Other Pid Settings; Troubleshooting Procedure; Tips For Specific Problems - Trane Tracer MP501 Installation, Operation And Maintenance Manual

Other PID Settings

Use the following settings to manage PID loops:
•
•
•
•
Note: For more information, refer to the PID Control in Tracer Multi-Purpose Controllers

Troubleshooting Procedure

Important:
Follow these steps to troubleshoot a PID loop:
41. Ensure that the system is not in override.
42. Graph the process variable, setpoint, and valve position over time to determine how the system
43. Check for failure conditions that are always TRUE.
44. Check PID settings for:
45. Check the system for disturbances from:
46. Change PID gains.

Tips for Specific Problems

Table 11
Table 11. Tips for specific problems
Problem
Measured value is cycling
around setpoint
Overshooting setpoint
Undershooting setpoint
Output at maximum
Output at minimum
CNT-SVX08F-EN
Proportional bias, which takes the place of derivative gain in proportional-only control
Minimum and maximum output, which limit the range of output of the PID algorithm
Enabled and disabled modes, which enable the PID output or disable it to a default value
Fail-safe mode sets the PID output to a "safe" value if the hardware input that provides the
process variable fails.
Applications Guide (BAS-APG002).
Remember to change only one troubleshooting step at a time.
performs.
Look at the overall situation— Can the system do what is expected of it? What is happening to
the process variable? Is it oscillating or failing to reach setpoint? Is the output oscillating?
– Output minimum incorrectly set to 100%
– Output maximum incorrectly set to 0%
– Sampling time that is too fast or too slow
– Bad actuator linkages
– Faulty sensors
– Reduce gains if experiencing system overshoot, output at minimum or maximum, or cycling
of output around setpoint
– Increase gains if experiencing system undershoot
lists tips for troubleshooting specific problems.
Tips
Slow the sampling frequency
Decrease PID gains
Reduce gains
Increase gains
Ensure that minimum output is not set to 100%
Ensure that maximum output is not set to 0%
PID Control
41