What is Digital Meter and How Does It Work?

What Is Digital Energy Meter?

A digital energy meter, often referred to as a smart meter, employs advanced digital technology to measure and record electrical energy consumption. This electronic device plays a crucial role in managing and safeguarding electricity in intelligent systems. Utilizing microprocessor and computer technologies, it ensures precise energy measurement, data collection, and industrial control applications. In modern power systems, digital energy meters have become indispensable devices. This article provides an introduction to the characteristics, applications, and operational principles of digital energy meters.

Key Features

Digital meters offer several noteworthy performance characteristics, including:

1.      High Resolution: Most digital meters possess exceptionally high digital resolution, making them adept at detecting even the slightest fluctuations in current and voltage.

2.      High Precision: These meters utilize microprocessor technology to provide highly accurate data, typically with an accuracy level of 0.2% to 0.5%, surpassing traditional energy metering instruments.

3.      High Reliability: Digital ammeters, thanks to their advanced digital technology, are renowned for their high reliability. They generally have a service life exceeding 10 years and can reliably function in various environmental conditions.

4.      Low Energy Consumption: Digital meters consume significantly less power compared to traditional counterparts, leading to substantial energy savings when efficiently managing electricity consumption.

Application Scenarios for Digital Meters

Digital energy meters find application in a variety of scenarios:

1.      Energy Management: They are used to measure capacity, monitor current and voltage, consider time and power factors for precise energy management, and offer features like energy-saving alerts, ensuring continuous power supply.

2.      Power Industry: In the power sector, the installation of digital energy meters aids in remote measurement, monitoring, and control, contributing to energy conservation, safety, and cost-effective operation.

3.      Intelligent Buildings: Smart buildings benefit from these meters by identifying and controlling power usage in various facilities, reducing power consumption and overall operational costs through effective management.

4.      Industrial Management: Digital DIN-rail mounted energy meters assist in data measurement and industrial production management. They record electricity consumption, evaluate factors such as door and window usage time, helping factories reduce energy consumption, cut costs, and enhance production quality.

5.      Vehicle Electronics: Digital energy meters can be applied to vehicle electronics, tracking power usage, determining the timing and load on each system, and aiding in fault diagnosis and protection, thereby enhancing car safety and reliability.

Working Principle of Electric Energy Meters

Electric energy meters function on the basis of the following principle:

When connected to the circuit under test, alternating current flows through the current coil and voltage coil, inducing alternating magnetic flux in their respective iron cores. This magnetic flux induces an eddy current in the aluminum disk. The eddy current experiences a force in the magnetic field, causing the aluminum disk to rotate (active torque).

The magnitude of the torque is directly proportional to the power consumed by the load, with greater power resulting in a faster rotation of the aluminum disk. The aluminum disk is also influenced by a braking torque generated by a permanent magnet, which is proportional to the rotational speed of the disk. When active and braking torques balance, the aluminum disk rotates at a constant speed, and the number of rotations is proportional to the electric energy consumed by the load. This rotation drives a counter, indicating the amount of electric energy consumed.


Maintaining a single-phase electric energy meter follows the principles of responsibility, prevention, regular maintenance, and timely repairs. Maintenance activities can be categorized as follows:

1.      Routine Maintenance: Includes external cleaning, lubrication, fastening, and visual inspection, conducted according to operational regulations.

2.      First-Level Maintenance: Encompasses comprehensive cleaning, lubrication, fastening, and may involve partial disassembly for inspection and adjustment.

3.      Secondary Maintenance: Focuses on internal components, involving inspection, adjustment, replacement of vulnerable parts, and precision calibration for older meters. This ensures the meter remains clean, lubricated, safe, and functional.

How Digital Energy Meters Operate

As electronic technology has advanced, standard energy meters have evolved into digital and intelligent counterparts. Compared to traditional mechanical energy meters, electronic energy meters offer various benefits, such as enhanced measurement accuracy, reduced power consumption, and improved anti-theft features. So, what is the underlying working principle of electronic energy meters, and what functions do they serve?

Types of Energy Smart Meters

Electric energy meters come in two main categories: electromechanical electric energy meters and electronic electric energy meters. Electromechanical meters rely on changes in electromotive force to convert variations in current and voltage parameters into mechanical energy. Electronic energy meters, on the other hand, employ electronic components like analog circuits, digital circuits, and microprocessors to measure voltage and current changes and calculate the consumed electric energy.


An electronic energy meter comprises two primary functions: electric energy measurement and microprocessor control. The energy measurement section utilizes a large-scale application-specific integrated circuit to generate a pulse sequence indicating electricity consumption. This pulse sequence is then transmitted to the microprocessor for energy measurement. The microprocessor, upon receiving the pulse signal, accumulates the number of input pulses and calculates electric energy accurately using the pulse constant. The meter also transmits data through various interfaces to facilitate diverse control functions.

The energy meter can also monitor power factor changes and display real-time data, including voltage, current, power factor, and active power. This feature enables efficient power consumption management and enhances power utilization efficiency.

How It Works

In a circuit, changes in voltage and current generate power, and the cumulative power represents electrical energy consumption. Hence, an electric energy meter is an instrument that calculates electric energy by monitoring voltage and current changes.

Electric energy meters function based on magnetic field induction. The primary components of an electric energy meter include the current coil, voltage coil, iron core, turntable, and counting mechanism. When current passes through the current coil, it creates a magnetic field proportional to the current's magnitude. Simultaneously, alternating current flowing through the voltage coil generates an electric field proportional to the voltage.

The interaction between the magnetic and electric fields of the current coil and voltage coil, due to the presence of the iron core, generates a magnetic flux within the core. The magnitude of this magnetic flux is directly proportional to the current and voltage magnitudes. The turntable, a vital component of the electric energy meter, rotates in response to the magnetic field's changes when the meter is powered on. As the turntable rotates, it measures electric energy, and the results are recorded and displayed by the counting mechanism.

In summary, the working principle of a single-phase DIN-rail energy meter relies on the induction principle of magnetic fields. It uses the interaction between magnetic and electric fields generated by the current coil and voltage coil to produce a magnetic flux within the iron core, thereby facilitating electric energy measurement.

Operational Characteristics of Smart Meters

Smart meters, designed with electronic integrated circuits, offer several advantages compared to inductive meters, including:

1.      Power Consumption: Smart meters typically have a low power consumption of about 0.6-0.7W, which is significantly less than the average power usage of inductive meters, around 1.7W.

2.      Accuracy: Smart meters, especially those with an accuracy level of 1.0, provide precise measurements, with an error range of ±2% for the range of 5% to 400% of the calibrated current. In contrast, inductive meters tend to have larger errors as they age.

3.      Overload and Frequency Range: Smart meters offer higher overload capabilities, with some reaching ratios of 6 to 8 times, and a broader operating frequency range (40-1000Hz), whereas inductive meters typically have an overload multiple of 4 times and a narrower frequency range (45-55Hz).

4.      Functionality: Smart meters can connect to computers via relevant communication protocols, enabling hardware control and management through programming software. This allows for features such as remote control, multi-rate pricing, detection of unusual loads, anti-theft measures, prepaid billing, and the ability to modify control functions by adjusting parameters in the control software. These functionalities are challenging or impossible to implement with traditional inductive meters.

Prasun Barua

Prasun Barua is an Engineer (Electrical & Electronic) and Member of the European Energy Centre (EEC). His first published book Green Planet is all about green technologies and science. His other published books are Solar PV System Design and Technology, Electricity from Renewable Energy, Tech Know Solar PV System, C Coding Practice, AI and Robotics Overview, Robotics and Artificial Intelligence, Know How Solar PV System, Know The Product, Solar PV Technology Overview, Home Appliances Overview, Tech Know Solar PV System, C Programming Practice, etc. These books are available at Google Books, Google Play, Amazon and other platforms.


Post a Comment (0)
Previous Post Next Post