Modernizing emergency power

Modernizing a hospital’s emergency power system doesn’t have to be a big pill to swallow, according to Allen Meadors, electrical engineer with CTA Architects Engineers in Great Falls, Montana.

The work can be completed in small doses, without unpleasant budgetary side effects. That’s exactly the prescription that Benefis Healthcare in Great Falls, Montana, is following for its East Campus. The campus occupies 15 square blocks in Great Falls and encompasses the state's largest hospital, a skilled nursing center, a number of medical-office buildings, and the main location of the Great Falls Clinic, the region's largest physician practice. Together with the West Campus, which comprises eight blocks, Benefis is licensed for 347 acute beds and 144 skilled nursing beds.

Rebuilding Emergency Power in Phases

“Benefis is deep into a multi-phase project that is overhauling a decades-old emergency power system,” said Meadors. And it’s accomplishing that feat without interrupting its 24/7 operations, whether it’s the operating rooms or the admissions desk. 

The healthcare organization’s emergency power system carries a huge responsibility. It must keep NFPA 1101-mandated life safety loads, chillers and critical-service departments such as radiology powered through oftentimes frequent utility outages.

“High winds coming down from the eastern front of the Rockies during the fall and into December can affect the lines from Butte,” Benefis Facilities Manager Dawn Willey explained. “The power fades enough to make the generators kick in two or three times a week. It only lasts a few seconds, but we run the generators for up to half an hour each time to make sure the episode is over.”

Benefis’ precautionary procedure reflects the center’s scope of responsibility. The center provides tertiary services for more than a quarter-million residents in north central Montana. Outreach services cover the region’s 45,000 square miles. 

“It’s not like being in a major metropolitan area with other large hospitals that might help care for patients,” said Pete Haugan, Benefis’ head electrician. “If something goes wrong here, we’re by ourselves and in deep trouble if the emergency power system doesn’t operate.”

It was enough to make Willey nervous.

“Everybody in the department was nervous,” she said. Worrying about the demands on the outmoded emergency power system kept her up at nights.

“Power is a life or death matter in a hospital,” she added. “We didn’t want to leave it to Murphy’s Law for the system to fail when we really needed it. It had to be absolutely reliable.”

The old power system had followed Benefis’ growth over the last quarter-century. Every time the center built an addition, another automatic transfer switch to service the addition’s loads became part of the emergency power system.

Willey recognized that the decentralized and over-taxed system would not be able to sustain the center and the planned additions. Besides her lack of confidence in the old system, she wanted to reduce the amount of manpower required to maintain, test, monitor, and control the system.

On some shifts, there’s only one person from the department on duty,” she explained. “With several normal feeds into buildings and a generator at each location, he would go crazy if any of them went down.”

There was no way, however, that the center could swallow that size pill from a budget standpoint for the total emergency power system. That’s why the modernization process had to be completed in phases.

Meadors and CTA designed a system that would centralize equipment and operations, supply current loads, and provide for ongoing expansion. Work started about six years ago with a review of the center’s normal power supply. 

The Power Picture

At least three normal 15kV feeds are stepped down from two, 15kV substations. Power is distributed throughout the campus at 480V with numerous feeders serving separate numerous transformers. The power mains connect with a normally open automated tie switch. Each transformer has a switch in the primary compartment that enables personnel to take the circuit off-line for maintenance. The new 480V emergency power network uses the existing infrastructure throughout the campus. The emergency network splits into 480V circuits that feed approximately five emergency power centers. These centers feed approximately 30 automatic power transfer switches. Emergency power centers are comprised of a distribution panelboard at 480V that feeds the transfer switches.  “Because we knew what the eventual system capacity was going to be, we designed the first phase with a 10,000 ampere bus,” Meadors said.

Phase One: Centralizing the System

The first phase encompassed the generator building and the first of four 1500kW engine-generators. This phase also included a basic engine-generator control system comprising master, engine-generator and two distribution sections, and one automatic transfer switch—all manufactured by ASCO Power Technologies.
We selected ASCO because we knew they were reliable,” Haugan said. “And Power Control Products is always available when we call. I’ve got to talk to someone who knows what they’re doing right off the bat.” Power Control of Denver, Colorado is the sales agency that provided the equipment.

The 3,600 sq.ft. plant allows the emergency power system adequate room to grow through each phase. 
The master control section initiates automatic system operation. It integrates AC metering of volts, amps, kilowatts, frequency and synchroscope, visual annunciation, and control circuitry. It adds and sheds loads in the priority established by Benefis.

Power Control customized the section’s operation to Benefis’ specific requirements using the section’s built-in microprocessor-based programmable logic controller.

As the healthcare center’s requirements evolve, however, an operator interface terminal will enable authorized personnel to change operational variables, such as time delays and set points. The menu-driven terminal is, of course, password protected. 

A manual control station on the master section allows personnel to control the entire system with a combination of selector switches and push-buttons. Paralleling, bus under frequency resetting, and alarm silence priority load shedding/load adding can be controlled from the station. Operation also can be monitored and controlled remotely.

The engine-generator control section includes AC metering of volts, amps, kilowatts, frequency, visual annunciation, and control circuitry for automatically starting, stopping and paralleling the 1500kW gen-set to an emergency bus. Power Control also customized this section’s operation to Benefis’ specific requirements.  

As with the master section, this section incorporates a manual control station, but operation also can be monitored and controlled remotely. The station includes switches for engine control and automatic synchronization and a push-button for resetting operation if synchronization fails.

The distribution sections house a total of four drawout power circuit breakers and AC switchboard meters that indicate volts, amps, kilowatts, and other parameters. Meters in the switchgear are analog, allowing personnel to easily monitor parameters at a glance. Digital meters in the SCADA system are convenient for monitoring generator steady state conditions. 

Benefis’ existing approximately 25 automatic transfer switches remained in place near their loads. They are a combination of older open transition and newer closed transition transfer switches with bypass-isolation feature and range from 70 amps to 1,200 amps.

The new power transfer switches, ranging from 260 amps to 2,000 amps, are closed transition bypass-isolation transfer switches. All seamlessly transfer power and provide additional control redundancy because their loads can be manually transferred to either normal or emergency power when two sources are available. This facilitates mandated monthly tests and retransferring loads after utility power failures. All also are listed to UL 1008, the only standard for true transfer switches, are four pole, and are rated to 600VAC.

Seven Differentiating Points

Seven points of design differentiate the transfer switches. Differentiators include how the transfer switches transfer power, ensure contact integrity and performance, extinguish arcing, and withstand and close-on on fault currents. Other differentiators include how the transfer switches handle motor loads, control emergency power system operation, and can be tested, maintained, and serviced.

The closed transition transfer switches feature overlapping main contacts that make before they break. This eliminates power interruptions during system testing, providing both sources are within plus or minus five percent voltage, plus or minus 0.2Hz and five electrical degrees. The transfer switch accomplishes this without controlling the engine-generator.  

Each bypass-isolation transfer switch includes a closed transition transfer switch for regular operation and a bypass switch that allows the closed transition transfer switch to be inspected, tested, and maintained without interrupting power to the load.

The transfer switch easily draws out from the enclosure for safe access to its components. Bypass and transfer switches have identical ratings.  

Bypass contacts carry current only during bypass operation. The bypass switch is fully rated as a manual, three-position transfer switch and transfers loads between live sources using dead front quick-make, quick-break operation.

Phase Two: A Real-Life Test

Phase two included the second 1500kW engine-generator, an engine-generator section and a supervisory, and a data acquisition system.

No sooner had the second phase been commissioned than the emergency power system got a real-life, extended test of its capabilities.

Besides the new emergency power system, Benefis also had been constructing new operating room suites, which required digging in an open-air courtyard. The hoe found, and pulled, a 1200A, 480V feed from the normal source to a large switchboard in the heart of the hospital. The main had not appeared in a comprehensive search of blueprints prior to construction.

When the main experienced a bolted fault, the new emergency power system got its first test. It operated continuously for two weeks while Benefis replaced electrical equipment, repaired the electrical room, and ran new wiring.

The two generators ran alternately, allowing the other to be maintained over the two-week period.
“It worked seamlessly,” Willey remembered. “We were thankful for deciding to build a new emergency power system. It was a good plan.”

The system’s overall load includes almost all the campus’ facilities. Besides life safety loads, a good part of radiology, the heart catheter lab, air conditioning, and the dialysis department all are protected by emergency power.

And what wasn’t protected became obvious in a hurry. The elevator for the dialysis department, which is on the second floor of one of the buildings, was added to the system so patients needing treatment would not have to climb stairs. Cooling equipment in radiology also is now on the system.

The experience underscores the complexity of re-building a hospital’s emergency power system.
Meadors said, “It’s difficult to coordinate work around the 24-hour schedule of a healthcare center, which can’t tolerate any shutdown for extended time periods.” 

Phase Three: Life-Saving Redundancy

After the episode with the main, Benefis installed phase three. Like phase two, phase three included a 1500kW engine-generator and another engine-generator section.

Although two gen-sets can easily support the campus at peak hours, Benefis considered its responsibilities and geography and decided to add the life-saving redundancy of a third gen-set.

Willey said, “Redundancy is critical. I want to avoid having to close our doors because of power failures, which has happened in several places around the country.”

To help manage the sophisticated emergency power system with minimum manpower, the healthcare center installed a PC-based automated monitoring and control system.

Haugan said, “It’s an ASCO system and still brand new, so we’re still experimenting with it.” It communicates with the three engine-generators and the newer 27 transfer switches. The number of transfer switches will jump as older transfer switches are upgraded or replaced.

What Haugan likes about the automated system is that the desktop PC can be located anywhere and the status of the emergency power system can be monitored from anywhere.

“Even at home, through the Web,” he said. But he doesn’t have to log on to know if power system operating conditions exceed set points for selected system alarms that they have established. Automatic paging via e-mail or pager will actively alert him.

Benefis also wants to monitor and control the power system from the West Campus, according to Meadors, and the automated control system will enable it to do so.

The automated control system delivers detailed information on the status of all power transfer settings for all buildings. Operators know at a glance the normal and emergency voltages and frequency, transfer switch position (normal, emergency, or maintenance) and source availability, logged transfer switch events, and transfer switch test schedule.

In terms of control, the system enables authorized engineering personnel to transfer and retransfer loads for system testing, adjust and set transfer switch controller parameters, and override automatic load trip orders. Personnel also can activate transfer switch control functions, such as inphase transfer, selective load disconnect time displays, and engine-exerciser programming. 

Data on generator operating conditions including emergency failure mode, load demand, bus optimization, shutdown indications, and circuit breaker status are readily – indeed, instantly – available.

The system is connected to the healthcare center’s intranet and to the Web via Benefis’ Internet service provider. The center’s elaborate firewalls protect the system from unauthorized access.

The control system also can be connected to remote networks. The initial installation included one PC in engineering, but Benefis plans to add another for the maintenance area. Monitoring and controlling equipment from a PC saves considerable time and manpower compared to having to visit 12 locations to do the same thing. 

While the control system can automatically test the engine-generators and transfer switches, Haugan currently tests them manually.

“I want to see them so I can notice if something is not up to par,” he explained. Once a month he makes the rounds, tripping each transfer switch and running the generator for 30 to 45 minutes.

In the future, the tests will be conducted from the engineering control console. The automated system records test data and prepares reports, which can be used to satisfy JCAHO2 requirements for testing and maintenance.

Once the older transfer switches are replaced or upgraded, Benefis will have one of the most sophisticated and reliable emergency power systems in Montana.

Phase Four: Preparing for the Future

Finally, a fourth 1500kW engine-generator—and the corollary switchgear—could join the trio of gen-sets to accommodate continued expansion.

“The phased approach has worked incredibly well,” Willey said. “We were more comfortable allocating costs over time and we’ve prepared for ongoing expansion.”

Because the emergency power system is new, powerful and sophisticated, a natural question is whether Benefis plans to use it as a distributed generation resource.

“Not at this point,” explained Willey. “We looked at several scenarios, but anything the engineers penciled out was borderline on whether it would save money on utility bills.”

While the question may be considered in the future, she said a major issue is wear and tear on the engine-generators, which reduces the gen-sets’ lifespans. If the benefits prove out, the system can easily be reprogrammed to provide for distributed generation operation.

With the major phases completed, Willey said, “As the facilities manager, I sleep better at night having a more reliable system that was tested shortly after it was commissioned.”

Haugan said, “I had my doubts about the old system, whether it would run and keep running. But now I’m more comfortable than I’ve been in the last 15 years. It’s really improved the whole hospital.”
And that’s a powerful statement for an emergency power system.