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By Joshua J. Gepner
February 2013 -
Data Centers Article Use Policy
AS DEMAND for data center whitespace continues to increase, there’s often a need to expand existing mission critical facilities. Because the expansion often shares its power source with an existing data center, a major challenge lies in commissioning the newly installed equipment and systems prior to supporting any real critical load.
Ideally, the new equipment and systems will be designed and integrated into the existing infrastructure in a manner that allows them to be isolated for commissioning activities. However, if the new infrastructure isn’t isolated, portable generators can be used to supply power during commissioning.
Portable generators can be a viable solution for commissioning, specifically in cases where construction and commissioning activities occur prior to connecting to the existing building. However, the issues associated with portable generators should encourage engineering teams to focus on design solutions that will allow future data center expansions to be electrically and mechanically independent from existing infrastructure.
Recently, in the commissioning of a data center expansion building in the southern United States, the new equipment was served by an electrical system that also powered an existing, live data center. Portable generators were employed to simulate complete electrical isolation. The whitespace expansion was supplied with two utility feeds serving the main switchgear and was equipped with its own cooling systems, utilizing no cooling support from the existing building. The full design server load and cooling load for the expansion building was 2 MW.
While using portable generators was appropriate in this case, many challenges surfaced as a result. Here are a few.
1. Equipment logistics, schedule and budget. Because the two 2 MW portable generators originally rented for both sources of the building had continuous operational problems, the commissioning team rented two paralleled 1 MW portable generators for each of the two utility sources (totaling four). The smaller portable generators were not supplied with sophisticated paralleling equipment, capable of properly sharing load or able to support step loads exceeding the capacity of one generator and were never intended to operate as a generator plant.
In addition, the portable generator fuel levels required constant monitoring to avoid invalidating tests, commissioning delays and ultimately postponing project delivery. During one instance, a generator was not fully filled during routine fueling, which resulted in the generator shutting down and termination of an extended ongoing test. The portable generators were also the only source of power to the building and running out of fuel forced all work in the building to be halted. As the sole power source to the building, at least one portable generator was running 24 hours per day, which led to several noise complaints from the residential neighborhood situated near the site.
1. Do the construction or commissioning activities pose a significant risk to the live load?
2. Does required completion date limit the ability to conduct commissioning in preplanned scheduled work windows?
3. Is the commissioning team comfortable with the known problems associated with portable generators as a power source?
4. What expected effects will the portable generators have on the test results of the equipment and systems?
5. Does schedule allow for added testing and verification after final electrical connections are complete to confirm that problems caused by portable generators are no longer present?
— Joshua J. Gepner
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