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Regulator device for electric current

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US2978665A
US2978665A US59729256A US2978665A US 2978665 A US2978665 A US 2978665A US 59729256 A US59729256 A US 59729256A US 2978665 A US2978665 A US 2978665A
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material
conductive
current
expansible
particles
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Vernet Sergius
Asakawa George
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Antioch College
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Antioch College
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20Conductive material dispersed in non-conductive organic material
    • H01B1/24Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C7/00Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/02Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
    • H01C7/027Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • H02H9/026Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient

Description

April 4, 1961 s. VERNET ETAL 2,978,665

REGULATOR DEVICE FOR ELECTRIC CURRENT Filed July 11, 1956 INVENTOR Sees/us Vsmver 5y GEORGE AsAK/Ju/A 5mm, 0mm [my/W4;

regulating function,

partially conductive material 12.

mid-States tent REGULATOR DEVICE FOR ELECTRIC CURRENT Sergius ,Vernet and George Asakawa, Yellow Springs, Ohio, assignors, by direct and mesne assignments, to Antioch College, Yellow Springs, Ohio, a corporation of Ohio Filed ul 11, 1956, Ser. No. 597,292 6 Claims. (Cl. 338-223 load, thereby preventing any overload condition from existing for any substantial period of time,

(4) The device is responsive to ambient temperature and/or'current input for the performance of its current- The device automatically increases its resistance to current'fiow with increasing temperature before a maximum temperature is reached; thereby choking off the current before it becomes excessive and giving a very sensitivecurrent control action with a minimum fluctuation in current flow. I

Otherobjects of thisinvention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in i the several views.

In the drawings: I

Fig. '1 is anelevational view of one embodiment of the invention.

' Fig. 2 is a plan view of'the Fig. l embodiment.

. Fig. 3 is an enlarged sectional view on line 3--3 in to be understood that the invention is not limited in its application to the details of construction and arrange .ment of parts illustrated in the accompanying drawings,

since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also,

'it is to be understood'that the phraseology or terminology employed herein is for thepurpose of description and not of limitation;

In the drawings' there'is shown a current regulating device 2 including two spaced electrodes 4 and 6. Each of electrodes 4 and 6 includesa circular disk 8 and a rod 10, both being formed of brass or other metal having the ability to conduct electric current.

Between disks 8 there is secured a disk or wafer of The term partially conductive is used to indicate a material wherein a portion of the material is conductive and another portionis non-conductive. Material 12 preferably comprises finely divided conductive particles dispersed in a mixture of (l) thermally expansible, non-conductive materialand 2) material preventing flow of the expansible material from' b'etweenthe electrodes in the transition temperature range of'said expansible material.

The purpose of the finely divided conductive particles is to impart a degree of electrical conductivity to material 12 by forming a number of conductive paths through said material. The conductive particles may be formed of different materials, as for example carbon, a metal such as copper or aluminum, silicon, silicon carbide, lead sulfide, iron sulfide, or molybdenum sulfide.

The purpose of the thermally expansible, non-conductive material is to (1) spread the conductive particles apart as the temperature of material 12 is increased, and (2) thereby increase the resistance of material 12 to current flow. The thermally expansible, non-conductive material may be formed of different materials, as for example waxes, parafiin, polyethylene or polysiloxane. The term thermally expansible material will be understood to refer to a material which undergoes a substantial increase in its volumetric displacement when its temperature is increased. The term non-conductive Will be understood as being used in a relative sense to indicate a material having substantially greater resistance to current flow than the dispersed conductive particles, it being appreciated that the non-conductive" material conducts small quantities of electricity but offers a higher resistance to its passage than the conductive particles.

The purpose of the flow-preventing material is to contain the 'expansible material when it is in a liquid or semi-liquidistate, as when it has undergone a transition from a lowtemperature contracted condition (in the solid state) to a higher temperature expanded condition (in the liquid or semi-liquid gel state). The flow-preventing material may, be formed of different materials, as for example rubber; a high melting plastic such as polytetrafluoroethylene, polymonochlorotrifiuoroethylene, polyadipamide, polyvinyl chloride or acrylonitrile resin; or a high melting wax. The term high melting as used herein refers to a material which is solid in the transition temperature range of the thermally expansiblemateri-al, i.e. a material which'changes from a solid to a liquid at a temperature above the transition temperature range of the expansible material.

Preferably the volumetric proportions of the component materials making up material 12 are about 40% conductive particles, 40% thermally expansible material and 20% flow-preventing material.

Mixing of the component materials together can be effected on a two-roll rubber mill. The product emerges from the rubber mill as a sheet of material. When relatively rigid materials such as polytetrafluoroethylene and polyethylene are used ascomponent materials the sheet of material is pulverized in a hammer mill and subsequently compressed into the desired wafer shape by suitable molding mechanisms. When relatively soft materials are used as components for material 12 the hammer mill operation can be omitted. Wafer 12 is secured against the inner faces of disks 8 by conventional bonding agents.

Operation of the illustrated device is such that when rods 10 are connected into an electrical circuit and the temperature of material 12 is relatively low the conductive particles are quite close together so as to form a great number of conductive paths through material 12. As the temperature of material 12 is increased (due to the passage of electric current and/or an increase in ambient temperature) the thermally expansible material expands. As the temperature nears and reaches the transition range of the expansible material there is a proportionately large increase in the volume of material 12, which spreads the conductive particles apart and causes a large increase in scrapes disks 8 occupying substantially the Fig. 3 dotted line position at full expansion. The precise positions of disks 8 are of course determined by the expansion characteristics of the expansible material and the relative amount of expansible material employed.

When the device is positioned in an atmosphere having changing temperature characteristics an increase in the ambient temperature will heat material 12 so as to expand the expansible material and thereby increase the resistance to current flow. In this way the current or wattage through the device can be controlled in accordance with the ambient atmosphere temperature. By proper choice of the expansible material it is possible to regulate the current in many temperature ranges. Also, the choice of expansible material may be used to determine the width of the range, from a few degrees to a wide range.

"When the device .is operated by electric current (as distinguished from ambient temperature) an increase in the input wattage willheat material 12, and the resultant increase in resistance will tend to choke off the current before a maximum temperature is reached. As a result the heating" capacity of the current is reduced and the temperature of material 12 is decreased so as to contract the expansible material and thereby establish an equilibrium current through the device. The character of the expansible material, particle size of the conductive particles, and the proportions of component materials will determine the current carried.

The above described choke ofilaction is in contrast to that of a conventional fuse wherein no increase in resistance is experienced until the fuse material melts. .By reason of the choke off action there is less wattage fluctuation because the resistance of the device is constantly changing to meet changingcurrent conditions/1t will also be understood that there is usually no off position of the device in the sense that current flow through the device is completely stopped. A certain amount of current is always free to flow through the device. a f i It will be noted that the diameter of wafer 12 is relatively large compared to its thickness. As a result the expansible material is very quickly enabled to expand and contract in response to changes in the temperature of material 12. When the device is operated by electric current the current is enabled to spread over the entire extent of disks 8 so as to subsequently travel through all portions of material 12. The small thickness of wafer 12 (preferably about .050 inch) gives relatively short current paths and thereby allows changes in current flow to be reflected almost immediately in volumetric changes of material 12. a

When the device is operated by ambient temperature changes disks 8 act to transfer heat between material '12 and the ambient atmosphere. The surface area of the disks is relatively large for the volume of material 12, and the heat transfer action is very rapid. Thisrapid heat transfer action contributes to the prevention of any undesired wattage variation by enabling quick volumetric change of material 12.

During the expansion andcontraction of material 12 the flow-preventing material must have a slight movement in accordance with the movement ofthe expansible material. However this movement is so slight that conventional plastics, waxes and rubbers can be employed .asfiow-preventing materials without difiiculty. The use of a mixed-in flow-preventing material is advantageous by reason 'of its extremely low cost. However it is contemplated that the flow-preventing materials could be distributed around the periphery of wafer 12 in order to perform the flow-preventing or sealing function. Also a rubber sleeve or rubber coated fabric sleeve or other non-conductive sheathing can be connected between the peripheral edges of disks 8 to perform the (sealing" function.

We claim:

1. A current regulator comprising spaced electrodes; and partially conductive material therebetween; said material comprising finely divided carbon particles dispersed in a mixture of polyethylene and polytetrafluoroethylene; said polytetrafluoroethylene preventing flow of the polyethylene from between the electrodes in the transition temperature range of said polyethylene; whereby, during the passage of an electric current between the electrodes the carbon particles are caused to heat and expand the polyethylene so as to increase the spacing between adjacent ones of the carbon particles in such manner as to control the current flow through the partially conductive material.

2. A current regulator comprising spaced electrodes; and partially conductive material therebetween; said material comprising 40 volumetric parts finely divided carbon particles dispersed in a mixture of about 40 volumetric parts polyethylene and 20 volumetric parts polytetrafluoroethylene, said polytetrafluoroethylene preventing flow of the polyethylene from between the electrodes in the transition temperature range of said polyethylene; whereby, during the passage of an electric current between the electrodes the carbon particles are caused toheat and expand the polyethylene so as to increase the spacing between adjacent ones of the carbon particles in such manner as to control the current flow through the partial ly conductive material.

3. A current regulator comprising two parallel'electrically conductive disks spaced apart about .050 inch to'form spaced electrodes; and partially conductive material in the space therebetween; said material comprising solid finely divided electrically conductive particles dispersed ina mixture of (l) softenable thermally expansible non-conductive material and (2) solid non-com ductive flexible material preventing flow of the expansible material from between the disks in the transition temperature range of said expansible material; whereby, during the passage of an electric current between the disks the conductive particles are caused to heat the expansible material so as to increase the spacing between adjacent ones of the conductive particles in such manner as to control the current flow through the partially conductive material.

4.'A current regulator comprising spaced electrodes; and partially conductive material therebetween; said material comprising solid finely divided electrically conductive particles dispersed in a mixture of (l) softentable thermally expansible non-conductive polyethylene and (2) solid non-conductiye flexible material preventingflow of the expansible material from'between the electrodes in the transition temperature range of said expansible material; whereby, during the passage of an electric current between the electrodes the conductive particles are caused to heat the expansible material so as to increase the spacingbetween adjacent ones of the conductive particles in such manner as to control the current flow through the partially conductive materiaL' -,5. A current regulator comprising spaced electrodes; and partially conductive material therebetween; said material comprising solid finely divided electrically conductive particles dispersed in a mixture of (1) softenable -thermally expansible non-conductive 'materialand (2) solid non-conductive polytetrafluoroethylene preventing flow of the expansible material fi'om' between the electrodes in the transition temperature range of said expansible material; whereby, during the passage of an electric tive particles dispersed in a mixture of (1) softenable thermally expansible non-conductive material and (2) solid non-conductive flexible material preventing flow of the expansible material from between the electrodes in the transition temperature range of said expansible ma terial; whereby, during the passage of an electric current between the electrodes the conductive particles are caused to heat the expansible material so as to increase the spacing between adjacent ones of the conductive particles in such manner as to control the current flow through the partially conductive material; said flow-preventing material being selected from the group consisting of rubber and polytetrafluoroethylene.

6 References Cited in the file of this patent UNITED STATES PATENTS Benkelman Oct. 3, 1933 Ruben May 1, 1945 Edgar et al. Oct. 2, 1945 Brubaker et al. May 14, 1946 DAlelio Sept. 10, 1946 OTHER REFERENCES pages 103107.

Claims (1)

1. A CURRENT REGULATOR COMPRISING SPACED ELECTRODES, AND PARTIALLY CONDUCTIVE MATERIAL THEREBETWEEN, SAID MATERIAL COMPRISING FINELY DIVIDED CARBON PARTICLES DISPERSED IN A MIXTURE OF POLYETHYLENE AND POLYETETRAFLUROETHYLENE, SAID POLYTETRAFLUOROETHYLENE PREVENTING FLOW OF THE POLYETHYLENE FROM BETWEEN THE ELECTRODES IN THE TRANSITION TEMPERATURES RANGE OF SAID POLYETHYLENE, WHEREBY, DURING THE PASSAGE OF AN ELECTRIC CURRENT BETWEEN THE ELECTRODES THE CARBON PARTICLES ARE CAUSED TO HEAT AND EXPAND THE POLYETHYLENE SO AS TO INCREASE THE SPACING BETWEEN ADJACENT ONES OF THE CARBON PARTICLES IN SUCH MANNER AS TO CONTROL THE CURRENT FLOW THROUGH THE PARTIALLY CONDUCTIVE MATERIAL.
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Cited By (54)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3138686A (en) * 1961-02-01 1964-06-23 Gen Electric Thermal switch device
US3164796A (en) * 1961-09-11 1965-01-05 Phillips Petroleum Co Compositions of graphite and polyethylene
US3204066A (en) * 1961-10-24 1965-08-31 Gen Electric Thermal-electrical control device having thermally expansive material as a switch actuator
US3238355A (en) * 1962-12-10 1966-03-01 Douglas Aircraft Co Inc Particle filled conductor
US3243753A (en) * 1962-11-13 1966-03-29 Kohler Fred Resistance element
DE1218589B (en) * 1963-07-16 1966-06-08 Lehigh Valley Ind Inc Thermoelectric switch, especially flasher
US3327272A (en) * 1964-06-22 1967-06-20 Barry J Stern Negative resistance device
US3359521A (en) * 1965-10-26 1967-12-19 Cognitronics Corp Bistable resistance memory device
US3410984A (en) * 1966-05-03 1968-11-12 Gen Electric Flexible electrically heated personal warming device
US4177376A (en) * 1974-09-27 1979-12-04 Raychem Corporation Layered self-regulating heating article
DE2948281A1 (en) * 1978-12-01 1980-06-19 Raychem Corp Electrical circuitry and circuit-protection device
US4237441A (en) * 1978-12-01 1980-12-02 Raychem Corporation Low resistivity PTC compositions
EP0038715A1 (en) 1980-04-21 1981-10-28 RAYCHEM CORPORATION (a Delaware corporation) Circuit protection devices
US4318220A (en) * 1979-04-19 1982-03-09 Raychem Corporation Process for recovering heat recoverable sheet material
US4329726A (en) * 1978-12-01 1982-05-11 Raychem Corporation Circuit protection devices comprising PTC elements
US4330703A (en) * 1975-08-04 1982-05-18 Raychem Corporation Layered self-regulating heating article
US4352083A (en) * 1980-04-21 1982-09-28 Raychem Corporation Circuit protection devices
US4450496A (en) * 1979-08-16 1984-05-22 Raychem Corporation Protection of certain electrical systems by use of PTC device
EP0128664A1 (en) * 1983-05-11 1984-12-19 RAYCHEM CORPORATION (a Delaware corporation) Laminar electrical heaters
US4543474A (en) * 1979-09-24 1985-09-24 Raychem Corporation Layered self-regulating heating article
US4548662A (en) * 1983-05-11 1985-10-22 Raychem Corporation Method of providing a protective covering over a substrate
US4650972A (en) * 1985-10-04 1987-03-17 Emerson Electric Co. Heating cable and method of making same
EP0250776A1 (en) 1983-06-30 1988-01-07 RAYCHEM CORPORATION (a Delaware corporation) Method for detecting and obtaining information about changes in variables
US4764664A (en) * 1976-12-13 1988-08-16 Raychem Corporation Electrical devices comprising conductive polymer compositions
US4866253A (en) * 1976-12-13 1989-09-12 Raychem Corporation Electrical devices comprising conductive polymer compositions
US4876440A (en) * 1976-12-13 1989-10-24 Raychem Corporation Electrical devices comprising conductive polymer compositions
US4935156A (en) * 1981-09-09 1990-06-19 Raychem Corporation Conductive polymer compositions
EP0388990A2 (en) 1986-02-20 1990-09-26 RAYCHEM CORPORATION (a Delaware corporation) Method and articles employing ion exchange material
EP0487920A1 (en) * 1990-10-30 1992-06-03 Asea Brown Boveri Ab PTC element
US5174924A (en) * 1990-06-04 1992-12-29 Fujikura Ltd. Ptc conductive polymer composition containing carbon black having large particle size and high dbp absorption
US5294374A (en) * 1992-03-20 1994-03-15 Leviton Manufacturing Co., Inc. Electrical overstress materials and method of manufacture
US5537286A (en) * 1991-06-27 1996-07-16 Raychem S.A. Method of preparing planar PTC circuit protection devices
US5802709A (en) * 1995-08-15 1998-09-08 Bourns, Multifuse (Hong Kong), Ltd. Method for manufacturing surface mount conductive polymer devices
US5849129A (en) * 1995-08-15 1998-12-15 Bourns Multifuse (Hong Kong) Ltd. Continuous process and apparatus for manufacturing conductive polymer components
US5864280A (en) * 1995-09-29 1999-01-26 Littlefuse, Inc. Electrical circuits with improved overcurrent protection
US6020808A (en) * 1997-09-03 2000-02-01 Bourns Multifuse (Hong Kong) Ltd. Multilayer conductive polymer positive temperature coefficent device
US6023403A (en) * 1996-05-03 2000-02-08 Littlefuse, Inc. Surface mountable electrical device comprising a PTC and fusible element
US6128168A (en) * 1998-01-14 2000-10-03 General Electric Company Circuit breaker with improved arc interruption function
US6144540A (en) * 1999-03-09 2000-11-07 General Electric Company Current suppressing circuit breaker unit for inductive motor protection
US6157286A (en) * 1999-04-05 2000-12-05 General Electric Company High voltage current limiting device
US6172591B1 (en) 1998-03-05 2001-01-09 Bourns, Inc. Multilayer conductive polymer device and method of manufacturing same
US6215636B1 (en) * 1997-03-24 2001-04-10 Siemens Automotive, S.A. Device for supplying electric power to several parallel-fed circuits, and method for making same
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US6236302B1 (en) 1998-03-05 2001-05-22 Bourns, Inc. Multilayer conductive polymer device and method of manufacturing same
US6242997B1 (en) 1998-03-05 2001-06-05 Bourns, Inc. Conductive polymer device and method of manufacturing same
US6282072B1 (en) 1998-02-24 2001-08-28 Littelfuse, Inc. Electrical devices having a polymer PTC array
US6429533B1 (en) 1999-11-23 2002-08-06 Bourns Inc. Conductive polymer device and method of manufacturing same
US6582647B1 (en) 1998-10-01 2003-06-24 Littelfuse, Inc. Method for heat treating PTC devices
US6597551B2 (en) 2000-12-13 2003-07-22 Huladyne Corporation Polymer current limiting device and method of manufacture
US6628498B2 (en) 2000-08-28 2003-09-30 Steven J. Whitney Integrated electrostatic discharge and overcurrent device
US20030218851A1 (en) * 2002-04-08 2003-11-27 Harris Edwin James Voltage variable material for direct application and devices employing same
US20040201941A1 (en) * 2002-04-08 2004-10-14 Harris Edwin James Direct application voltage variable material, components thereof and devices employing same
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US20090027821A1 (en) * 2007-07-26 2009-01-29 Littelfuse, Inc. Integrated thermistor and metallic element device and method

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Cited By (67)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3138686A (en) * 1961-02-01 1964-06-23 Gen Electric Thermal switch device
US3164796A (en) * 1961-09-11 1965-01-05 Phillips Petroleum Co Compositions of graphite and polyethylene
US3204066A (en) * 1961-10-24 1965-08-31 Gen Electric Thermal-electrical control device having thermally expansive material as a switch actuator
US3243753A (en) * 1962-11-13 1966-03-29 Kohler Fred Resistance element
US3238355A (en) * 1962-12-10 1966-03-01 Douglas Aircraft Co Inc Particle filled conductor
DE1218589B (en) * 1963-07-16 1966-06-08 Lehigh Valley Ind Inc Thermoelectric switch, especially flasher
US3327272A (en) * 1964-06-22 1967-06-20 Barry J Stern Negative resistance device
US3359521A (en) * 1965-10-26 1967-12-19 Cognitronics Corp Bistable resistance memory device
US3410984A (en) * 1966-05-03 1968-11-12 Gen Electric Flexible electrically heated personal warming device
US4177376A (en) * 1974-09-27 1979-12-04 Raychem Corporation Layered self-regulating heating article
US4330703A (en) * 1975-08-04 1982-05-18 Raychem Corporation Layered self-regulating heating article
US4866253A (en) * 1976-12-13 1989-09-12 Raychem Corporation Electrical devices comprising conductive polymer compositions
US4876440A (en) * 1976-12-13 1989-10-24 Raychem Corporation Electrical devices comprising conductive polymer compositions
US4764664A (en) * 1976-12-13 1988-08-16 Raychem Corporation Electrical devices comprising conductive polymer compositions
US4238812A (en) * 1978-12-01 1980-12-09 Raychem Corporation Circuit protection devices comprising PTC elements
US4329726A (en) * 1978-12-01 1982-05-11 Raychem Corporation Circuit protection devices comprising PTC elements
DE2948281A1 (en) * 1978-12-01 1980-06-19 Raychem Corp Electrical circuitry and circuit-protection device
US4237441A (en) * 1978-12-01 1980-12-02 Raychem Corporation Low resistivity PTC compositions
US4318220A (en) * 1979-04-19 1982-03-09 Raychem Corporation Process for recovering heat recoverable sheet material
US4450496A (en) * 1979-08-16 1984-05-22 Raychem Corporation Protection of certain electrical systems by use of PTC device
US4543474A (en) * 1979-09-24 1985-09-24 Raychem Corporation Layered self-regulating heating article
EP0038715A1 (en) 1980-04-21 1981-10-28 RAYCHEM CORPORATION (a Delaware corporation) Circuit protection devices
US4352083A (en) * 1980-04-21 1982-09-28 Raychem Corporation Circuit protection devices
US4935156A (en) * 1981-09-09 1990-06-19 Raychem Corporation Conductive polymer compositions
EP0128664A1 (en) * 1983-05-11 1984-12-19 RAYCHEM CORPORATION (a Delaware corporation) Laminar electrical heaters
US4517449A (en) * 1983-05-11 1985-05-14 Raychem Corporation Laminar electrical heaters
US4548662A (en) * 1983-05-11 1985-10-22 Raychem Corporation Method of providing a protective covering over a substrate
EP0250776A1 (en) 1983-06-30 1988-01-07 RAYCHEM CORPORATION (a Delaware corporation) Method for detecting and obtaining information about changes in variables
US4650972A (en) * 1985-10-04 1987-03-17 Emerson Electric Co. Heating cable and method of making same
EP0388990A2 (en) 1986-02-20 1990-09-26 RAYCHEM CORPORATION (a Delaware corporation) Method and articles employing ion exchange material
US5174924A (en) * 1990-06-04 1992-12-29 Fujikura Ltd. Ptc conductive polymer composition containing carbon black having large particle size and high dbp absorption
EP0487920A1 (en) * 1990-10-30 1992-06-03 Asea Brown Boveri Ab PTC element
US5382938A (en) * 1990-10-30 1995-01-17 Asea Brown Boveri Ab PTC element
US5537286A (en) * 1991-06-27 1996-07-16 Raychem S.A. Method of preparing planar PTC circuit protection devices
US5294374A (en) * 1992-03-20 1994-03-15 Leviton Manufacturing Co., Inc. Electrical overstress materials and method of manufacture
US5802709A (en) * 1995-08-15 1998-09-08 Bourns, Multifuse (Hong Kong), Ltd. Method for manufacturing surface mount conductive polymer devices
US5849129A (en) * 1995-08-15 1998-12-15 Bourns Multifuse (Hong Kong) Ltd. Continuous process and apparatus for manufacturing conductive polymer components
US5849137A (en) * 1995-08-15 1998-12-15 Bourns Multifuse (Hong Kong) Ltd. Continuous process and apparatus for manufacturing conductive polymer components
US6059997A (en) * 1995-09-29 2000-05-09 Littlelfuse, Inc. Polymeric PTC compositions
US5864280A (en) * 1995-09-29 1999-01-26 Littlefuse, Inc. Electrical circuits with improved overcurrent protection
US5880668A (en) * 1995-09-29 1999-03-09 Littelfuse, Inc. Electrical devices having improved PTC polymeric compositions
US6023403A (en) * 1996-05-03 2000-02-08 Littlefuse, Inc. Surface mountable electrical device comprising a PTC and fusible element
US6215636B1 (en) * 1997-03-24 2001-04-10 Siemens Automotive, S.A. Device for supplying electric power to several parallel-fed circuits, and method for making same
US6020808A (en) * 1997-09-03 2000-02-01 Bourns Multifuse (Hong Kong) Ltd. Multilayer conductive polymer positive temperature coefficent device
US6223423B1 (en) 1997-09-03 2001-05-01 Bourns Multifuse (Hong Kong) Ltd. Multilayer conductive polymer positive temperature coefficient device
US6128168A (en) * 1998-01-14 2000-10-03 General Electric Company Circuit breaker with improved arc interruption function
US6282072B1 (en) 1998-02-24 2001-08-28 Littelfuse, Inc. Electrical devices having a polymer PTC array
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