What is Wattmeter for Portable Generators?


In Brief: What are Power Meters for Portable Generators

Power meters or wattmeters for portable generators are the devices that can tell how much power your electric appliances are consuming.

You are considering getting a new portable generator unit for your home, but you are not quite sure how much capacity the unit you need for your home.

Your generator output wattage is not enough for your home; you want to find out which appliances are consuming more energy.

In the above cases, power or wattmeter could be your ultimate guide.

In this article, we will let you know about the functionality of power meters work along with their benefits and limitations.

What are Power Meters for Generators

Power meters are the devices that will let you know how much power or wattage your electrical appliances are using up.

There are different kinds of power meters, depending on their applications. Most famous of them are portable wattmeter, professional-grade wattmeters, and plug-in wattmeters.

Portable wattmeters, as the name indicates, are portable, and you can carry them easily anywhere.

Professional electricians mostly use them as they are golden standard to observe power in any device’s circuit.

These are mainly used to find if there is any problem in the circuit’s getting power supply.

Professional grade wattmeters are used by the power supply companies to check how much power you are using in your home.

They are usually fixed near the power supply, and the readings tell you the total power consumed.

Plug-in wattmeters are the most common types of power meters used by ordinary people.

You can check the power consumption of your appliances through the digital reading on the meter.

How Power Meters Work

A power or wattmeter comes in both analog and digital models.

A traditional wattmeter consists of a current coil and a potential coil which is connected to a needle or pointer and deflects over a scale representing the measured power.

On a DC circuit, a power meter gives you the power measurement P=VI as the deflection of the pointer is proportional to the current (I) and the voltage (V).

But for AC power, the deflection of the pointer is proportional to the average instantaneous product of voltage and current.

The readings from the meter will give active power, unlike for DC circuits.

These active power calculations done by the meter might be more than the actual power transmitted by the generator unit.

The modern digital wattmeter takes the samples of voltage and the current passing through the appliances about thousands of times a second.

For each sample, an in-built computer unit calculates the power (P) by multiplying the voltage (V) and current (I) instantly, giving P=VI.

Usually, the readings are readily displayed on the meter for your easy understanding. Sometimes, they can be stored to calculate averages or transmitted to other devices for extended use.

Benefits of Power Meters

Wattmeters for Portable Generators
Power meters offer many advantages for increasing the efficiency of your portable unit. In this section, we will let you some of the significant benefits of a Power meter.


Power meters, especially plug-in models, are very cheap, costing around 25 dollars or below.

Though expensive ones can go up to $50, considering the electricity bill, they will save you by telling you the power consumption statistics they prove to be economical in the long run.

Ease of availability

Power meters are of the conventional measurement devices used at homes, offices, industries everywhere.

So they are readily available in hardware stores, electrical sections in the malls.

Ease of Usage

It doesn’t take a scholar to use power meters. Their operation is smooth, and you can directly get the readings on the meter.

Just plug in the cable of your appliance to the meter and get the readings.

Generator sizing

You shall get the correct size, capacity, and type of the portable generator unit is critical to ensure continuous power supply for your home in the case of blackouts or emergencies.

Power meters can help you eliminate the guesswork while you are trying to decide how many wattage generators you need for your home.

Simply measure the power consumption patterns of each of your appliances and calculate the whole amount of power required.

Limitations of Power meters

There are some downsides to the power meters amongst all its benefits.

Here, we will discuss in detail a few key disadvantages of power meters for portable generator units.

Precision problem

Typically, the voltage and current are not in phase for AC power.

ecause of this, the meter deflection gives you the active power reading, which is proportional to the average instantaneous product of voltage and current.

This means the power observed by the multiplication of voltmeter and ammeter readings might be less than the actual power transmitted by the generator.

Overheating problem

The power meters are prone to overheating as the circuits of a wattmeter can be damaged by excessive current flow.

Usually, when an overload occurs, the pointer in the wattmeter deflects to the end of the scale. This indicates that the wattmeter is overheated.

Sometimes, even when an overload occurs, and the circuits of wattmeter are overheated, the pointer might not indicate it.

Accuracy problem during low power measurements

One of the downsides of using inexpensive wattmeters is its inefficiency to precisely measure very low power measurements.

The readings are usually not accurate when measuring the power usage from low-end electronic devices, which are in standby mode consuming less than 10 watts.

Most of the time, this error in measurement is shown by indicating a range in plug-in meters.

For example, when the actual value is 100W, but there is an error of 5% plus 10W, it is shown by the meter as ±15 W indicating the original wattage could be anywhere between 85-115W.

Because of this, if you measure the power consumed by a laptop computer in sleep mode, let’s say 5W, the meter will give a value 0 to 15.25 W, without considering the errors due to sine wave.

When to use Power meters?

Here are some of the situations where power meters can be used for generators –

  1. If you want to know how much energy your household appliances need to work, you shall use a power meter.
  2. If you are going to buy a new portable generator but unsure of the capacity you need, you can use a power meter to find your power needs first.
  3. If you are looking to cut off the devices that are unimportant but utilize more power, you can easily find them using a power meter.
  4. If you want to know whether your appliances are working correctly or not, you can use a power meter to verify it.


Power meters for portable generators can help you cut your costs and make better usage of your portable unit’s power supply.

But, at the same time, they also come with their own set of disadvantages.

Here, we have done our best to explain the working of a power meter along with its pros and cons.

We hope it will help you decide if you need to use a power meter with your portable generator unit.

About Michelle

Michelle has been fascinated with machines and tools since her childhood. She contributes with articles on how things work, repairing, and troubleshooting. She holds an engineering degree and pursuing her passion for travel.