Bad Control Loop or Bad Instrumentation

Before you try to tune that loop…

Many operators find themselves in a situation where their control loop is swinging around excessively.   Where just last month things were working nicely, now your regularly lifting a safety valve of scrapping a batch of product; your first reaction may be “It’s a logic problem”…  More often then not, your wrong.  Adjusting PID parameters in this situation may cause more problems than it fixes.  Before diving into your tuning parameters consider checking your hardware.  Maybe your primary flow element is showing signs of wear, or your pressure transmitter is out of calibration.  These are good starting points, but an even more common problem is the valve positioner is not working as well as it could be.  Check for worn feedback linkage, and leaky pneumatic components…  Consider Montana Controls for a free control loop checkup.  Contact Us