Rockwell Automation 1746-BTM Barrel Temperature Control Module User Manual - Manual (Page 35)

Publication 1746-UM010B-EN-P - April 2001
Configuring the Module 3-9
Thermal Integrity Loss
Detection Words 16 and 17 for Channel 1
The loss of thermal integrity is detected when the loop, in automatic
mode, is not responding to a CV at 100% Detecting the loss of thermal
integrity requires an assumption of a minimum rate of change in the
temperature (PV) when the output (CV) is at 100%. Examples of a loss
of thermal integrity could be the failure of a heating–band contactor to
close, or a sensor not in proper position to measure true temperature.
The values you enter in words 16 and 17 for loop 1 establish a
minimum rate of change (
°
/min.) in the temperature input (PV) that
you allow when the output (CV) is at 100% in automatic mode. The
temperature change value you enter in word 16 divided by the period
value you enter in word 17 is the thermal integrity rate.
Ramp Rates Words 18 for Channel 1
This value ramps the setpoint in steps to the new setpoint.
Non-barrel Autotune
Disturbance Size Word 20 for Channel 1
This is a pure %–output step function for performing a non-barrel
autotune. It is added to the current output (%). It should be applied
under steady–state conditions. The loop operating mode must be
non–barrel.
IMPORTANT
Once loss of thermal integrity is detected, you must
clear this condition by disabling the affected loop
and then re–enabling it. To disable this feature, enter
zero in for both setpoints.
EXAMPLE
Consider this:
•
CV is 10%
•
non-barrel Autotune Disturbance Size is 10%
If an autotune is invoked the CV’s output would go
to 20% for the duration of the Autotune.