Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Patent
1986-07-17
1988-05-10
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
318696, 318490, G01R 3102
Patent
active
047438487
ABSTRACT:
A three-phase stepping motor is automatically tested for excessive friction and winding shorts in less than four seconds. The stepping motor accelerates its rotor at a constant rate to a first predetermined velocity. The level of the current applied to the rotor windings to effect commutation is very low so that the rotor will stop and fail to complete any further steps in the test cycle if there is excessive binding or friction. After the rotor is rotated one revolution, it is accelerated at a constant rate to a second and higher predetermined velocity with the current applied to the rotor windings being increased to a second and higher level at a selected velocity during acceleration. When the rotor reaches the second predetermined velocity, commutation is stopped immediately but current is still applied to at least one phase of the motor. An acceptable motor will continue to turn and generate an AC back electromotive force (EMF) signal in the energized phase of the windings. A motor, which has excessive friction or a winding short, will not produce an AC back EMF signal because it will not be moving. With an acceptable motor, the elapsed time between stopping the application of current to the rotor windings to stop acceleration and when the rotor coasts to a stop is displayed and enables comparison of the degrees of friction between acceptable motors.
REFERENCES:
patent: 3942111 (1976-03-01), Pfouts
patent: 4422040 (1983-12-01), Raider et al.
Krimm David L.
Stidham, deceased James O.
Yount William R.
Brady John A.
Eisenzopf Reinhard J.
International Business Machines - Corporation
Leach, Jr. Frank C.
Nguyen Vinh P.
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