Electric Meters

[MinnieCauldwell]

Question for the electricians out there.

I presume (maybe I am wrong) that the electricity meters work by measuring current, Amperes, and a form of clock to generate KWhrs.

Would I also be wrong in thinking that the meter will have been calibrated using 220V?

My theory is this - If the meter is "BASED" on 220V and doesn't actually know the ACTUAL voltage, it simply assumes 220V and then relates the Amperes used over time to calculate this, e.g 1KWhr, would be something like 4.54 Amps at 220V for 1 hour?

So, assuming as in my case, I do not get 220V, at worst I get about 190, so put this into the same reasoning, if I have an appliance that is requires 1000W to operate, it will take 1000W of energy from the supply, that would give me 5.26 Amps per hour at 190V.

You see where I am going with this...if this is how the energy used is calculated, then I am being overcharged by approximately 14%! All due to the Electricity Company's inability to supply enough oomph!

Is this possible or not?

Cheers!

[Crossy]

NO, your assumption is incorrect.

Electricity meters, even the old electomechanical ones, are true Watt-Hour meters, directly measuring the number of Watts you are consuming using continuous measurements of voltage, current and power factor.

Demonstated in our Uni. 'machines' lab by a lecturer called Mr (Fray Bentos) Bentley, one regular kWh meter with volt and ammeters, connected to a capacitor load (PF=0). Lots of Volts, quite a few Amps but NO power, the meter did not move

Additionally, only heating appliances have a linear voltage / current curve. Motors and even regular light bulbs have very strange characteristics when being under-volted, you cannot assume that an appliance will 'always' pull its rated power.

Unless your mains is VERY (50%) low or has a severely distorted waveform then the meter will quite happily bill you correctly

Edited October 23, 2008 by Crossy

[MinnieCauldwell]

NO, your assumption is incorrect.

Electricity meters, even the old electomechanical ones, are true Watt-Hour meters, directly measuring the number of Watts you are consuming using continuous measurements of voltage, current and power factor.

Demonstated in our Uni. 'machines' lab by a lecturer called Mr (Fray Bentos) Bentley, one regular kWh meter with volt and ammeters, connected to a capacitor load (PF=0). Lots of Volts, quite a few Amps but NO power, the meter did not move

Additionally, only heating appliances have a linear voltage / current curve. Motors and even regular light bulbs have very strange characteristics when being under-volted, you cannot assume that an appliance will 'always' pull its rated power

Unless your mains is VERY (50%) low or has a severely distorted waveform then the meter will quite happily bill you correctly

OK, thanks again Crossy!