Keith Bowden of Health Care Corp. of St. John's in Newfoundland, Canada needed a way to prove that the installation of the hospital's new emergency generators would shorten the transfer time between a power failure and the initialization of the facility’s backup emergency diesel generators.

Why was this so important? In healthcare situations, hundreds of people may be relying on electrically-run equipment to furnish their health requirements, from intravenous feeding to heart monitoring to oxygen intake to ongoing surgical procedures. Electrical power is essentially their life-line.

The hospital estimated that in the event of a utility power outage, the emergency generators began operating between 15 to 30 seconds after the failure. This time lapse, however, was often in dispute. With no one constantly monitoring the generators, and the uncertain nature of a power outage itself, it was difficult to determine exactly how much time passed.

Bowden evaluated several loggers and monitoring systems to verify the transfer time, but they were either too expensive or did not have the memory required. He also needed accuracy within plus/minus 1 second.

Ultimately, Bowden selected HOBO® H6 State on/off data loggers from Onset. These are compact, battery-powered devices that are used for recording on/off status changes, and storing time, data, and state information for each change. Four data loggers are attached to each of the hospital's three power substations and one for the diesel generators themselves to show the exact on/off status of each area. During the very first power outage, the loggers were able to record the time from normal utility-provided power going off until their new emergency generators started providing power. Once the data was collected, it was offloaded onto a computer and analyzed using Onset’s BoxCar® Pro graphing and analysis software. The transfer time for the hospital's critical care area, which includes the operating rooms, intensive care, etc. was just 11.5 seconds, and the transfer time for the hospital's other two substations was just 14 seconds. With this data, Bowden was able to easily and cost-effectively verify that the transfer times for the new generators was shortened.

"The HOBO State loggers are perfect for this type of application,” states Bowen. “These units will remain ‘online’ as a permanent feature to record the transfer times from normal to emergency power in any future outages.”

For more information about data loggers, please contact Onset Computer Corporation at 1-800-LOGGERS, or visit


Application Story