Industrial Engineer · phase 11 of 16 · noun

Internal PID

Drive-based proportional-integral-derivative controller that adjusts motor speed to regulate process feedback.

The Explain card

Plain English
The internal PID is a control loop built into the drive that adjusts motor speed to hold a process measurement at a setpoint. The transmitter wires to the drive and the drive does the whole job.
Example
A booster pump holds 60 psi in a building. The pressure transmitter feeds the drive's analog input, the setpoint is 60, and the drive speeds up or slows down to keep it there with no PLC involved.
Why it matters
For a single pump or fan holding one variable it removes a controller, its program and a network. The loop lives in the drive's parameters, so its tuning and its setpoint are invisible to whoever is looking at the PLC.
Hook
A whole control loop, hiding in the drive.

Word knowledge

How the word is built, where it came from, and what it sits beside in memory.

In a sentence

During commissioning, the technician enabled Internal PID, scaled the 4-20 mA pressure signal, and set the proportional gain and integral time.

Why these words
  • Internal Latin internus, inward or within marks the feature as residing inside the drive rather than in separate control hardware
  • PID English initialism of proportional, integral, and derivative compresses the three control-action names into a standard engineering abbreviation
Where it came from
Origin
English engineering compound combining internal, from Latin internus, with the control initialism PID
Entered the language
late 20th century
What changed
Internal broadened from physical location to built-in functionality, while PID became the conventional abbreviation for three named mathematical control actions.
How it is spelled
Pattern
Internal keeps the regular adjective ending -al.
Pattern
PID keeps uppercase letters because it is an initialism.
Breaks the pattern
PID is pronounced as three letter names rather than as a single word.

Spelled like

  • external
  • regional
  • PLC
  • VFD
Broken into chunks
  • intern-al
    • external
    • regional
  • P-I-D
    • PI
    • PD
What it sits beside

Same subject

  • PID setpoint
  • process feedback
  • analog input
  • VFD commissioning

Same shape

  • external PID
  • internal PLC
  • built-in I/O

PID tuning terms

  • proportional gain
  • integral time
  • derivative time

drive control features

Where it sits in the deck

Phase 11: VFD Control Modes and Tuning

How a drive decides what to send the motor, from plain volts per hertz up to closed loop vector control, and how each mode is tuned.

Neighbours in this phase