lag time utility in control system

E

Thread Starter

engineer

in many pid controllers, i have seen the option of lag time setting. it has been my observation that it has been kept at a minimal value, and this is what it should be (generally). in which situation the lag time value should be increased and can be used favourably?
 
that's not the way its supposed to be..

even if someone is not very sure about this issue, we can still have discussion. i just can't digest nobody has ever set the time lag thing!
 
my own experience has been that "lag" settings need to be minimal with process plant, continuous controls.

the simulation runs and experience in a sampled data system with long transport delay was that "lag compensation" hurt as much as helped. In our case, product buildup in the final control element, and system non-linearities (hysteresis)led to instability that proportional control handled more effectively.

lag compensation seemed to fit command controls in a servo arrangement much better
 
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