In this note, we will know about the Circuit Diagram of Single Phase Energy Meter (Induction Type) and also its definition, specifications, working, applications as well. Welcome to Poly Notes Hub, a leading destination of electrical engineering notes.
Author Name: Arun Paul.
What is Single Phase Energy Meter?
A Single Phase Energy Meter is an electrical instrument that measures the quantity of electricity was used by a home, commercial organization, or small industrial unit that runs on a single-phase power supply (230V, 50Hz in many countries). It measures energy consumption in kilowatt-hours (kWh).
A single-phase energy meter is a vital tool for monitoring electricity consumption in residential and small commercial settings. With advances in smart metering, digital energy meters now offer real-time data and remote access, making electricity management more efficient and cost-effective.
Specifications of Single Phase Energy Meter
- Voltage Rating: 230V (Nominal)
- Current Rating: 5-30A, 10-40A, or higher
- Frequency: 50Hz / 60Hz
- Accuracy Class: Class 1 or Class 2
- Display: Analog (Electromechanical) or Digital (LCD/LED)
- Power Consumption: Low (typically < 2W)
- Meter Constant: Imp/kWh (e.g., 1600 imp/kWh)
- Communication (for Smart Meters): Modbus, Wi-Fi, GSM, or Bluetooth
Circuit Diagram of Single Phase Energy Meter
Here is the single phase energy meter circuit diagram or single phase induction type energy meter circuit diagram –
The circuit diagram of a single-phase electromechanical energy meter (induction type) depicts the working principle and main components. This sort of meter uses electromagnetic induction to measure energy usage. The major components are the current coil (series coil), pressure coil (voltage coil), aluminum disk, magnets, and counter mechanism.
The current coil is linked in series with the load, carrying the entire load current and producing a magnetic field corresponding to the current. The pressure coil is linked in parallel with the supply voltage, generating a magnetic field proportionate to the voltage. These two coils create eddy currents in the aluminum disk, forcing it to rotate. The series magnet (M₂) and shunt magnet (M₁) control the disc’s movement, ensuring that the speed of rotation is proportional to the power consumed. A horseshoe magnet, also known as a brake magnet, induces eddy currents in the disc, opposing its motion and regulating its speed for precise energy measurement.
As the disc rotates, it activates the counter mechanism, which records energy usage in kilowatt-hours (kWh). The counter is connected to the rotating disc by a spindle, guaranteeing that the total number of rotations equals the energy consumed by the associated load. The phase (P) and neutral (N) connections provide the necessary AC power to both the energy meter and the associated load.
Single Phase Energy Meter Working Principle
Here is the working principle of single phase energy meter –
The functioning principle of a single-phase energy meter is based on electromagnetic induction. When electrical power passes through the meter, the current coil linked in series with the load generates a magnetic field corresponding to the load current. Simultaneously, the pressure coil, coupled in parallel with the supply voltage, produces a magnetic field proportionate to the voltage. These two alternating magnetic fields interact with one another, causing eddy currents in the metal disc sandwiched between them.
These eddy currents provide torque, which forces the aluminum disk to rotate. The speed of rotation is related to the power absorbed by the associated load. To ensure precise measurement, a brake magnet (horseshoe magnet) is placed near the rotating disc, creating an opposing force due to eddy currents. This brake system regulates the disc’s speed, making it proportional to actual power usage. The rotating disc is linked to a counter mechanism, which counts the number of revolutions and turns them into an energy reading in kilowatt-hours (kWh). Throughout this process, the meter correctly measures and records the energy consumption of the associated electrical load.
📌 Some important equations of Single Phase Energy Meter
1. Power Equation
The instantaneous power consumed by the load is given by –
Where;
- P = Power in Watts.
- V = Voltage in Volts.
- I = Current in Amp.
- cosϕ = Power factor of the load.
2. Energy Consumption Equation
Energy consumption in kilowatt-hours (kWh) is given by –
Where;
- E = Energy consumed in kWh.
- P = Power in kW.
- t = Time in hours.
3. Speed of the Disc
The speed (N) of the rotating disc is proportional to the power consumption –
A properly adjusted braking magnet ensures that the meter records the correct energy consumption.
4. Torque Equation of Single Phase Induction Type Energy Meter
The driving torque (Td) that causes the aluminum disc to rotate is given by –
This means that the driving torque is directly proportional to the power consumed by the load.
Single Phase Energy Meter Advantages
Here we have listed some advantages of single phase energy meter –
- It provides precise readings of energy consumption.
- The modern electronic meters are small in size and easy to install.
- These devices protect against electricity faults and theft.
- It does not consume significant power for operation.
- These meters have long operational life with minimal maintenance.
Single Phase Energy Meter Applications
Here we have listed some applications of single phase energy meter –
- These are used to measure energy consumption in houses.
- Used in small businesses and commercial spaces for electricity measurement.
- Used in small scale industries with a single phase supply.
- Used as an individual meter for tenants in buildings.
- Used to measure energy consumption and generation in solar setups.