Industrial Engineer · phase 8 of 16 · noun

Control Terminals

Low-voltage terminals for digital inputs, analog signals, references, relays, and auxiliary power.

The Explain card

Plain English
The control terminals are the low voltage strip where digital inputs, analog references, relay outputs and the 24 volt supply land. They are how a panel tells the drive what to do without a network.
Example
Terminal one gets the run command from a PLC output, terminal five gets a 0 to 10 volt speed reference, and a relay contact on the strip reports a fault back.
Why it matters
Every terminal has a function assigned by a parameter, so the same wire on two drive brands does different things. Check what the terminal is configured for before you trust the drawing, and keep control wiring away from the motor leads or the reference will wander.
Hook
The drive's own I/O card.

Word knowledge

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

In a sentence

During VFD commissioning, the technician lands the 4–20 mA speed command on the designated control terminals and verifies polarity against the wiring diagram.

Why these words
  • control Anglo-French contrerolle, a duplicate register used for checking acts as a noun modifier that identifies the terminals by their operating purpose
  • terminals Latin terminalis, pertaining to an end or boundary serves as the plural head noun of the phrase
Where it came from
Origin
an English compound combining control, from Anglo-French contrerolle, with terminal, from Latin terminalis
Entered the language
20th century
What changed
Control moved from checking records to governing machinery, while terminal moved from a boundary marker to an electrical connection point.
How it is spelled
Pattern
Only the head noun takes the plural ending: control terminal becomes control terminals.
Pattern
Control doubles its final l before vowel-led suffixes, as in controlled and controlling.

Spelled like

  • power terminals
  • motor terminals
  • signal terminals
  • patrolled
  • compelling
Broken into chunks
  • control
    • controller
    • controlled
    • controlling
  • termin
    • terminal
    • terminate
    • terminus
What it sits beside

Same subject

Same shape

  • power terminals
  • motor terminals
  • communication terminals

VFD terminal groups

  • power terminals
  • control terminals
  • motor terminals

common terminal designations

  • DI1
  • AI1
  • AO1
  • COM

Where it sits in the deck

Phase 8: VFD Drive Hardware and Power Path

Inside the drive: rectifier, DC bus and inverter, the three stages every variable frequency drive uses to rebuild the waveform a motor sees.

Neighbours in this phase