Industrial Engineer · phase 11 of 16 · noun
Speed Control
Operating mode in which motor speed or frequency is the primary regulated variable.
The Explain card
- Plain English
- In speed control the drive regulates the speed or frequency and supplies whatever torque it takes to hold it, up to its limits. This is the normal mode for almost everything.
- Example
- A conveyor is set to 40 hertz. As boxes land on it the load rises, the drive supplies more torque, and the speed stays at 40.
- Why it matters
- Most applications want a speed and let the torque follow, so speed mode is the default and torque mode the exception. How well it holds speed under load depends on the control mode underneath, from V/Hz drifting a few percent to closed loop vector holding within a fraction.
- Hook
- Hold the speed, spend whatever torque it takes.
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 enabled Speed Control and verified the encoder feedback against the commanded frequency.
Why these words
- speed Old English spēd, success or prosperity identifies the measured aspect of motor motion
- control Middle English control, from Anglo-French contrerolle, a counter-register used for checking marks the phrase as a regulated operating function
Where it came from
- Origin
- English compound formed from speed and control
- Entered the language
- 19th century
- What changed
- Speed moved from success and prosperity to swiftness and rate of motion, while control moved from checking records to directing machinery.
How it is spelled
- Pattern
- The ee digraph in speed represents the long vowel sound heard in feed.
- Pattern
- Control doubles its final l before vowel-initial suffixes, as in controlled and controller.
Spelled like
- feed
- seed
- controlled
- controller
Broken into chunks
-
speed
- speedometer
- speedy
-
control
- controller
- controllable
What it sits beside
Same subject
- variable frequency drive
- encoder feedback
- frequency reference
- acceleration ramp
Same shape
- torque control
- position control
- pressure control
Drive control modes
- Speed Control
- torque control
Motor feedback signals
- encoder feedback
- tachometer feedback
Where it sits in the deck
Phase 11: VFD Control Modes and Tuning
How a drive decides what to send the motor, from plain volts per hertz up to closed loop vector control, and how each mode is tuned.
