Working of energy meter?

An electric meter or more commonly used term, the electricity meter is meant for measuring the total electrical energy consumed in a house, shop, offices etc and the units of measurements are usually kilowatt-hour (KWh). The electric meter working involves computing the integral over time of the electrical power in Watts consumed on the power network delivered to a particular connection. This electrical power is measured by performing the product of the line current in Amps and the line voltage in Volts.

Let us know have a look at the working of an electric meter. The electric meters generally comprises of two parts -- a transducer to convert the power into a mechanical or electrical signal, and a counter to integrate and display the value of the total energy that has passed through the meter. One of the easiest and the simplest ways to measure the line current and voltage for single phase electronic meters are line current and line voltage.

In multi-phase meters (many homes have 2 or 3 phases of electricity supply, providing more power), voltage and current measurements have to be electrically isolated for each phase and transformers are used instead of shunts for current sensing.

Let us have a look at the working of an electric meter which is meant for residential connections. Usually domestic electric meter is enclosed in a glass case in which contains a revolving disk which in turn rotates a series of numbers or dials. When the electric current passes through the meter, the disk rotates to measure the exact amount of kilowatts used. The speed of rotation varies depending on how much electricity you are using in your house for particular device such as running a washing machine, microwave and water heater etc. It is important to note that different electric appliance uses different amount of electricity for its operating. More the utilization of electric power, the faster the speed of rotation of disks.

The electric meter working in case of watt hour meters is explained here. The electromechanical type meter has the spinning wheel in it and the other type of meter is a solid state type. The solid-state types make use of a current transformer to measure the current produced in the current-carrying conductors, which means that the current carrying conductors need not be connected to the actual measuring device. The electromechanical type uses an aluminum disc acted upon by two coils. One coil is positioned in such a way as to produce a magnetic flux in proportion to the voltage on the disc, and the other coil produces magnetic flux proportional to the current.