Parts & Function of Kilowatt Hour Meter

Hunker may earn compensation through affiliate links in this story.
Kilowatt-hour meters measure the consumption of electrical energy.

Energy meters refer to devices designed to calculate the amount of electrical energy used by offices and residences. Kilowatt-hour meters are one type of frequently used energy meter.


A kilowatt-hour meter contains an aluminium disc, which is supported by a spindle with a worm gear. The worm gear drives the register, or series of dials used to record how much energy is used. The kilowatt-hour meter also contains coils, which work in conjunction with the disc, and a permanent magnet.


Kilowatt-hour meters calculate electrical energy consumption in billing cycles, which are measured in kilowatt-hours, or units of energy equivalent to 1,000 watt-hours. Periodic readings taken by kilowatt-hour meters establish billing cycles utilized by utility companies.


One coil connects to the disc and creates a magnetic flux in proportion to the voltage received. The other coil generates a magnetic flux proportional to the current. The voltage coil's magnetic field is delayed via a lag coil, which results in eddy currents flowing through the disc. These currents exert force on the disc proportional to the coil's current and voltage. A permanent magnet exerts an opposing force on the disc. These forces result in a disc-speed rotation proportional to the power generated. The disc activates a register device, which counts disc revolutions in order to calculate energy consumption.


Andrea Stein

Andrea Stein has been writing since 2004. She was a features editor for "Hallmark Magazine" and has served as newsletter editor for several nonprofit organizations. Stein has also worked in public relations, marketing and administration. She earned her Bachelor of Arts in English from the College of Dupage in Illinois.