In an electrical system, there are two devices used to measure electrical parameters: the energy meter and the wattmeter. These devices differ in the specific quantities they measure and the information they provide.
In this article, you’ll understand the differences between an energy meter and a wattmeter. You’ll be clarified on their respective roles in electrical systems.
What is an Energy Meter?
An energy meter, also known as an electric meter or kilowatt-hour meter, is a device that measures the total amount of electrical energy consumed over a period of time.
The primary function of an energy meter is to provide an accurate measurement of the total energy consumed. In simple terms, it will show you how much power is being consumed by the load in the circuit, in kWh.
Therefore, when you want to find out how much energy has been consumed by the load in a specific time, you will need an energy meter to measure it.
Anssin din rail Energy meter SDM630MCT
Working Principle of Energy Meter
An energy meter, also known as an electric meter or kilowatt-hour meter, is a device that measures the total amount of electrical energy consumed over a period of time.
The primary function of an energy meter is to provide an accurate measurement of the total energy consumed. In simple terms, it will show you how much power is being consumed by the load in the circuit, in kWh.
Therefore, when you want to find out how much energy has been consumed by the load in a specific time, you will need an energy meter to measure it.
Working Principle of Energy Meter
The energy meter works on the principle of Faraday’s law of electromagnetic induction. That is, when a current flows through a conductor, it will generate a magnetic field around it. An energy meter uses this principle to convert electrical energy into mechanical energy. Below is a step-by-step working mechanism of an electronic energy meter:
- Current measurement: First, an energy meter measures the current flowing through it. It accomplishes this by connecting a wire from the power source to a current coil on the energy meter. When current passes through the coil, it forms a magnetic field around it.
- Voltage measurement: Aside from current, an energy meter measures voltage. It does this by directing the voltage from the power source to a voltage coil on the energy meter. The goal is to produce a magnetic field whose magnitude corresponds to the voltage.
- Energy calculation: The energy meter interacts with the magnetic fields of a current coil and a voltage coil. This interaction creates a moment of force that causes the aluminum disc in the meter to rotate. The aluminum disc revolves to determine the power consumption of the load. A counter mechanism is used to count the revolutions of the disc in a certain period of time.
The reading on the counter screen displays the amount of energy consumed in the electrical circuit.
What is a Wattmeter?
A wattmeter, also called a power meter, is a device you use to measure the instantaneous electrical power being consumed at a given time. It provides readings in watts (W) or kilowatts (kW), displaying the rate at which energy is being used.
In simple terms, a wattmeter will show you how much power is currently present in a circuit, in Watts. Sometimes, it is used with an energy meter to provide a comprehensive measurement of energy consumption.
Anssin PMB01 wattmeter eu standard
Working Principle of Wattmeter
A wattmeter has two coils: the fixed or current coil and the pressure coil. The current coil carries the load current while the pressure coil measures the voltage. When you connect a wattmeter to a load, a large current flows through the current coil while a small current flows through the pressure coil.
As the current flows through the current coil, it creates a magnetic field around it. The magnetic field acts on the pressure coil. In other words, the magnetic field generated by the current coil helps to rotate the pressure coil.
When the current flows through the pressure coil, it begins to rotate. Thus, both the current and pressure coils must have current flowing through them for the wattmeter’s needle to rotate. This rotation causes the wattmeter to measure power.
If more current flows through both coils, a strong magnetic force will be generated, resulting in a higher wattage reading.
Core Differences Between an Energy Meter and a Wattmeter
Here is a comparison chart of the difference between an energy meter and a wattmeter.
| Criteria | Energy Meter | Wattmeter |
|---|---|---|
| Quantity Measured | Measures electrical energy | Measures electrical power |
| Measuring unit | Indicate readings in joules, watt-hour, kilowatt-hour, etc | Indicate readings in watts, kilowatts. |
| Types | Electromechanical, electronic, and smart energy meters | Electrodynamometer-type wattmeter and induction-type wattmeter. |
| Components | Consists of an aluminum disc, a driving system, a moving system, a braking system, and a counting mechanism. | Consists of a current coil, a pressure coil, a control system, and a damping system. |
| Measurement Type | Cumulative energy consumption over time | Instantaneous power at a given moment |
| Installation Location | Utility companies, customer premises | Laboratories, industrial settings |
| Primary Use | Billing and energy management | Circuit analysis and power monitoring |
| Data Logging | Records data over extended periods | Can log data, but typically for shorter durations |
| Smart Features | Many modern energy meters are smart meters with smart features | Some digital wattmeters offer smart features |
Conclusion
In conclusion, you’ve seen the differences between an energy meter and a wattmeter. While energy meters provide long-term energy consumption, wattmeters provide real-time power measurements. Recognizing these differences will help you optimize your electrical system and achieve greater efficiency.
Anssin is a manufacturer of energy meters and wattmeters, offering a wide variety of models. Please contact us if you have any requirements.
FAQ
Watts measure power, that is, the instantaneous rate at which energy is used. Energy, on the other hand, measures the total amount of work done over time. In other words, Watts are the speed of usage, while energy is the overall amount consumed.
Yes, a wattmeter can measure AC power by accounting for the voltage, current, and phase angle between them.
Energy meters can measure both AC and DC. However, they are designed for one specific type and are not interchangeable.
An energy meter and an electric meter are the same. Both devices are used to measure the total energy consumed in a household or business over time.
Other names for an energy meter are an electricity meter, electric meter, or kilowatt-hour meter.