Energy meters are the devices used to measure power consumption. They are installed by electric utilities at home, industries, and other places to know electricity consumption. Watt hour meters or energy meters measure the power consumed by various appliances such as lights, fans and television.
The meters display the number of units of electricity consumed at a particular point of time or over a period of time. A unit is equal to consumption of one kilowatt of power in one hour. While watt is basic unit of power, a thousand watts makes one kilowatt.
Energy meters are useful in gauging electricity demand, when energy savings are targeted for a desired period of time. The meters can be helpful in providing details on the peak and off-peak power demand during a day. They operate continuously to measure the consumption.
Many types of energy meters have been introduced over the past several decades as electricity consumption went up sharply. Direct current meters were among the early types of meters developed to measure the electricity consumption. Energy meters are of various types depending on several factors such as display type, metering point, and end usage. There are three basic types of energy meters that include electromechanical energy meters, electronic energy meters, and smart meters.
Electromechanical energy meters: These are one of the most common types of energy meters that operates through electromagnetic induction. The meters consist of a non-magnetic metal disc that rotates at a speed proportional to the power passing through the meter. Power consumed by users will be calculated based on the revolutions of the metal disc. Voltage coils present in the meters constantly use a little amount of power, which is not measured by the devices. Likewise, current coil in the meters also consume power. Power consumption measured by this type of meters should be noted manually. Person employed by utilities usually take readings from the meters to prepare power bills for consumers for a specified period.
Image: Mechanism of electromechanical induction meter in UK. Photo courtesy of en:User:Ali@gwc.org.uk/Wikipedia.
Electronic meters: Energy consumed by users will be displayed on an LCD or LED screens in this type of meters. Some of the electronic meters can also send data to remote places. Apart from power consumption, other parameters of the load and supply are also measured by electronic meters. It can record usage demand, voltages, and reactive power, among others. Besides, the meters can measure the amount of electricity consumed during on-peak and off-peak hours. The meters mainly consist of a metering engine, and a processing and communication engine.
Image: Smart meter used by EVB Energie AG. Photo courtesy of EVB Energy Ltd/Wikipedia.
Smart meters: Apart from simple automatic meter reading, smart meters come with additional functionalities. They can give real-time or near real-time readings, notifications on power outages, and monitor power quality. Smart meters allow power utilities to fix seasonal prices for power consumption. It will also utilities to charge varying prices for power usage during a day. The advanced metering features provided by these devices have prompted many nations to install them on a large scale. In March 2017, E.ON had launched pilot projects to rollout smart meters in four selected regions in Germany. In November 2017, Landis+Gyr introduced new generation of smart meters for electricity and gas in the UK. The smart meters, part of Landis+Gyr's UK smart metering family, were claimed to be the first to comply with the UK government's smart energy standard, smart metering equipment technical specifications 2 (SMETS2). SMETS2 smart meters deliver a wide range of improvements, including interoperability, high security and renewable energy support.