Definition: An electric meter, also known as an electricity meter, electrical meter, energy meter, or kilowatt-hour meter, is used to measure the electrical energy consumed in a specific time period by a building, tenant space or electrically powered equipment.
Electric utilities install electric meters at customers’ premises to measure the amount of electric energy delivered to them for billing purposes. These meters are calibrated in billing units, the most common being the kilowatt hour [kWh]. They are read once during each billing period. One kilowatt hour [kWh] is equal to one unit of energy.
Electricity meters can be used to measure the maximum power usage in a specific period, referred to as demand, to save energy during certain times. “Time of day” metering allows utility companies to charge different rates for kWh consumption during peak, high-cost periods and off-peak, lower-cost periods. Additionally, electricity meters can be programmed to reduce the demand during peak periods. This is known as demand response load shedding.
Units of Energy Measurement
The most widely used unit of measurement on an electricity meter is the kilowatt hour (kWh). One kWh is the amount of energy consumed by a load of one kilowatt in one hour, which is equivalent to 3,600,000 joules.
Types of Electric Meters
There are two types of electric meters- analog and digital meter
Analog Electric Meter
An analog electric meter has two conductor coils that produce magnetic fields. One coil creates a magnetic field by the voltage across the conductor, while the other creates a magnetic field by the current passing through the conductor.
The magnetic fields produced by voltage and current interact and rotate a thin aluminum disc at a controlled speed. The rotating disc moves the dials, and the dial shows the total electricity consumed in kilowatt-hours.
Digital Electric Meter
Digital meters have AC (alternating current) sensors that detect the voltage and current. The measured voltage and current quantities are converted into digital signals using the analog-to-digital converter. The measured energy is displayed in the numeric format.
Digital meters are more accurate than analog electricity meters because they do not have any moving parts. The digital electric meter can be interfaced with the computer, and reading can be shown at remote locations. The past history of electrical energy can also be retrieved from a digital electricity meter.
Smart Meters
Smart meters provide advanced features such as real-time or near real-time readings, power outage alerts, and power quality monitoring. The meter can be set for varying prices based on consumption time and seasonal changes. It is possible to manage energy consumption using smart meters.
These meters use non-intrusive load monitoring to automatically calculate the number, type, and energy consumption of each appliance in a household. Thus, it is a good tool for electric utilities to conduct energy use surveys and eliminates the need to install timers on every appliance in a home to determine their energy consumption.
Why Electric Meter Important?
Electric meters are important for the measurement and management of electrical energy consumption. Here are some key reasons why electricity meters are important:
- Electric meters measure the amount of electricity consumed for accurate billing. Users are billed based on the amount of electricity consumed, usually measured in kilowatt-hours (kWh).
- Electric meters facilitate utility companies to allocate resources effectively by monitoring electricity consumption patterns of areas and customers to plan and distribute power generation and maintenance.
- The load profile of consumers can be determined by load data recorded by Electric meters. The load profile data helps utility companies in balancing the supply and demand of electricity. The data are used for optimization of infrastructure for a reliable power supply.
- Consumers can track their energy uses and, they can take necessary steps for energy conservation. The measurement and monitoring of energy leads to energy saving.
- Utility companies can identify the peak demand periods by measurement of energy and it helps them in upgrading infrastructure to meet growing demand and improving overall grid efficiency.
- Electric meters facilitate in implementation of various tariff structures. Time-of-use tariffs(TOU), for example, charge different rates for electricity consumption based on the time of day. Smart meters enable more sophisticated tariff structures and facilitate dynamic pricing.
- Electric meters help in fulfilling the regulatory standards related to energy consumption and billing. Accurate metering is a legal requirement.
- Based on the energy consumption pattern recorded by the electricity meter, utility companies plan investments in new power generation and distribution infrastructure.