Working in a Live DC

The brief outlined the requirements for a zero-downtime refresh of the trusts ageing power and cooling infrastructure in their main data centre, while also increasing resilience, adding capacity, and improving efficiency. As usual, the requirements were set out within the tender and APT was happy to put together a solution that best suited the brief. However, unbeknown to us, the tender documents would all too eerily foreshadow the coming events when asked how we would maintain project continuity should there be a global pandemic – we would follow the guidance given by the WHO of course. Thankfully, in the end, the pandemic had little impact on the schedule.

EcoStruxure IT Expert

The first step was to implement Schneider’s cloud based DCIM software, EcoStruxure IT. This gave both the hospital’s IT staff and APT full remote visibility from day 1. Having 24/7 remote visibility and alarming throughout the project was crucial for both parties. EcoStruxure IT Expert is now the primary DCIM for the Data Centre. EcoStruxure IT also enabled us to take accurate power consumption data from each of the critical assets within the Data Centre. This data would later be used to quantify the energy saving achieved.

We chose to adopt a phased approach in respect to the electrical and mechanical install. Phase one included the power upgrades and UPS replacement, phase two saw the full upgrade-replacement of the ageing cooling system.

Power Upgrade

To kick off we brought four new feeds into the Data Centre form two separate switchboards as the existing submain supplies were not sufficient to handle the planned capacity increase. Two feeds were allocated to the A and B UPSs and two for the cooling. These were terminated at new automatic transfer switch (ATS) boards. New distribution boards were also installed to provide A and B supplies to each rack and cooling unit. Once A and B supplies were established in each rack, it was possible to decommission UPS A while supporting the load on UPS B and raw mains. The load was then transferred to the newly commissioned UPS A and mains while UPS B was replaced. The possibility of running on generator and 1 UPS during UPS changeover was considered, however, certain hospital equipment can be adversely affected when supplied by onsite generation. Two Modular Symmetra PX 160 UPSs were installed providing increased capacity and an efficiency increase of 3%.

Cooling Upgrade

The cooling refresh started with the craned delivery of the temporary external chiller. The temporary unit was connected to the existing InRow cooling units through the original manifold and the cooling load was incrementally transferred away from the old chilled water system which was then decommissioned and removed. Once the hospital had completed the planned maintenance on the roof and our structural engineers had confirmed it could take the weight of the up-rated chillers without alteration, the new N+1 chilled water system was installed and commissioned along with the new Schneider ACRC301H InRow cooling units. The updated 2^nd generation InRow units provide an efficiency increase of around 20% and a max cooling capacity increase of 58%. However, the main efficiency improvements were achieved by implementing a free-cooling chilled water system to operate alongside the conventional chillers. The free cooler engages when the external ambient temperature drops below 12°C, thus reducing the power consumption of the entire cooling system to around 4kW. Based on historical weather data, we can predict that the free cooler will supply chilled water to the data center for roughly half the year. The combination of the free cooler and the updated chillers will see an 80% reduction in cooling expenditure per year.