Generally, as PLCs sometimes do not handle PIDs well, I always do some tests on them to check on the operation of their control loops.
read more

The problems encountered in a heater outlet temperature control in a petrochemical refinery were causing considerable difficulties for the operators. Here is another wonderful example of the power of cascade control, even with a really bad control element.
read more

In the real world of industrial process control, P-only control should be used only on processes that are tuned with a large P gain value.
read more

To my amazement I find that people seem to think that because these days we are using ‘smart’ transmitters, the basic rules can be ignored.
read more

There is a commonly held belief in control circles that all PID controllers are similar and relatively simple. This is a dangerous fallacy.
read more

The problem with the pressure control was that it seemed to work intermittently and seldom got to setpoint, resulting in large and unacceptable variance on the control.
read more

There is a commonly held belief in control circles that all PID controllers are similar and relatively simple. This is a dangerous fallacy.
read more

The example given in this article illustrates some mistakes made by the system integrators and control engineers at a metals extraction plant that used a well-known make of PLC and scada for its controls.
read more

An inherent phenomenon occurring in most control valves that few people are aware of is ‘stick-slip’.
read more

A good example that shows how lack of knowledge of the practicalities of control can result in terrible control characteristics.
read more

Over the years I have had many requests to write a book giving more detailed explanations of some of the problems I have encountered in my work on practical loop optimisation. I am by nature and inclination ...
read more

Some of the biggest problems associated with the final control element are hysteresis and backlash.
read more