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Measurement of Motor Armature Temperature

IP.com Disclosure Number: IPCOM000073622D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Van Pelt, RW: AUTHOR

Abstract

The temperature of low inertia armature 1 is sensed by means of an analog model 2 of the armature. The model is connected in series with conductors 3 and 4. These conductors connect the brushes of magnetic tape unit capstan motor 5 to a source of DC voltage. The armature 1 is a hollow, thin-walled, tubular form which carries printed circuit conductors on the inner and outer surfaces. Data processing of magnetic tape produces rapid start-stop cycling of the capstan motor armature. The thermal time constant of the armature is low relative to the time constant of the remaining portion of the motor. As a result, sensing the temperature of the motor housing does not provide a fast, accurate, measurement of the critical armature temperature.

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Measurement of Motor Armature Temperature

The temperature of low inertia armature 1 is sensed by means of an analog model 2 of the armature. The model is connected in series with conductors 3 and 4. These conductors connect the brushes of magnetic tape unit capstan motor 5 to a source of DC voltage. The armature 1 is a hollow, thin-walled, tubular form which carries printed circuit conductors on the inner and outer surfaces. Data processing of magnetic tape produces rapid start-stop cycling of the capstan motor armature. The thermal time constant of the armature is low relative to the time constant of the remaining portion of the motor. As a result, sensing the temperature of the motor housing does not provide a fast, accurate, measurement of the critical armature temperature. Direct measurement of the armature temperature is difficult since armature slip rings must be provided to connect a measuring circuit to a sensor located on the armature.

Model 2 samples at least a portion of the current flowing to the armature. The thermal time constant of the model is identical to that of the armature. Cooling air source 6 supplies air to cool the armature, and also supplies a related quantity of air to cool the model. Thus, the instantaneous temperature of the model is closely related to the instantaneous temperature of the armature. The model temperature and the armature temperature are affected in a like manner by a change in armature current, a change in cooling air t...