Mitsubishi Electric MELSEC iQ-F FX5 - Page 611

35 CPU MODULE BUILT-IN ANALOG FUNCTION
35.5 Function (PID Control Via Instruction)
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Differential time (s3)+6
Use the differential time (TD) to respond sensitively to fluctuations in the measured value (PV) caused by disturbance, etc.
and to minimize the fluctuations. Setting range: 0 to 32767 ( 10 ms)
• When the differential time (TD) is large, it prevent large fluctuation in the control target caused by disturbance, etc.
• It is not always necessary to use the differential time (TD) (when disturbance is small, for example).
Ex.
PID operation in backward operation (heating)
Output value (MV)
Deviation
Disturbance
Deviation (EV)
Time
Time
TD3>TD2>TD1
TD3 (PID operation)
TD1 (PID operation)
TD2 (PID operation)
TD3 (PID operation)
TD1 (PID operation)
TD2 (PID operation)
Output value (MV)
Temperature
Target value (SV)
Time
Time
TD3>TD2>TD1
TD3>TD2>TD1
TD3 (PID operation)
PI operation (without differential operation)
PI operation (without differential operation)
TD2 (PID operation)
TD3 (PID operation)
Changes in output caused by disturbance
Changes caused by disturbance
TD1 (PID operation)
TD1 (PID operation)
TD2 (PID operation)