Eaton Corporation

Parker A Bollinger, Jr

James D Smith

Mark E Innes

Henry Anthony Wehrli, Iii

Denis A Mueller

Rick A Hurley

An improved PTC current limiting composition has been provided which comprises a chemically cross-linked thermosetting polyester resin and conductive particles dispersed in the resin. The thermosetting polyester resin is selected from the group consisting of polyethylene glycol fumarate, polypropylene glycol adipate fumarate, neopentyl glycol isophthalate fumarate, and neopentyl glycol phthalate fumarate. The conductive additive particles are selected from the group consisting of graphite and/or carbon black. The composition exhibits PTC behavior when cross-linked by a vinyl monomer selected from the group consisting of styrene, vinyl toluene and tertiary butyl styrene. Curing proceeds by free-radical addition across double bonds of the thermosetting polyester resin and is initiated by organic peroxides. Initial gelation which causes cross-linking but not final curing takes about 0.5 to 4 hours at a temperature of about 25.degree. C. to 125.degree. C. The final cure takes about 0.5 to 8 hours at a temperature of about 100.degree. C. to 160.degree. C. An effective amount of alumina trihydrate can be added to the current limiting composition to prevent dielectric breakdown, arcing and carbon tracking under high voltage conditions. It is respectfully submitted that the MPEP 608.01(b) states that abstracts should be between 50 and 250 words and up to 25 lines. Applicants' abstract in within these limits.

Positive temperature coefficient conductive polymer made from

An electrical contactor has first and second contacts movably mounted to engage for achieving continuity in an electrical circuit, via an electromagnet and armature defining a magnetic circuit with an air gap that closes in a first position of the contactor and opens in a second position of the contactor. A controller switches an alternating current voltage to the coil of the electromagnet during a timed portion of each AC half cycle, and senses the current level in the coil in a feedback loop. The controller adjusts the voltage-on time to achieve a predetermined average current as needed for accelerating the armature or coasting during a closing operation, for holding the armature in place when closed, etc. In order to sense whether the contactor is presently open or closed, the controller monitors and stores the phase angle between the previous voltage zero crossing and the time of voltage turn-on. When the inductance of the magnetic circuit including the electromagnet and armature changes rapidly due to opening or closing of the air gap between them, the controller detects a corresponding variation in the phase angle. The controller is preferably a microprocessor, programmed to normalize the phase angle over a range of coil drive voltages. The microprocessors of a number of such contactors can communicate in order to effect coordinated operations.

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Arden, NC, United States of America

Parker A Bollinger, Jr