Industrial Engineer · phase 9 of 16 · noun
Constant Torque Rating
Drive duty rating intended for loads requiring substantial torque across the speed range, commonly with a higher overload allowance.
The Explain card
- Plain English
- The constant torque rating is the drive's rating for loads that need full torque at any speed, like conveyors, extruders and hoists. It comes with a higher overload allowance, typically 150 percent for a minute.
- Example
- A drive is rated 40 amps constant torque and 50 amps variable torque. On a conveyor that has to start a full belt from rest, the 40 amp rating is the one that applies.
- Why it matters
- A drive sized on its variable torque rating and put on a constant torque load trips on overload the first time the machine starts loaded. The two ratings are the same hardware with different promises, and the application picks which promise counts.
- Hook
- Full torque, every speed, with something in reserve.
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 engineer verifies the Constant Torque Rating before entering the motor current limit for a conveyor drive.
Why these words
- constant Latin constans, standing firm modifies torque by marking it as the unchanged reference quantity
- torque Latin torquere, to twist names the rotational quantity used to classify the rating
- rating rate plus the noun-forming suffix -ing identifies the phrase as an equipment classification
Where it came from
- Origin
- English engineering compound formed from Latin-derived constant and torque with rating
- Entered the language
- 20th century
- What changed
- Earlier words for steadiness, twisting force, and assessed value were combined into standardized motor and drive terminology.
How it is spelled
- Pattern
- constant retains the common adjective ending -ant
- Pattern
- rating drops the final e of rate before -ing
- Pattern
- torque retains the French-derived final -que spelling
- Breaks the pattern
- The final -que in torque is pronounced as a single k sound.
Spelled like
- resistant
- driving
- antique
Broken into chunks
-
const
- constancy
- constantly
-
torque
- torques
- torquing
-
rate
- rated
- rating
What it sits beside
Same subject
- variable torque rating
- overload capacity
- motor nameplate
- current limit
Same shape
- variable torque rating
- constant horsepower rating
VFD duty ratings
- constant torque rating
- variable torque rating
rotational quantities
- torque
- speed
- horsepower
Where it sits in the deck
Phase 9: VFD Ratings, Sizing, and Motor Data
Nameplate arithmetic, where the currents, voltages and duty ratings decide whether a drive can actually run the motor you bolted it to.
