Marathon Monitors Inc.
AACC 2000 Carbon Nov. 1, 1997
59
Motorized valve control
The AACC 2000 can be configured for motorised valve control as an alternative to the
standard PID control algorithm. This algorithm is designed specifically for positioning
motorised valves.
These are ordered pre-configured as Model numbers:
• 2000/VC motorised valve controllers
• 2000/VP motorised valve controllers with a single setpoint programmer
• 2000/V4 motorised valve controllers storing four setpoint programs.
• 2000/VM motorised valve controllers storing twenty setpoint programs.
Figure 1-11 in Chapter 1 shows how to connect a motorised valve controller. The control
is performed by delivering open, or close, pulses in response to the control demand
signal.
The motorised valve algorithm can operate in one of three ways:
1. The so-called boundless mode, which does not require a position feedback
potentiometer for control purposes; although one can be connected and used purely to
display the valve’s position.
2. Bounded, (or position), control mode, which requires a feedback potentiometer.
This is closed-loop control determined by the valve’s position.
The desired control mode is selected in the ‘inst’ list in configuration level.
The following parameter list will appear in the navigation diagram shown in Chapter 2, if
your controller is configured for motorised valve control.
Name Description Values
mtrmtr Motor list Min Max Default
tm Valve travel time in seconds.
This is the time taken for the valve to travel
from its fully closed position to its fully open
position.
0.1 240.0 30.0
In.t Valve inertia time in seconds.
This is the time taken for the valve to stop
moving after the output pulse is switched off.
OFF 20.0 OFF
bAc.t Valve backlash time in seconds.
This is the minimum on-time required to
reverse the direction of the valve. i.e. the
time to overcome the mechanical backlash.
OFF 20.0 OFF
mp.t Output pulse minimum on-time, in seconds. Auto 100.0 Auto
U.br Valve sensor break strategy. rESt, uP, dwn dwn