A Quick and Complete Guide To Industrial Generator Maintenance

Regular, quality power is essential for industrial operations. A disruption in the power supply can halt the production process, incurring costly unexpected downtime. That is why most facilities use industrial generators and employ thorough generator maintenance procedures to keep these important pieces of equipment ready for when they are needed. 

In the following sections, we discuss the importance of regular generator maintenance and outline critical generator components and their maintenance requirements. At the end, we also feature some neat generator maintenance checklists to help you get started with building schedules for your equipment. 

The importance of generator maintenance

Generators are an important piece of equipment in every facility. They are the backup for inconsistent power from the grid. Consistent high-quality power is critical for plant operations. 

While generators might only be used on rare occasions, in those instances they are critical for the continuation of work at the facility. 

If a generator doesn’t work when it is needed, it is a complete failure of its purpose. 

Power shortages and equipment downtime are just part of the problem. In the worst-case scenario, generator malfunction can harm employees and destroy assets in your plant. In a 2016 generator explosion in a Texas oil refinery, for example, one employee was injured and production had to be halted.

It is obvious that keeping generators in pristine condition is important. Unfortunately, routine maintenance of equipment that is infrequently used is easy to overlook.

Types of industrial generators

There are various types of industrial generators. They vary by size, power output, fuel they use, etc. 

industrial generators

Industrial generators. Source: Clifford Power

Here are the more common categorizations used in the industry:

  • Diesel/Natural Gas/Petroleum: There are different types of generators depending on the fuel used to generate mechanical energy. Heavy fuel oils and propane are also viable options, but those are increasingly rare.
  • Portable Generators: These are small generators that can be easily transported. They produce a very small amount of power compared to most industrial generators.
  • Inverter Generator: These types of generators do not run at a constant speed, which is the case for most industrial generators. Inverter generators automatically adjust the speed to the power required. This reduces noise and fuel consumption.

This is not an exhaustive list. There are other types of generators and categorizations, but those would just unnecessarily complicate this discussion. 

Checklist for Creating a Preventive Maintenance Plan

Following a consistent Preventive Maintenance Plan can make life easier. Use this checklist to create your own!

Critical generator components

To perform maintenance on industrial generators, it is important to be familiar with its key parts. The following sections introduce you to the most critical components of an industrial generator from a maintenance perspective.


It is the core component of industrial generators. It is the part that converts mechanical energy to electrical energy. The alternator has a stator, rotor, and brushes to carry the power generated. The rotor has to rotate at speeds according to its specifications. Abnormally fast rotation is one of the major causes of generator explosions. 

The coils of alternators are prone to breakages and unwinding. Another problem are the brushes, which are generally made of carbon. They are very fragile and highly susceptible to damage. 

Look for those issues during routine maintenance work.

Fuel system

Fuel systems are tasked with maintaining fuel flow to the engine. The type of fuel system depends on the type of fuel used by the engine of the generator. 

The most common problems that occur with fuel systems are leaks and blockage of fuel cut-off valves. Problems with fuel systems can turn catastrophic as fuels are highly combustible.


The engine generates the mechanical energy for the alternator with the combustion of fuel. The engine is generally an internal combustion engine and has the same characteristics. 

Poor performance of the engine will cause a drop in the performance of the generator as the conversion ratio of fuel to electricity drops.


As any equipment with moving parts, generators use lubricants extensively. The engine components and alternator bearings require regular lubrication to reduce friction. 

The lubricant can easily get contaminated after long operating periods. They should be changed on a regular basis to keep up the performance of the generator.

Voltage regulator

The generator produces alternating current. The magnitude will vary depending on the speed of the alternator. Any variations or hiccups can cause the output voltages to change. 

And here’s the catch. Industrial use requires steady voltage for normal operations. Voltage regulators play the role of regulating power output from the generators.

Cooling and exhaust systems

The engine burns fuel to generate mechanical energy. The leftover from the combustion has to be expelled efficiently through an exhaust system. The alternator can get quite hot after prolonged use due to different operational and environmental factors. 

A cooling system has to be in place to ventilate heat. If these systems do not work properly, the generator can shut down or cause other types of failure.


The early models of generators had to be cranked to start operations. Luckly, things have changed. 

The start function of a generator is now battery operated. The battery is in turn charged when the generator produces electricity. Hence, if the battery does not hold any charge, the generator can’t be started.

Creating a generator maintenance schedule

The most straightforward way to start with generator maintenance is to look at the instructions provided by OEMs. They build, sell, and maintain many generators so they should know what they are talking about.

Use OEM guidelines, consult with your maintenance team, and consider operating conditions and environmental factors to create the initial maintenance schedule. Ensure that the schedule is strictly followed with the help of work order software.

Maintenance work that is performed on the generators can be streamlined by creating detailed maintenance checklists and SOPs for recurring tasks.

If you are using a mobile CMMS like Limble, those procedures and checklists can be attached to PMs and WOs and quickly pulled up on your phone or tablet, ensuring that generator maintenance is performed according to the required standards. 

Industrial generator maintenance checklists

Different types of industrial generators will have different maintenance requirements that vary both in the types of tasks and their frequency. The exact maintenance schedule for your generator(s) should be based on the factors we outlined in the previous section.

Nonetheless, there are some tasks that are common to most, if not all generators. We outlined the following checklist to give you a rough idea of the workload for preventive maintenance of industrial generators. 

Weekly checklist

  • Conduct visual inspection of the generator’s exterior.
  • Check for leaks in the generator’s fuel system.
  • Check the oil level before starting up the generator. If the generator is in continuous operation, check the oil levels at regular intervals. In case the generator is rarely used, check the oil level every week.
  • Start and run the generator for 30 minutes in case the generator is not in regular use. This load test is to be done every week.
  • Change oil after 100 hours of generator operation.

Monthly checklist

  • Check the generator’s exhaust system. Ensure that the exhaust does not have any blockages.
  • Check the cables and battery on the generator. Make sure they are in good operating condition.
  • Check the generator’s ventilation system. Ensure there is proper ventilation. If the generator has coolant, check the coolant level and make sure there is adequate coolant in the chamber.
  • Perform a load test longer than the ones in the weekly check-ups. If the weekly load test is 30 minutes, the monthly load test should be at least an hour.
  • Clean the generator and the surrounding area during the monthly checkup.
  • Change the starter plug and air filter. 

Annual checklist

  • Change oil, oil filter, air filter, and coolant during the annual inspection.
  • Change and/or top up the lubricant after inspecting its condition.
  • Check if the transfer switch is working without fault.
  • Inspect the complete electrical system of the generator, including the battery.
  • Test the auto mode and other settings of the generator along with load tests. The last thing you want to find out in an emergency is that your standby generator cannot provide the full power you need from it.

If you are using condition monitoring, you can employ vibration analysis and predictive maintenance to optimize your maintenance schedules for industrial generators. 

Final thoughts

A generator is critical equipment used in industrial facilities for backup power when the regular power supply fails. Performing maintenance of the generator is critical. Often, it is overlooked as generators are rarely used. Generator failure can lead to major catastrophes and generator maintenance has to be taken seriously.

Generators have many moving parts and each component should be inspected on a regular basis. The input from OEMs, maintenance teams, and operational data should be used to create a maintenance schedule for generators. Create checklists and SOPs for maintenance procedures. 

Use CMMS software to ensure that the maintenance schedule and procedures are followed ardently.


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