OMNI 4000/7000 Operations and Maintenance Guide
– Rev F
6-27
Front Panel Operations
Startup and Shutdown Ramping
Functions
Startup and shutdown ramping functions are enabled when a startup and/or shutdown ramp rate
between 0 and 99% is entered during PID configuration (Section 3.7).
On the bottom of the main PID Control screen (Figure 6-3), there are three command function
keys (besides Override, as discussed in Local and Remote Setpoints):
•
Start
– Begin the process of the valve ramping open (start the batch).
•
RampDown
– Begin the process of the valve ramping down to the minimum percent open.
•
Stop
– Immediately close the valve after it has been ramped to the minimum percent open
and stop the flow.
Figure 6-3: PID Control Screen
Inputs are provided for startup and shutdown ramp rates and minimum output percentage
settings. When these startup and shutdown ramp rates are applied to the control output,
movements will be limited to the stated percentage of movement per half-second. On receipt of a
shutdown signal (the RampDown function key), the output will ramp to the minimum output
percentage for top off purposes.
PID Control Tuning
Individual control of gain and integral action are provided for both the primary and secondary
control loops.
To tune PID loops, follow these instructions:
1.
In the
PID Control
screen for your
selected loop, press the
Override
function
key on the bottom left to enter the
Manual
Override
screen.
