DOMESTIC POWER LIMIT WARNING

Published:2013/5/7 21:26:00 Author:muriel | Keyword: DOMESTIC POWER LIMIT WARNING | From:SeekIC

Since a new electricity meter, the electronic variety, was installed at my place, I get cut off if I exceed the set power level, 3.3KWh in my case. The new meter is unforgiving and although there is a little tolerance built in, you really never know when it has gone over the cut off limit, given the number of electric appliances which are continuously switched on and off. The circuit was designed to give an audible warning when the 3.3KWh limit is exceeded. The transformer is a disused transformer from a soldering gun. It is relatively easy to remove the few turns of the secondary winding and rewind two turns of thick wire, as thick as the wire coming from the meter at least. One turn should be enough if you have a limit of 6.6KWh, but operation at this power level was not tested. As an alternative you may try a small toroidal mains transformer: it is easy to add a few turns of thick wire. Ignore all other windings, if any, except the primary winding, which in our circuit becomes the secondary winding. The circuit is to be installed between the electricity meter with its breaker and the house wiring. With the given components, the circuit will oscillate at 1 sec. on and 1 sec. off, depending on the load. Adjust the potentiometer so that there is no sound below the power limit. The varistor is necessary in case there is a short in the house wiring: the extra voltage at the secondary may damage the circuit. The piezo buzzer can even be placed away from the circuit in any place where it can be easily heard. It goes without saying that you must know what you are doing as working with the household mains can be dangerous and remember to switch off the mains breaker before doing any work on the electric wiring. Do not attempt to install this circuit if you have doubts on its operation, connections and relevant safety measures.



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