CSE Pure Power - Summer 2008 - (Page 25)

healthcare story 25 ❮❮ PURE POWER // SUMMER 2008 DATA lighting loads, but it might as well be 10 min as far as electronic data and computers are concerned. Even 1 sec. without power and everything shuts down—and shuts down hard. Hospital hardens to hurricanes A 60,000-sq-ft. data center is located in a stand-alone building on the hospital campus. One of the main construction focuses of the building was the hurricane hardening of the building. The data center is not served by the campus central utility plant, but instead has a single 1,000-kW generator dedicated to that building. Additionally, UPS is provided by multiple battery-powered power distribution units (PDUs). Each data rack is served by two PDUs—one primary and one redundant. This arrangement provides maximum reliability on the UPS side, but minimal reliability on the generator side. If the single generator fails to start, the batteries in the PDUs provide only enough power for a controlled shutdown. MAIN EMERGENCY POWER Before discussing the value of uninterruptible power supply (UPS) systems for short-term power ride-through and essential protection of critical healthcare data centers, let’s review the hospital’s main emergency power systems. Hospital emergency power systems come in all shapes and sizes, from the simplest single-engine, single-transfer switch arrangement to a complex system of multiple-paralleled generators serving multiple transfer switches— and everything in between. The goal is the same: to power the hospital when utility power is lost. The key components of the emergency power system include: The engine-generator, the emergency system’s main source of power. A diesel or gas engine drives an electrical generator. Paralleling switchgear, the brains of the emergency power system, provides electrical control and distribution when multiple engine-generators are paralleled to serve a common bus. Automatic transfer switch switches loads between normal and emergency power sources. Accessories, including all critical components that keep the enginegenerator operational, such as generator batteries, battery charger, fuel tanks, and fuel pumps. “So, how many engine-generators do I need? And what size?” the hospital administrator asks. Unfortunately, there is no one right answer to these questions. Every facility is different, every facility’s needs are different, and there are countless combinations of sizes and numbers of engine-generators. For example, if the emergency load is 2,500 kW, do you need a two-paralleled 1,250 kW enginegenerators? Or a three paralleled 900-kW engine-generators? A single 2,500-kW unit? An experienced engineer can wade through the myriad calculations to provide hospitals with cost-effective environmentally responsible and sustainable emergency power solutions. ENTER UPS Now enter the UPS—the backbone of data center backup power. Usually by means of batteries, or sometimes by using the inertia of a rotary disc, the UPS provides a constant source of clean, reliable, and uninterruptible power to ride through the time until the emergency generator systems can pickup to loads. Battery UPS systems are the most familiar types. Modern battery UPS systems use nickel-cadmium batteries wired in parallel to provide the emergency power through static transfer diodes. Batteries are sized in amphours, so the more load, or amps, you need, or the more time in hours you want the load to be served, the more batteries you need. The capacity of the UPS is really limited only by how www.purepowermagazine.com http://www.purepowermagazine.com

Table of Contents Feed for the Digital Edition of CSE Pure Power - Summer 2008

CSE Pure Power - Summer 2008 Contents In the News Industry Roundup Risk Assessments for COPS Grounding Requires More Power Systems to Protect Healthcare Important Changes Coming in NFPA 70E A Look at Arc-Resistant Switchgear Agencies and Associations New Products Ad Index

CSE Pure Power - Summer 2008

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