Abstract: The present invention discloses a method using a bismuth based alloy as power-off element, comprising: a bismuth based alloy is used as the power-off element and a melting point of the bismuth based alloy is between 100° C. to 380° C.; when the power-off element is in an environment below the melting point, two conductive elements are mutually contacted and capable of conducting currents, whereas the power-off element is only receptive of the currents but does not serve as a medium for conducting the currents; when a working temperature of a switch or the socket is close to or exceeds the melting point, the power-off element loses rigidity and enables the two conductive elements to be separated from each other, thereby forming an electrically disconnected state.

Abstract: A thermomagnetic trip is disclosed for an electrical switching device, especially a circuit breaker. In at least one embodiment it includes at least one first and one second terminal, a first heating element, a conductor able to be influenced by temperature, a yoke and a clapper armature. A current path is formed through at least the first terminal, the conductor, the first heating element and the second terminal. The current path is disposed at least in sections on and/or in the yoke such that a magnetic field acting on the clapper armature is induced in the yoke by the current flowing through the current path and wherein a second heating element is disposed in the current path especially between the first terminal and the conductor.

Abstract: An electrical switch is disclosed, especially an electrical circuit breaker, including an overcurrent tripping device which, in the event of an overcurrent situation, switches off the flow of current through the switch; and a thermal tripping device which, in the event of a thermal overload, switches off the flow of current through the switch. In at least one embodiment, the overcurrent tripping device includes a first shaft which is disposed such that, in the event of an overcurrent situation, it is rotated from a first position into a second position and thereby indicates the overcurrent situation; and the thermal tripping device includes a second shaft which is disposed such that, it is rotated in the event of a thermal overload and is also rotated as well in the event of a rotation of the first shaft and when rotated initiates a switching-off of the switch.

Abstract: A circuit breaker includes a short-circuit release and a thermal overload release. In at least one embodiment, the short-circuit release includes an armature and a pole which are disposed within a coil former, as well as a yoke plate and a terminal connection which are disposed around the coil former. The thermal overload release includes a metal strip made of at least two types of metal, around which a PTC thermistor is wound, wherein an electric insulator is disposed between PTC thermistor and metal strip. In at least one embodiment, the connection between the thermal overload release and the yoke plate is made by way of a separate bracket.

Abstract: An installation switching device includes a housing, a main contact point having an arc quenching chamber, an input terminal, an output terminal, an impact-style armature system configured to move the main contact point to an open position, a latching mechanism having a latching point and configured to open an isolating contact point disposed in a secondary current path parallel to a main current path, a main thermostatic bimetallic strip configured to act on the latching point to as to cause the main contact point to remain in the open position, a current limiting resistor disposed in the secondary current path, a selective thermostatic bimetallic strip disposed in the secondary current path and configured to act on the latching mechanism, a handle configured to act on the latching mechanism so as to open and close the main contact point, and a phase connecting rail.

Abstract: A dual protection device includes a cover, a first protection unit, a second protection unit and a base. The first protection unit includes an elastic contact piece and a first conductive member. The elastic contact piece has a first end fixed to the cover and a second end including a first contact point. The first conductive member has a second contact point to contact with the first contact point. The elastic contact piece bends to separate the first contact point from the second contact point when overloaded. The second protection unit has a second conductive member, which is respectively connected with the first conductive member and a second terminal by fuse members. A biasing member is compressed between the second conductive member and the base so as to separate the second terminal from the second conductive member when the fuse members melt.

Abstract: A dual protection device for a circuit includes a first protection unit and a second protection unit functioning independently. The first protection unit includes an elastic contact piece having a first contact point and a conductive member having a second contact point to contact with the first contact point. When overloaded, the elastic contact piece is deformed and bent toward an opposite direction to separate the first contact point from the second contact point, thereby protecting the circuit. The second protection unit has a fuse member and a second terminal. The fuse member is connected between the conductive member and the second terminal. If the first protection unit does not function as expected and the temperature climbs to a predetermined value, the fuse member melts. The conductive member is disconnected from the second terminal, thereby protecting the circuit.

Abstract: A dual protection device for a circuit includes a first protection unit and a second protection unit functioning independently. The first protection unit includes an elastic contact piece having a first contact point and a first conductive member having a second contact point to contact with the first contact point. When overloaded, the elastic contact piece is deformed and bent toward an opposite direction to separate the first contact point from the second contact point, thereby protecting the circuit. The second protection unit has a flexible second conductive member disposed between the first conductive member and the second terminal. A fuse member forces a free end of the second conductive member to connect with the second terminal. When the fuse member melts due to high temperature, the free end of the second conductive member is separated from the second terminal, thereby protecting the circuit.

Abstract: A dual protection device for a circuit includes a first protection unit and a second protection unit functioning independently. The first protection unit includes an elastic contact piece which has a first contact point. A first conductive member has a second contact point to contact with the first contact point. The elastic contact piece is deformed and bent toward an opposite direction to separate the first contact point from the second contact point when overloaded. A second protection unit has a second conductive member which is connected between the second terminal and the first conductive member. A fuse member and a biasing member are disposed at two opposite sides of the second conductive member. When the fuse member melts due to high temperature, the second conductive member is pushed by the biasing member to be separated from the second terminal.

Abstract: A lockable MEMS switching architecture provided having a clutch assembly, a switching member, and an actuator. The clutch assembly has one or more engagement features located in proximity to the switching member—particularly one or more receiving features located upon the switching member. The clutch assembly is actuated to disengage the engagement features from the receiving features. The switching member is actuated to move in relation to the clutch assembly. Once the switching member is in a desired position, the clutch assembly is de-actuated, causing the engagement features to re-engage with the switching member, thereby restricting its further movement.

Abstract: A protection device includes a bi-metallic plate having a first end fixed to a first terminal and a second of the bi-metallic plate has a first contact point so as to contact a second contact point on a first end of a carrier. A contact plate has a first end in contact with a second terminal and a second end of the contact plate is forced to connect to a second end of the carrier by a low melting point metal. When the protection device is overloaded, the bi-metallic plate is bent to separate the first contact point and the second contact point. Besides, if the bi-metallic plate does not bend as expected, the low melting point metal melts to separate the second end of the contact plate and the carrier when a pre-set temperature is reached.

Abstract: A protection device includes a bi-metallic plate electrically connected between the first and second terminals, and the bi-metallic plate is bent upward to separate two contact points when the protection device is overloaded to cut off the circuit. A contact plate has a first end in contact with the second terminal and a second end of the contact plate is forced to be connected to a second end of the carrier by a breakable piece that is made by low melting point metal. When the protection device is overloaded and the bi-metallic plate does not bend as expected, the breakable piece collapses or melts at a pre-set temperature to separate the second end of the contact plate and the carrier.

Abstract: A multiple output thermal detection and protection device providing an output signal representative of the temperature sensed by the device, and further providing a positive output signal representative of the sensed temperature reaching a predetermined set point temperature.

Abstract: A heating appliance having an electrical circuit that controls the temperature output of the heating appliance is provided with a bimetallic element that opens upon reaching a temperature level. A potentiometer in the circuit is used to select the temperature level within an acceptable range of temperatures. The potentiometer has a rotatable shaft including a first positioning element. A knob is secured to the shaft and has a second positioning element that engages the first positioning element on the shaft. The first and second positioning elements have portions that may be modified to compensate for variations in the temperature at which the bimetallic element opens. The first positioning element may be a rib, while the second positioning element is a slot in a tubular portion of the knob receives the rib and that may be located in a range of arcuate positions.

Abstract: A signal accessory for a molded case circuit breaker, with the circuit breaker (10) having an operating mechanism (40) with a cradle pin (41b), a cross bar (55) and a trip bar (54) and a main breaker cover (20). The signal accessory (300) comprises a signal accessory mounting (301) having a bottom mount (308) and a top mount (306) coupled to the bottom mount (308) with the top mount configured to receive a switch (302, 304) and engage the breaker cover (20) in an accessory socket (22). A switch member (311) is rotably mounted on the bottom mount (308) with the switch member (311) having an actuator lever (322) in contact with the operating mechanism (40) of the circuit breaker (10) and an actuator pad (314) in contact with a switch mounted on the top mount (306).

Abstract: A pair of spring mounted masses have sufficient inertia to remain stationary in response to a shock force applied to the housing of a trip assembly in a circuit breaker to block movement of the trip bar and thereby prevent a nuisance trip.

Abstract: The invention relates to a circuit breaker having a crossbar (7) that is supported swingably onto a base (1B) to hold swingably movable contacts (4), and has the small reduction of overtravel in the elapsed years, and can reduce its size. The bending modulus of elasticity Eb, Ec of the base (1B) and the crossbar (7) at the ordinary temperature/ordinary humidity satisfy following relationships.

Abstract: A MEMS thermal actuator device is provided that is capable of providing linear displacement in a plane generally parallel to the surface of a substrate. Additionally, the MEMS thermal actuator of the present invention may provide for a self-contained heating mechanism that allows for the thermal actuator to be actuated using lower power consumption and lower operating temperatures. The MEMS thermal actuator includes a microelectronic substrate having a first surface and at least one anchor structure affixed to the first surface. A composite beam extends from the anchor(s) and overlies the first surface of the substrate. The composite beam is adapted for thermal actuation, such that it will controllably deflect along a predetermined path that extends substantially parallel to the first surface of the microelectronic substrate. In one embodiment the composite beam comprises two or layers having materials that have correspondingly different thermal coefficients of expansion.

Abstract: A switch having closed and open positions moves from one position to the other in response to either an elevated temperature or an excessive pressure. A switch member of bimetal material or shape memory alloy operates in response to an elevated temperature, and a foil diaphragm that cooperates with a bumper operates the switch member in response to elevated pressure. The diaphragm may rupture to vent excessive pressure in the event pressure continues to rise despite operation of the switch member or due to failure of the switch member to operate.

Abstract: A thermostat comprises a first laminated metal plate and a second laminated metal plate in which a plurality of metal layers having different rates of expansion are laminated. The first laminated metal plate has a movable contact. The second laminated metal plate is disposed in such a position as to put the first laminated metal plate to the off and on positions. The first and second off temperatures, which put the movable contact in the off position by causing the first and second laminated metal plates to deform, and the first and second return temperatures, which return the movable contact from the off position to the on position, are set respectively at different temperatures.

Abstract: A circuit breaker includes an upper rail mounting device defined by a line terminal having a pair of spaced-apart jaws. A bimetal is adjusted by means of a calibration screw. An aperture is provided in an upper sidewall portion of a base of the circuit breaker for access to the calibration screw by a calibration device. The aperture is positioned so that the calibration device must pass through the jaws of the upper rail mounting device. This ensures that the calibration screw can only be operated when the circuit breaker is disconnected from an electrical supply.

Abstract: An overcurrent release device for protection switching devices, in particular automatic line circuit breakers or motor protective switches, with electromagnetic and thermoelectric release, includes a thermoconducting tubular supporting body onto which a coil is wound and which has a striking end and an opposite widened receiving end for bearing contact and radial support of a bimetal snap-action disk with a central bore, a core having a bore defined therein, an armature movable in the supporting body between its striking end and the core, and a slide extending through the bore in the snap-action disk and through the bore in the core in a direction towards the armature. The slide is provided for thermoelectric disengagement by means of the snap-action disk via a thickened portion and for electromagnetic disengagement by means of the armature via a slide actuator. In the operative state, the spacing between the armature and the core corresponds at maximum to the snapping travel of the snap-action disk.

Abstract: In an exemplary embodiment of the invention, a calibration arrangement and process for use in a circuit protective device are presented. An exemplary calibration assembly for use in the calibration process of the present invention includes a split clamp arm having a first opening for receiving and holding a calibration pin and a second opening for receiving an actuator key. A portion of the split clamp arm is divided into a first arm and a second arm by a channel which extends from a first end of the split clamp arm through the first opening and communicates with the second opening. The split clamp arm is opened by inserting the actuator key through the second opening and because of the preferred oblong or rectangular shape of the second opening of the split clamp arm, rotation of the actuator key therein forces the members forming the first opening of the split clamp arm apart from one another.

Abstract: A switch has a switching mechanism, which switches at a response temperature, for opening and closing a circuit that can be connected to external terminals of the switch. In this context, the switching mechanism has a movable contact, electrically connected to one external terminal, which as a function of the temperature of a bimetallic part is in contact with a fixed contact that is electrically connected to the other external terminal. The switching mechanism further has a safety element that changes its shape into a high-temperature shape if its temperature reaches a transformation temperature which is above the response temperature. The movable contact is in contact with the fixed contact as a function of the temperature of the safety element.

Abstract: A switch has a housing which receives a temperature-dependent switching mechanism and comprises a lower part on whose inner bottom a first countercontact for the switching mechanism is arranged, and a cover part, closing off the lower part, on whose inner side a second countercontact for the switching mechanism is provided. The switching mechanism has an electrically conductive spring disk which carries a movable contact element and operates against a bimetallic snap disk which sits approximately centeredly on the movable contact element, the spring disk being braced at its rim against the countercontacts and pressing the movable contact element against the countercontact when the switching mechanism is below its response temperature. The countercontact against which the spring disk is braced at its rim below the response temperature is magnetic.

Abstract: An overcurrent trip (1) for circuit breakers or motor safety switches has a very short reaction time. The short reaction time is achieved by connecting a bimetal snap-action disk (8) to the heating device (7) in such a way that its central region is always in contact with the heating device (7), irrespective of creeping movement. This heating device (7) is formed by a ferromagnetic core (5) on which the magnet winding (12) is directly fitted, without a further yoke, which magnetic winding simultaneously serves as the heating winding. The bimetal snap-action disk (8) is held on this heating device (7) with the aid of the electromagnetically actuated rod (21), while a plunger (43) which coaxially surrounds the electromagnetically actuated rod is moved by the bimetal snap-action disk (8).

Abstract: A protective apparatus for an electrical installation, includes a device for connecting the protective apparatus to an electrical installation in parallel intermediate phase and zero and under no current and temperature-sensitive disconnection element for disconnecting the electrical circuit when a predetermined temperature for the electrical circuit is attained. The temperature-sensitive disconnection element, preferably, operates the actuating a leakage relay when the predetermined temperature is reached.

Abstract: An actuator (144) for initiating a trip of a circuit breaker. Load current passes through a conductor (66) that is electrically coupled to a contact arm (56) by a braid (62). A thermally responsive bi-metal (64) has a first end portion which is disposed against a portion of the conductor (66) and through which at least a portion of load current carried by the contact arm, the braid, and the conductor passes. The bi-metal further has a second end portion that is disposed in spaced relation to the conductor and is cantilever-mounted on the portion of the conductor via the bi-metal's first end portion. The bi-metal is nominally flat and straight, but increasingly warps as thermal energy in the bi-metal increases. Upon attaining a certain degree of warping, the bi-metal initiates a trip of the circuit breaker by causing the contact arm to swing from a circuit-making to a circuit-breaking condition.

Abstract: A compact current limiting circuit breaker is equipped with a current limiting shunt for effective over-current circuit interruption. The circuit breaker trip unit responds to long time, short time and instantaneous over-current conditions by opening a set of contacts to isolate the protected circuit. Upon contact separation an arc is drawn, with the endpoints of the arc being initially rooted on the pair of open contacts. Further opening of the contacts commutates the arc into the current limiting shunt to redirect the current away from the trip unit and suppress the arcing current until the circuit breaker contacts are sufficiently open to isolate the protected circuit.

Abstract: A thermal protector includes a bimetal plate which is prevented from being vibrated by a magnetic field produced by a transformer or a motor. A member made of magnetic material is disposed in the vicinity of the bimetal plate. The fixed member for loosely holding the bimetal plate may be made of magnetic material. The fixed metal fitting for connecting a first fixed plate with a movable plate is extended near to the bimetal plate and is made of magnetic material.

Abstract: A component for a demagnetization circuit includes a thermistor with positive temperature characteristic having a first electrode and a second electrode, another thermistor with negative temperature characteristic having a third electrode and a fourth electrode and being disposed such that the first and third electrodes are opposite to each other, a heat-sensitive switch disposed between these two thermistors, a case which contains the thermistors and a heat-sensitive switch, and terminals which extend outward from inside the case.

Abstract: A new Automatic Thermal Shut-Off Switch for preventing heat damage to a high pressure low volume water pump. The inventive device includes a T-shaped housing having a longitudinal cavity, a bimetallic compression spring within the cavity, a disc within cavity on top of the spring, a pin orthogonally secured to the disc, a first contact, and a second contact electrically in contact. The housing is positioned within an unused port within a pump housing and conducts the heat produced by the pump. The conducted heat expands the spring thereby forcing the pin upwardly to separate the first contact from electrically contact with the second contact.

Abstract: A pre-assembled holder (11) for a bimetallic switching device (12) in a temperature-dependent switch (10) comprises a supporting part (13) made of an electrically insulating material and two electrically conductive contact parts (14, 15) which are fastened to the supporting part (13) before the switching device (12) is inserted. The holding ends (24, 25) of the two electrically conductive contact parts (14, 15) protrude beyond the supporting part (13) and are designed to bear and clamp the switching device (12) between them outside the supporting part (13). An insulating cap (31) can be placed over the holding ends (24, 25) after the switching device (12) has been inserted (FIG. 1).

Abstract: A bimetallic reed for a circuit protecting device includes an integral fusible portion as a failsafe interrupting mechanism. The bimetallic reed includes a body of electrical conductive materials and having a first end mountable to a terminal and a second end forming an interruptible contact portion. The body is shaped to deform at a central portion of the body when the body is heated to a predetermined temperature. The body includes a plurality of apertures adjacent to the contact portion defining a plurality of electrical conductive pathways connecting the central portion and the contact portion, wherein the plurality of conductive pathways is fusibly responsive to a predetermine electrical load condition to form a fusible link.

Abstract: A molded case circuit breaker for residential use employs an additional safety feature to ensure a fail-safe condition in the event that the circuit breaker is installed within a circuit that may be subjected to an excessive over-current fault that disables the circuit breaker trip unit. The integral bimetal-fuse within the circuit breaker trip unit responds to interrupt circuit current before any damage can occur to the associated electrical wiring system.

Abstract: A thermally responsive switch for protecting electric motors against overcurrent and overheating conditions includes a metallic receptacle having an elongated dome-shaped portion and an opening opposite to the dome-shaped portion, a metallic header plate secured to the one end of the receptacle so as to hermetically close the opening afterwards and having a through-aperture, a thermally responsive element disposed in the receptacle in parallel with the header plate and carrying a movable contact at one end, a rod terminal secured in the aperture of the header plate by an electrically insulating material filled in the aperture for hermetic sealing so that the terminal extends through the aperture, a fixed contact support disposed in the receptacle to be perpendicular to the terminal and having an end to which a fixed contact is secured, the support being connected at the other end to the end of the terminal projected into the receptacle, by solder, and a spring for urging the support so that it is disconnected

Abstract: A thermally responsive switch includes an elliptic dome-shaped metal receptacle, a header metal plate hermetically secured to the receptacle and having a through-aperture at one of two longitudinal ends, an electrical conductor inserted through the aperture of the header plate and secured with an electrically insulating material such as glass, a support having at one of two longitudinal ends a fixed portion secured to the end of the conductor in the receptacle and a supporting portion positioned away from its other end in the direction of the fixed portion, a bimetal secured at one of its two ends to the supporting portion of the support and carrying a movable contact at the other end, the bimetal having a central shallow dish-shaped portion reversing its curvature with a snap action in response to the temperature, a fixed contact secured to the header plate in the vicinity of its other longitudinal end, and a calibrator interposed between the inner wall of the receptacle and the other end of the support oppo

Abstract: An overload protective device to the disposed in an electric circuit serving to supply current to a load has a pair of fixed contacts provided inside of a case and an inversible disk-like bimetal of a curved shape having a pair of movable contacts capable of coming in contact with the fixed contacts, respectively. A shaft is fixed to the case at one end thereof and formed with a head portion at the free end portion. The shaft extends though a hole formed in the central portion of the bimetal. When the bimetal breaks, a circuit breaker breaks the electric circuit permanently to thereby prevent the load and the overload protective device from being burnt out.

Abstract: An electrical component, particularly a fuse for a surface-mount component, is formed by sputtering an electrical conductor onto a square tube, sleeving the tube into an outer tube, filling the assembly with a room-temperature vulcanizing silicone sealant, cutting the assembly into segments, and metallizing the ends of each segment.

Abstract: A thermal relay is disclosed which can be remotely re-set and/or tripped by means of remote control electromagnets.The case of the relay has second fixing means adapted to receive first fixing means belonging to one and the same electromagnet can in which an extension of the core or plate is orientable so as to come opposite each of the re-setting and testing pushers placed on the front face of the relay.

Abstract: A thermally and electrically conductive housing having a solid tip portion is shown mounting a heating element thermally and electrically coupled to the tip portion which in turn is electrically coupled to a switch mechanism mounted within the housing. The switch mechanism includes a thermostatic snap acting disc adapted to bias a movable electrical contact away from a stationary electrical contact at preselected temperatures. The housing is shown mounted in a carburetor of an automobile to contact energization of a honeycomb heater disposed in the carburetor, however; the device can be used in other locations where it is desired to maintain a body within a selected temperature range.

Abstract: A safety cutout device for electric loads, particularly for use in pressing irons and portable heating apparatus, has a temperature switch, such as a bimetallic switch, which is adapted to be connected in series with the electric load. An electrical component adapted to be connected in parallel with the load and having an open and a closed switching state, and being normally open, is connected in series with a resistor adapted to be connected in parallel with the load and arranged in heat transfer relationship with the temperature switch and for heating the temperature switch to its operating temperature to open the switch. A further resistor, which continuously bridges and heats the temperature switch to an extent sufficient to maintain the temperature switch in its actuated open position, is connected in parallel with the temperature switch and adapted to be connected in series with the load.

Abstract: An improved device for protecting an electrical load from a current overload combines an electrical switch and a re-settable circuit breaker in a single housing. The device avoids the use of gate plates, visually alerts an operator to the existence of a tripped conditions, and provides automatically self-aligning, evenly-wearing contacts for the switch.

Abstract: A thermally controlled electric switching arrangement with a temperature controller, having a snap-action switch actuated by a bimetallic strip and of which the dead center position is displaceable by a manually operable setting device in order to influence the control point, and with a temperature limiter which is constructed as a melting metal fuse which comprises a fusible element, pressure elements engaging therein and at least one switching contact held in the closed position by the pressure element, so long as the limiter has not responded, is structurally simplified, the simplification also being intended to improve the variability of installation of the switching arrangement. This is achieved in that the movable contact of the temperature limiter which is actuated by a thrust pin biases a first contact face of the fixed contact of the temperature limiter, which is opposite a second contact face of the fixed contact which is biased by the movable contact of the temperature controller.

Abstract: A thermal sensor assembly is shown as having a housing formed of first and second body sections with the first being a probe-like portion for introduction into a medium the temperature of which is to be monitored; a thermistor and an electrical switch are electrically isolated from each other and situated within the housing; the thermistor is in series with and between one of the body sections and a terminal which is connectable to associated circuitry external of the sensor assembly; the electrical switch is effective to close an electrical circuit as between the same one of the body sections and a second terminal which is connectable to additional associated circuitry external of the sensor assembly.

Abstract: A thermal relay includes a housing, two fixed contacts secured to respective terminals disposed in the housing, a disc-shaped bimetal disposed in the housing and having two movable contacts made into and out of engagement with the respective fixed contacts, an adjusting screw including a screw portion and a head portion which are coupled with each other by a meltable metal, and a coil spring biasing the disc-shaped bimetal to the head portion of the adjusting screw to thereby support it.

Abstract: A switch is shown having a thermostatic member which deforms in response to variations in temperature to thereby control the state of energization of the switch. The thermostatic member is shown cantilever mounted or centrally mounted using material to affix the member to a support which melts at a selected temperature to cause the member to separate from the support upon the occurrence of selected conditions.

Abstract: A thermally responsive control especially for a clothes iron combines an adjustable, temperature-regulating thermostat and an over-temperature control for limiting maximum temperature levels on a plastic mounting bracket where the over-temperature control also protects the mounting bracket against damage from overheating.

Abstract: A thermal relay is provided comprising, in a first cavity of a case, bi-metallic strips through which pass currents of a multi-phase network feeding a load through an electromagnetic contactor and, in a second cavity, an electromagnetic sub-assembly including break and signalling switches whose mobile contacts have pivoting axes and actuating points cooperating with a common piece, the whole forming a deformable parallelogram. The second cavity also contains toggle transmission means between the bi-metallic strips and said common piece as well as means for selecting the mode of operation of the switches. Toggle springs are associated with said mobile contacts.

Abstract: A sensing device for monitoring engine coolant temperature comprises a two leaded thermistor, a single lead thermistor and a single lead bimetal switch in a compact shell. The switch and one thermistor are electrically grounded to the shell. A bimetal leaf is welded to the end of the shell and its free end extends to an adjustable central contact. A spring assembly biases the grounded thermistor against a shelf near the end of the shell. The leaf and the spring assembly are canted at an angle to conserve space. The other thermistor is supported by an insulated closure in one end of the shell.