138 Program features
Parameter lock
The user can prevent parameter adjustment by activating the parameter lock.
Settings
PID control
There are two built-in PID controllers in the drive:
• Process PID (PID1) and
• External/Trim PID (PID2).
The PID controller can be used when the motor speed needs to be controlled based
on process variables such as pressure, flow or temperature.
When the PID control is activated, a process reference (setpoint) is connected to the
drive instead of a speed reference. An actual value (process feedback) is also
brought back to the drive. The drive compares the reference and the actual values,
and automatically adjusts the drive speed in order to keep the measured process
quantity (actual value) at the desired level (reference).
The control operates on a 2 ms time level.
Process controller PID1
PID1 has two separate sets of parameters (
,
). Selection between parameter sets 1 and 2 is defined by a parameter.
In most cases when there is only one transducer signal wired to the drive, only
parameter set 1 is needed. Two different parameter sets (1 and 2) are used eg when
the load of the motor changes considerably in time.
External/Trim controller PID2
) can be used in two different ways:
• External controller: Instead of using additional PID controller hardware, the user
can connect PID2 output through drive analog output or fieldbus controller to
control a field instrument like a damper or a valve.
• Trim controller: PID2 can be used to trim or fine tune the reference of the drive.
See section
on page
Aotewell Ltd
www.aotewell.com
Industry Automation
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