AVR stands for ‘Automatic Voltage Regulator.’ According to this guide from the USNRC Technical Training Center, AC generators possess voltage regulation systems that maintain the unit’s field current under varying electrical loads. Clearly, that is an essential function, but what does it mean practically? This is what you should know:
1). What Does The AVR Do?
As the name suggests, the AVR regulates the generator’s voltage. It keeps the unit’s output within the appropriate range. A generator’s voltage levels tend to fluctuate, especially when the load and operating temperatures change.
According to Swift Equipment, the AVR works with the alternator’s excitation system to stabilize the output. You’re not wrong if you compare it to the motherboard because the functions it performs are complex.
They include tracking the voltage the generator produces and contrasting it with the correct voltage level. When it detects a problem in the voltage levels, this solid-state device sends a signal to the exciter stator. The exciter stator responds by increasing or reducing the current flow.
2). Where Do You Find The AVR?
You will find the AVR in the main control box or alternator’s terminal box. You should know the location of the AVR because it can accumulate dirt and debris, which interferes with the component’s performance. Knowing the AVR’s location allows you to clean it.
3). Why Does Your Generator Need The AVR?
If you want to know what happens to a generator without AVR, you should first understand the benefits this component brings to the table:
- The AVR maintains a constant voltage output. In other words, it protects your equipment from spikes and surges. This makes AVRs vital to commercial settings. You don’t want a generator without AVR to damage sensitive and expensive equipment in your business.
- An AVR will extend the generator’s lifespan. It will do the same for the devices connected to the generator by protecting them from a dangerously high voltage output.
- The AVR allows the generator to handle overloads, preventing shorting in the long run.
- An AVR allows a generator to meet your equipment’s power requirements. This is particularly important if you expect one generator to support multiple devices with varying electrical needs.
4). Can The AVR Fail?
Like every electronic component, the AVR is susceptible to damage and malfunctions. Kohler blames an AVR’s malfunction on the following:
- Current overload
- Short circuit
- Unstable engine speeds
The AVR will warn you when it fails. You will observe one or more of the following symptoms:
- Your equipment may burn out sooner than you expect because of overheating. Equipment can overheat because the generator is outputting too much voltage. Your machines are running too fast and too hot.
- You will record lower voltage levels than you need. Lower voltage sounds safer than higher voltage levels. However, your equipment can fail due to low voltage because the motors must work harder to compensate for the current deficit. It is also worth noting that a low voltage will result in a higher amperage. Don’t be surprised if the generator’s engine overheats.
- The instrument cluster will malfunction.
- Erratic engine performance.
- From what Welland Power has seen, a generator with a dead or defective AVR won’t produce any power. They associate voltage readings of 50 to 70V on each phase with a malfunction in the AVR. They expect consumers that record such readings to get a new AVR. A reading of 0 to 5V on each phase points to the alternator (Loss of residual magnetism).
Power Continuity encourages consumers to look for frequency fluctuations using the control panel. This will show you whether or not you have an operational AVR. A failed AVR will manifest erratic increases and decreases in the frequency on the control panel.
5). Can A Generator Work Without AVR?
Yes, a generator can run without an AVR. However, the practice is dangerous because it exposes you to the following risks:
- Insufficient Power
The connected devices won’t get the power they need. Without a voltage regulation system, a generator’s terminal voltage tends to taper off, especially when you connect multiple devices that require more power.
Don’t assume the generator’s voltage output will automatically rise to meet this challenge. As you now know, the absence of sufficient power can overwhelm certain machines because their motors must work harder to compensate for the deficit. Some devices won’t even start.
A generator without AVR exposes your equipment to surges and spikes. A voltage regulator sustains the generator’s output at a predetermined level. This gives your equipment a stable power supply.
In the absence of the AVR, the generator may overwhelm your equipment with a higher voltage than it can handle, leading to an overload. This is dangerous because it can damage the equipment in question. It will also create fire and electrocution hazards.
An AVR usually defends against surges and short circuits. You can also take advantage of the noise and harmonic filtering.
What if you have heavy-duty assets that are unlikely to succumb to the generator’s highest voltage output? What if the generator is too weak to overload your equipment? You still have a problem.
Without a voltage regulator, the generator’s voltage output can fluctuate wildly. This can damage sensitive electrical components. At the very least, you will lower their lifespans.
It is worth noting that AVRs are not present in every generator. Woodstock Power admits as much when they explain that some unregulated generators cannot regulate their voltage. This means some generators have voltage regulation systems that don’t rely on AVRs.
Such models won’t fall prey to the consequences above. This portable generator buying guide has highlighted a category of portable generators with fixed excitation. The terminal voltage drops because of internal impedance when the alternator is loaded.
The generator uses an AVR to keep its output within tight limits. The schematics in the guide explain the role the AVR plays. This further cements the idea that some generators can run successfully without an automatic voltage regulator.
Keep this in mind if you just bought a portable generator that doesn’t have an AVR. Check the unit to determine whether it has a current transformer that manages the voltage. Some consumers are a little too quick to add an AVR to a generator that doesn’t have one.
You should only take that step if the unit manifests concerning symptoms, such as over-voltage or under-voltage. If you want to install an AVR, pay attention to the quality. Welland Power has discouraged consumers from adding fake AVRs to their generators.
They expect a decent AVR to cost anywhere between $140 and $3000. A cheaper, lower-quality AVR is a fire hazard. You can’t trust it to safely regulate the generator’s voltage. Instead, the following consequences will plague you:
- The generator will fail continuously, forcing you to tolerate extended downtime.
- The fake AVR will damage the alternator.
- The generator will damage the connected equipment.
The key to avoiding fake AVRs is to stay away from unauthorized distributors. Limit your purchases to reputable brands such as Engga, Stamford, Leroy-Somer, Caterpillar, Kutai, and Mecce-Alte, to mention but a few.
The generator type and size will influence your selection. Different generators have different needs. Don’t assume that one AVR can accommodate the needs of multiple generator types and sizes.
If you’ve acquired a decent AVR and successfully installed it, maintain the device. Otherwise, it won’t last. Maintenance involves the following:
- Remove any dirt you see using a cloth or sandpaper
- Make sure the connectors are secure. Fasten them if they become loose.
- Replace damaged connectors.
- Adjust the air gap of various contacts if they don’t meet the recommended standards.
It goes without saying: shut the generator off before removing the cover to access the AVR.