General Theory, and Experimental Confirmation, of the Moving Coil Fluxmeter

1. An inclusive mathematical theory of the operation of the unshunted fluxmeter is developed. Previously published accounts of the theory of the unshunted fluxmeter are analyzed and found to be encompassed as special subcases of the theory developed in this paper. 2. From the general equation of operation a simple approximate equation is deduced which can be utilized for accurate calculation, provided the stated pertinent boundary conditions and restrictions are observed. 3. Experimental data are advanced which confirm the correctness of the general theory and make clear the necessity of observing the stated boundary conditions and restrictions. 4. Analysis and experimental confirmation analogous to that outlined in the three preceding paragraphs is advanced for the shunted fluxmeter. 5. Experiment reveals that a considerable amount of inductance can be inserted in series with a fluxmeter without substantially changing the working constant of the instrument. 6. Experiment indicated that a fluxmeter can be used in a searchcoil circuit of arbitrary resistance up to, in general, several times its internal resistance, provided that the corresponding numerical value of the working constant C' is selected from the calibration curve of C' versus circuit resistance. A combined numerical-experimental procedure for effecting this calibration curve is advanced. This procedure is illustrated by effecting the calibration curves of several fluxmeters. 7. A procedure for determining the mechanical and electrical parameters of a fluxmeter is advanced and illustrated by calculation of the parameters of several different fluxmeters. 8.