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Why load banks are important in testing that your critical infrastructure works

Published by Lee Kelly on 08 July 2019

Backup power sources like UPS systems and generators, as well as essential components such as cooling banks and the like, are critical infrastructure in relation to powering your business or home.

A UPS ensures uninterrupted power supply in the event of mains power loss while protecting your electrical equipment. A generator can then take over, providing power for extended periods of time. These power sources' cooling systems are imperative to their proper operation, while IT systems and other sensitive electronics also have cooling systems which prevent them from overheating.

It is imperative that this critical infrastructure is operating correctly at all times and under all possible conditions. Running diagnostic tests when systems are idle may reveal certain issues, but to ensure your alternative power source equipment will perform correctly when an incident occurs, it is important to test while under load.

Of course, you do not want to test your alternative power supply by having it power your protected equipment – if there is a problem, this puts your IT system and other equipment at risk. The solution – load bank testing.

Critical Power Supplies - Backup power engineers load bank testing

What is Load Bank Testing?

Load Bank Testing allows a simulation of the load your auxiliary power system will experience in the event of a power loss through a ‘dummy’ load known as a load bank. Because the load is adjustable, it is also possible to apply a larger load to ascertain the alternative power source’s ability to handle more equipment as your IT system grows.

The most common type of load bank is the resistive load bank, which creates load by converting electrical energy to heat. These load banks do a good job of simulating the types of loads created by the motors and transformers in generators.

So-called ‘reactive’ load banks (Inductive load banks and Capacitive load banks) mimic the loads created by electromagnetic devices. Capacitive load banks, in particular, are excellent at recreating the electronic and non-linear loads of some UPS, computer and telecommunication equipment.

A common practice is to use a combined load bank that incorporates both resistive and reactive elements. By including both, it is possible to more realistically recreate the mixed load that your alternate power supply will experience in the event of an actual power loss. Electronic load banks also exist. Fully programmable, these are useful when extremely specific loads are called for.

How Is Load Bank Testing Done?

First, the load bank is placed a suitable distance away from UPS and generator equipment. Close proximity to sensitive heat/fire systems, sensitive equipment, and employees are also to be avoided. This is because load banks generate quite a bit of heat and their cooling systems can be somewhat noisy.

The load bank is connected to the auxiliary power system using high-quality cables with ratings appropriate for the expected power load. The kW load is gradually increased in specific increments for set time periods with data recorded at each stage. Eventually, the load bank is run at ‘full load’ for a sustained but reasonable period of time.

Following the test, the information gathered is reviewed. Equipment performance that falls outside acceptable parameters is further examined, and technicians are able to discern any components that are in need of repair or replacement, or system settings that need to be adjusted.

Why Are Load Banks Important?

As previously mentioned, load banks allow testing of your alternative power system under load conditions without risking damage to your IT system and other protected loads. The specific advantages of this process are many, and result in a healthier and more reliable alternative power system.

Early issue detection – Without regular load bank testing, some issues may become obvious during other maintenance or operation. By that time, however, the solution may be significantly more expensive and additional problems may have arisen due to a ‘domino effect’.

Ensures availability of your alternate power system – There are sometimes undiagnosed issues that will cause your UPS and/or generator to not engage at all in the event of a power failure, or fail soon after engaging. A load bank test immediately catches such issues without endangering your IT systems and other important equipment.

Verifies full load capability – Your auxiliary power system may be able to operate just fine given smaller loads, but a problem may render it unable to operate at full load for an extended period of time. Discovering this can prevent disaster in a real-world situation.

Ensures cooling/oil systems will perform under full load – It is often forgotten that, just like any combustion engine, a cooling system is a necessary part of a generator. If the cooling system cannot perform its task properly in load situations, the engine will overheat and fail. The same is true for the oil system and its ability to provide lubrication for moving engine parts. It is therefore just as important to verify the health of the cooling and oil systems as it is the health of the power components.

Measures battery autonomy – This measures the time UPS batteries will support the critical load. Through this testing, the health of a UPS battery or individual cells can be ascertained, and replacements made if necessary.

Verifying ATS performance – The ATS (Automatic Transfer Switch) is the device that seamlessly transfers power from the mains to the UPS (and often from the UPS to the generator). This must operate correctly under full load conditions for the safe redistribution of power.

Emission Testing – The emissions profile of a generator changes depending on the load on the motor. For accurate measurement of the emissions that will be produced in real-world operation, data must be recorded when the generator is supporting a comparable load.

Wet Stacking

This is not a testing or analytics concern, but it is a vital part of preventative maintenance. Most diesel generators will only be used intermittently, and this makes them prone to ‘wet stacking’ – the buildup of unburned fuel and carbon deposits (soot). This not only makes the generator work less efficiently, but it can also result in component damage and even be a fire hazard. This still occurs when the motor is run with light loads or no load at all, so regularly running the generator during maintenance is not a solution here. Running a generator at full power and temperature, as during a load bank test, successfully burns off any wet stacking.

U.K’s Critical Power Specialists

With a quarter-century of experience, Critical Power is the U.K.’s power protection solution specialist. As the country’s leading independent multi-brand supplier, we are able to provide you with the best equipment and overall solution for your particular application. We also provide professional support through our extensive 24/7 support and monitoring network. Whether you’re looking for a new UPS and/or generator, genuine replacement parts, ancillary parts, expert service or simply advice, Critical Power has you covered. Want to ensure your valuable equipment and data is protected from disastrous power failures? Contact us today!