scope:

Foreword 

This guide is the result of 20 years of evolution from the initial 1980 document, IEEE Std 587™, IEEE Guide for Surge Voltages in Low-Voltage AC Power Circuits, which promptly became IEEE Std C62.41™ with the same title. The guide was updated in 1991 as IEEE Std C62.41-1991, IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Power Circuits, reflecting new data on the surge environment and experience in the use (and misuse) of the original guide. The purpose of the document was and still is to provide information on the surge environment and offer recommendations to interested parties involved in developing application standards related to surge protective devices (SPDs) as well as recommendations to product designers and users.

The 1980 version, based on data available up to 1979, proposed two novel concepts:

1) The reduction of a complex database to two representative surges: a new "Ring Wave" featuring a decaying 100 kHz oscillation, and the combination of the classical, well-accepted 1.2/50 µs voltage waveform and 8/20 µs current waveform into a "Combination Wave" to be delivered by a surge generator having well-defined open-circuit voltage and short-circuit current.

2) The concept that location categories could be defined within an installation where surge voltages impinging upon the service entrance of an installation or generated within an installation would propagate, unabated, in the branch circuits, while the associated currents, impeded by (mostly) the inductance of the conductors, would be reduced from the values observed in circuits located close to the service entrance to lower values observed in circuits located at the end of long branch circuits.

The 1991 version, based on additional data as well as experience in the use of the 1980 guide, maintained the concepts of the location categories and the recommendation of representative surge waveforms.

The two seminal surges, Ring Wave and Combination Wave, were designated as "standard surge-testing waveforms," and three new "additional surge-testing waveforms" were added to the "menu." Meanwhile, a companion document, IEEE Std C62.45™-1992, IEEE Guide on Surge Testing for Equipment Connected to Low-Voltage AC Power Circuits, was developed, outlining procedures for error-free application of the waveforms defined by IEEE Std C62.41™-1991 while enhancing operator safety.

The perceived need to justify the expansion of the two-only waveforms to a menu of five led to the growth in the document volume, from the 25-page IEEE Std 587-1980 to the 111-page IEEE Std C62.41-1991.

Additional data collected toward an update of the 1991 version (which was reaffirmed in 1996) would have increased further the volume of the document. Instead, a new approach was selected: to create a "Trilogy" by separating the information into three distinct documents, making their use more reader-friendly while maintaining the credibility of the recommendations:

-A guide on the surge environment in low-voltage ac power circuits h(the present document)

-A recommended practice on characterization of surges in low-voltage ac power circuits (IEEE Std C62.41.2™-2002)

-A recommended practice on surge testing for equipment connected to low-voltage ac power circuits (IEEE Std C62.45™-2002)

In this manner, interested parties will have a faster, simpler access to the recommendations for selecting representative surges relevant to their needs. A comprehensive database will be available for parties desiring to gain a deeper understanding of the surge environment and an up-to-date set of recommendations on surge testing procedures.

Scope

This is a guide describing the surge voltage, surge current, and TOV environment in low-voltage [up to 1000 V root mean square (rms)] ac power circuits. This scope does not include other power disturbances, such as notches, sags, and noise.

The surges considered in this guide do not exceed one-half period of the normal mains waveform (fundamental frequency) in duration. They can be periodic or random events and can appear in any combination of line, neutral, or grounding conductors. They include surges with amplitudes, durations, or rates of change sufficient to cause equipment damage or operational upset (see Figure 1). While surge protective devices (SPDs) acting primarily on the amplitude of the voltage are often applied to divert the damaging surges, the upsetting surges may require other remedies. The rationale for including a description of TOVs in this guide on the surge environment is given in 1.2.