Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Patent
1988-03-21
1990-10-16
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
324686, 324176, 324177, 34087037, G01R 2726
Patent
active
049638297
ABSTRACT:
A variable capacitor whose capacitance is a function of shaft position is coupled to a rotating shaft. A constant voltage is applied to the capacitor. As the shaft rotates, the changing capacitance of the variable capacitance causes current to flow into and out of the variable capacitor in response to the shaft rotation--thus providing a current source with no inherent practical frequency response limitations. A transresistance amplifier converts the current to an output voltage which is proportional to instantaneous shaft velocity. Various arrangements are used to eliminate the discontinuity associated with the inherent sign change of the capacitance time derivative while retaining the signal components associated with instantaneous velocity changes of the rotating shaft. The broadband instantaneous velocity response of the resulting shaft rotation analyzer has numerous applications in the detection of "signatures" of rotating shafts--such as shaft speed variations attributable to electric motor commutator contact, cogging variations, and torque pulsations due to the firing of cylinders in reciprocating engines.
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Eisenzopf Reinhard J.
Mueller Robert W.
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