Offset

What it means

Offset is what a proportional-only controller leaves behind. Proportional action produces output in proportion to error, so it needs error to produce output — the loop settles where the proportional term balances the load, not at setpoint.

Integral action exists specifically to remove offset. A loop showing persistent offset either has no integral action, has integral action so slow it has not finished, or has an output sitting at a limit where no amount of integral action can help.

Related

Where this comes up

• Sluggish control loop
• Controller output saturated
• Control loop will not hold setpoint
• Reset units converter
• Tuning level control loops
• Integral windup