Low Load: How It Impacts Generators & Preventive Measures


The health and reliability of every one of your equipment are critical in your business operations. Especially when it comes to your generator – it’s especially crucial for it to always be at tip-top condition. It is essential equipment in the power system as it helps to ensure your business is up and running at all times.

That said, a malfunctioning generator can negatively impact your business tremendously. You may need to consider generator rewinding so you can get to the bottom of your equipment’s condition. And if need be, go for a repair or replacement.

While there are many reasons for a generator failure – one of the leading causes is low load mode. Read on to discover what kind of damage can a low load mode do to your generator, and eventually business.

What exactly is a low load?

Manufacturers usually specify a minimum allowable load on the generator (by stating a percentage of its rated capacity) to give operators a recommended load to follow. This does not prevent the generator from being turned off; it only prevents it from functioning at too low a load.

For instance, the minimum load is set to 40%. If the required power from the generator is 50% of its capacity, it operates at 50%. On the other hand, if it’s 30% – it still starts running at 40%. The surplus power will be used to charge the batteries, serve as the deferrable load, or simply be dumped aside.

In this case, anything below 40% is considered as low load. Operating at a low load will only lower the performance of your generator, and in the worst-case scenario – cause it to break down completely.

The impact of low load

The consequences of low load on generators are aplenty – but here are some of them:
Note: This is not an exhaustive list

  • Excessive wear of moving parts.
  • Leads to low fuel temperature and causes the percentage of unburned fuel in the oil to increase – this oil goes through the crankcase and degrades the properties and the quality of the lubricant.
  • Lack of cylinder pressure also causes the oil to enter combustion chambers and forms ash deposits. It affects the compression ratio and reduces the detonation margins, and this will cause damage to the components, failures, or unplanned shutdowns.
  • Power losses and poor equipment performance leading to unplanned downtime failure and increased maintenance costs.

Preventive measures

What you can do is avoid running your generator uninterruptedly in low load mode – or you can lower the usage to minimum periods of time. The recommended period of time for using generator sets in low load conditions is 15 minutes or less.

After which, you should increase the load for a short period to increase the pressure and temperature. That way, you can avoid some of the above incidents. You could always give a call to your manufacturer to receive advice on safe, low load operation durations and values.

On the flip side, it’s important to note that once every year – there should be a ‘load bank’ test. The generator will run for a couple of hours at full load to clean the engine completely, to remove the carbonised oil deposits in the exhaust system and engine.

However, if any of the above issues still persist, and you notice that your generator’s performance is still deteriorating – your engineer has to be called in for sure. They’ll do a thorough generator overhauling, and determine what action to take.

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