Watt Meter

[adaml]

Just wondering whether anyone had played with one of these on a 12v system as a toy?  I am guessing it will not work as a watt hour meter being 240v?



Any thoughts otherwise it is scrap.

Thanks as always.

[prasadbodas2000]

this has been of interest for me too, but I have an electronic version with me - a probably faulty (hence discarded) meter from the utility company. When I did some post-mortem on it, it has 2 inductors in it, some very small sized circuitry, 2 button sized batteries (which seem to have gone dead) and a LCD display

the idea to use/adapt this for some meaningful RE measurements of power (may be within 5-10% of accuracy) is fantastic, but need some guidance....

[Flux]

"Just wondering whether anyone had played with one of these on a 12v system as a toy?  I am guessing it will not work as a watt hour meter being 240v? "

The 240v is an issue but not the major one. The big snag is that it is an ac omly induction device thet doesn't work on dc.

Flux

[prasadbodas2000]

rite - but then can it be somehow converted to read lower voltage range and higher current ranges in one of the 3 phase lines of the homemade wind turbine generator? I guess the inductors which sense the voltage and/or current need to be wound with different coils or replaced with something matching....?

[Flux]

Anything is possible but it would not be particularly accurate. They tend to only be accurate over a small frequency range over which the various compensations work. Most wind turbines run at relatively low frequency and you would have trouble with the iron circuits saturating.

If you had a turbine with more poles than usual then you could probably modify it to work over the 50/60hz region at lower volts but the phase angle of the voltage circuit would probably be way off. the current could be dealt with with a current transformer. Far better to use it to measure the output of your inverter but again it may not be too accurate with a modified sine inverter.

Flux

[adaml]

Dear All,

Thanks for the comments.  What I ended up doing was taking the input into the meter from my invertor then obviously the output to the loads I run, being a small system, small loads.  However, the meter does indicate that in the last month this has saved £1.30!!!!!!  A long, long way to go to get any payback for the investment over the last few years but for me that is not the point anyway.