GB524080A - Improvements in eddy current dynamometers - Google Patents

Abstract

524,080. Rotary-absorption dynamometer. HEENAN & FROUDE, Ltd., and ROSS, E. G. Jan. 21, 1939, No. 2111. [Class 106 (ii)] Comprises an eddy current machine of the type employing a drum or cylindrical motor having two separate variations of the excitation thereof, a normal one varying with the speed of the dynamometer and a second with a different characteristic, wherein the field coil of the dynamometer operates in an unsaturated magnetic state and has a major excitation of series characteristic and another generating an appreciable potential difference at the start of the rotation of the armature and a further one to overcome the armature reaction, when the speed and load increases. The exciter dynamo 1 for the field coil 2 of the dynamometer operates in an unsaturated magnetic state and is provided with a series coil excitation 5, an excitation 3 from an external supply through a potentiometer 4, and an auxiliary shunt winding 6 of high resistance which is converted to the field coil 2 of the dynamometer. By suitably choosing the excitations 3, 5 and 6 the required relationship between torque and speed is obtained. A potentiometer 7 may be arranged in parallel with the field coil 2. A regulating resistance 8 in series with the winding 6 may be used. Further, the excitation of the dynamometer may be divided so that a portion 9 may be excited from the same source as the field 3. The coils 2 and 9 may be additive or subtractive. A potentiometer 10 may be arranged in parallel with the coil 9. If desired, the resistances 4, 10 may be connected mechanically so that the regulation of coil 3 will bear a definite relationship to the excitation of coil 9. Further, resistances 4 and 8 may be connected mechanically so that the regulation of coil 6 has a definite relationship to the excitation of coil 2. Other variations may be used by connecting mechanically resistances 10, 7 or 4, 10 and 8. Variable resistances in series with coils 2, 9 as at 13, 14 may be manually controlled, controlled by the movement of the dynamometer carcase or from a governor on the dynamometer shaft.