Paralleling and load acceptance demands
The demands on two generator sets operating in parallel in a hospital application are understandably extreme. Power outages or variations in power quality can wreak havoc in the high-pressure, high-stakes world of health care providers.
The new mtu generators meet the challenge with the capacity to start, accelerate and parallel-connect onto the hospital’s emergency power generation bus in less than0ten seconds for the first genset and within ten seconds for the second. Additionally, the gensets must automatically share steady state loads and transient step loads over the full range of power within 0.1 +/- 5% of rated kW capacity.
The generator sets are UL Recognized and CSA Certified. Full-load generator testing at least once per year for two hours per generator is recommended for hospitals in accordance with NFPA 110 (National Fire Prevention Association), which Canada adopted in 2007.
According to Randy Arnett, head project consultant with Genivar, a professional services firm in Vancouver, the system’s design incorporated innovative features that allow the hospital to conduct these routine test cycles on each generator set without having to connect them to an external load bank, thus saving fuel and avoid risking a power interruption. To accomplish this, the generator control systems integrate a closed transition transfer automatic transfer switch, which permits the generators to pick up the hospital load without interruption by paralleling its output to the local utility provider, while transferring the load from the utility source to the generators. Once the generators are carrying the hospital load, the control system allows one of the two generators to operate at a fixed load, adjustable up to its full load rating, while the other generator set carries the balance of the hospital load.
Seismic certification important
Arnett explained that another feature of the mtu generator sets is their seismic rating, confirmed by independent testing in accordance with International Building Code requirements. This rating was particularly important to Royal Jubilee, given its location in a seismically active area of Canada. “Following an earthquake, emergency power is considered to be critical for a hospital to continue to function and service the needs of the community,” he said.
The heart of each 28,000 kg (60,000 lb.) mtu model 3000LXC6DT2 generator is an mtu 20V4000 diesel engine. Certified to U.S. Environmental Protection Agency (EPA) Tier 2 emissions standards, the engine produces less nitrogen oxides (NOx) than any engine in its class, and only 107 decibels under full load in standby mode—important characteristics for Royal Jubilee’s Pacific Green goal. The 20V4000 also delivers high horsepower-per-liter and impressive fuel economy thanks to advanced digital engine controls and high-pressure common rail fuel injection.
Because the new mtu generators replaced existing units, Cullen and Genivar technicians had to carefully plan the logistics of the installation during energy center construction. “It was a challenge to coordinate a new energy center without shutting down existing facilities at RJH,” said Rudi van den Broek, chief project officer for VIHA. “The fact that we managed to complete this piece of the project ahead of schedule and under budget is a testament to the work of everyone involved.”
“The new power system enables us to continue providing excellent health care, even in the most extreme situations,” said Jac Kreut, board chair of VIHA. “The generators provide safe, reliable, efficient and long-lasting power and were the logical choice in keeping with the overall green project design.”