Madigan Army Medical Center Eliminates Momentary Power Interruptions

The challenge for Madigan Army Medical Center was to conduct mandated emergency power system tests without getting “nasty phone calls” from medical personnel because of power interruptions.  As a solution, the hospital converted open transition transfer switches that protected critical loads to closed transition, which connects with one power source before breaking with another.

Conducting NFPA 110-mandated monthly tests of its emergency power system caused momentary power interruptions at the 414-bed Madigan Army Medical Center at Fort Lewis near Tacoma, Washington. Sensitive electronic equipment often would need to be rebooted.

During controlled transfers from the live utility source to the hospital’s five, 850 kW engine-generators and back, the hospital’s 29 open transition transfer switches would break one connection before making the other.

The ASCO switches performed according to spec from the beginning. However, facility engineers frequently received complaints about the interruptions, so the hospital decided to convert eight of the transfer switches that protected the most critical loads to closed transition.

The closed transition type automatically eliminates momentary power interruptions by connecting with one power source before breaking with another when both sources are available. When utility power fails, the transfer switch controller automatically provides an open transition load transfer.

ASCO Services, coordinating with the company’s sales representative, S.F. Griggs of Redmond, Washington, managed the conversion and assumed all responsibility for a turnkey project including installation, startup testing and user training. Madigan’s engineers were so pleased with the results that they contracted ASCO Services to convert the remaining transfer switches to closed transition type.

Now, all 29 transfer switches, 16 of which also include bypass-isolation capability, are the make before break type. Testing is conducted during peak hours with no transfer-induced power interruptions during testing or retransfers to the utility source. ASCO paralleling switchgear controls the engine-generators.

Electrical Branch Chief Bill Pitts reports that his people now test the entire emergency-power supply system with confidence. “The tests are transparent to our medical personnel,” he says, “we no longer get those nasty phone calls when we test.

“The converted ASCO switches have performed so satisfactorily that 14 ASCO closed transition transfer switches have been installed in Elmendorf Army Medical Center in Anchorage, Alaska. They also have been selected for the Basset Army Hospital near Fairbanks, Alaska. And when a previous Madigan engineer began working at Valley Medical Center in Renton, Washington, he installed 10 ASCO closed transition transfer switches for a new wing.