ELECTRICAL RESILIENCE
the HTM 06-01, an essential load includes equipment that directly affects the ability of the hospital to operate, or would be damaged if not correctly shut down, and must be kept running without a break in power. These applications should be reconnected within 0.5 seconds, and may include operating theatres, medical imaging equipment, life support and critical care equipment, medical sockets, and emergency evacuation systems.
One of the standby diesel generators supplied by Power Control in situ at Scarborough General Hospital; the entire installation was completed in under a month.
Hospital just before Christmas last year, the ramifications could have been catastrophic. Due to the cold temperatures, the winter season sees more hospitalisations than any other in the UK, so for a largest NHS acute Trust, which provides trauma and intensive care services to a population across the north- east Yorkshire coast, a situation where there is only limited back-up power is not a viable option. Given that this situation arose a month before Christmas, the chances of sourcing two new generators of such a size was slim, and at the time it appeared that the only feasible option was an expensive temporary solution until after the holiday season. As part of the North of England
Commercial Procurement Collaborative (NoE CPC), and also being on the NHS SBS Hard Facilities Management Framework, Power Control is already a known supplier of critical power supplies, including UPS, IPS, and generators. Scarborough General Hospital was able to call on the company’s supply chain in the hope of sourcing a quick and appropriate
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Power Control not only sourced two 770 kVA generators for the hospital, but also delivered them to site, and installed and commissioned them in a matter of weeks
60 Health Estate Journal April 2022
solution that would meet for the hospital’s needs. Power Control, in fact, not only sourced
two 770 kVA generators for the hospital, but also delivered them to site, and installed and commissioned them in a matter of weeks, with the entire project completed in under a month.
Stepping in in record time Nigel Watkinson, Electrical Services manager (East Coast) of Yorkshire Teaching Hospitals Facilities Management LLP at Scarborough Hospital, said: “When two of our main generators went down just before Christmas, we were very worried about the consequences. We couldn’t risk not having the secondary power supply, but with limited budgets, we were also reluctant to use temporary generator sets. Thankfully Power Control was able to step in and supply us with exactly what we needed in record time. The company is a pleasure to work with, and all the staff – from Sales and Account managers to Project managers and engineers – are professional and knowledgeable. We would not hesitate to use the company again for future critical power replacement projects.”
Sizing a UPS/generator pairing When paring a UPS and generator, sizing is one of the most critical aspects to get right, especially in a healthcare facility. The electrical load must first be categorised into two types of load: essential and non-essential, and the overall risk profile understood.
Essential load: Also referred to as ‘important risk areas’ in
Non-essential: Non-essential loads aren’t fundamental to patient and staff safety, and can be temporarily dropped (but must be restored within 15 seconds) in the event of a power failure; they include general lighting, general heating, hand dryers, and non-IPS-backed general plug sockets. Once categorised, the total load requirement of the generator can be determined. As a rule of thumb, generators should be sized to: n Twice the nominal UPS capacity for the typical UPS system using IGBT rectifier technology.
n Add the additional non-essential load and allow additional capacity (‘head room’).
n Take account of the load to be supplied within 15 seconds of cold start
Ensuring UPS and generator reliability Similarly to UPS systems, generators have intricate parts, which must all work harmoniously to ensure that they do not fail when they are needed. In order to maximise the reliability of a diesel generator, a maintenance schedule should be in place, and this should include the periodic replacement of batteries, lube oil, and antifreeze. An adequate fuel supply should also be established to keep the generator working at optimum condition. Water jacket heaters can also prolong
the life of a diesel generator, as they are designed to keep the engine at an optimum temperature for start-up and load acceptance. The warmth is generated by heating and circulating the engine’s coolant. Each of these items has environmental consequences, and a safe disposal policy should be enforced – including an audit trail documenting the controlled disposal.
Location, location For a new hospital site, planning for a UPS/ generator installation can be a lengthy process. The first step is to establish the
compatibility of secondary and tertiary power systems. Some UPS systems are more compatible than others, and are designed and manufactured with special features. Once the compatibility of the secondary and tertiary power systems has been established, and industry guidelines
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