Dyson Digital Motor (Vacuum Cleaners)

[Gary]

Who said it was a 20000 RPM motor?
The description doesn’t, the specification only mentioned the no load speed.
In fact the motor is not a 12000 RPM motor, but it will do 12000 RPM continuous at the torque specified inthe torque curve, just like it will do 20000 RPM at the speed is shows in the curve.
The only person who made the misguided assumption that it was 20000 RPM was you, and then claimed it was crap becasue the power at 20000 RPM was not as you expected.
These motors have a variable speed and are designed to be used throughout this speed range, so the torque curves are there to show what you will get at a specific speed.
Show me an AC induction motor manufacture that offers a speed curve?
They don’t offer them because they rate their motors at a known speed.
When you buy a AC induction motor and you ask for a 2800 RPM motor they will sell you a 2 pole motor, but the speed may not be 2800 RPM, and generally varies by about 150 RPM due to slip, but this does not mean that the motor is faulty it is just the design of the motor.
Would you send it back if you were getting 2734 RPM if you run it at 50hz? no you wouldn’t.

When I buy a 2800 RPM motor I expect a 2800 RPM motor....No semantics just what I want.

[Gary]

You made the assumption not me, i was just pointing out your assumption was wrong.