How about vacuum cleaners with HP? I guarantee that there isn’t a 3HP motor that works on a 120VAC (RMS) 15A (RMS) circuit.

A friend worked on a blender. The wattage number was derived from the inrush current when first turned on.

I’m glad I don’t have that blender. :) (I’m the proud owner of a blender with a bona fide brushless motor. I don’t know specifically what type, but I suspect the inrush current is quite low. It also outputs considerably more power than most brushed motors can probably manage for any length of time.)

edit: The product blurb says it’s an induction motor. The nameplate says 1000W. It would be fairly straightforward to estimate the efficiency by blending a known amount of water and measuring the temperature change over some period of time.

To be fair, that might be the current draw in stall.

They are basically the same quantity - the motor doesn't care if the rotor is stopped because it's physically locked in place, or just because it was previously not running.

I don’t think so. Attempt the opposite experience: If you turn the motor, electricity comes out. So I don’t know what is the draw when stalling but I guess the draw must vary a lot even inside a north/south cycle.

In fact, the draw varies enough during the cycle that it’s a well known method in industrial ecology to put a condenser on a 60Hz motors when the supply is 50Hz. So there must be a visible cycle.

The magnetic behavior of the windings can depend on this, though. A good example would be a toroidal transformer, which tends to have a high inrush current, even if the output is open circuit.

Yeah I remember when they switched from RMS to PMPO. Overnight a big speaker system went from 50-100W to 2kW or something ridiculous.

Yes, some amplifiers would be advertised with nonsense like “watts RMS”. The concept of “watts RMS” makes no goddamn sense.

Actually in the US, the term "Watts RMS" specifies that the measurement is done according to the FTC Amplifier Rule. Now that rule has its own pro's and con's of course, but at least it's pretty definite. With all of these things, there's a corresponding European rule as well.

Whether the measurement method is appropriate to your use of an amplifier is of course anybody's guess.

Considering that the load impedance of audio amplifiers isn't always the same, it'd be a bad idea to measure output voltage in terms of gain compression points/clipping/max continuous.

I agree the term "RMS" is kinda miss-appropriated, but it's short and tends to understood as something reasonably close to what it's actually about.

No, that's just shitty vendors being shitty.

Accurate RMS can easily be calculated and advertised. Check out Steve Meade and his tools/videos if you're unaware.

Most prominent brands just choose to market absolute bullshit numbers - people who know what they're actually after know how to find the brands who publish real numbers.