ABSTRACT

The most important power quality concern is voltage sags and momentary interruptions. The sensitivity of power electronic equipment coupled with the likelihood of voltage sags and momentary interruptions occurring may actually cause this to be the most prevalent power quality event. ASDs, computers, office machines, programmable controllers, and induction heating furnaces can be very sensitive to the undervoltage conditions known as voltage sags and to the short term loss of power known as momentary interruptions. Typically, voltage sags occur when there are temporary faults on the utility system. While the fault is on the system, voltage levels are depressed. Therefore, voltage sags are much more numerous than momentary interruptions because the customer must be located on the faulted line section to experience a momentary or permanent interruption. The sensitivity of equipment to voltage sags and momentary interruptions is important because nuisance tripping of sensitive industrial loads can cause equipment downtime and lost productivity.

This presentation will address voltage sags and their effect on end-user equipment. A brief overview of the cause of sags and interruptions will be given along with case studies that show how problems with voltages were mitigated. Reference information will be provided for more detailed research into this power quality area.

ABOUT THE SPEAKER

Mr. Melhorn is Manager of Industrial and Commercial Applications at Electrotek. He is responsible for developing marketing strategies, coordinating industrial and commercial studies, and developing and supporting seminars. These studies and seminars focus primarily on industrial and commercial power quality concerns and typically involve monitoring and computer simulations.

Since joining Electrotek in 1990, Chris has been involved in numerous projects which involved monitoring, simulating, and analyzing power quality phenomena. Some major projects include; the EPRI Distribution Power Quality project (RP-3098-1), power quality case studies for PG&E, Con Edison, and Pennsylvania Power and Light. He is currently the project manager for the power quality monitoring effort at Consolidated Edison Company of New York. Chris is currently working on a project for EPRI known as the Power Quality Diagnostic System. This system incorporates the use of ANNs for waveform recognition and expert systems.

He develops software for the power system engineering environment. He recently developed the FlukeView software for the Fluke 97 and Fluke 41 instruments. He has also developed software packages for evaluating harmonics and facilitating the use of the EMTP.

He has written over 20 technical papers for organizations like the IEEE, CIRED, PQ/PCIM, and PQA. He has presented over 50 talks and seminars on power quality that include tutorials and workshops on power quality monitoring and analysis. He is a senior member of IEEE, and active in various sub-commitees and working-groups.