Abstract :
During the past 10 years meter designers have met with considerable success in extending the working range of the induction meter in the overload direction, and this paper opens with a brief review of some of the more important considerations involved in such improvement. It is shown that this subject of curve extension ultimately compels some consideration of the conditions which govern the registration on low loads, and it is suggested that the meter curve might possibly be further extended by a better understanding of the factors which control low-load registration. In this connection a mathematical theory is developed, the experimental determination of the various torques is described, and the low-load curve of the meter is derived from calculations. The theoretical curve is compared with the curve obtained by an actual test on the meter. There is sufficiently close agreement between the curves to leave little or no doubt as to the validity of the mathematical treatment, and this in turn shows clearly that the anti-creep device is the cause of the large registration errors on very low loads.
