US3418454A - Electric bedcover overtemperature control system - Google Patents

Electric bedcover overtemperature control system Download PDF

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Publication number
US3418454A
US3418454A US517598A US51759865A US3418454A US 3418454 A US3418454 A US 3418454A US 517598 A US517598 A US 517598A US 51759865 A US51759865 A US 51759865A US 3418454 A US3418454 A US 3418454A
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US
United States
Prior art keywords
contacts
heater
blade
layer
control system
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US517598A
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English (en)
Inventor
Jr William D Ryckman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Priority to US517598A priority Critical patent/US3418454A/en
Priority to GB42509/66A priority patent/GB1137567A/en
Priority to SE12914/66A priority patent/SE311200B/xx
Priority to ES0331628A priority patent/ES331628A1/es
Priority to CH1416766A priority patent/CH468767A/de
Priority to BE687891D priority patent/BE687891A/xx
Priority to NL666614080A priority patent/NL155109B/xx
Priority to DE1966G0048097 priority patent/DE1565559B2/de
Priority to FR80122A priority patent/FR1496670A/fr
Application granted granted Critical
Publication of US3418454A publication Critical patent/US3418454A/en
Assigned to BLACK & DECKER, INC., A CORP. OF DE reassignment BLACK & DECKER, INC., A CORP. OF DE ASSIGNS AS OF APRIL 27, 1984 THE ENTIRE INTEREST Assignors: GENERAL ELECTRIC COMPANY A NY CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B1/00—Details of electric heating devices
    • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
    • H05B1/0202—Switches
    • H05B1/0213—Switches using bimetallic elements
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/1906—Control of temperature characterised by the use of electric means using an analogue comparing device
    • G05D23/1913—Control of temperature characterised by the use of electric means using an analogue comparing device delivering a series of pulses
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H61/00—Electrothermal relays
    • H01H61/01—Details
    • H01H61/013—Heating arrangements for operating relays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H61/00—Electrothermal relays
    • H01H61/02—Electrothermal relays wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
    • H05B3/34—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs
    • H05B3/342—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs heaters used in textiles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/002—Heaters using a particular layout for the resistive material or resistive elements
    • H05B2203/003—Heaters using a particular layout for the resistive material or resistive elements using serpentine layout
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/014—Heaters using resistive wires or cables not provided for in H05B3/54
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/017—Manufacturing methods or apparatus for heaters

Definitions

  • the present invention relates to control systems for electrically heated bedcovers or the like and, more particularly, to control systems which utilize a temperature sensor including a layer of sensor material having a negative temperature coeflicient of electrical impedance.
  • a typical electrically heated bedcover includes heating wire distributed between two plies of fabric; and, in addition, there is usually provided means for the user to regulate the heat output of the bedcover.
  • heat is dissipated through the bottom surface of the :bedcover to the body of the user, and through the top surface to the air in the room.
  • the normal dissipation of heat may be inadvertently obstructed such as if an insulating object is placed over a localized area of the surface, or if the blanket is folded or bunched.
  • an overtemperature condition may occur in the sense that the amount of heat in this localized area obtains such a degree as to cause scorching of the fabric. It therefore becomes necessary to provide a control system which will open the power circuit to the heating wire before the overtemperature reaches dangerous proportions.
  • control system In the design of an efiective control system several factors must be taken into consideration. As one consideration, it is desirable that the control system be fail-safe in that should one of the elements in the control system become inoperative for one reason or another, the power circuit to the heating wire of the blanket is opened. While fluctuations in line voltage in the power supply to the control system may occur upon the starting of motors and other devices also operated from this same power supply, these fluctuations are not as a result of overtemperature in the blanket; therefore, it is desirable that the control system not be affected by these fluctuations. Furthermore, there may be slight variation in the normal line voltage to the homes of different users; consequently, the control system should be effectively operable through out normal variation in line voltages.
  • control system it is also advantageous for the control system to have an automatic recycling feature so that in the event the cause of the overtemperature condition is corrected, such as by the user in his sleep, heat will once again be supplied in a normal manner from the blanket to the user.
  • control system includes a relay which is actuated as a result of overtemperature condition in the bedcover.
  • the relay may be located in a control housing remote from the blanket and the relay should not be affected by normal change in room ambient temperature.
  • a further object is to provide a control system of the character indicated which utilizes a line switch in a control case remote from the blanket, and operation of the line switch is not affected by normal changes in room ambient temperature.
  • Another object is to provide a control system of the character indicated which combines the features of safety 3,418,454 Patented Dec. 24, 1968 with comfort to the user and utilizes a relay which is inexpensive to manufacture.
  • I provide a control system for an electrically heated bedcover which includes a temperature sensor distributed over the heated area of the bedcover.
  • the sensor comprises a pair of electrical conductors separated by a temperature sensor layer which is essentially an insulator at normal operating temperatures and conducts current of control magnitude at an elevated temperature.
  • the electrical heater for the blanket is controlled by a line switch having cooperating contacts, each of which includes an actuator. Movement of each contact by its actuator depends upon the energy supplied to it.
  • the electrical element of one actuator is in a parallel circuit with the sensor layer, while the other actuator element is in electrical series with this parallel circuit.
  • the energy ratio supplied to the actuators is selected to cause the contacts to close.
  • conduction through the temperature sensitive layer changes the energy ratio supplied to the actuators so that the contacts open.
  • FIG. 1 is an electrical schematic diagram of a preferred embodiment of the invention
  • FIG. 2 is a partial perspective view of a control box broken away to illustrate a line switch used in the circuit of FIG. 1;
  • FIG. 3 is a partial perspective view of another embodiment of a line switch.
  • numeral 10 indicates a blanket
  • numeral 11 indicates a control box.
  • Power leads 12 and 13 extend from the control box to a conventional power plug 14 to be inserted into an ordinary alternating current household outlet.
  • conductor leads 15 through 19 extend from the control box to appropriate receptacles in a female connector plug 20.
  • the blanket carries male plug portions 21 through 25 which are received in respective ones of the receptacles in the female connector plug.
  • a heater wire 26 is connected between plugs 21 and 25.
  • the heater wire may be distributed through the blanket in a conventional serpentine pattern.
  • a temperature sensor 27 is also distributed through the blanket in a pattern which may be similar to the pattern followed by the heater wire so that the temperature sensor is in heat transfer relation with the heater wire.
  • the temperature sensor includes a pair of conductors 28 and 29 separated by a layer 30 of material which is essentially an insulator at normal operating temperatures of the blanket and a conductor of significant current at an elevated temperature corresponding to an overtemperature condition of the blanket.
  • the conductor 28 is connected between plugs 22 and 24, and the conductor 29 is connected between plugs 23 and 25.
  • power lead 12 is connected to a fixed end 31 of a first bimetallic blade 32 via a manual switch 33.
  • the blade 32 has a deflectable end 34 which carries a contact 35.
  • a second bimetallic blade 36 has one end 37 secured to the control box, and the other end 38 is deflectable and carries a contact 39.
  • the bimetallic blades thereby function as a line switch 40 in that the contacts 35 and 39 are adapted to be engaged or disengaged with each other depending on certain operating conditions of the entire system as will be hereinafter pointed out in more detail.
  • the fixed end of the bimetallic blade 36 is connected to conductor lead through an ambient responsive control 42.
  • the bimetallic blades 32 and 36 are so arranged as to have the contacts normally open or disengaged, and they deflect in the same direction under the influence of heat.
  • a first heater 43 in the form of a resistance element is positioned in intimate heat transfer relation with the blade.
  • the heater is connected between the power line 12 via switch 33 and the conductor 16.
  • a second heater 44 is positioned in intimate heat transfer relation with this latter blade, and is connected between conductors 17 and 18.
  • the heaters 43 and 44 thereby function as actuators respectively for the bimetallic blades 32 and 36.
  • the resistance of heater 44 is preferably greater than the resistance of heater 43.
  • the heaters are thereby in electrical series with each other, and the conductors 28 and 29 are also in the series circuit.
  • the temperature sensor layer 30 is in circuit parallel with the second heater 44.
  • a pilot lamp 45 is connected between line 12 and plug 23 and is energized at all times when the switch 33 is on.
  • a current limiting resistor 46 is in electric series with the pilot lamp.
  • the ambient responsive control 42 includes a bimetallic blade 47 which carries a contact 48 adapted to engage a fixed contact 49.
  • the bimetallic blade is of such a character as to move the contact 48 away from the contact 49 under the influence of heat.
  • a heating resistor 50 is connected in electrical series in the line with the bimetallic blade, and the resistor is in thermal transfer relationship with the blade. The blade is thereby influenced both by the resistor 50 and by changes in the ambient temperature. Assuming that the blanket is cold, the contacts 48 and 49 will be engaging each other. Now, if the other line switches are closed, current will flow through the contacts and also through the resistor 50. The resistor will warm the blade until it deflects moving the contacts out of engagement.
  • An adjustment knob 51 is operatively associated with the bimetal to permit the user to exercise control over the temperature at which the contacts open, and thereby regulate the heat output of the blanket.
  • the control system of FIG. 1 operates as follows: When the switch 33 is closed, current flows in a path through the heater 43 to the male plug 22. Assuming there is no overtemperature condition, the layer is essentially an insulator; therefore, current flows from the plug 22 through the conductor 28 to the plug 24. From the plug 24 the current continues through heater 44, thence to the other power lead 13 via conductors 17, 29 and 19. The heater 44 supplies more heat to bimetal 36 than the heater 43 supplies to bimetal 32; therefore, the blade 36 will be deflected a greater distance than the blade 32.
  • the gap between the blades is so callbrated with respect to the deflection properties of the blades that this greater deflection causes the contact 39 to engage contact 35. All of the above takes place in a relatively short period of time on the order of about one-half minute.
  • the electrical impedance of the layer 30 increases to a point where the contacts 35 and 39 will be engaged. If, however, the reason for the overtemperature condition still exists, there will soon be an overtemperature condition again so that the layer will once again become conducting causing the contacts 35 and 39 to open. The system will thereby continue to recycle until the cause of the overtemperature condition is corrected.
  • the user in his sleep, may remove the cause (such as a bunching of the blanket) of the overtemperature condition and then the blanket will continue to supply heat in a normal manner to the comfort of the user.
  • control system is fail-safe in the sense that should an open circuit occur in any of the elements including the heaters 43 and 44, or the conductors 28 and 29, there will be no power to either of the heaters and the contacts 35 and 39 will open. Furthermore, should a short circuit occur between the conductors 28 and 29, the effect on the system will be the same as if an overtemperature condition exists, and the contacts of the switch will open.
  • FIG. 2 a preferred embodiment of a relay or line switch 40 used in the control system is illustrate-d in more detail.
  • the manner of mounting the heating resistors 43 and 44 on their respective bimetallic blades 32 and 36 assures that the resistors are in intimate heat transfer relation with the blades. Because of the good thermal transfer relationship between the heaters and the blades, the resistance value of the heaters can be so chosen that, while they provide suflicient heat individually to their respective blades to cause deflection of the blades in a desired manner, the heat supplied from these heaters to other components in the control box is kept at a minimum.
  • the mounting in blade 32 is accomplished by providing parallel slits 52 through the blade.
  • Integrally formed arcuate portions 53, 54, and 55 extend alternately in opposite directions from the plane of the blade thereby forming a channel 56 having an axis extending through the slits.
  • the heater is positioned in the channel and, if desired, a thermally conducting adhesive may be applied to the outer surface of the heater to aid in holding the heater in place in the channel.
  • the heater 44 is mounted on blade 36 in the same manner.
  • the surfaces 57 and 58 are of a metal having a relatively low coefiicient of thermal expansion
  • the surfaces 59 and 60 are of a metal having a relatively high coeflicient of thermal expansion.
  • the heaters 43 and 44 are preferably in the form of molded composition resistors and are coated with a material that is electrically insulating and thermally conducting. As a specific example, I have found that by using a resistance value of 2,400 ohms for the heater 43 and a value of 10,000 ohms for the heater 44, the control system operates very well. i
  • the temperature sensor layer 30 which I have used is a plasticized polyvinyl chloride having approximately .825 of tetrabutylammonium picrate compounded therewith. By utilizing auniform average wall thickness on the order of .010 inch between the conductors this material has an impedance between the conductors 28 and 29 on the order of 200,000 ohms at room temperature. When the blanket achieves warmest normal operating temperatures of approximately 135 F. at the heater wire, the resistance of the sensor material is still at a value of from 35,000 to 54,000 ohms so it is still considered, for present purposes, to be an insulator.
  • the impedance of the layer 30 drops to a value of say 9,000 ohms before the overtemperature reaches dangerous proportions. At this latter value the layer 30 is considered to be a conductor of substantial current because at this value (and also at higher temperaturesof the heating wire) the layer conducts enough current to operate the line switch 40 in the manner set forth above.
  • a permanent magnet 61 near the defiectable end of the blade 32.
  • the magnet cooperates with a metal surface 62 to assure a snap action in opening and closing the contacts.
  • operation of the line switch is predicated on the basis of a difference in the amount of heat supplied to the respective bimetallic blades 32 and 36.
  • the switch is calibrated so that the contacts will be open when the ratio is unity; that is approximately the same amount of heat is supplied to each blade. Then if more heat is supplied to the second blade than to the first blade, this ratiowill increase to a calibrated value (for example, .1 watt difference) Where the contacts are closed, and the contacts will remain closed as long as the ratio is above this value.
  • the ratio will decrease to a value where the contacts will open.
  • plasticized polyvinyl chloride having, as an additive, approximately 0.75% stearyldimethylbenzyl ammonium chloride.
  • Other materials which may be used are disclosed in United States Patent 2,846,560 to J. F. Jacoby, Aug. 5, 1958, and assigned to General Electric Company, assignee of the present application.
  • FIG. 3 illustrates a line switch which may be utilized to maximize the heat differential
  • I have used like numerals to indicate like parts correspondng to the line switch 40 of FIG. 2.
  • the fixed ends of the bimetallic blades 32' and 36 are mounted in a metal, such as steel, mounting bracket 64 having good heat dissipating properties.
  • the blade 32 is in good heat transfer relation with this bracket.
  • the blade 36 is thermally insulated from the bracket 64 through the medium of a plastic insulating block 65.
  • the blade 32' will tend to give up heat through the heat dissipating bracket 64; and, in this manner, the heat differential between the blades is maximized so as to speed up the time it takes for the contact 39' to engage contact 35'.
  • An overtemperature control system for an electrically heated bedcover or the like adapted to be connected to a source of power comprising:
  • thermosensor having a pair of electrical conductors separated by a layer of material which is essentially an insulator at normal operating temperatures and a conductor of significant current at an elevated temperature;
  • a control system for an electrically heated bedcover or the like comprising:
  • thermosensor in heat transfer relation with the bedcover and having a pair of electrical conductors separated by a temperature sensor layer of material which is essentially an insulator at normal operating temperatures and a conductor of significant current at an elevated temperature;
  • an electrical line switch including first and second thermally responsive elements with cooperating contacts, said contacts being separated when said elements are at the same temperatures and engaged only when said second element is heated to a predetermined higher temperature than said first element;
  • a parallel electrical circuit including said second said bimetallic blades are substantially identical in conheater and said temperature sensor layer whereby v struction and are mounted to deflect in the same direcsaid second heater is shunted upon an overtemperation under the influence of heat.
US517598A 1965-12-30 1965-12-30 Electric bedcover overtemperature control system Expired - Lifetime US3418454A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US517598A US3418454A (en) 1965-12-30 1965-12-30 Electric bedcover overtemperature control system
GB42509/66A GB1137567A (en) 1965-12-30 1966-09-23 Improvements in control systems for electrically heated devices
SE12914/66A SE311200B (de) 1965-12-30 1966-09-26
ES0331628A ES331628A1 (es) 1965-12-30 1966-09-27 Un sistema de control para una manta o similar calentada electricamente.
CH1416766A CH468767A (de) 1965-12-30 1966-09-30 Uberwachungsanordnung für eine elektrisch beheizbare Bettdecke
BE687891D BE687891A (de) 1965-12-30 1966-10-06
NL666614080A NL155109B (nl) 1965-12-30 1966-10-06 Regelstelsel voor een elektrische deken.
DE1966G0048097 DE1565559B2 (de) 1965-12-30 1966-10-06 Steuerschaltung fuer eine elektrisch beheizte bettdecke oder dgl.
FR80122A FR1496670A (fr) 1965-12-30 1966-10-14 Dispositif de protection des couvertures électriques contre les échauffements excessifs

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US517598A US3418454A (en) 1965-12-30 1965-12-30 Electric bedcover overtemperature control system

Publications (1)

Publication Number Publication Date
US3418454A true US3418454A (en) 1968-12-24

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ID=24060451

Family Applications (1)

Application Number Title Priority Date Filing Date
US517598A Expired - Lifetime US3418454A (en) 1965-12-30 1965-12-30 Electric bedcover overtemperature control system

Country Status (8)

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US (1) US3418454A (de)
BE (1) BE687891A (de)
CH (1) CH468767A (de)
DE (1) DE1565559B2 (de)
ES (1) ES331628A1 (de)
GB (1) GB1137567A (de)
NL (1) NL155109B (de)
SE (1) SE311200B (de)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3591765A (en) * 1968-06-17 1971-07-06 Dreamland Electrical Appliance Electric blankets
US3814899A (en) * 1972-12-18 1974-06-04 Gen Electric Overtemperature control system
US3890486A (en) * 1973-05-01 1975-06-17 Equipment Dev Corp Aquarium-tank heating control
US4034185A (en) * 1975-09-02 1977-07-05 Northern Electric Company Electric blanket control circuit
DE3007932A1 (de) * 1979-03-05 1980-09-18 Sunbeam Corp Elektrische heizdecke
DE3008221A1 (de) * 1979-03-05 1980-09-18 Sunbeam Corp Schutzvorrichtung fuer eine elektrische heizdecke
EP0026571A1 (de) * 1979-08-16 1981-04-08 RAYCHEM CORPORATION (a California corporation) PTC-Vorrichtungen verwendender Schutz für elektrische Systeme
US4450496A (en) * 1979-08-16 1984-05-22 Raychem Corporation Protection of certain electrical systems by use of PTC device
US4814583A (en) * 1986-05-02 1989-03-21 Safeway (Australasia) Limited Temperature controller for a waterbed

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2354918A (en) * 1942-08-26 1944-08-01 Gen Electric Temperature control system for electric heating devices
US2510040A (en) * 1947-01-17 1950-05-30 Landers Frary & Clark Electric blanket control
US2565478A (en) * 1949-05-04 1951-08-28 Gen Electric Temperature responsive control circuits
US2704803A (en) * 1951-07-11 1955-03-22 Gen Electric Control circuits for electric blankets

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2354918A (en) * 1942-08-26 1944-08-01 Gen Electric Temperature control system for electric heating devices
US2510040A (en) * 1947-01-17 1950-05-30 Landers Frary & Clark Electric blanket control
US2565478A (en) * 1949-05-04 1951-08-28 Gen Electric Temperature responsive control circuits
US2704803A (en) * 1951-07-11 1955-03-22 Gen Electric Control circuits for electric blankets

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3591765A (en) * 1968-06-17 1971-07-06 Dreamland Electrical Appliance Electric blankets
US3814899A (en) * 1972-12-18 1974-06-04 Gen Electric Overtemperature control system
US3890486A (en) * 1973-05-01 1975-06-17 Equipment Dev Corp Aquarium-tank heating control
US4034185A (en) * 1975-09-02 1977-07-05 Northern Electric Company Electric blanket control circuit
DE3007932A1 (de) * 1979-03-05 1980-09-18 Sunbeam Corp Elektrische heizdecke
DE3008221A1 (de) * 1979-03-05 1980-09-18 Sunbeam Corp Schutzvorrichtung fuer eine elektrische heizdecke
EP0026571A1 (de) * 1979-08-16 1981-04-08 RAYCHEM CORPORATION (a California corporation) PTC-Vorrichtungen verwendender Schutz für elektrische Systeme
US4450496A (en) * 1979-08-16 1984-05-22 Raychem Corporation Protection of certain electrical systems by use of PTC device
US4814583A (en) * 1986-05-02 1989-03-21 Safeway (Australasia) Limited Temperature controller for a waterbed

Also Published As

Publication number Publication date
NL155109B (nl) 1977-11-15
DE1565559A1 (de) 1970-05-06
GB1137567A (en) 1968-12-27
BE687891A (de) 1967-03-16
CH468767A (de) 1969-02-15
ES331628A1 (es) 1967-07-01
DE1565559B2 (de) 1976-12-02
SE311200B (de) 1969-06-02
NL6614080A (de) 1967-07-03

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