Power Quality for Healthcare Facilities

by Philip Keebler, EPRI

The healthcare environment is made up of perhaps the most unusual combination of electronic loads found in any facility. Healthcare facilities not only rely upon commercial loads (such as computers, servers, and lighting system) and industrial loads (such as food preparation equipment, laundry equipment, medical gas systems, but also rely on electronic medical loads (that is, medical equipment to operate the facility and provide patient care services.

As in other facilities, when an electrical disturbance such as a voltage sag, voltage transient, or voltage swell reaches the service entrance of the healthcare facility or medical location, computers in the accounting department may shut down, and motor starters and contactors providing power to the air-conditioning and ventilation system may change the environment within the facility. Unlike other places, however, a patient’s life could be threatened when an aortic balloon pump trips off-line during a cardiovascular surgery. The costs associated with downtime can be staggering, but no bounded cost can be placed on the irreversible result of loosing a patient.

Building, electrical, and healthcare codes in the United States require that hospitals and other medical clinics have emergency power ready to activate upon the detection of a power quality problem and assume the load within 10 seconds of the detection. However, even though a generator may be used at a healthcare facility or medical location, it cannot be on-line to support critical medical equipment with an activated transfer switch in less than about 2 to 3 seconds at best. This duration of time might as well be forever in terms of the ability of electronic medical equipment to continue operating. In fact, an undervoltage as short as ¼ of a cycle (about 4 milliseconds) is often sufficient to confuse sensitive electronic devices.

This PQ TechWatch will introduce the typical problems found in healthcare facilities, enlighten the reader on some new issues, and provide practical guidelines for avoiding those problems.