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Do Brushless Generators Have AVRs?

Do Brushless Generators Have AVRs?

Understanding how generators work can help you decide which type best suits your needs. You need to know how each component works and how to care for your generator. For example, do brushless generators come with AVRs?

Brushless generators have AVRs that maintain the generator power output at a present value. An AVR senses the output voltage of the generator terminals and compares it to a stable reference. It adjusts the current flow to the exciter, increasing or lowering the voltage at the stator terminals.

In the rest of this article, I will explain what AVRs are, their purpose in generators, and how brushed generators differ from brushless ones.

What Is an AVR?

An AVR (or automatic voltage regulator) is a solid-state electronic device used in generators to regulate voltage by automatically adjusting the fluctuating voltage to become constant. AVRs stabilize generators’ output voltage at variable loads.

AVRs also divide reactive loads between generators connected in parallel and help the generators to respond to overloads. 

Functions of AVRs in Generators

A generator without an automatic voltage regulator can’t sufficiently meet the power demands of every electronic device connected to it. This is because an unregulated generator can’t control its voltage, so its terminal voltage continues to drop as the power demand increases. 

If the voltage isn’t maintained at a fixed rate, the generator’s performance will deteriorate. Consequently, this will affect the performance of the machinery or utilities connected to the generator.

Therefore, an AVR is needed to match the generator’s performance and longevity with the appliances it’s powering. It ensures the output voltage is consistent even when fluctuations occur. Therefore, an AVR eliminates the damage voltage fluctuations may cause to the machinery, electrical appliances, and equipment.

AVRs keep the generator’s output current constant, but they also protect your appliances from electrical spikes, surges, and overloads. They help generators respond to short-circuiting and divide the reactive electrical load between generators running in parallel.

Where Is a Voltage Regulator Located on a Generator?

An AVR can be located either in the generator’s main control box or the alternator’s terminal box. The AVR can be under the alternator’s cover for small portable generators. Check the product manual if you cannot seem to find it in any of these three places.

This Youtube video details where an AVR is located on a generator:

How to Change your Generator's Voltage Regulator (AVR)

What Happens if an AVR Fails?

Your generator will lose excitation if its AVR fails. This excitation loss will make the generator’s output voltage drop suddenly. Consequently, this sudden voltage loss will trigger the generator’s under-voltage fault, causing it to shut down.

Generators without the under-voltage protection kit may continue to run even after the voltage drop, which might severely damage your machinery or equipment.

How To Know Your AVR Is Failing

It’s worth noting that all AVRs fail over time. For that reason, you need to know the signs that your AVR is failing — either to fix the problem yourself or to refer the issue to a professional.

Here’s how you determine if your AVR is faulty:

  • Your generator doesn’t produce electricity.
  • You’re unable to adjust your generator’s terminal voltage fluctuation of 20%.
  • Your generator’s terminal voltage suddenly rises above 500V.

For brushless generators, you can try the Walfront AvGAVR-20B AVR (available on It comes with an inbuilt high-breaking capacity fuse for improved protection.

Can You Run a Generator Without a Voltage Regulator?

You can operate your generator without an automatic voltage regulator. However, this will limit the generator’s output and limit the number of devices you can power. Also, you run the risk of flickering lights and excess output damaging your devices.

An automatic voltage regulator (AVR) is essential for your generator. Without one, you’re at risk of sparks, power shortages, and unstable voltage. Voltage instability will severely affect the performance of your generator.

Do All Generators Have an AVR?

Some generators may not have AVRs. A generator without an AVR is not equipped to regulate its voltage. In case of massive power demand, its terminal voltage will taper off, supplying less voltage to the equipment it powers, causing an insufficient power supply.

Brushed Generators vs. Brushless Generators

The main difference between brushed and brushless generators is that the brushed models use carbon brushes while their brushless counterparts use magnets to generate electricity.

A brushless unit motor uses a small generator located at the end of the generator to transfer electricity. Brushed generators use motors and carbon brushes instead.

Pros of Brushless Generators

Brushless generators possess the following advantages:

  • They produce less noise. The brushed generator’s motor rotates while in contact with the carbon brushes to transfer electrical current. However, this is not the case with brushless generators. Instead, the motors rotate quietly in a magnetic field.
  • They are easy to maintain. Brushless generators have fewer moving parts. Therefore, they require less cleaning, repair, and replacements. You don’t have to dust them or replace the carbon brushes like in the case of brushed generators.
  • Brushed generators don’t overheat. Since there’s no contact between the motor and the carbon brushes like in brushed generators, brushless units don’t generate friction which would otherwise cause overheating.
  • Brushless generators are cheaper than brushed units in the long run. Although their initial cost is higher, they last five times longer than brushed units.
  • Brushless generators are portable. They are three times lighter and more compact than brushed generators making them easy to transport.

Final Thoughts

Brushless generators outperform brushed units, requiring less maintenance, and last almost five times longer. They come with automatic voltage regulators that stabilize their terminal voltage. AVRs maintain the terminal voltage of brushless or brushed generators at a preset value, which is crucial to avoid inconsistent terminal voltage and damaging equipment connected to the generator.

Keep an eye on your generator’s performance to know when the AVR begins to fail. If you see an inconsistent power supply, the AVR is faulty and should be repaired or replaced. A qualified technician is needed if you can’t fix or replace it yourself.

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