The Institute of Electrical and Electronics Engineers, Inc.

GUIDE FOR PROTECTIVE RELAYING OF UTILITY - CONSUMER INTERCONNECTIONS
 N C37.95

Annotation

Scope and Purpose

This guide has been prepared to aid in the effective and uniform application of fuses, relays, and their associated switching equipment located at the point of interconnection between the utility and the consumer electrical systems. Descriptions of the various devices, definitions of terms, and references to other technical publications have been included to make the guide useful not only to relay engineers, but also to other technical people who may not be intimately familiar with the art of relaying, but who nevertheless have a responsibility for the installation and operation of such interconnections. It includes examples for relaying of typical installations, both with and without consumer generation, and with service from utility radial or loop feeders, either directly from the utility substation bus or from a transmission line. It is expected that the guide will be used by consulting engineers, utility relay and sales engineers, and by consumer engineering and maintenance personnel.

The scope of this guide does not include the subject of lightning protection for electrical systems as provided by shielding or lightning arrester devices. Lightning is, of course, often the cause of short circuits on power systems, but only the clearing of these short circuits through the use of protective devices is within the scope of this guide. Reference material pertaining to lightning protection may be found in

(1) IEEE Std 28-1972, Surge Arresters for AC Power Circuits (ANSI C62.1-1971)

(2) ANSI C62.2-1969, Guide for Application of Valve-Type Arresters for AC Systems

This guide does not establish standards or recommendations with regard to personnel safety at the interconnection area with respect to ground-voltage-rise, transferred-potential, step-potential, and touch-potential considerations for faults on the utility system or on the consumer's system. Reference material pertaining to grounding and safety may be found in the following: