Texas Instruments Corporation

Radi Pejouhy

John R D'Entremont

Joseph G Nield, Jr

Michael L Bouffard

Wilfred W Cardin

Hideharu Furukawa

Keith F Boivin

Norman Yarworth

Joseph L McMorrow

Stephen J Benner

Joshua Loring

Beggs, Louis C

Motor protection for air conditioning and refrigeration compressors includes in a first embodiment a cluster block (22) having a seat for a hermetic motor protector (24, 24') and mounting a combination terminal/fusible link (26/26d, 26d') in which the motor protector and combination terminal/fusible link can be exposed to cooling fluid contained in the compressor container and the cluster block is mounted on a lead-through pin (18a) of a header (18) in the container wall. In a second embodiment the cluster block (30) is mounted on all three pins (18a, 18b, 18c) of header (18) with pin connectors received in parallel extending channels (30a, 30b, 30c) of the cluster block. In another embodiment the cluster block (40) is irregular in configuration in order to accommodate available space in certain compressor containers and has a lid (40g) to enclose the motor protector. In another embodiment a base member (52) is tied directly to the stator winding and has a snap-on member (58) to capture the motor protector (24) in the motor protector seat.

Overcurrent protection apparatus for refrigeration and conditioning

A motor protector having a thermostat metal element thermally coupled to an electrical motor in a refrigerator compressor motor system has a heater responsive to motor current thermally coupled to the thermostat metal element and has an improved component arrangement to provide locked rotor and ultimate trip protection for the motor without requiring calibration of the operating temperature for the protector after assembly or after incorporation in the motor system.

Protected refrigerator compressor motor systems and motor protectors

A miniature thermostatic switch of the type that can be inserted into the windings of electrical devices in order to sense the temperature of the windings is disclosed having an improved liquid tight seal to prevent seepage into the switch of varnish or other liquids to which the windings are subjected during assembly. The switch has a two part metallic housing with lips of one part clamped to the other part with an electrically insulating gasket interposed between the two parts. After assembly of the switch the gasket material is softened and the lip is subjected to a force to deform the gasket material, wetting the housing contiguous to the gasket and forming fillets therebetween to completely fill in any voids between the gasket and the contiguous housing.

Method of providing an improved seal for thermostatic switch housings

A snap-acting thermostatic electric switch in which a snap-acting thermostatic disc is physically attached to a heater plate which in turn mounts movable contacts. A stepped rivet loosely mounts the disc and is headed over to tightly mount any one of a series of heater plates having different thicknesses. The heater plate is shaped to allow unimpeded snap motion of the disc yet provide improved heat conduction to the disc. The disc and plate are mounted on a spider support which is adjustably positioned within the switch compartment by means of a combination rivet and screw received in a threaded bore of the base of the switch. An insulator is loosely received on the base and is biased thereagainst by a spring which also biases the spider upwardly to provide positional stability. Another spring is placed between the spider and the heater plate to optimize contact opening.

Snap-acting thermostatic switch assembly

An electrical lighting fixture adapted for recessed mounting has structure for mounting and energizing a lamp and has an insulation detecting protector device adapted to interrupt operation of the lamp to prevent overheating of the fixture if thermal insulation is disposed around the fixture in such a way as to excessively block heat dissipation from the fixture. The protector device has structure for mounting the device on the fixture to be subject to representative fixture conditions, has a thermally responsive switch which is actuatable in response to heating to a selected temperature for interrupting operation of the lamp, and has an electrical resistance heater which is thermally coupled to the switch for actuating the switch if thermal insulation excessively blocks dissipation of heat from the protector device. Thermal barrier elements are incorporated in the leads which connect the switch and heater to a power source and to the lamp and limit heat-transfer out of the protector device via the leads to a minor proportion of the heat output of the heater, thereby to permit operation of the heater at a low power level while assuring that the protector device prevents overheating of the fixture and avoids nuisance interruption of the lamp even during anticipated levels of variation in line voltage and ambient temperature.

Recessed lighting fixture and an insulation detecting protector device

A miniature, solid state motor protector has a metallic housing with two hingedly connected recessed portions with a wafer of positive temperature coefficient (PTC) of resistivity material disposed in each recess in electrical connection with the housing and a center spring contact located intermediate the two PTC wafers and in electrical connection therewith so that the wafers are electrically connected in parallel relation.

Miniature motor protector apparatus and method for assembling thereof

A current interrupting device having improved contact life includes a hermetically sealed housing in which a thermostatic member is adapted to cause electrical contacts to move into and out of engagement depending on the temperature of the thermostatic member. The atmosphere within the housing is a gas having a dielectric strength slightly over the impressed voltage.

Current interrupting apparatus having improved contact life

A current interrupting device having improved contact life incorporates a thermostatic member adapted to cause electrical contacts to move into and out of engagement depending on the temperature of the thermostatic member. The device is evacuated and back-filled with a mixture of argon and helium and then hermetically sealed.

Current interrupting apparatus

A motor protector characterized by low cost, by improved service life and by improved cycling properties has a bimetallic element mounted in a metal housing to move a first contact along a selected axis to engage and disengage a complementary contact in response to changes in element temperature. An electrical resistance heater coil, preferably with less than one full coil convolution, is oriented and secured externally of the housing so that the axis of the magnetic field established by the heater coil is coincident with the axis of movement of the first contact. The properties of the heater are selected relative to the thermal mass of the protector so that, when the heater and the protector contacts are arranged in series with motor windings, the external heater is adapted to heat the entire thermal mass of the protector to a sufficient temperature in response to the occurrence of selected overload or fault currents in the motor windings to actuate the bimetallic element to open the winding circuit before excessive overheating of the motor windings can take place. In this arrangement, the heater orientation avoids magnetic deflection of arcs occurring during opening of the protector circuit, thereby improving service life, and the heating of the entire thermal mass of the protector in opening the protector circuit retards subsequent reclosing of the circuit, thereby improving cycling properties of the protector. Preferably, the protector is mounted in a common housing with motor starter means to utilize common terminals with the stater means. Also, where the protector is used to protect a motor in a sealed refrigeration compressor system, the protector is preferably mounted in spaced but closely adjacent relation to the compressor shell, thereby to avoid reduction in cycling time by avoiding draining of heat from the protector into the shell and thereby to avoid opening of the protector when the shell is heated during normal compressor operation while permitting heat transfer from the shell during the occurrence of a sustained fault condition in the motor to further improve protector cycling time.

Motor protector and system

A motor protector for use in motors having a high operating temperature employs a snap-acting composite thermostat element to actuate the protector wherein the multilayer thermostatic material embodied in the element has an electrical resistivity value from 20 ohms/c.m.f. to 400 ohms/c.m.f. and a flexivity value from 90 .times. 10.sup.-.sup.7 inches per inch per degree Fahrenheit to 110 .times. 10.sup.-.sup.7 inches per inch per degree Fahrenheit to provide for better calibration, longer life, and better space control in the protector for use in motors having higher operating temperatures.

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Marshfield, MA, United States of America

Radi Pejouhy