Industrial Engineer · phase 14 of 16 · noun
DC Bus Undervoltage
Trip or warning caused when DC-link voltage falls below the level needed for reliable operation.
The Explain card
- Plain English
- A bus undervoltage warning or trip means the DC link has dropped below what the drive needs to run the motor properly. The line sagged, a phase went missing, or the supply was switched off.
- Example
- A large motor starts across the line on the same feeder. The voltage dips for half a second, the drive's bus falls below its limit, and the drive trips or rides through depending on its settings.
- Why it matters
- Undervoltage tells you about the supply rather than the drive. Ride through settings, a kinetic buffering function that uses the load's inertia to hold the bus up, and a stiffer feeder are the answers, and none of them is a new drive.
- Hook
- The drive noticing that the lights flickered.
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 traced a DC Bus Undervoltage fault to input-voltage sag while the conveyor drive accelerated.
Why these words
- DC abbreviation of direct current identifies the electrical domain of the bus
- Bus English busbar, shortened from omnibus bar names the shared electrical conductor or link
- Undervoltage English under- plus voltage classifies the voltage condition affecting the bus
Where it came from
- Origin
- English engineering compound formed from DC, bus, and undervoltage
- Entered the language
- 20th century
- What changed
- Bus narrowed from a general shared carrier to a common electrical path, while undervoltage became a standard technical compound.
How it is spelled
- Pattern
- DC remains an uppercase initialism
- Pattern
- bus is spelled with one final s in the singular
- Pattern
- undervoltage is normally written as one closed compound
Spelled like
- DC link overvoltage
- AC bus undervoltage
- DC bus overvoltage
Broken into chunks
-
DC
- DC link
- DC supply
-
bus
- busbar
- fieldbus
-
under
- undercurrent
- underfrequency
-
volt
- voltage
- voltmeter
-
age
- amperage
- wattage
What it sits beside
Same subject
- DC link capacitor
- input phase loss
- line reactor
- drive fault
- acceleration ramp
Same shape
- overvoltage
- undercurrent
- underfrequency
drive voltage conditions
- DC bus overvoltage
- input undervoltage
- output overvoltage
compound electrical quantities
- undervoltage
- overcurrent
- underfrequency
Where it sits in the deck
Phase 14: VFD Safety, Faults, and Diagnostics
What a drive does when it trips, what the fault codes are telling you, and how safe torque off stops the motor without killing the panel.
