How reliable is your backup power?
Author: Beatrice
By Paul Brickman, Commercial Director at Crestchic
What does good look like?
It’s no surprise that the data centre sector’s reliance on UPS is on the up, and the onus is often on the site manager or maintenance teams to ensure the equipment that provides this power is reliable, well-maintained, and fit for purpose.
The maintenance and regular testing of a UPS primary power source is considered best practice and any business that runs this sort of system will likely have a programme of maintenance in place. But this is only half a job done. There remains an astonishing number of data centres that fail to regularly test their backup power system, despite it lying dormant for the majority of the year. Instead, data centres are putting their trust in fate, hoping that the backup system will activate without fail – a fool’s game given the increasing cost of downtime.
Why factory testing is not enough
UPS systems and backup generators are typically tested at the factory as part of the manufacturing and quality testing process. Some businesses mistakenly think that this will be sufficient to ensure the equipment will operate effectively after installation. The reality is that on-site climatic conditions such as temperature and humidity often vary between locations. These variations in environment, combined with the impact of lifting, moving and transporting sensitive equipment, can mean that the manufacturer-verified testing may be thrown off kilter by on-site conditions or even human intervention during installation. For this reason, it is absolutely critical that backup power systems are commissioned accurately and tested in-situ in actual site conditions using a load bank.
Where unplanned downtime is likely to be costly or even devastating to a business’ financial stability – having backup power such as a generator is crucial. Wherever power is generated, there is also a need for a load bank – a device that is used to create an electrical load that imitates the operational or ‘real’ load that a generator would use in normal operational conditions. In short, the load bank is used to test, support, or protect a critical backup power source and ensure that it is fit for purpose in the event that it is called upon.
Backup power testing best practice
A robust and proactive approach to the maintenance and testing of the power system is crucial to mitigate the risk of failure. However, implementing a testing regime that validates the reliability and performance of backup power must be done under the types of loads found in real operational conditions. What would be considered best practice for testing a backup power system?
Ideally, all generators should be tested annually for real-world emergency conditions using a resistive-reactive 0.8pf load bank. Best practice dictates that all gensets (where there are multiple) should be run in a synchronised state, ideally for eight hours but for a minimum of three.
Where a reactive-only load bank is used, testing should be increased to four times per year at three hours per test. In carrying out this testing and maintenance, fuel, exhaust and cooling systems and alternator insulation resistance are effectively tested, and system issues can be uncovered in a safe, controlled manner without the cost of major failure or unplanned downtime.
Why is resistive-reactive the best approach?
Capable of testing both resistive and reactive loads, this type of load bank provides a much clearer picture of how well an entire system will withstand changes in load pattern while experiencing the level of power that would typically be encountered under real operational conditions.
Furthermore, the inductive loads used in resistive-reactive testing will show how a system will cope with a voltage drop in its regulator. This is particularly important in any application which requires generators to be operated in parallel (prevalent in larger business infrastructures such as hospital or data banks) where a problem with one generator could prevent other system generators from working properly or even failing to operate entirely. This is something which is simply not achievable with resistive-only testing.
Secure your power source
The importance of testing is being clearly recognised in many new data centres, with the installation of load banks often being specified at the design stage rather than being added retrospectively. Given that the cost of a load bank is typically only a fraction of that of the systems which it supports, this makes sound commercial sense and enables a preventative maintenance regime, based on regular and rigorous testing and reporting, to be put in place from day one.
While testing of power systems is not yet a condition of insurance, some experts believe it is only a matter of time before this becomes the case. At the very least, by adopting a proactive testing regime, data centres can take preventative action towards mitigating the catastrophic risk associated with power loss.
