How healthy is our power infrastructure?


    Power Control’s Robert Mather looks at the implications of the August blackout and highlights the importance of applying best practice within hospitals, and other critical facilities, to avoid risk…

    Following the blackout on 9 August, National Grid confirmed that due to the fall in frequency of the system, it followed its planned isolation process by disconnecting selected segregated areas. 

    Although regarded as standard procedure by National Grid, it has raised some questions. How have these areas been chosen? Is it done at random? Can the businesses affected by the scheduled shutdown be compensated? And to what extent can this be the acceptable safeguard? 

    Satisfying the latter question, National Grid has recently issued a statement confirming that it is accelerating its plans to increase its backup power provision. 

    With the 1,000MW reserve completely exhausted from the latest power outage, which drew 1,400MW of power from the energy system, the company’s priority is to avoid another ‘system shock’ at all costs. The firm has also admitted that “a lot of lessons have been learnt” from the recent blackout. 

    Critics believe that National Grid’s conflict of interest in safeguarding the nation’s electrical framework will be detrimental to the successful implementation of its power protection strategy. The company owns the UK energy infrastructure and has overall responsibility for balancing electricity supply and demand. 

    It is also facing widespread criticism for its lack of foresight. Despite endless warnings that a large-scale blackout could occur, nothing has been done to mitigate the impact. 

    Not only does National Grid need to take responsibility for increasing the amount of storage available but our power plants do too. It is already acknowledged that sudden drops in power are becoming increasingly common and, as recently discovered, there is not enough in reserve. While backup power is being positioned on a large scale, in power plants up and down the country, businesses of all sizes should also be adopting the same backup power protection principles.

    UPS systems

    Society continues to embrace technology, which only means an even greater strain on our electrical infrastructure. Backup power solutions such as uninterruptible power systems (UPS) are fast becoming commodities with more and more homes and organisations including them within their IT and electrical infrastructures. A UPS system provides emergency backup power not just in the event of a complete power loss but it also provides a constant clean power source to safeguard against sags, spikes and surges – frequencies that are becoming a common occurrence. 

    Power Control is helping businesses across the country to implement more resilient power protection policies. Ensuring the correct UPS system is specified is a key part of Power Control’s role. 

    It does not just address the initial backup power necessity but looks at the complete critical power path. This ensures that UPS capacity is measured appropriately to accommodate growth and achieve efficient total cost of ownership (TCO). 

    Future proofing and understanding TCO form an essential part of power management strategies. It is important to analyse the complete life span of equipment from initial purchase through to management and maintenance. Heightened demands on the grid have made this close analysis more critical than ever as a measure towards safeguarding against the increased vulnerabilities in the UK’s power source.

    Hospitals: the importance of HTM compliance

    The power outage on 9 August also highlighted the importance of applying best practice within healthcare trusts. It was reported that a prominent hospital and a number of other critical care facilities were left without power after a backup diesel generator failed to start. It could be assumed that these sites had not recognised the best practice guidance within the guidance HTM 06-01 as they were left vulnerable to the power failure.

    Potential failures of a secondary power supplies are clearly overlooked compared with primary power supply failures. Businesses ignore the possibility of a concurrent failure to mains power (primary) and the backup generator (secondary) only to be thrown into darkness when a power cut happens. To be HTM compliant a tertiary power solution, such as UPS, must be installed.

    For those with tertiary backup power provisions, it is important that the internal components meet the design set out in the HTM. It is not enough to simply plug in a basic UPS system. Careful consideration must be given to the size, location, configuration and internal structure of the UPS to meet best practice and guarantee patient safety.

    However, the batteries control the reliability of the entire system. To adhere with the HTM guidelines, the batteries should have a 10 year life expectancy to ensure the long-term security of function.

    UPS batteries require a suitable environment, as detailed in the manufacturer’s operating manual, to fulfil their life expectancy. Typically, the ambient temperature around the UPS should be 20°C with adequate ventilation and cooling. At 30°C, the life expectancy of a typical valve-regulated lead-acid (VRLA) battery is reduced to 50% and 25% at 40°C.

    A VRLA battery is recognised as being a near-zero-gassing battery by the HTM and so presents a lower environmental hazard to the UPS and surrounding area. 

    It is also important to note that the VRLA battery must comply with the BS EN 60896 (21 and 22) standards with threaded insert connection posts and flame retardant case materials.

    Another UPS component mentioned in the HTM guidelines is the bypass switch. These should be rotary locking switches located on the input. Furthermore, external battery DC isolators are required in hospital environments. These are ideally situated on the front of the cabinet or an accessible wall. Although isolation (zero-phase shift) transformers do not feature inside the UPS, they are essential to the overall infrastructure to prevent problems occurring when the input neutral is switched or broken. 

    These transformers can be placed on the output. However, it is more beneficial for them to be installed on the UPS input. Consideration needs to be given based on the electrical infrastructure design.

    The UPS system itself should conform to the following standards:

    • BS EN 62040-1
    • BS EN 60146-1-1
    • BS EN 61439-6
    • Energy Networks Association’s G514-1

    To meet the minimum requirements of redundancy, an N+1 configuration must be in place. Furthermore, the HTM requires each UPS to be sized with enough capacity to individually be able to fully support the whole load. For example, where the critical load is 100kVA, two UPS systems carrying an absolute maximum of 50% load each would be necessary.

    Although the updated 2017 edition of the HTM 06-01 suggests that modular UPS systems can be used, further consideration is required. Modular redundancy is not treated as true redundancy due to there being multiple points of failure. 

    Regular maintenance

    All too often dutyholders become complacent because a UPS is already installed. However, without regular maintenance, how do you know whether it is still effective and fit for purpose? The HTM covers some of the components within a UPS, but there are many more delicate electrical parts that all need to be working in harmony to provide the power when it’s needed.

    A popular choice of UPS system for hospitals is the Borri B9000 FXS as it is fully compliant with all international product standards, can run off two power sources and the batteries come with a 10 year design life as standard.Identifying the correct UPS system for hospital facilities requires careful planning and expertise. 

    With more than 25 years of experience in providing backup power solutions, Power Control is ideally placed to offer guidance and support for ensuring the healthcare unit’s critical power complies with HTM guidelines.


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