Crossy & Forkinhades:

1. "A conventional kWh meter connected to a purely reactive load (L or C) will not spin regardless of the current being drawn." Correct, the power factor is zero (0), hence zero disk torque developed and minimum disk rpm.

2. "The rotational speed is directly proportional to the Real Power consumed, Reactive Power (the bit at 90^o) is mostly ignored by the meter." Correct, with no reactive power present the real power is maximum and the power factor is unity (1), hence 1 per-unit disk torque and maximum disk rpm.

3.Between minimum and maximum disk rpm, between a power factor of 0 and 1, the torque (rpm) on the disk is proportional to the power factor. Example, with a power factor of 0.5 the aluminum disk will rotate at 50% of it's 1 per-unit speed.

4. Real power in a single phase circuit is directly proportional to [Volts*Amps*Power factor]. The greater the power factor the faster the aluminum disk spins and more kWhr registered.

5. Therefore, kWhr disk speed (rpm) is proportional to power factor.

OK, IO (sorry for calling you IA earlier) agreed.

You should have included the constraint, with constant VA (Apparent Power)

Either way, these "power saving" devices (with, as noted earlier, the exception of voltage optimisation) are either snake oil or (at the very least) illegal.

So we do agree (phew)

They don't do anything illegal in LOS do they? Certainly not the nice young man who graduated from computer programming in my village selling and installing creative devices...........that aren't snake oil. So tempting.........but time in a Thai prison or being blacklisted has a way of doing away with temptation. Whilst my neighbours steal the available power by running the AC with the door open.