Title: Motor protection circuit

Abstract: A motor protection circuit employs a resistance bridge circuit with one side having multiple branches containing temperature responsive resistances for sensing an overheat condition in the motor. Semiconductor voltage sensing devices, such as high gain amplifiers, are responsive to voltages between a standard sensing node and each of the sensing nodes in the multiple branched side of the bridge circuit. Logic facilities respond to any of the sensing devices to operate switching facilities controlling energization of the motor. Additionally, the protection circuit may include a lubricating oil pressure responsive control which is not affected by power loss or spurious signals, and which may be controlled by the operation of a motor control switch.

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Inventors: Tyler, Hugh J. (Santa Ana, CA, US)
Newell, Dennis E. (El Segundo, CA, US)

Application Number: 503814
Filing Date: 1974-09-06
Publication_date: 1976-08-10
Assignee: Robertshaw Controls Company (Richmond, VA)
Primary Class(es): 318/473 318/481, 318/484, 361/27
Other Classes:
US Patent Ref:

3742303	Jun, 1973	Dageford	317/13.
3753043	Aug, 1973	Plouffe	317/41.
3777240	Dec, 1973	Neill	318/471.

Other Refs:
Primary Examiner: Rubinson, Gene Z.
Assistant Examiner: Feldhaus, John J.
Attorney: O'Brien & Marks