Industrial Engineer · phase 1 of 16 · noun

Power Supply

Module that converts incoming plant power to the regulated voltages required by the controller and its modules.

The Explain card

Plain English
The power supply takes the plant's incoming AC or DC and turns it into the steady low voltages the CPU and modules run on. It feeds the backplane, and often nothing else.
Example
A 120 VAC supply on the end of the rack delivers 5 V and 24 V to the slots. The field devices out on the machine usually get their own separate 24 V supply.
Why it matters
A supply sized for today's rack browns out when you add three more cards, and a brownout shows up as random faults nobody can reproduce. Check the load budget before you blame the software.
Hook
Weird faults after an expansion usually start at the end of the rack.

Word knowledge

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

In a sentence

On a ControlLogix chassis, the power supply on the left end puts 5 V and 24 V on the backplane once 120 VAC is landed on its input terminals.

Why these words
  • power Anglo-French poer, ability, from Latin posse, to be able names what is being furnished, so the phrase is about electrical energy rather than political might
  • supply Latin supplere, to fill up, from sub- and plere names the providing, so the phrase points to a source that keeps furnishing rather than a one-time stock
Where it came from
Origin
English open compound, from Anglo-French poer (ability, from Latin posse, to be able) and Latin supplere (to fill up)
Entered the language
1920s
What changed
Power meant ability in Middle English, then political might, then the work a machine could do, then the electricity that does that work. Supply meant to fill up, then the stock on hand. Radio parts lists of the 1920s paired the two words for the box that feeds a set, and plant drawings kept that open compound for the module on a PLC rack.
How it is spelled
Pattern
ow spells the diphthong /aʊ/ in power, as it does in tower and flower
Pattern
Latin sub- assimilates to sup- before p, doubling the consonant
Pattern
final y after a consonant becomes i before a suffix, so supplies and supplied
Breaks the pattern
the noun phrase stays two words; a hyphen appears only when the phrase modifies another noun

Spelled like

  • tower
  • flower
  • support
  • applied
Broken into chunks
  • power
    • powerful
    • empower
    • overpower
  • ow
    • tower
    • flower
    • shower
  • sup
    • support
    • suppress
    • suppose
  • ply
    • apply
    • imply
    • comply
What it sits beside

Same subject

Same shape

  • power plant
  • power factor
  • water supply
  • air supply

Rack modules

Open power compounds

  • power plant
  • power factor
  • power quality

Supply compounds

  • water supply
  • air supply
  • blood supply

Where it sits in the deck

Phase 1: PLC Controller Hardware

The box itself, from processor and rack to the modules that plug into it, because nothing else in the deck lands until you know what a PLC physically is.

Neighbours in this phase