FAQ #2: Why is Load Testing necessary?

Why is Load Testing necessary?  At Power Generator Systems, we respond to this common question, by breaking it into a few key areas

 What is a load bank used for?

Load banks are primarily used for testing electrical power output on Electrical power supplies by simulating real electrical loads on the power supply, distribution system and switchgear to ensure all are rated and operating as required, to meet the demands expected in real conditions.

The power supply under test could be from:

  • Normal grid or utility supply
  • Generators; diesel, gas, turbines, or alternate fuel supplies
  • UPS or other forms of battery or storage devices
  • Renewables

Whilst testing your site’s power system under real load conditions provides a multitude of advantages to prove the system and ensure parameters are within tolerance to support critical infrastructure, load testing is a vital component to ensure the performance and longevity of diesel generators.


Why is load testing critical for my Diesel Generator?

A generator can typically run at a level less than the unit’s rated output capability.  However, over time, lightly loaded generator sets develop wet-stacking and carbon build-up in the combustion chambers and exhaust system.  Some visible symptoms include ‘cloudy’ exhaust discharge and ‘slobbering’ oily discharge found around exhaust manifolds and turbo chargers.

This can lead to increased oil and fuel consumption, poor engine performance, and degrade its ability to adequately accept load steps and full load capacity. Ultimately this can reduce engine lifecycle and efficiency by fouling the fuel injectors, engine valves and exhaust system. Additionally, the piston rings can seize within the pistons which in-turn can allow the superheated fuel/air mixture to sneak past the rings and scorch the sides of the pistons.


How does load testing help my diesel generator?

The use of a load-bank helps to prevent these above effects by loading the engine up to correct operating temperature, thereby burning off oil and carbon deposits. This also confirms the generator’s capability to produce dependable required output in terms of alternator amperage and engine horsepower.

It is recommended a load-bank testing be performed on a regular basis to improve the life of the engine and alternator.


Why do I need to Load Test my equipment?

Apart from increased reliability and efficiency of the equipment, your site may have some regulatory and compliance requirements for building or site occupancy, to prove and provide records that the equipment is suitably maintained and tested to ensure correct operation under stress – that’s what it’s there for after all.

Load testing gives you peace of mind that your generator system will remain reliable throughout power interruptions and keep your business or life safety services running.   Load testing is one of your risk mitigation tools, in supporting continuity of services on site.


Key Points

  • Running a generator on full load helps to avoid “wet stacking” where the engine’s performance is compromised by unburnt fuel, lubricating oil and condensation caused by a light load on the alternator and low engine temperature and exhaust gasses.
  • Using a load bank to simulate actual demand will prove whether the controls and switch panels work as expected under real conditions.
  • Regular “black start” testing will ensure that in the event of a power failure, the standby system is capable of taking on the full load in 10 to 15 seconds of the generator starting.
  • Frequent operation of an automatic transfer switch (ATS), will ensure its proper operation.
  • Regular discharge of the UPS using a load bank will ensure it can provide its required output for the duration required.
  • Load testing of the site will ensure that any changes to the power profile of the building or process can be monitored, such as a change or upgrade to site infrastructure or a change in the generator itself (e.g., fuel, air flow, acoustics or change in the exhaust).


PGS are specialists in the operation and maintenance of generator systems, and have various sized load banks to suit different applications and site access.  We have been reliably providing these services and reports for many years to hospitals, data centres and various other applications.

Contact us on 08 8349 7854 if you have questions.

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