IEEE 1250-1995 pdf download IEEE Guide for Service to Equipment Sensitive to Momentary Voltage Disturbances
1.1 Scope
This guide describes momentary voltage disturbances (short-duration transients) occurring in ac power dis-tribution 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 utilizationequipment as well as information on harmonic distortion limits.
1.2 Problem definition
Computers, computer-like products, and equipment using solid-state power conversion have created entirelynew areas of power quality considerations. There is an increasing awareness that much of this new userequipment is not designed to withstand the surges, faults, and reclosing duty present on typical distributionsystems. In addition to the usual steady-state concerns, designers and users of these types of equipment, aswell as suppliers of utilities, re concerned with transients, brief momentary disturbances, and harmonics otthese often sensitive loads.
Most voltage problems associated with computers and other sensitive equipment are related to not only highor low steady-state voltage levels, but also to momentary voltage disturbances, such as surges, sags, interruptions. or rapid changes in voltage. The starting of a large motor, for example, can result in voltage sag due tothe high inrush current A fault on the utility lines, even though cleared, can result in a momentary sag.surge, or interruption. Momentary voltage disturbances may result from a wide variety of causes on a utilitysystem or within a user’s facility.
Site monitoring with disturbance recorders helps to identify the nature of the problem and the frequency ofoccurrence. Such information can then be correlated to events on either side of the meter to help identifypossible solutions. However, difficulty often arises in matching recorded disturbances to equipment sensitiv-ities
A variety of power-conditioning equipment is available to buffer the sensitive load from various disturbancesand in some cases, from harmonics) where necessary. Ideally, the power-quality tolerance of the particularsensitive equipment should be analyzed to determine the proper solution; however, this information is oftenunknown. In addition, the user should be aware of some of the nonlinear characteristics of certain types ofconditioning equipment.
1.3 Purpose of guide
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 considerableharmonic content into the system and can be detrimental to other equipment in the area, Because of increas-ing use of computers and other sensitive equipment, such problems will continue to grow unless correctivemeasures are taken.
IEEE 1250-1995 pdf download
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