The Accuracy of Commercial Electrical Measurements

The paper discusses the accuracy required in commercial electrical measurements, and the means of obtaining it, namely, proper choice, installation, use, and maintenance of instruments. Conditions of use, external disturbing influences, and features of design and construction affecting the accuracy are considered in detail. The best types of instrument for measuring voltage and current are mentioned. The sources of error in electrodynamic wattmeters are discussed, including the effect of instrument transformer errors. The principal factors affecting the accuracy of watthour meters are given. In conclusion, some improvements which should be soon forthcoming are mentioned.