Should the utility care about your standby power system? Many health care facilities today are not satisfied with standby power capacity for code-mandated life safety, critical, and equipment loads, installing enough on-site generation to allow them to continue normal or near-normal operation during utility outages.
In these larger systems, generators not only operate in parallel with each other but invariably operate in parallel with the utility. Parallel or “interconnected” operation is defined as having the generator and the utility connected to the facility power system at the same time with each source providing part of the power consumed. Generators may be interconnected to the utility briefly to transfer load without a “blink” or for extended periods of time for testing, peak shaving, or cogeneration. This article will introduce you to some of the regulatory and technical issues to keep in mind when planning, designing, and installing such an interconnected power system.