A small electric meter, often referred to as an energy monitor or power meter, is designed to measure the energy consumption of individual appliances or circuits within a house, rather than measuring the total wattage used by all appliances simultaneously. These devices work by monitoring the power usage of different appliances one at a time in a cyclical manner.
Here's how it typically works:
Sampling Rate: The electric meter cycles through various appliances or circuits in your home at a high sampling rate. It may quickly measure each appliance's power usage for a short period, such as every few seconds or milliseconds.
Multiplexing: The meter uses a technique called multiplexing to switch rapidly between different appliances or circuits being monitored. It measures the power consumption of one appliance for a brief moment, then switches to the next, and so on.
Calculating Energy Consumption: While the meter is measuring each appliance, it records the power usage data for that specific appliance. By multiplying the power usage (measured in watts) by the time the appliance was monitored (measured in seconds), the meter can calculate the energy consumption (measured in watt-hours or kilowatt-hours) of that particular appliance during that time interval.
Aggregating Data: Over time, the meter gathers data from all the appliances or circuits it monitors. It stores and aggregates this data to provide information about the energy consumption of each individual appliance and the overall energy usage of your home.
Display: Many small electric meters have a display that shows real-time or historical energy consumption data. Some may also provide information on the cumulative energy consumption of all monitored appliances since the meter was installed or reset.
It's important to note that these small electric meters are generally designed for informative and educational purposes, helping homeowners understand which appliances are consuming the most energy and identify potential energy-saving opportunities. For precise and comprehensive energy billing purposes, utility companies use more sophisticated meters that measure the total energy consumption of an entire household continuously. These utility-grade meters typically have higher accuracy and are subject to strict regulations and calibration standards.