Publications

Power Quality Evaluation of 480-V, 2-MVA UPS Systems

Corey, Garth P.; Corey, Garth P.

A mobile 480-V, 2-MVA UPS System utilizing battery energy storage was installed at S and C Electric Company's Polymer Products Fabrication Building in Chicago, Illinois in May 1999 to provide uninterrupted power to the building for up to 15 seconds in the event of a voltage sag or momentary interruption in the local utility supply. Similar units can be applied at medium voltage through the application of a step-up transformer to provide momentary power disturbance ride through of up to 30 seconds for loads up to 15 MVA at system voltages ranging from 4.16 kV to 34.5 kV. A power quality evaluation of the installation was performed over a six-month period from July 1999 to early January 2000. This paper describes the details and results of this power quality evaluation, which involved two phases. Phase I involved the collection and review of power disturbance data and the effects on process equipment, while Phase II involved power quality monitoring of utility source and building load voltages and currents over a period of six months. Review of power disturbance data and equipment power-disturbance ride-through characteristics during Phase I of the project indicated that the polymer fabrication process in the building is affected by the tripping of motors driving hydraulic pumps for the thermal set molding machines. The tripping of these motors may have resulted in direct production losses in 1998 of approximately $468,000. The monitoring conducted during Phase II of the project showed that the PureWave UPS operated as intended during 12 utility voltage sag events to protect the building's load against momentary power disturbances. In addition, the unit operated successfully during many staged interruptions involving opening of a source-side circuit breaker.