scope:

FOREWORD

IEEE Std 242-2001, the IEEE Buff Book™ , has been extensively revised and updated since it was first published in 1975. The IEEE Buff Book deals with the proper selection, application, and coordination of the components that constitute system protection for industrial plants and commercial buildings. System protection and coordination serve to minimize damage to a system and its components in order to limit the extent and duration of any service interruption occurring on any portion of the system.

A valuable, comprehensive sourcebook for use at the system design stage as well as in modifying existing operations, the IEEE Buff Book is arranged in a convenient step-by-step format. It presents complete information on protection and coordination principles designed to protect industrial and commercial power systems against any abnormalities that could reasonably be expected to occur in the course of system operation.

Design features are provided for

- Quick isolation of the affected portion of the system while maintaining normal operation elsewhere

- Reduction of the short-circuit current to minimize damage to the system, its components, and the utilization equipment it supplies

- Provision of alternate circuits, automatic throwovers, and automatic reclosing devices

IEEE Std 242-2001, commonly known as the IEEE Buff Book™, is published by the Institute of Electrical and Electronics Engineers (IEEE) as a reference source to provide a better understanding of the purpose for and techniques involved in the protection and coordination of industrial and commercial power systems.

IEEE Std 242-2001 has been prepared on a voluntary basis by engineers and designers functioning as a working group within the IEEE, under the Industrial and Commercial Power Systems Department of the Industry Applications Society. This recommended practice is not intended as a replacement for the many excellent texts available in this field. IEEE Std 242-2001 complements the other standards in the IEEE Color Book Series™, and it emphasizes up-to-date techniques in power system protection and coordination that are most applicable to industrial and commercial power systems. Coverage is limited to system protection and coordination as it pertains to system design treated in IEEE Std 141-1993¹ and IEEE Std 241-1990. No attempt is made to cover utility systems or residential systems, although much of the material presented is applicable to these systems.

This publication presents in a step-by-step, simplified, yet comprehensive, form the principles of system protection and the proper application and coordination of those components that may be required to protect industrial and commercial power systems against abnormalities that could reasonably be expected to occur in the course of system operation. The principles presented are applicable to both new electrical system design and to the changing, upgrading, or expansion of an existing electrical distribution system.