Texas Instruments Corporation

Diethard Unterweger

Pravin N Popat

Ronald J Candelet

Gennady Baskin

Gary L Tonnies

Leo A Plouffe

A surge protection device to protect telecommunication equipment coupled to telephone lines is shown having in a first embodiment three cells with each cell having a semiconductor element with a reverse breakdown PN junction mounted on a heat sink. The device includes a lead frame having a first pair of leads formed with a platform raised out of the plane of the remainder of the lead frame to provide suitable clearance relative to the semiconducting elements and each platform has a finger extending downwardly into engagement with a top electrode of a respective semiconducting element and is soldered thereto. A second lead lies in the plane of the lead frame and is soldered to a first heat sink plate mounting two semiconducting elements and another finger extending from one of the platforms is soldered to a second heat sink plate mounting the third semiconducting element. The heat sinks, semiconducting elements and portions of the leads are encapsulated in thermally conductive, electrically insulative epoxy. The device, when subjected to excessive current and voltage conditions, is adapted to fail closed. A second embodiment has two cells mounted on a single heat sink plate mounted in the same manner as in the first embodiment.

Telecommunication equipment protector

A surge protection system has a surge protection device comprising a semiconducting disc element disposed between two electrodes. The element is operable to selectively conduct electrical energy between the electrodes in providing a first level of surge protection for the circuit, and the electrodes are adapted to move toward each other to maintain a short circuit condition between the electrodes in the event the element is destroyed in providing a second relatively greater level of surge protection. The semiconducting element provides a critical energy conduction path between a selected limited portion of one side of the element and the other element side along which destruction of the element preferentially occurs due to overheating in providing the second level of surge protection. One electrode has a selected limited post portion disposed in electrical engagement with said selected limited portion of said one element side to facilitate establishment and maintenance of the short circuit condition between the electrodes in providing the second level of surge protection.

Surge protection device and system

A simplified solid state transient voltage and overcurrent protector for telecommunications equipment providing uniform protection characteristics between telephone lines and between either line and ground is shown in which two symmetrical thyristor chips are mounted with their normal common layer connected together on an enlarged heat sink. The assembly, together with current limiting PTC elements is encapsulated to form a dual-in-line package.

A protection system for a dynamoelectric machine providing a plurality of protective functions comprises a module having as a first function over temperature protection including thermal sensors adapted to be placed in heat transfer relation with the windings of the machine. The sensors which may be connected in series or in parallel are connected to a sensing circuit provided with shorted sensor protection. When connected in parallel a channel is provided for each sensor and is isolated from one another. Other functions include a minimum off delay timer which prevents rapid cycling of the machine. An oil pressure timer particularly useful with a compressor motor to sense oil pressure between the output of the oil pump and the crankcase in order to deenergize the motor should there be inadequate oil pressure for a selected period of time, a low voltage cut out network in the event of the occurrence of low voltage conditions, and a circuit to facilitate use of controls in the output side of the system if desired while permitting operation of the system only on the condition of output current flow. The minimum off delay timer can be modified to provide a manual reset circuit which will lock out or prevent energization of the machine each time the protection circuit is tripped. Reset can be accomplished only by removing power to the module and reapplying said power.

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Plainville, MA, United States of America

Diethard Unterweger