GB543437A - Improvements in and relating to alternating electric current induction type watt hour meters - Google Patents

Abstract

543,437. Compensating meters for temperature errors. WALL, G., McCALLUM, G., and METROPOLITAN - VICKERS ELECTRICAL CO., Ltd. Nov. 28, 1940, No. 17007. [Class 37] An induction meter is provided with pieces 5, 6 of magnetic material of negative temperature coefficient of permeability carried by a non- magnetic support 4 so as to be located in close proximity to the outer edges of the faces of the current poles 2, 3 and separated from these edges by such a small air gap that errors due to increase in the resistance of the voltage coil are at least partially compensated. The support 4 is a rectangular loop of brass, copper, or resistance alloy and may have a cut in one of its shorter sides so that it does not itself form a closed circuit. A block 14 of magnetic alloy having a negative temperature coefficient of permeability is inserted centrally in the face of the voltage pole 1 in order to compensate for the reduction in the braking power of the permanent magnet on rise of temperature. This block may have a negative co-efficient effective over a different range from the alloy 5, 6. For further compensating errors due to increase in resistance of the voltage coil a winding 9 on the current poles is connected to a resistance 10 thermally associated with the voltage winding, for example by insertion between the winding and the core. The resistance 10 has a high temperature coefficient, for example it may be of iron or nickel wire. The magnetic alloy may be a ferro-nickel alloy as described in Specification 30297/10, [Class 37]. Specification 520,786 also is referred to.