Temperature errors in induction watthour meters: An analysis and the development of a temerature-sensitive magnetic material suitable for compensation

Abstract

This paper is presented in two principal divisions, Part I and Part II. The first deals with the general problem of small errors due to temperature changes in watthour meters and describes methods of segregating the various components of these errors. It is shown that they may be divided into two principal groups, termed Class 1 and Class 2. Class 1 errors are operative at all power factors and are of the greater importance; Class 2 errors are important only at low power factors, and methods of eliminating these are pointed out. Both of these classes are further subdivided into their component parts. In Part II of the paper is described a method of compensating for Class 1 errors by means of magnetic shunts made of thermalloy. The term “Thermalloy” is applied to a series of copper-nickel-iron alloys having a large negative temperature coefficient of permeability and other unusual properties. These alloys are discussed in some detail, their manner of preparation and application being considered original. In the appendix, a novel magnetic thermometer utilizing thermalloy is described.