Industrial Engineer · phase 16 of 16

ASD

Adjustable Speed Drive, another broad term for a motor-speed control system.

The Explain card

Plain English: Adjustable speed drive is another general term for a motor speed control system, used mostly in North American standards and utility programs. It means the same thing as VSD.
Example: A utility rebate program pays for ASDs on HVAC fans. The equipment installed is an ordinary VFD, and the paperwork calls it an ASD.
Why it matters: You will meet this word in codes, rebate forms and older engineering documents, and it refers to the same equipment. Knowing the aliases keeps a standard from looking like it is talking about something else.
Hook: Same drive, different acronym, usually on a form.

How the word is built, where it came from, and what it sits beside in memory.

In a sentence

During commissioning, the technician enters the motor nameplate data into the ASD before running autotune and checking rotation.

Letter by letter

Where it came from

Origin: an English electrical-engineering initialism formed from the initial letters of adjustable speed drive
Entered the language: 20th century
What changed: The label was applied to several drive technologies and later remained an umbrella term alongside the more specific VFD.

How it is spelled

Capitalisation: Written ASD in uppercase, including mid-sentence
Plural and possessive: The plural is ASDs, the singular possessive is ASD's, and the plural possessive is ASDs'.
Out loud: Spelled out letter by letter.

Same family

Broken into chunks

What it sits beside

Same subject

Same shape

motor-drive initialisms

drive commissioning terms

Phase 16: VFD Related Drive Terms

The drive family's wider vocabulary, from soft starters and servo drives to the regenerative units people also call a drive.