ELECTRICAL ENGINEERING
Transforming power supply at Vancouver Island hospital
In an article first published in Canadian Healthcare Facilities, Lisanne Naeth, P.Eng, a senior electrical engineer at AES Engineering, describes plans for a new, remotely located, electrical energy centre at Victoria General Hospital on Vancouver Island. The project will see essential electrical supply greatly improved, increase resilience, address safety issues related to the proximity of the current main electrical room to two water mains, and provide additional future site flexibility.
Located on the south end of Vancouver Island, Victoria General Hospital (VGH) is a 347-bedded acute care facility. The 1981-constructed hospital comprises a main diagnostic and treatment (D&T) podium and two seven-storey patient towers. Over the years, the facility has been expanded and renovated, and includes a new Emergency Department. The hospital is supplied from utility at 25 kilovolts (kV) via an underground feeder into the main electrical room located on Level 1. Much of the original main electrical distribution is still in service. While meticulously maintained, including some breaker upgrades, the equipment is 40 years’ old, and has reached the end of its expected service life. Examination of the essential power
distribution revealed that the two 600-kilowatt, 600-volt generators no longer provide N+1 redundancy. (Both generators are required to meet the demand of the vital and delayed vital branches.) This is a result of the ongoing organic growth of essential power requirements in the facility. The limitation of available essential power poses a
significant challenge for routine equipment refreshes, upgrades, and renovations, as most new imaging modalities have a higher power demand than that of the equipment being replaced. In addition to equipment age and capacity issues, there are two active capital regional district (CRD) trunk water mains – of 1,220 and 1,067 mm in diameter – routed across the site approximately 30 metres from the main electrical room. The site has a natural dip or low point near the main electrical room. If both water supply mains were to rupture due to a natural disaster or piping failure, this electrical room would flood to an elevation of nine metres in 4.5 hours, because there is no automatic control function to shut down water flow.
Electric distribution equipment replacement Given that the current state of the electrical distribution system is calamitous, Island Health has proactively engaged a consulting team to design the replacement of the existing electrical distribution equipment, and address some of the
facility resiliency risk, with a remotely located new electrical energy centre (EEC). The EEC will be located on an elevated greenfield site away from existing structures to mitigate risks, such as flood, fire, and seismic concerns. The design of the new EEC includes capacity to support all existing and anticipated future power requirements at the VGH campus. The EEC will house BC Hydro service
entrance equipment, BC Hydro metering, transformation equipment, generator paralleling and synchronisation controls, dual bypass transfer switches, and the vital, delayed vital, conditional, and normal primary distribution switchboards. It will also contain all the relays and sensors required for protection, control, and monitoring of this new system – both locally and via remote operation from the D&T building’s control room. The new generators will be located in outdoor rated walk-in enclosures adjacent to the EEC. The generator synchronisation bus will be arranged with generator connections, feeder positions, and additional positions for temporary generator, load bank, and future generator connections.
Located on the south end of Vancouver Island, Victoria General Hospital is a 347-bedded acute care facility. The 1981-built hospital comprises a main diagnostic and treatment podium and two seven-storey patient towers.
30 Health Estate Journal May 2024
Dual redundant supply Two utility selectable BC Hydro 25 kV services will replace the single existing service. The dual redundant supply will allow the utility to supply the site from one of two separate substations as required for increased facility resiliency, to upstream outages and eliminate a single point of failure. Two 3-megavolt amperes (MVA) transformers will be used to step down the 25 kV BC Hydro supply to the 12.5 kV distribution in an N+1 configuration. Provisions for replacing these transformers with 5 MVA units have been included in the design for future site demand. Distribution from the EEC to the existing VGH facility and future buildings will be at 12.5 kV. The new EEC design includes 3 MVA of generator capacity on day one to support the current site peak demand, with N+1 redundancy. Allowances in
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