What is a generator load bank testing?

What is generator load bank testing

A load bank is a portable artificial resistive or reactive load that can be connected to your generator or UPS. It allows you to perform testing on your power supply equipment at specific load values to test your equipment’s capabilities of handling load.

Why is it necessary to do a load bank test?

Generators are tested to their full rated capacity for a defined period of time to validate correct and safe operation of the engine, alternator, auxiliary systems and control and protections. This is important for a business as you need to feel confident that in the case of power-loss, your equipment will not fail to accept your site loads.

Load bank testing keeps your businesses operations moving with non-intrusive testing.

How can a load bank reveal points of failure better than running the generator once monthly?

When a generator is run without load, or exercised for a better word, the machine is not worked hard enough to test its components effectively.

Some factors to explain this below:

  • The torque demand from the engine is very low due to the lack of alternator loading causing low electromechanical forces on the drive shaft. When load is applied, a higher torque is required from the engine and this demands a higher supply of fuel through the supply system including the fuel filters and pump. Applying the full load will prove that there are no restrictions such as clogged filters that can starve the engine and cause shutdown.
  • The higher load demand on the engine will also prove airflow through the air supply, exhaust flow and turbocharger operation.
  • The lack of load on the alternator cannot prove the integrity of the alternator main and auxiliary windings and associated components such as diodes and AVR. The full loading will also expose any weakness in the cabling and connections.
  • The cooling system under no-load operation will very likely not need to operate as a complete loop, which means that the engine coolant does not reach the temperature level required to open the thermostat and allow coolant flow through the radiator. Operating on full load will ensure thermostat operation and enable observation of adequate heat transfer through the radiator. Sometimes a clogged radiator core will not cause issues for no-load tests but can be the point of in a mains fail scenario and result in over temperature shutdown.

As you can see from above, using a load bank on your generator is an effective way of ensuring that your generator can perform when you need it to!

Why not just prove the generator on the building load?

One of the benefits of using a loadbank is that you don’t always need to disrupt your operations. For an emergency generator or standby generator this means that you can perform the load test during business hours without any disruption as the building load is supplied by the mains as usual.

If disruption is not an issue there are other factors that need to be considered as below;

A suitably sized generator will often be rated higher than the building load, to allow for various factor such as transient loading from starting motors and additional capacity for future circuits to be added to the distribution system.

Ideally, a suitably sized generator will have at least 50-60% load when run at all times. In reality due to the majority of machinery and three phase equipment having motors, a generator is often run on very little load after the initial inrush of starting motors has passed. This means that there are cases where very low loading on the generator takes place (under 30%).

Without sufficient building load, the generator cannot be put through its paces as described above.

Protect your engine from premature failure

When a generator is run for regular periods of no-load or light load (<30%) issues occur such as ‘cylinder glazing’ and ‘wet stacking’ which effectively cause carbon deposits in your engine and exhaust that if left to accumulate, can cause expensive repairs due to premature engine or turbocharger failure. By connecting a load bank and testing to a higher load rating, this will burn of the carbon deposits and protect your engine and extend the working lifetime of your asset.

To learn more about protecting your generator with our load banking services or to book a service with us please contact us.

Your Power is Our Priority.

Paul Phelps
Paul Phelps

Paul is the MD of Solent Power and specialises in emergency power solutions, helping to protecting your facilities from power loss. Get in touch with us today to discuss the different power brands that we can offer and how they can suit your needs.

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