with the appropriate Aux Raise or Lower contact. That allows the control to compensate
for multiple neutrals.
Contact KeepTrack Method II – Using Neutral Contact Input
This method provides Contact KeepTrack for LTC transformers that have dedicated
Raise, Lower, and a Neutral contact that stays closed while the LTC is on neutral,
including multiple neutrals. A Counter contact may also be required.
This Contact KeepTrack method requires a pulsed input for each tap operation either raise
or lower. The raise contact input to the TCC300 must close and open each time the tap
position raises by one tap as is the case when the contacts are derived from Cam switches.
Likewise the lower contact input to the TCC300 must close and open each time the tap
position lowers by one tap.
If the contacts are derived from 84R and 84L relays, an additional contact derived from the
operations counter must be placed in series with them to provide the required pulsed input.
With these inputs the TCC300 Control can "keep track" of the tap position since it will
always receive either a raise or lower pulse as an indication of which direction the
tapchanger is moving.
The neutral contact input recalibrates the control tap position to neutral if needed. This
provides an extremely positive indication that the tapchanger is performing either a raise
or lower operation.
To implement the Contact KeepTrack™ Method II scheme with contacts derived from
Cam switches, the Contact KeepTrack method requires that three contacts be available
and accessible in the LTC to operate correctly.
•
Aux Raise contact – This contact closes when the LTC takes a tap in the Raise
direction.
•
Aux Lower contact – This contact closes when the LTC takes a tap in the Lower
direction.
•
Neutral contact – This contact must close when the unit moves onto the Neutral tap
position and open when leaving it.
All three contacts must be either dry contacts or run through auxiliary relay contacts if wet.
The TCC300 Voltage Reduction inputs, now used for the Aux Raise and Aux Lower
contact inputs, and the Neutral input require dry contacts wetted internally with 12 Vdc.
1VAC388793-MB A
Section 6
Configuration
TCC300
449
User Manual
Summary of Contents for TCC300
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