Testing times: critical facilities putting backup at risk

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Crestchic’s Paul Brickman warns that many sites are not properly testing their standby power systems. In light of recent events, critical facilities need to up their game…

The UK’s energy mix is going through a transition from fossil fuel-generated electricity to an increased reliance on renewable sources – posing challenges to the National Grid when it comes to balancing demand with ensuring a stable, consistent supply. That said, managing frequency deviations on the transmission grid at times of low inertia is already a priority for the power giant – with a spokesperson recently announcing investment in new technology which will collect data readings 50 times per second to monitor changes in the grid’s stability and predict the inertia needs up to 24 hours in advance.

Yet, despite the apparent reassurances offered by National Grid, the outage in August rendered many businesses and institutions powerless (in more ways than one). Businesses are often aware of the impact of a break in mission-critical power – from machinery in industrial settings, computers in banks, financial institutions and data centres, to the need for constant power in our hospitals and operating theatres. While many look to alleviate this risk by ensuring that they have their own backup power in place, an astonishing number fail to implement a robust testing regime – making an assumption that the backup will kick-in if an outage occurs. 

Most backup generators and uninterruptible power supply (UPS) systems are tested by the manufacturer in the factory prior to delivery. As a result, many businesses believe this to be enough to ensure that the equipment will operate effectively when installed. However, generators are not resistant to environmental fluctuations. Onsite conditions such as temperature and humidity often vary between locations and the impact of lifting, moving and transporting sensitive equipment can mean that manufacturer-verified testing may be thrown off kilter during installation. For this reason, it is absolutely critical that backup power systems are commissioned accurately and tested in-situ, under real site conditions to ensure that they will work as they should in the event of a power outage. The ideal way to do this is to use a loadbank. 

Back to basics

When businesses rely on power to remain operational, having backup power such as a generator is crucial. Yet generators and backup power systems are not infallible. Wherever there is standby power, there is also a need for a loadbank – a device which is used to create an electrical load which imitates the operational or ‘real’ load that a generator would use in normal operational conditions. In short, the loadbank 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. 

Generators are known for being robust, offering durability, reliability and reassurance that they will do the job and kick in if the worst happens. However, like any other internal combustion engine, lubrication, cooling systems, fuel system and electrics, all need to be tested to ensure faultless operation. Robust and proactive approach to the maintenance and testing of the power system is crucial to mitigate the risk of failure. Properly planned and implemented preventative maintenance strategies can minimise the likelihood of unscheduled breakdowns and outages, negating the potential risk of costly commercial, reputational and legal issues.

However, it is vital that this does not become a tick-box exercise. Implementing a testing regime which validates the reliability and performance of backup power must be done under the types of loads found in real operational conditions. 

Ideally, all generators should at the very least be tested annually for real-world emergency conditions using a resistive-reactive 0.8pf loadbank. 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 resistive-only loadbank is used (1.0pf), testing should be increased to two to four times per year at three hours per test minimum. 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.

 

Inadequate testing 

The reality is, in many instances, that those in charge of maintaining backup power have no regular testing schedule, making an assumption that occasionally powering the generator up, or testing for a minimal period, will suffice. By not testing the system adequately, the generator is put at risk of failure. 

In the event of a power outage, like the one in August, the impact on businesses such as data centres can be enormously costly, while for hospitals failed backup power could mean a threat to life. 

Capable of testing both resistive and reactive loads, this type of loadbank 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. 

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 major telecoms or data centres) where a problem with one generator could prevent other system generators from working properly or even failing to operate entirely. This is something that is simply not achievable with resistive-only testing. 

The recent power cut was the first of its magnitude in more than a decade and unforeseen vulnerabilities were exposed, throwing into question the resilience of the UK’s power network. 

While the government, regulators and power companies are working closely together to mitigate the risk of power failure to the country’s infrastructure, businesses for whom power is critical would do well to consider taking a more localised approach. At the very least, by having backup power in place and adopting a proactive testing regime, businesses are taking preventative action towards mitigating the catastrophic risk associated with power loss.

 

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