The Protective Gear Handbook [antikvár]

FOREWORD There are still many electrical engineers who remember the time when the open-type fuse and the circuit-breaker with overload trip-coil were the only practical safety devices known to the supply industry. Such devices were reasonably satisfactory for use on the simple distribution systems of that time, but the great increase in size and complexity of distribution systems has rendered essential the development of a wide range of ingenious protective systems and devices. In those early days a protective device was intended to protect only the circuit or item of plant directly associated with it; but to-day the protective apparatus is concerned more with guarding the system as a whole and with maintaining continuity of supply than with protecting individual circuits or apparatus. Thus, the protective gear must be highly discriminative so that it will isolate a faulty item and leave the remainder of the system undisturbed. The means by which such results are procured are so numerous that to do justice to them all would require a volume much larger than the present one. But the selection here presented is sufficiently representative and affords an admirable insight into the methods by which discriminative protection is secured. The book can best be described as a critical survey of modern protective systems, with notes on their operation, maintenance, and testing, and although intended primarily as a manual for operating engineers and maintenance staffs, will prove useful also to technical students and many others interested in the generation and application of electrical energy. It is perhaps unnecessary to say that there may be more than one opinion as to the best protective system to adopt for any particular case. The opinions expressed in this book are those of an engineer with a wide experience of protecti ve systems, and his views are therefore at least worthy of serious consideration. J. S. PECK Trafi'oiid Park, October, 1943