Diesel Generators: Preventative maintenance is key to cost saving – Part Two

Diesel Generators: Preventative maintenance is key to cost saving – Part Two

By Jack Ward, MD of Powermode

In my last blog, I looked at how monitoring and maintenance regimes for diesel generators are also keys to cost saving. I stressed that a well-maintained generator will work at full capacity every time it’s called upon to do duty. I listed a number of tasks that had to be regularly carried out in order to meet maintenance and reliability objectives.

Let’s continue: It’s important to remember that diesel fuel is hydroscopic, attracting water which contaminates it. Thus it’s necessary to use any stored fuel well before it degrades. In additional to other fuel system services recommended by the engine manufacturer, the fuel filters should be drained on a weekly basis. Water vapour also accumulates and condenses in the fuel tank and must also be drained annually - along with any sediment present.

The generator’s charge-air piping and hoses should be inspected regularly for leaks, holes, cracks or loose connections. Tighten the hose clamps as necessary. The frequency with which air cleaner filter elements is replaced is generally determined by operating conditions. Air cleaners typically contain a paper cartridge filter element which can be cleaned and reused if not damaged.

The electrical system could be the root cause of many problems. Check the battery and its terminals for clean and tight connections. Trouble here will make starting problematic. Weak or undercharged batteries are among the most common causes of standby power system failures. It’s a fact that even when kept in tip-top condition - fully charged and maintained - lead-acid batteries are subject to deterioration over time.  

Only regular maintenance and a rigid schedule of inspection and testing under load can prevent premature battery failure and consequent generator starting and power provisioning problems.

You shouldn’t simply check the output voltage of the battery as this reading is not indicative of its ability to deliver adequate starting power. As batteries age, their internal resistance to current flow goes up. Therefore, the only accurate measure of terminal voltage is achieved under load.

In addition, load transfer testing of automatic transfer switches at regular intervals will keep track of the generator’s electrical and mechanical integrity. Other components to be checked regularly include starting and timing relays, start signal continuity and utility power phase sensing.

Like us humans, diesel generators need regular exercise. Units that are on continuous standby must be able to go from a cold start to fully operational status in seconds. This imposes a severe burden on engine parts. However, regular exercise keeps engine parts well lubricated, fluid lines unclogged and prevents harmful oxidation of electrical contacts.

I believe it’s critical, from both operational and safety perspectives, that servicing and maintenance be carried out by qualified technical personnel. Ideally, the task should be outsourced to a specialist firm well versed in diesel generator technology.

I’m sure you’re aware that diesel engines are quite different from petrol engines like those used in automotive or trucking applications. They require specialist knowledge when it comes to maintenance and repair.

Remember to maintain records and take precautionary measures for safety as suggested by the manufactures. When performing routine maintenance, each action should be logged and the readings and various parameters should be recorded along with the date of inspection and the hour meter reading of the generator.

These readings should be compared with the next set of data collected. A marked variation would most likely indicate faulty performance. This is a call to action.

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