Industrial Engineer · phase 14 of 16 · noun
Input Phase Loss
Loss or severe imbalance of an incoming AC phase that increases rectifier and DC-bus stress.
The Explain card
- Plain English
- Input phase loss means one of the three incoming phases has gone missing or is badly unbalanced. The rectifier is left working on two phases, the bus ripple climbs, and the capacitors take the strain.
- Example
- A fuse on one incoming phase blows. The drive keeps running for a moment on the remaining two, then trips on input phase loss as the bus ripple exceeds its limit.
- Why it matters
- Running on two phases cooks the bus capacitors and the remaining diodes, so the trip is protecting the drive. Check the incoming fuses and the disconnect before you look at anything inside.
- Hook
- One leg of the supply is gone and the drive is limping.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
The drive records an Input Phase Loss fault when commissioning tests disconnect one incoming line conductor at the supply isolator.
Why these words
- input English in plus put identifies the equipment side where the condition is detected
- phase Greek phasis, appearance, through French phase names one branch of a polyphase AC system
- loss Old English los, destruction or loss marks the missing or unavailable element
Where it came from
- Origin
- English technical compound formed from input, phase, and loss
- Entered the language
- 20th century
- What changed
- Input moved from the act of putting something in to an electrical supply designation, while phase and loss acquired specialized power-system uses.
How it is spelled
- Pattern
- The phrase is written as three separate words.
- Pattern
- Phase forms open technical compounds such as phase angle and phase sequence.
Spelled like
- output phase loss
- input voltage
- phase sequence
Broken into chunks
-
in-put
- output
- throughput
-
phase
- phase angle
- phase rotation
-
loss
- power loss
- signal loss
What it sits beside
Same subject
- phase imbalance
- phase sequence
- DC bus
- rectifier
- undervoltage fault
Same shape
- output phase loss
- input overvoltage
- input undervoltage
VFD input faults
- Input Phase Loss
- input overvoltage
- input undervoltage
three-phase supply terms
- phase imbalance
- phase sequence
- phase rotation
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.
