Underload Smart Reset
Dynamic (Factory Setting)
If a motor underload fault condition occurs, the most likely cause is an over-pumped or dry well.
The underload trip level is defined as a percentage of rated load at rated speed, the default
being 50%, which can be adjusted via the COMM Board user interface. Once tripped, the
timeout applied before a restart attempt varies according to the Dynamic Smart Reset schedule.
The intent is to adjust the "Off Time" as a function of the level of water in the well using
the formula: Off Time = Rule Time – Run Time. (Figure 2)
For wells having a slower recovery rate, an extendable Rule Time that adjusts automatically is used.
The Rule Time is initially set to 5 minutes when the drive is first activated. However, if after restarting
from an underload, the drive quickly trips again (arrow 1), the Rule Time is extended. This process
continues until the Rule Time grows long enough to keep the Off Time near the center range (arrow
2), up to a maximum of 80 minutes. If, later on, the well begins to recover more quickly, the system
runs longer between trips and the Rule Time is gradually reduced in 5 minute increments (arrow 3).
This adaptive process allows for seasonal changes in well behavior.
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Run Time (Minutes)
Figure 2: Dynamic Reset Model
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Run Time (Minutes)
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