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positions and ~120VAC on neutral. Occasionally, it may be necessary to adjust the TapInPulse
to increase or decrease the sensitivity of the operations counter sensing. Cooper tap changers
have a Hold Switch circuit rather than an actual Op Counter switch. Once the tap change
initiates from the control, the Hold Switch circuit picks up and completes the tap change.
Changing the R/LOnTime and TapInPulse settings is the best way to improve the tap tracking if
you are experiencing problems on a Cooper mechanism. Because of Hold Switch, the accuracy
of tracking tap position when making manual tap changes depends upon how long the operator
holds the Raise/Lower switch in position before releasing it. After manual operations, it is
always a good idea to verify (and possibly adjust) the ta
p position in memory by going to “Tap =”
under the <COUNTERS> menu.
Suggested Alternate Settings from Customer Experience
Although the default settings for each type of tap changer have been tested and are defined
according to our knowledge of each tap changer type, sometimes adjustments to the algorithm
are made to improve performance. Below are some various settings for different tap changer
types that some customers have used to improve performance on troublesome regulators.
Cooper Spring Drive
TapChgr = COOP SD; <DIAGNOSTICS> TapInPulse = 0.12; all other settings are
defaults
TapChgr = COOP QD; <DIAGNOSTICS> R/LOnTime = 1.0; TapInPulse = 0.12; all
other settings are defaults
TapChgr = COOP SD; <DIAGNOSTICS> TapInPulse = 0.12; R/L OnTime = 3.5, R/L Off
time = 5.0; Tap Chg T/O = 5.0; Fixed R/L OnTime = Yes; all other settings are defaults
Cooper Direct Drive
TapChgr = COOP DD; <DIAGNOSTICS> TapInPulse = 0.15; all other settings are
defaults
Recommendation for tap track errors with the Cooper SD Tap Changer:
Decrease R/L ON-Time to less than the time it takes to make one full tap change (i.e. from
8 raise to 7 raise). R/L Off-Time + R/L ON-Time should be greater than the time it takes to
make one full tap change.
The reason for this issue is that Cooper tap changers have a Holding switch and does
not need to be monitored throughout the whole operation.
