kungfufighter wrote: ↑Thu Jul 02, 2020 5:19 pm
v12 wrote: ↑Thu Jul 02, 2020 4:22 pm
Take care to monitor the AC voltage, there is the trick.......
Yes. In most of the pics they seem to be measuring the voltage with a ring meter. Which is no good, as the supply goes up and down all the time. They should install a parallel meter and check it after a month. I suspect that the problem isn't with the meter though.
Have a look at an ohm's law calculator and just put in the watts of the appliance and muck about changing the resistance. Watch what happens to the voltage.
Leave everything blank except for the watts and add 50 ohms resistance.
1000 watts @ 50 ohm's = 223.6068 volts.
Now blank everything and try 1000 watts at 25 ohms.
It should read 158.11388 volts.
That may be your problem.
Better stick with your Kung Fu.
The metering device does measure the (effectively integrated over time) current. The current corresponds with a speed of the rotating wheel and the number of wheel rotations ends up as digits on the metering device.
The "ring meter" does measure the current (and I do think, it does have some averaging function build in, to come to a similar value as the metering device itself).
So, the ring meter does show "the same" as the metering device, so everything should be "OK", NOT.
A parallel meter mounted will show the same.
What you "pay" to EDC is the energy delivered, ie power * time, ie current * "assumed voltage" * time. The metering device does only measure the current and time, voltage is assumed to be 230V AC.
When the "actual voltage" gets structurally lower than the "assume voltage", the amount of energy delivered is lower than the energy paid for, based on the figures shown on the metering device.
The amount of energy is relevant, because if the AC does run at a lower voltage, it'll run for a longer time, will consume the same real energy, but consume a higher EDC energy amount.
That is how it works. That is what does cheat.
(And of course, it could be, in the past, the voltage was "higher" (270 V AC or so) and is now "normal" or "lower").
(And technically, there are some more options, like the actual wave form and the effective cos-Phi).