Industrial Engineer · phase 3 of 16 · noun
PID Control
Closed-loop control calculation using proportional, integral, and derivative action to regulate a process variable.
The Explain card
- Plain English
- PID is the loop that steers a process toward a setpoint by looking at the error between where it is and where it should be. Proportional reacts to the size of the error, integral to how long it has lasted, and derivative to how fast it is changing.
- Example
- An oven setpoint is 350 degrees and the temperature reads 340. The loop raises the heater output, and as the error shrinks it eases back so the oven settles instead of overshooting.
- Why it matters
- Almost every continuous process, from tank level to line pressure to drive speed, is held by a PID loop. Tuning the three gains is where an engineer earns the title, and a badly tuned loop oscillates for years.
- Hook
- Now, how long, and how fast.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
During commissioning, the engineer tuned PID Control in the PLC while watching the tank level trend from the 4-20 mA transmitter.
Why these words
- PID English initialism of proportional, integral, and derivative identifies the three mathematical terms associated with the control method
- Control Middle English control, from Anglo-French contrerolle, a duplicate register used for verification serves as the head noun and places PID within automatic control engineering
Where it came from
- Origin
- English engineering phrase formed from the initialism PID followed by control
- Entered the language
- 20th century
- What changed
- Control broadened from checking records to governing machines and processes, while proportional, integral, and derivative was compressed to the initialism PID.
How it is spelled
- Pattern
- PID keeps all three letters capitalized because each represents a separate word
- Pattern
- Control doubles its final l before vowel-led suffixes, as in controlled and controller
Spelled like
- PLC
- VFD
- controlled
- controller
Broken into chunks
-
PID
- PLC
- VFD
-
control
- controller
- controlled
Where it sits in the deck
Phase 3: PLC Program Organization and Execution
How the logic is arranged and how the scan actually runs it, which is the difference between code that works and code that works every time.
