The goal of our project is to design a low-cost power meter that accurately measures and displays the instantaneous active power, and kilowatt/hour usage of 4 individual 120V/20A household circuits. The meter should be able to display this information on each individual circuit along with the total instantaneous power and kilowatt/hour usage for all circuits. The accumulated kilowatt/hours should not be erased when the unit is disconnected, but can be cleared manually by hitting the reset button. The meter must be easily expandable to support up to 16 circuits. The meter will interface directly to a household circuit breaker box with clip-on current transformers. This meter should be easy to read and use. Our target budget is to not exceed $100 for the prototype.

The only measurable technical goals of the power watt meter are its accuracy. The instantaneous power error of the meter should not exceed 5% of the actual instantaneous power of the circuit. This will also ensure that the kilowatt-hours error is less than 5%. This meter should be able to keep this tolerance within its normal operating range of 0°C-50°C.