Future Design MCT-CM, Руководство пользователя

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MCT-CM
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Thus, if the source loop output range is 0 to 100%, at 0% output, the loop set point
will be 40, at 50% output the set point for the loop will be 55 and at 100% output the
loop set point will be 70.
Process: This mode uses the low and high set points as the upper and lower range of the cascade loop set
point.
The output of the source loop is then used to calculate the loop’s set point by generating a
linear value between the low and high set points.
Example: If the cascade Low SetPoint is 10 and the High SetPoint is 150, the loop set point will
be in the range of 10 to 150. The actual set point value is then calculated by using
the percentage of output of the source loop and creating a linear set point range from
10 to 150.
Thus, if the source loop output range is 0 to 100%, at 0% output, the loop set point
will be 10, at 50% output the set point will be 80 and at 100% output the loop set point
will be 150.
The deviation mode has the benefit of limiting the maximum and minimum temperature that the cascade loop
can achieve relative to the source loop set point. This allows the system to be fine-tuned to the minimum
amount of overshoot required to obtain the desired control response.
The process mode has the benefit of maximum change rates by allowing the cascade loop to go to absolute
limits. This allows the process to achieve set point temperature as quickly as possible, but does so at the cost
of stability. If the process has a considerable amount of lag, the cascade loop control may oscillate
uncontrollably once the source loop reaches set point because of the large overshoot that can be created.
The
Source Loop is often referred to as the
“outer loop” for cascade control. The source loop selection tells
the MCT which control loop to use in calculating the set point for the cascade loop. The MCT will monitor the
output percentage of the source loop and generate a set point using the
Low Setpoint and High Setpoint
entries as the upper and lower ranges for calculating the set point according to the selected cascade mode.
4.3 Monitor Setup
In order for the MCT to properly display values from the optional monitor input modules and/or input 2 of the
loop controls, the MCT must be given the proper configuration settings for each monitor input used. These
settings are accessed from the
“Monitor Setup” screen under the Setup menu.
The left and right scroll (arrow) buttons allow the user access each monitor point in the system, by pressing left
or right to go to the previous or next monitor point.