In a normal setup, a UPS (uninterruptible power supply) is found between alternative sources of power and the protected loads. The reason behind this is to protect the loads from unexpected power failures which could damage the loads. To make this successful, most UPS are designed to power connected loads through an inverter whose main function is to is to enable conditioning the main supply voltage or break-free electrical energy supply when there is a failure to avoid potential damage. UPS are therefore considered paramount in the continuity of businesses because loads cannot be able to operate in case of power outage. This is the prime reason which has made testing a load bank to implement UPS to meet the requirements they mostly need in their functioning.
A load bank test is used to test the UPS and generator which is under load conditions to ensure that they are working optimally. This method is a way of validating the true operational performance as well as the battery autonomy used in UPS system. The main reason for testing load banks is to carry out preventative maintenance necessary to avoid future damages or breakdowns. In addition to preventative maintenance, load bank tests are used to ascertain the current conditions of UPS batteries as well as battery sets to show whether any of the cells are holding the charge, approaching the end of their working life or whether they are about to fail.
This facilitates their replacement before they cause a critical application problem. It is important to note that load bank test services are sometimes offered by suppliers of power protection equipment e.g. Uninterruptible Power Supplies Limited as a part of UPS commissioning process.
However, when carrying out this commissioning, caution should be exercised to ascertain reliable results and operations. Ideally, the testing services should be carried out at least after a week after the UPS has been commissioned. This is very vital because it not only permits the voltage across the battery but also allows the battery to be fully charged. You should understand that carrying out load bank tests before a week of commissioning would neither yield accurate results nor give you the true picture how the system is running. Therefore, this would be a waste of time and money and should be avoided.
The second important point to note is that the suppliers of load testing equipment usually carry their small load banks which are usually 100 kW or less but if you want to test a larger UPS system, they hire a larger set capable of testing the UPS. The load banks that they use are mostly resistive in nature i.e. they are neither inductive nor capacitive and current rises immediately into a steady state because they don’t have the first switch on the surge.
Generator load banks are available for both AC and DC systems depending on your requirement. DC systems are used to test batteries while an AC load block is used to test an entire UPS system. Also, if you are in need of reactive load banks, they are also available although they tend to be larger and heavier in design than the AC/DC load banks.
What is the essence of a load bank test? The idea behind this is to test the power protection system and its components while the system is under load conditions without risking the supply of protected loads. Mainly, it shows whether the system is in its right conditions by just conducting some tests.
UPS and power supply systems need periodical testing to ascertain that they will work when the need arises. This can be compared to fire alarms which require consistent maintenance practices to ensure that in the case of dire they are working properly. The operators usually want surety that it will run when fully loaded and hence a load bank test is responsible for taking the power protection system into a test in a controlled environment.
To carry out the testing process, the load banks should be supplied with quality rated cables to facilitate effective charge transfer. The load bank should not be placed more than 20 meters from output power distribution unit (PDU) or UPS terminals. You should understand that load banks are made up of heating elements and fans which are responsible for cooling the system.
Therefore, allowances should make to allow heat dissipation and attenuation of noise during the testing process. Also, you should not test the UPS system close to an area where people are working, near sensitive alarms or sprinkler systems as a precautionary measure.
After carrying out the test, measurements are taken during discharge where the battery and system performances are determined. A load bank test identifies the problems with the generator and the UPS prompting for immediate actions to be taken to facilitate its efficiency.
In case there is a standby generator, load bank testing will indicate:
After making the above observations, the generator load bank testing will help in removal of deposits from the pistons, removing engine castings and exhausts as well as noting potential weaknesses. This will be followed by a recording of the results and doing any other work that needs to be done.
It should be understood that, although power protection equipment should be maintained and tested regularly, load bank testing should be carried out wisely and cautiously because it can reduce the resilience of the system, discharge batteries or in extreme cases place the connected loads at risk. Hence, this testing is carried out by experienced and skilled professionals outside normal working hours. For generator load bank testing to be carried out in your systems, it entails hiring equipment if you’ve large systems, pay engineer time and pay for temporal cable provision and connection. Necessary precautionary measures should be considered to enhance safety and prevent potential damages to the system.
Itis advisable to carry out regular a load bank test because they will ensure that the components in the power protection system will perform effectively and optimally when needed to support a critical load.
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