GB851745A - Improvements in or relating to eccentricity measuring devices - Google Patents

Abstract

851,745. Electric tests. WESTINGHOUSE ELECTRIC CORPORATION. Oct. 4, 1957 [Oct. 9, 1956], No. 31148/57. Class 37 In apparatus for determining the concentricity of a shaft in bearings an A,C bridge circuit has a pair of variable inductive arms positioned close to the shaft and means for comparing the extreme values of cactance of the inductive arms with the instantaneous values. As shown, coils 5, 6 inductively coupled to the shaft 1, which may be eccentric or which may climb in the bearings, form two arms of a bridge circuit supplied from A,C. source 7. The other arms are constituted by coil 10 divided into sections 10a, 10b and a central section 10c. Unbalance is detected by transformer primaries 14, 16 responsive respectively to the change in impedance of coils 5, 6. Each transformer feeds two secondaries 18, 19 and 26, 27. Secondaries 18, 26 supply the rectified output to circuit 21, 29 of long time constant, e.g. several seconds the voltages developed across which are added and to circuit 24, 32 of short time constant, e.g. four degrees of rotation, the voltages developed across which are also added. The two resultant voltages are connected in opposition in the grid cathode circuit of a triode 35 having an indicator 37 in the cathode circuit. The voltages occurring across capacitors 21, 29 indicate the maximum distance between the shaft and coils 5, 6. The voltage across capacitors 21 and 29 indicates the maximum distance between the shaft and coils 5, 6. The voltage across capacitors 24, 32 indicates the instantaneous size of the gap between shaft and bearing. Indicator 37 is said to indicate eccentricity directly. In the arrangement of Fig. 2 (not shown) one pair of secondary windings of transformers 15, 17 and associated condensers 24, 32 are replaced by a constant voltage source. This constant voltage represents the potential across capacitors 24, 32 (above) representing the total coil to coil and gap which in the absence of external factors, should be constant.