Electric Watt Hour Meter

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A Watt-hour meter is a measuring device that can evaluate and record the electrical power passing through a circuit at a certain time. By implementing a Watt-hour meter, we can know how much electrical energy is used by a home, business, or an electrically powered device. Electrical utilities install watt-hour meters at their consumer’s premises to evaluate their electrical usage (for billing purposes).

The reading is taken in each billing period. Usually, the billing unit is Kilowatt-hour (kWh). This is equal to the total usage of electrical energy by a consumer of one kilowatt during a period of one hour, and it is also equal to 3600000 joules.

The Watt-Hour Meter is often referred to as an energy meter or electric meter or electricity meter, or electrical meter.

Mainly the watt-hour meter comprises a tiny motor and a counter.

The motor will operate by diverting the exact fraction of current flowing in the circuit to be measured. This motor’s running or turning speed is directly proportional to the amount of current flow through the circuit.

Thus, every revolution of the motor’s rotor is analogous to the given quantity of current flow in the circuit. A counter is attached to the rotor to add, and the usage of electrical energy is displayed from the total number of rotor revolutions.

Attaching a magnet outside of the old energy meter is the common tampering method seen.

The combination of some capacitance and inductive load also results in a reduction in rotor speed. The most modern meter can store up the previous value with time and date.

So the tampering is avoided. Utilities install remote reporting meters to detect tampering. Basically, the watt-hour meter is classified into three different types as follows:.

Electromechanical type induction meter. Electronic energy meter. Smart energy meters.


A non-magnetic and electrically conductive aluminum metal disc is made to revolve in a magnetic field in this type of meter.