Industrial Engineer · phase 13 of 16 · noun
Twelve-Pulse / Eighteen-Pulse Drive
Multipulse rectifier arrangement using phase-shifted transformer windings to reduce selected line harmonics.
The Explain card
- Plain English
- A multipulse drive feeds two or three rectifier bridges from transformer windings that are shifted in phase. The pulses interleave, and the low order harmonics cancel in the transformer.
- Example
- An eighteen pulse drive on a 500 horsepower compressor has a phase shifting transformer in front of three bridges. Its current THD is near 5 percent with no active electronics.
- Why it matters
- Multipulse is the passive, robust way to meet a harmonic limit on a large drive, and it costs a heavy transformer and cabinet space. The cancellation depends on balanced load and balanced supply, so it works less well than the brochure on a soft line.
- Hook
- More pulses, smoother current, bigger transformer.
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 verifies the Twelve-Pulse drive's transformer connections before measuring input current at the switchboard.
How it is built
- twelve number root the number 12
- - hyphen joins the number to the following technical noun
- pulse noun root a distinct electrical wave or event
Where it came from
- Origin
- English engineering compound formed from Old English twelf and pulse, from Latin pulsus through French
- Entered the language
- 20th century
- What changed
- Twelve retained its numerical sense, while pulse developed from a beat or thrust into a term for a distinct electrical event.
How it is spelled
- Pattern
- A spelled-out number is hyphenated to pulse in multipulse equipment terms.
- Pattern
- Pulse remains singular after the number when the compound labels or modifies equipment.
Spelled like
- six-pulse
- eighteen-pulse
- twenty-four-pulse
Broken into chunks
-
twelve
- twelfth
- twelvefold
-
pulse
- impulse
- pulsation
What it sits beside
Same subject
- phase-shifting transformer
- rectifier bridge
- variable frequency drive
- line reactor
- harmonic filter
Same shape
- six-pulse
- eighteen-pulse
- three-phase
- four-wire
multipulse drive names
- Twelve-Pulse Drive
- Eighteen-Pulse Drive
- Twenty-Four-Pulse Drive
hyphenated electrical compounds
- three-phase
- four-wire
- two-level
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.
