering the voltage and
a lower is indicated on the front panel LEDs.
Return to Neutral
– To use this feature, a counter input must be provided, and
KeepTrack™ tap information modes must be enabled.
The Return to Neutral feature will cause the tap position to be driven to neutral when
reverse power is detected. Tap position will be driven to neutral regardless of the voltage
or currents present at the control. Once neutral is reached, the tap position will remain
unchanged as long as reverse power is present. Normal operation will resume when
forward power is detected.
This mode is intended as a safe response to a power reversal on a system which can have
conflicting situations. As described earlier, a radially operating system with reverse power
should be set to "Regulate Reverse Measured" However, if a DG causes a power reversal,
the proper setting is usually "Ignore". In an application where both conditions are possible
and it is not possible for the control to determine the cause of power reversal, the proper
setting of "Return to Neutral" is advised.
Distributed Generation
– Distributed Generation allows alternate LDC R and X values
to be applied to the control when reverse power is detected. The factory setting is BLOCK.
This mode is intended for use on distribution systems that have the possibility of power
reversal because of distributed generation (DG) on the feeders. In these applications, the
DG usually does not have the capacity to control the voltage with the more powerful
system intact.
The condition required for DG to control the voltage is the generation and transmission of
large amounts of VArs through the line impedance back towards the system source.
Usually two items prohibit this action:
Section 7
1VAC388793-MB A
Setpoints
528
TCC300
User Manual
Summary of Contents for TCC300
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