58 Program features
Combined
The combined is suitable for applications where you need to maintain tension from
zero speed to maximum speed
Combined method is a combination of direct and proportional mode. Here, the trim for
zero speed is defined by 40.54 Set 1 trim mix and the trim for speed greater than zero
speed is defined by 40.55 Set 1 trim adjust. The trim value is directly proportional to
value of 40.53 Set 1 trimmed ref pointer.
The process speed reference is connected in 40.53 Set 1 trimmed ref pointer. For
example, if EXT1 control mode is used and the reference source is AI scaled, then
22.11 Ext1 speed ref1 and 40.53 Set 1 trimmed ref pointer should be configured to
AI1 scaled.
The 40.05 Process PID trim output act is calculated using below formula:
The below graph shows the trim increase in combined mode.
Note: In the above graph, it is assumed that the PID output is limited/stable at 100.
This is for understanding purpose only. In real case scenario, PID output can vary
based on the setpoint and actual.
Example
If,
Par. 40.52 Set 1 trim selection = Speed
Par. 40.56 Set 1 trim source = PID output
Par. 30.12 Maximum speed = 1500 rpm
Par. 40.53 Set 1 trimmed ref pointer = AI1 scaled
Par. 22.11 Ext1 speed ref1 = AI1 scaled
Par. 12.20 AI1 scaled at AI1 max = 1500
Par40.05 Par30.12 Par40.541 Par40.54–Par40.53+Par40.55=
40.05 Process PID trim output act
40.55 Set 1 trim adjust
40.53 Set 1 trimmed ref pointer
0
40.55 Set 1 trim adjust
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