Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Motion control and drives

Adjustable-speed drive (ASD)

Also known as: Adjustable-speed electrical power drive system, Variable-speed drive

German: Drehzahlveränderbarer Antrieb

In industrial automation, an adjustable-speed drive (ASD) is a drive system whose motor speed can be set and changed during operation, typically by power electronics that control the voltage and frequency or current fed to the motor. IEC 61800 calls the complete arrangement an adjustable-speed electrical power drive system.

  • Motion control
  • Standards

In one sentence

An adjustable-speed drive lets a machine run its motor at a set, changeable speed, usually via power electronics such as a frequency inverter.

Example

A pump skid uses an adjustable-speed drive to reduce motor speed at partial load instead of throttling the flow with a valve.

How it applies

  • Engineering: Drive, motor and cable are selected as one system. The drive's rated current, overload capacity and braking concept must match the load cycle, not only the motor's nominal power.
  • Commissioning: Motor nameplate data, ramps, speed limits and the control mode are entered as parameters and saved as part of the machine's configuration.
  • Operation: Speed is set by an analog signal, a fieldbus or a drive profile such as PROFIdrive. Diagnostics report faults like overcurrent or overtemperature.
  • Documentation: Describe speed ranges, parameter sets and fault codes in the Operating manual and Maintenance manual. Warn that the DC link can hold Stored energy after the drive is switched off and state the waiting time given by the drive manufacturer.

Adjustable-speed drive vs. variable-frequency drive

Adjustable-speed drive is the umbrella term: it covers DC drives, Servo drives and Variable-frequency drive (VFD)s. A VFD is the most common kind for AC motors; it changes speed by changing the output frequency.

By knowledge.aitechdoc.world · Published September 26, 2026 · Last reviewed

Source: IEC 61800-2, Adjustable speed electrical power drive systems — Part 2: General requirements — Rating specifications for low voltage adjustable speed AC power drive systems

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Blog and are not part of any standard.

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