Duplication of electrical apparatus to secure reliability of service

The question of the proper reserve in an electrical installation is a problem that, like many engineering problems, must be settled largely upon a basis of cost. It is nearly always a question involving a balance between a power company's obligation to its customers and the obligation to its stockholders. From the standpoint of the consumer the more reserve the surer will be his supply of power. On the other hand, to the power company's stockholders the less the investment in reserve the larger the dividends, unless the reserve has been cut down to a point where the power company's reputation is endangered by interruptions to service. The question is purely a practical one and no definite laws can be enunciated, nor can any curves be plotted which will indicate the proper amount of reserve to be installed under various conditions. The decision in each case must be based on intimate knowledge of the local conditions and requirements of the particular installation in question. All that will be attempted in this paper will be a discussion of the general principles involved.