The financial community probably exemplifies the digital economy more than any other indus-try. In the United States alone, the uninterruptible flow of electrons (or photons) in the data centers and communication systems of the stock exchanges, banks, insurance and credit card companies make nearly $100,000 per second. According to the U.S. Economic Census of 2002, for those with NAICS code of 52, there are more than 440,000 establishments employing 6.6 million people that generate $2.8 trillion in revenue annually. That is just the revenue and doesn’t account for the value of the transactions flowing through their systems.
The digital economy (DE) industry can come to a screeching halt when the quality of the electric supply becomes incompatible with the requirements of the servers, routers, modems and the rest of the information technology (IT) equipment. According to the Electric Power Research Institute, depending on which quoted data from which survey you want to use, there are $13.6 billion in annual losses in the digital economy due to power interruptions and disturbances. As expected, other industry groups had losses three times that or more. The DE companies have understood the need for double and sometimes triple redundancy on the power systems. But that doesn’t make them immune. It just makes them more complicated.
In the flesh
Recently, I was able to visit two of the more notable DE companies. Both had substantial investments in the power sources and moni-toring systems, with multiple generators with double the capacity of the load, rooms full of batteries for the redundant uninterruptible power supplies (UPS) systems, and monitor screens, showing how the system was performing in the present and past. But there was a distinct feeling that one of the two systems would have a much better chance of maintaining the uninterruptible operation that its busi-ness requires. It is an area that is often negatively impacted by belt-tightening—electrical equipment and system maintenance.
In the first facility, the one-line diagrams of the electrical infrastructure were updated continually. Each time a change was made to the equipment, wiring or significant load change, the drawings were sent back to the architecture and engineering firm to reflect the changes. There is an ongoing program of replacing the wiring in the facility, with about 75 percent of the project completed. The gen-erator room was one of the cleanest I have seen. Since generators aren’t worth much for sustained interruptions without adequate fuel supply (a hard lesson learned by many in the August 2003 blackout), they have resources for several days’ operation on hand. The facil-ity was basically in compliance with the new article in the 2008 National Electric Code on Critical Operation Power Systems even be-fore the revised Code is published.
They also understand that even with all of the backup power systems, there is a need to continually monitor the local electric utility’s sup-ply. Full transfer load tests are scheduled periodically, though sometimes they occur unscheduled.
A few days before the visit, the facility was subjected to an “unannounced temporary undervoltage condition.” They have an agreement with the utility that if there are going to be some switching operations for maintenance of the utility system, they will be notified ahead of time to be prepared. While their backup systems made it a “nonevent” for all of the occupants (and equipment) in the facility, the electrical maintenance group was well aware of the event and on the utility company to explain the source and what steps were being taken to remedy such.
By monitoring numerous points throughout the system and how it performs during such events and nonevents, they are able to verify that transfers between the utility power, uninterruptible power sources and generators happen in the proper time frame without any impact on the supply voltage to the critical loads.
By conducting full-load tests, they also are able to verify that noncritical loads aren’t draining the capacity of the backup systems. The one-line diagrams are only valuable if they are accurate reflections of how the system was really wired. Otherwise, they can make troubleshooting even more of a challenge in such complex systems.
The knowledge of the staff and their proactive maintenance and monitoring program gave even the non-PQ-centric visitors on the tour the feeling that this facility was about as close to immune as it could get. Of course, having the financial support of a management group that understands the return on investment is essential.
As for the second facility, let’s just say their immunity level could use another vaccination.
BINGHAM, a contributing editor for power quality, can be reached at 732.287.3680.