Hospital Expands Services with Digital On-Site Power

For more than 50 years, Hancock Memorial Hospital and Health Services (HMHHS) has served Greenfield, Ind. and surrounding Hancock County with an emphasis on primary care, patient comfort and convenience. Located 30 miles east of Indianapolis, Hancock Hospital aims to be one of the best suburban/rural health-care systems in the United States.


For more than 50 years, Hancock Memorial Hospital and Health Services (HMHHS) has served Greenfield, Ind. and surrounding Hancock County with an emphasis on primary care, patient comfort and convenience. Located 30 miles east of Indianapolis, Hancock Hospital aims to be one of the best suburban/rural health-care systems in the United States.

This emphasis on excellence and growth prompted facility officials to go beyond a traditional standby power system when they upgraded their on-site power. Instead of relying on conventional analog technology, they opted for a system controlled by digital technology: a 2-MW power generation system with digital controls.

Redundancy, reporting, expansion

"We wanted a state-of-the-art installation," says Brad Stevens, team leader of building services at HMHHS. "We had seen other digital installations and were impressed with the amount of information and control that was available. Other manufacturers we looked at would have supplied digital equipment through a third party, but [the vendor we went with] was the only manufacturer who provided the entire system."

Analog transfer switches have provided reliable service for decades, but digital controls are becoming an industry standard—and for a number of reasons. Chief among them is the increased reliability. Redundancy that prevents single-point failures from causing system-wide failures can be built into digital circuitry at very low cost. Another difference is that real-time information, available at the touch of a computer screen, immediately tells operators the status of the system. Digital controls also require less space in the mechanical room because of their smaller footprint.

BSA Lifestructures, Indianapolis, specialists in health care, designed the new power system. Engineers specified redundancy, real-time reporting and diagnostics, and the ability to meet future expansion needs, including the ability to parallel with the utility grid for energy management.

"The existing system lacked redundancy, and that was its major drawback," says Daniel Campbell, P.E., project lead engineer with BSA. "If one of the generators failed, the area of the hospital being served by that generator set did not have emergency power."

The hospital's three existing generator sets—300 kW, 400 kW and 500 kW—served different portions of the campus and could not be paralleled. "Our design sought to improve the standby power distribution system," says Campbell. "A primary goal was to put the standby distribution system on a common bus, so that if one of the generator sets failed, the others could take up the load."

"We removed all three of the existing generator sets, installed two 1-MW units and paralleled the new ones together," explains Campbell. "The paralleled system provides full redundancy to three power branches: life safety, critical circuits and equipment circuits. The hospital dramatically increased its standby power reliability."

Real-time info

The hospital's existing standby system included 11 analog transfer switches, none of which provided reporting capabilities. Operators never knew the position of the switches—either emergency or utility—or how much load they carried, without physically going to look at the switches. But digital controls changed all that. A monitoring module was added to each analog transfer switch, which, in effect, "digitized" the switches. And the modules were networked together and fed back to the digital paralleling controls.

Now, operators can call up on their computer screens all 18 transfer switches—seven digital switches were added—and determine their position and load in volts, amps and kW. This real-time information is routed over the hospital network, so the entire operation can be monitored remotely.

"Information is a benefit that everybody likes about digital," said Bob Fulcher, generator account manager, Cummins Mid-States Power, Inc. "It provides a comprehensive reporting capability that analog cannot match."

Remote access to the control system was also an important issue for hospital facility staff. The maintenance director and other authorized staff can monitor the power system via laptop and check on the status of the power system, any time, anywhere. "Before, we had to come into the control room and look at each transfer switch individually," says Stevens. "Now we can see their status displayed together on one screen."

Added cooling power

The previous standby system could supply the HVAC system's blowers, but not the chillers. Patient rooms could become uncomfortably warm in the event of an extended utility outage. As a result of the redesign, equipment circuits supply the AHUs—for heat and ventilation—as well as the chillers. The new digital paralleling control analyzes the load on the entire standby system and allocates power as necessary. Moreover, the system automatically reduces the chiller load if an established set point is exceeded.

Future expansion

Beginning in the summer of 2004, the hospital will add another 110,000 sq. ft. and expand the power plant to bring in more chiller capacity. Plans call for another 1-MW genset, for a total of 3 MW of standby power. Because of the unit's small footprint, all three 1-MW units will fit in the space originally intended for the 500-kW units. This solution not only saves room, it also reduces installed costs. Two 1-MW units are cheaper than four 500-kW units on a cost per installed kilowatt basis.

The hospital has the added advantage of being able to shed part of its electrical load during peak demand if utility rates increase in the future. The standby system can also run in parallel with the utility.

"This gives a revenue source if the situation arises," said Fulcher. "When electric rates are high, the hospital can run the standby generators and sell the electricity back to the utility. When demand is high, they can shed some of their load from the utility and simply run those shed loads on their self-generated power."

Hancock Hospital's new on-site power system has already proved its reliability. Last summer, a lightning strike knocked out power at two major utility substations, causing the utility feeds to the hospital to fail. "The ... system came on immediately and ran flawlessly for the four hours we were without power," said Stevens. "The hospital operated normally, and nobody really noticed anything different."

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