Industrial Engineer · phase 13 of 16 · noun

DC Link Choke

Inductor in the DC link used to smooth current and reduce stress and line harmonics.

The Explain card

Plain English
A DC link choke is an inductor in the DC bus, between the rectifier and the capacitors. It smooths the current into the capacitors and reduces the line harmonics in much the same way a line reactor does.
Example
Many mid sized drives ship with a DC choke built in. Their input current is cleaner than a bare six pulse drive without any external reactor.
Why it matters
A drive with a built in choke may need no line reactor for harmonics, though it still gains transient protection from one. Knowing whether the drive has one changes what you specify and what the harmonic study assumes.
Hook
The reactor that lives inside the drive.

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 verified the DC link choke rating before energizing the rectifier and inverter power path.

Why these words
  • DC English initialism of direct current specifies the electrical domain of the link
  • link Old Norse hlekkr, a chain link names the intermediate circuit joining the rectifier and inverter
  • choke Middle English choken, to constrict serves as the component head noun through an electrical analogy
Where it came from
Origin
English technical compound formed from DC, link, and the electrical sense of choke
Entered the language
20th century
What changed
Direct current became DC; link broadened from a chain ring to an electrical connection; choke acquired its electrical coil sense in the late 19th century.
How it is spelled
Pattern
DC remains uppercase as an initialism
Pattern
The three elements form an open compound with spaces
Breaks the pattern
DC is pronounced as separate letters rather than as a single word

Spelled like

  • AC line reactor
  • DC bus capacitor
  • DC link capacitor
Broken into chunks
  • DC
    • AC
    • HVDC
  • link
    • linkage
    • interlink
  • choke
    • choked
    • choking
What it sits beside

Same subject

Same shape

  • DC link capacitor
  • DC bus reactor
  • AC line choke

VFD power-path components

reactive components

  • choke
  • reactor
  • capacitor

Where it sits in the deck

Phase 13: VFD Power Quality, Wiring, and Motor Protection

Harmonics, reflected waves, shielded cable and bearing currents: the side effects a drive inflicts on everything around it.

Neighbours in this phase