Wattmeter: What is it and how to choose the Best?

November 2, 2021

wattmeter , or wattmeter, does complex work, measuring the power that flows through an electrical circuit. It simultaneously measures voltage and current values ​​and multiplies them to give power in watts. The three main types are electrodynamic, electronic, and digital.

A wattmeter is used to measure voltage in an electronic circuit. Originally just a tool from professionals, there are now many different types of devices available that are cheap and easy to use and available for home use.

The wattmeter is generally used to check the power supply of a given outlet in a home and to estimate the electricity costs of different appliances. Like many technologies, the device has gone digital.

Next, we will talk in more detail about this material that is not usually missing in any of the laboratories, such as beakers . Join us!

What is a wattmeter?

Generally speaking, the wattmeter is an instrument that provides a visual indication of the amount of electrical energy being supplied to a circuit. This indication is expressed in watts, which is the standard unit of measure for the supply or consumption of electrical energy.

There are two types of wattmeter in common use: analog and digital. Analog meters indicate energy supply through a needle and scale indicator, while digital instruments show energy use on a liquid crystal display (LCD). Wattmeters are typically rated for a set voltage range, but can include features such as coil taps that allow for multiple voltages.

It may sound like a catchphrase, but the wattmeter is actually a very useful tool used by electricians and anyone in the electrical business to measure the amount of electricity being used.

If you live in a house with electricity, then you have a wattmeter connected to your house somewhere. These wattmeters measure how much electricity you are using . Yes, it is these meters that your utility company comes in and looks at from time to time to figure out how much to charge you each month.

What does a wattmeter measure?

All electrical equipment uses energy subject to a set of known constants that include nominal voltage, current use in amperes, and overall power use in watts. Some types of appliances or installations use much more energy than others of similar voltage ratings.

The wattmeter allows you to monitor energy use to establish if the circuits are working properly. This information is crucial in larger installations where large resistive loads are used. Watt meters in such installations allow operators and technicians to keep track of the status of individual circuits and the overall balance and consumption of the power supply.

How does a wattmeter work?

You can plug a wattmeter into your outlet, plug in your laptop, and it will tell you how much electricity your laptop is using. You see your results measured in watts. This is a good way to remember the name of the wattmeter and the units of measure it provides.

A watt is a unit of measurement for power and can be calculated by multiplying voltage times current in DC circuits.

P = V * I For AC circuits, you have an additional power factor, since your electricity in AC circuits is a sine wave, so you will need to multiply it by an additional factor of cos theta.

P = V * I * cos (theta) Many appliances have a stated amount of power on them. This shows the maximum power that a particular device will use in one hour. For example, a 13 watt compact fluorescent light bulb will use a maximum of 13 watts in one hour.

So if this bulb is on for 3 hours, it will use 13 * 3 = 39 watts in those three hours. You will see these numbers on your wattmeter if you have one plugged in to measure the bulb.

Types of Wattmeter

Wattmeters are generally presented in one of two basic formats . The first is the traditional analog wattmeter. These are electrodynamic instruments and consist of three internal coils: two static current coils and a moving potential coil that has the indicating needle attached to it.

When an electric current is passed through the two current coils, an electromagnetic field is generated. This field causes the potential coil to move and display a value on the scale behind the needle.

Electrodynamic or analog

Electrodynamic wattmeters are a design that dates back to the early 20th century. They work using three coils : two fixed in series with the electrical charge and a moving coil in parallel with it. The series coils measure the current flowing through the circuit, the parallel coil measures the voltage. A series resistor limits the current through the voice coil. It is located between the two stationary coils and is connected to an indicator needle.

The magnetic fields in the three coils influence the movement of the needle. A spring returns the needle to zero when no voltage or current is present. This design is simple, reliable, and rugged, although the coils can overheat.

The current coils are connected in series with the circuit, while the potential coil is connected in parallel. Also, in analog wattmeters, the potential coil carries a needle that moves on a scale to indicate the measurement. A current flowing through the current coil generates an electromagnetic field around the coil.

The strength of this field is proportional to the line current and in phase with it. The potential coil has, as a general rule, a high value resistor connected in series with it to reduce the current flowing through it.


The second type of wattmeter is the electronic or digital meter. These devices differ from electrodynamic meters in the way that they calculate energy use.

People who use radio and microwave equipment need to measure watts at frequencies much higher than the 60 hertz of the electrical network. Electrodynamic wattmeters are fine for AC power line measurements, but the coils are frequency-dependent parts that don’t work for radio. For radio, you need a fully electronic approach.

Here, an electronic circuit measures current and voltage, multiplies the two in another circuit, and returns the result as a current or voltage proportional to a standard movement of the meter.

Electronic wattmeters are used for small, direct power measurements or for power measurements at frequencies beyond the range of electrodynamometer-type instruments.


Digital wattmeters measure current and voltage electronically thousands of times per second, multiplying the results on a computer chip to determine watts. The computer can also run statistics such as peak, average, low watts, and kilowatt-hours consumed. They can monitor the power line for power surges and power outages. In 2009, a variety of inexpensive digital wattmeters are available to consumers.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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