136 Application macros
PID control macro
The PID control macro is suitable for process control applications, for example
closed-loop pressure, level or flow control systems such as
• pressure boost pumps of municipal water supply systems
• level-controlling pumps of water reservoirs
• pressure boost pumps of district heating systems
• material flow control on a conveyor line.
The process reference signal is connected to analog input AI1 and the process
feedback signal to AI2. Alternatively, a direct speed reference can be given to the
drive through AI1. Then the PID controller is bypassed and the drive no longer
controls the process variable.
Selection between direct speed control (control location EXT1) and process variable
control (EXT2) is done through digital input DI3.
The stop/start signals for EXT1 and EXT2 are connected to DI1 and DI6 respectively.
A constant speed (by default, 300 rpm) can be activated through DI4.
Note: When commissioning the PID loop, it is useful to run the motor in speed control
first using EXT1; this allows testing of the PID feedback polarity and scaling. Once
the feedback has been proven, the PID loop can be “closed” by switching to EXT2.
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