Mr Rowley wanted a switch board for his new hotel, the Medina Palms in Watamu. It needed to handle enough power for lights, heat and air conditioning in all 50 separate villas, the pool’s filtration system, security cameras, and the hotel’s kitchens and bars: drawing approximately 1000kVA from the national grid and directing it through hundreds of individual switches and control units built into one central console. I picked up my pencil- this was not an electrical engineering exam at school: instead of lounging at the beach with my friends, I had chosen to spend my summer at Specialised Power Systems (“SPS”), designing and building Mr. Rowleys‘s switchboard.
As the engineers and I gathered around and started to draft designs for the switchboard, we quickly recognised several key issues. Mr Rowley wanted the switchboard to have power capacitors to increase general efficiency, and the capability to work coherently with generators and invertors to account for the Kenyan grid’s frequent blackouts and power surges. Both capabilities are extremely important in Africa, not only for luxury hotels but also for the health of national infrastructure. By working on Mr. Rowley’s luxury hotel, I could learn to implement the technical knowledge from study into real-world projects, such as expanding and improving the Kenyan national grid and bringing cost-efficient generators to rural areas.
We set to work. Mr. Rowley’s first requirement for his switchboard was to have a power-factor capacitor bank, which allowed me to explore in depth a component I first studied through my A-levels physics classes, and one that is crucial to energy efficiency and modern electrical systems. Essentially, capacitors are used to store electrical charge. Mr. Rowley’s requirement meant that his system, which normally drew 1000kVA from the grid, would have to be able to utilise 100kVA in order to account for the extra power occasionally needed to start water pumps, electric lights, electronics and emergency equipment.
Yet an additional multiplier, called the diverse factor (generally calculated to be 80%), is added to the equation to account for the fact that not every piece of equipment is required to turn on at once. We took the textbook equation to determine capacitor requirements:
KW = cosϕ X kVA
cosϕ =0.9 minimum requirement
And calculated the Medina Palm’s specific capacitor requirements: KW = 0.8 X 500 = 400kVAr kVAr =1000kVA X 0.5 X 0.8 In order to build a system capable of handling 400kVAR, we determined that a bank of 8 connected 50kVAr power capacitors would be the best solution as a automatic unit. For a generator capability we fitted the control panels with Tem Transfer Relays, devices that work in conjunction with Auto-Start-enabled generators to automatically supply power to the system in case of a power failure. By working with the generators at the Medina Palms, I learned skills that are critical to the infrastructure of Kenya.
For example, only 30% of Kenya receives electricity from the national grids, and the grids are unreliable and confined to major cities. Generators can bring power and all its benefits to the rest of Kenya, and projects like the Medina Palms bring the technical skills and economies of scale that can make generator power accessible to the wider population. I hope to leverage my previous study of A-level physics, experience with SPS, and future degree in Engineering to bring such modern, affordable electrical capabilities to Kenya.
Courtney from Study Moose
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