Menu: Control - ABB PositionMaster EDP300 Operating Instruction

8.4.4

Menu: Control

.../ Control
Mask contents Value range
Zone 1 ... 100 in steps of 1
Dead Band 0.10 ... 10.00 % in steps
of 0.01 %
DB Approach Fast
Medium
Slow
DB Timeout
Kp Up 1.0 ... 400.0
Kp Down 1.0 ... 400.0
Description
This parameter specifies the point at which the control structure is switched over when the dead
band is being approached.
The dead band defines a +/- range around the position setpoint. Once the position of the valves
and fittings reaches this range, the positioner maintains this position.
This parameter specifies the speed at which the dead band is approached.
In rare cases, overshooting can occur when the valve position is being compensated. This can be
prevented by reducing the speed of the dead band approach.
Slow
Medium
Fast
Use this parameter to enter a monitoring time up to the point at which the dead band is reached.
If the dead band around the new position setpoint is not reached again within the specified time,
an alarm is triggered.
Once the setpoint has been reached, the alarm is automatically reset.
IMPORTANT (NOTE)
The stroke time selected for monitoring should be 5 x greater than the shortest
stroke time determined during Autoadjust (Device Info. -> Stroke Time Up / Dn).
The KP value is the gain of the controller. The control speed and stability are influenced by the KP
value. With higher KP values, the control speed increases.
To compensate for existing dissymmetries in the controlled system, the KP value should be set
separately for both positioning directions (up / down). For most actuators, satisfactory control
behavior is achieved with a KP value between 2.0 ... 10.0.
Use this parameter to adjust the KP value for the up positioning direction (towards 100 %).
IMPORTANT (NOTE)
The control precision is not affected by the KP value.
The KP value is the gain of the controller. The control speed and stability are influenced by the KP
value. With higher KP values, the control speed increases.
To compensate for existing dissymmetries in the controlled system, the KP value should be set
separately for both positioning directions (up / down). For most actuators, satisfactory control
behavior is achieved with a KP value between 2.0 ... 10.0.
Use this parameter to adjust the KP value for the down positioning direction (towards 0 %).
IMPORTANT (NOTE)
The control precision is not affected by the KP value.
PositionMaster EDP300 | OI/EDP300-EN 37