Generator Hunting and Surging
- May 4, 2023
Common Causes of Generator hunting and surging
Have you noticed generator hunting and surging while running on standby power? Power surges from power generators are never normal and indicate a fault somewhere in the generator. In the remainder of this article, we’ll review the most common reasons for generator hunting and surging and give you some ways to fix them.
Old age
As generators age, the parts will inevitably wear out from normal wear and tear, making them prone to hunting and surging. If you start experiencing power surges and your generator is nearing (or exceeding) its expected lifespan, consider replacing it with a newer model.
Fuel problem
A surge from fuel problems is usually due to one of three things: incorrect fuel, low fuel level, or poor fuel quality. Most generators have particular fuel needs, and using any fuel outside of these parameters can cause operational problems, including surging and hunting.
Fuel clogging is another way fuel can cause generator surges, although this is much less common. Before attempting to remove a fuel blockage or restriction, check the fuel filter and assess the fuel quality to make sure nothing is obstructing the fuel filter or fuel lines.
A fuel pump failure can also be the cause of the surge. In order to identify the source of the hunting and surging, it’s crucial to check the condition of your fuel pump. Check the fuel lines for any leaks or blockages that would reduce fuel flow.
Poorly maintained
Like any other piece of equipment, a generator requires regular maintenance to keep it running in top condition. Neglecting maintenance intervals can lead to increased wear and other, more severe problems, making your generator more prone to hunting and surging.
Sudden start
Starting large machinery while running on standby power can cause load spikes. This can push you beyond the generator’s ability to generate electricity and cause the generator to struggle to keep up with power demands. Sometimes this causes other devices to drain power for a split second, then everything smooths out, and you don’t notice any difference in power quality. Other times, the additional load is too much for your generator to handle, and this might result in a power surge or even force the generator to shut down completely from overload.
Unbalanced load
Depending on what you’re trying to connect to the backup power, the load may climb and decrease rapidly. Verifying that the load is balanced over the three phases is crucial. This is also an excellent time to ensure you’re not overloading the generator continuously or with short spikes in load due to equipment starting up. Motors are often the biggest culprits in unbalanced load situations because they require a lot of power to start.
Unstable motor
Electric motors that drive machinery that fluctuates in power demand are the biggest culprits when looking for the cause of the surge. Especially if the motor is older and doesn’t have a governor; due to this, power consumption may significantly fluctuate, resulting in erratic power surges that can damage all other electrical equipment powered by the same backup source.
Intermittent AVR failure
AVR stands for automatic voltage regulator. The AVR is a little device that checks the generator’s power output and is mounted on the alternator. It maintains constant voltage and “utility-like” conditions for equipment loads. This is done under various conditions, especially when the load on the generator varies widely. The generator’s steady power output is aided in its smoothing by AVR. Problems with the AVR can cause power surges due to lack of power control.
Clogged carburetor
A clogged carburetor is usually caused by fuel left in the generator for a long time. Over time, some fuel components may evaporate, leaving behind a thicker, more viscous substance that cannot flow efficiently through the fuel system. The engine may stall or run roughly as a result of this viscous fuel clogging the carburetor. Try cleaning your carburetor with a carb cleaner if it’s clogged. If cleaning the carburetor is ineffective, you may need to rebuild or replace it to see positive results.
Faulty spark plugs
Check the spark plugs for signs of wear or damage. If the porcelain insulator is cracked, the electrodes appear charred or damaged, or there is a large amount of carbon deposits on the electrodes, the spark plugs need to be replaced. Use a spark plug tester to determine if your spark plugs are defective. There should be a noticeable spark between the tester’s terminals when the engine starts. If there is no visible spark, it strongly indicates that the spark plug is defective and needs to be replaced.
Clogged fuel filter
The most common cause of a clogged fuel filter is old fuel. As we discussed with carburetors, over time, the components in the fuel evaporate, leaving behind a more viscous substance. This sticky fuel residue has the potential to clog the fuel filter, stall the engine, or make it run rough. Replace the fuel filter if it is clogged or otherwise not working properly.
Conclusion
As mentioned earlier, generator hunting and surging when running on backup power are never normal. Your generator should be able to provide a constant “utility-like” power quality at all times. If you notice a power surge and troubleshooting it yourself doesn’t help, it’s time to call in a qualified generator technician for help.
Generator Hunting and Surging FAQ
What is a surging generator?
Generators can experience surges when idling (no load) or running at high speed (powering equipment under load).
The generator is "looking" for fuel. The RPM of the engine cycle goes up for a second when it gets what it needs and then goes down for a second when it can't get enough again. This process is usually repeated over and over in a rhythmic pattern.
What does it mean when a generator is hunting?
In short, when a generator is hunting, you notice a change in its speed or power after a certain interval or randomly. Sometimes it goes high and then suddenly goes low, causing a change in the generator's power output.
What is a surge arrester in a generator?
Many generators now have surge protectors that limit the shock wave magnitude and protect the generator insulation. Overvoltage transients often occur on conductors, so the role of surge arresters is to protect your equipment from such overloads and thus keep you safe.
How to test a generator for an overspeed trip?
It can be tested by increasing the engine speed with no load using the speed governor. The gas supply will stop at 115% of normal speed if you drive too fast.
