Future Design MCTB 4.3, Руководство пользователя

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MCTB
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9.1 Tuning
The loop Tuning screen allows for manual and automatic tuning of the MCTB control loops. Tuning parameters
should only be manually adjusted by skilled users familiar with proportional control. Improper settings can result
in control loop instability and equipment damage. The loop automatic tune function is the recommended method
of loop tuning. If the control response achieved after performing an auto tune does not provide the desired
control response, then minor adjustment of the tuning parameters may be done manually to obtain the desired
response.
The available tuning parameters are dependent upon the loop configuration. If programmed for heat or cool
only control, then the available parameters will be PB (proportional band), TI (integral time period) and TD
(derivative time period). If the loop is configured for heat/cool operation then two additional parameters for
Cooling PB (cooling proportional band) and Dead Band (heat/cool dead band) will be provided.
The tune screen also provides a live real time chart for monitoring the control response of the control loop while
adjusting tuning parameters. The chart is fixed at a 10-minute time period and updates once per second.
Pressing the
SP button allows the user to adjust the loop set point without having to leave the tuning screen in
order to observe the control response.
Pressing the
AT button allows the user to activate/deactivate the loop auto tuning feature. When auto tune is
active, the indicator on the button will be illuminated. In addition, the process value of the loop on the Loop
view screen will flash while auto tune is active. This allows the user to activate auto tune and then return to the
main Loop view screen to observe system operation while being informed of the loop auto tune status.
NOTE: The auto tune function does not affect any of the configured PID sets. The auto tune only updates
the current PID values currently used in the loop control. If auto tune is being used to determine PID
set values for a specific operating range, the values determined by the auto tune function must be
manually entered into the proper PID set. They will not be transferred automatically when the auto
tune is complete.
Pressing the
PID Set button provides access to the loop PID Set Configuration screen that allows multiple PID
values to be utilized by the loop at varying process ranges. See section 9.1.3 Configuring PID Sets for more
information.
9.1.1 Heat or Cool only P (or PD) Control
When a loop is programmed for heat or cool only control, it is possible to set the integral time to zero in order
to eliminate reset
action. A “PB Offset” field will then be shown for entering a manual reset value to correct for
the control offset that will occur once the loop has stabilized. The offset entry is measured in percent with a
range of 0-100%.