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XT-70 Control Panel 41
E2 Parameters Definition:
FILTER The filter is a value from 1 to 10. This number will weight the analog values for all the
temperatures, humidity and CO
2
readings. The default value is 6. Increasing this
value will cause the readings to be more highly filtered and slower to change.
KP_P Cooling proportional gain. The default value is 30. Increasing this value will cause the
overall system performance to become faster. P is most effective on sudden changes.
KI_P Cooling integral gain. The default value is 20. The integral gain produces an error
based on small errors over time. Increasing this value will cause the small error to be
amplified over time, leading the system to be more sensitive to small errors.
KD_P Cooling Derivative gain. The derivative is produced by a sudden change in the error. If
the temperature is several degrees above setpoint, the PID will ramp quickly. The error
may not change much until the door reaches a given position. At this point the tempera
ture would drop quickly. The derivative acts like a brake and will offset the error when
large changes are being made. If the temperature overshoots at start up, increase this
value. The default setting is 0.
UPDATE_TP This value is in 1/10’s of a second, and determines when the PID loop is updated. The
default value is 50. Increasing this value will slow down the entire loop. Decreasing
will cause the loop and response to speed up. A value that is too low will cause the sys-
tem to cycle around setpoint.
SCALE This value is used initially for testing and is the overall scaling for the PID response.
The default setting is 0. This is an engineering variable and should normally not be
changed.
THRESHOLD This is the switch over point for the KI divisor. The default setting is 150. This is an
engineering variable and should normally not be changed.
MIN_PW: This is the minimum pulse width time. A value of 0 will disable this function. The
default setting is 150 and the value is in milliseconds. Some door controllers will not
respond to small pulses so, if this value is set to a number greater than zero, the panel
will accumulate pulses until the MIN_PW is reached and the correction is made.
CELL_EFF: Cell efficiency. The efficiency of different evaporative cooling cells can vary greatly
depending on a number of variables. CELL_EFF allows the efficiency of a given
evaporative cooling system to be set. This value can be determined by setting the
cell to 100 percent and watching it on a good warm dry day. The setting is from 0 to 100
percent. The default setting is 85%.
MIN_COOLING_RUN: This variable is in minutes and will guarantee that once in the Cooling mode,
the system will stay in there for a minimum run time and will not short cycle. Typical
settings would be from 15 to 30 minutes. The default setting is 30 minutes.
RAS: Rise above Setpoint. The RAS variable is the amount the plenum can rise above
setpoint before cooling air is terminated. For this variable to be active, the OSA needs
to be above the start temperature. This setting is in 1/10ths of a degree. The default
setting is 3, or .3°.
6.1
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