IEEE 1250-1995

This guide describes momentary voltage disturbances (short-duration transients) occurring in ac power distribution and utilization systems, their potential effects on sensitive equipment, and guidance toward mitigation of these effects. Also provided is a description of the operating environment of sensitive utilization equipment as well as information on harmonic distortion limits.

Equipment application problems exist today because of certain incompatibilities among the sensitive equipment and various disturbances present on typical power systems. Some of the newer sensitive loads are particularly vulnerable to momentary disturbances. In addition, some of these loads introduce considerable harmonic content into the system and can be detrimental to other equipment in the area. Because of increasing use of computers and other sensitive equipment, such problems will continue to grow unless corrective measures are taken. The primary purpose of this guide is to assist in identifying potential problems and to suggest effective ways to satisfy sensitive equipment voltage requirements. This discussion should provide insight into the distinction between those voltage-related problems that are controlled by the utility and those that can only be addressed by the user or equipment designer. Cooperation among users, utilities, and equipment designers is needed to ensure both adequate electric service to all users and proper equipment operations. Solutions are presented from the perspectives of both the customer and the utility provider, since the problems users of sensitive equipment experience often originate from either area. The secondary purpose of this guide is to help provide the designers of sensitive equipment with an understanding of the environment in which their equipment is expected to operate.

New IEEE Standard - Superseded. Computers, computer-like products, and equipment using solid-state power conversion have created entirely new areas of power quality considerations. There is an increasing awareness that much of this new user equipment is not designed to withstand the surges, faults, and reclosing duty present on typical distribution systems. Momentary voltage disturbances occurring in ac power distribution and utilization systems, their potential effects on this new, sensitive, user equipment, and guidance toward mitigation of these effects are described. Harmonic distortion limits are also discussed.