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Topic: How, specifically, does an electric meter measure wattage? (Read 3 times) previous topic - next topic

David82

Would inductive coupling be detected by the meter?

radman

Quote
We have to power something, like a light bulb without the meter registering it.


That seems a very strange task, what exactly are you supposed to learn from it?

If you don't wire round the meter as suggested then the power will flow through the meter which will register it unless you tamper or mess with the meter in some way.

retrolefty

How about you try powering a light bulb with a series capacitor, that may throw off the phase angle enough to cheat the meter. Just be sure you use a non-polarized cap rated for well above the line voltage you are using. Look for 'motor starter capacitors'.

http://www.galco.com/buy/NTE-Electronics/MSC250V161?gclid=COmO7sKh3LQCFWGnPAodOgwAqw

Lefty

PeterH


....the whole circuit is under your control, then you could try either using DC (I have no idea whether meters would detect that) of a very high frequency AC well outside the range the meter is designed to pick up.

what do you mean by this?


Well, if the meter is designed and optimised to detect AC current then it may not detect DC current - or may not detect it well. If you have complete control over the circuit and can arrange for your supply to be DC rather than AC (or to have a significant DC component in addition to the AC) and IF the meter does not measure DC current then you'd be able to get power through the meter without it registering.

Alternatively, if the meter has been designed to selectively pick up mains frequency signals then it may not be able to pick if signals at a much higher frequency. For example, it's possible that if you send an RF signal down the line, the meter would ignore it (it would be filtered out). I'm speculating, because I have no idea what range of frequencies the meter deals with, but if you have full control over the circuit then it would be worth a try.

I don't feel optimistic that any of these approaches will work, but if you have a meter and time to play with it, what do you have to lose? Probably the most promising way to obtain power without it registering at the meter is to cheat. But that's hardly going to get you any credit when it's found out.
I only provide help via the forum - please do not contact me for private consultancy.

David82


How about you try powering a light bulb with a series capacitor, that may throw off the phase angle enough to cheat the meter. Just be sure you use a non-polarized cap rated for well above the line voltage you are using. Look for 'motor starter capacitors'.

http://www.galco.com/buy/NTE-Electronics/MSC250V161?gclid=COmO7sKh3LQCFWGnPAodOgwAqw

Lefty


yea, AC compressors use them right? So digital utility meters measure the phase angle to measure current?

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