Abstract
The paper deals with dynamic characteristics of the fixed cross coils, moving magnet type indicator. As a meter of this type has several nonlinear elements, its dynamic characteristics can not be expressed by a simple linear differential equation.
In the author's analysis the transfer characteristics of individual elements are mathematically calculated, and some experimental data are given as supplement.
The damping ratio and natural frequency were adopted as parameters to evaluate the overall dynamic performance and calculated values are compared with the test data under various conditions.
The results are summarized as follows:
(1) The damping ratio ζ varies considerably with the input span. When the input span is changed from 10mV to 50mV, ζ decreases from 1.51 to 0.32.
(2) The damping ratio ζ also varies in accordance with the pointer position. For example, when the pointer position is changed from center to low or high extreme of scale, ζ decreases from 1.00 to 0.69.
(3) The natural frequency also depends on the pointer position. Typical figures are: 1.43Hz at center and 1.55Hz at extreme positions of scale.
(4) The effective damping ratio which governs the response to a large step input is close to the damping ratio at the final settling position of the pointer.
