Electricity Meters: their Construction and Management

Abstract

THE function of an electricity meter is to make an accurate record of the energy expended in a consumer's appliances. The principles on which it works are well known, but without having recourse to the integral calculus it is difficult to explain how it fulfils its functions. On p. 3 of this book, for instance, the author has to explain that what it measures is the integral of the product of two functions of the time, namely, the pressure and the current. In fact, an electricity meter is a most wonderful calculating machine, which has been gradually evolved by the joint labours of mechanical inventors, electricians, and mathematicians. Although it is generally placed in some out-of-the-way position, where it is looked on with disfavour by the domestics, yet it performs its wonderful operations with the highest accuracy from year to year. Manufacturers also turn out many thousands of “tariff” meters—that is, meters which will let you have a cheaper supply at one period of the day when the demand is small, and a dearer supply at the times of the “peak” load. In addition, many thousands of penny, sixpenny, and shilling “in the slot” meters are in daily operation. In nearly all cases when the electricity paid for is exhausted, the lights go out, but in some cases an intolerable blinking of the lights occur. As more than one coin can usually be inserted in a meter, there is a dial showing the number of “unconsumed coins” remaining in it.

Electricity Meters: their Construction and Management.

A Practical Manual for Central Station Engineers, Distribution Engineers, and Students. By C. H. W. Gerhardi. Second edition, revised and enlarged. Pp. xx + 504. (London: Benn Bros., Ltd., 1917.) Price 15s. net.