US3566225A - Magnetic circuit opening and closing motor starting switch in response to heat varying macnetic permeance - Google Patents

Magnetic circuit opening and closing motor starting switch in response to heat varying macnetic permeance Download PDF

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Publication number
US3566225A
US3566225A US762757A US3566225DA US3566225A US 3566225 A US3566225 A US 3566225A US 762757 A US762757 A US 762757A US 3566225D A US3566225D A US 3566225DA US 3566225 A US3566225 A US 3566225A
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starting
switch
winding
magnet
circuit
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US762757A
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Erik Kurt Poulsen
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Danfoss AS
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Danfoss AS
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
    • H02P1/42—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual single-phase induction motor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K17/00—Asynchronous induction motors; Asynchronous induction generators
    • H02K17/02—Asynchronous induction motors
    • H02K17/30—Structural association of asynchronous induction motors with auxiliary electric devices influencing the characteristics of the motor or controlling the motor, e.g. with impedances or switches

Definitions

  • This invention relates generally, to single-phase asynchronous motors and more particularly to a starting switch for a single-phase motor in the starting branch circuit thereof.
  • a starting switch for single-phase asynchronous motors which is actuated electromagnetically by the main winding of the motor in dependence upon the current and opens when this current falls below a certain value. Also there is known a starting switch having a temperature-dependent component, eg a bimetallic element which is heated during the starting operation, so that the switch opens some time after the commencement of the starting operation.
  • a starting switch is also known wherein only a FTC-resistor, i.e. a resistor, the resistance of which increases with temperature, is connected in the starting branch circuit. This is heated by the starting current and consequently assumes a resistance of a magnitude such that the current through the starting winding is negligible small.
  • a starting switch is kept closed by means of a magnetic system which consists of a permanent magnet and a yoke which bridges its poles and is made of a ferromagnetic material that loses its magnetic conductivity and is rendered nonmagnetic upon being heated.
  • the yoke is heated by a'PTC-resistor, which is connected in parallel with the switch and a resistor arranged in series therewith. When the ferromagnetic materialis rendered nonmagnetic the starting switch opens.
  • the starting switch comprises a movable contact kept closed by the fully effective magnet. Consequently, the starting current is limited only by the series resistor in series with the starting switch.
  • the value or rating of the series resistor can be selected asrequired, and, of course,
  • the starting current is affected by the resistance of the starting winding itself.
  • the motor when the motor is started current also flows through thebridging FTC-resistor.
  • the PTC-resistor heats the yoke of the magnetic system.
  • the Curie point of the ferromagnetic yoke When the Curie point of the ferromagnetic yoke is reached, it is rendered nonmagnetic and the switch opens.
  • r e v The length of the starting period of the motor can be influenced by various factors, for example by the choice of different ferrites having different Curie points, by the choice of the FTC-resistor material, by the choice ofthe thermal capacity of the heating resistor and the yoke, by the nature of the heat transfer, and so forth.
  • the yoke and the FTC-resistor are interconnected in a thermally conductive or best heat-transfer manner, since then the smallest possible amount of heat suffices to bring the yoke to the Curie point.
  • a very simple construction of the starting switch is obtained if the moving contact of the switch is a'pretensioned leaf spring.
  • the spring force should be such'that the magnet, in the cold condition, or deenergized condition of the motor is able to close the'switch and to keep it closed.
  • the permanent magnet is disposed on the movable contact of the switch and the yoke/PTC-resistor combination is stationary.
  • a main winding 4 is connected by a main switch 3 to two supply terminals 1 and 2, and a starting starting switch 7 are connected in series with the motor starting winding.
  • a contact 8 of the starting switch is attached to an upwardly pretensioned spring 9 jointly forming therewith the movable contact of the switch.
  • Apermanent magnet 10 is attached to the leaf spring 9.
  • This magnet together with a ferromagnetic member comprising a ferrite plate 11, form a magnetic system.
  • the ferrite plate 11 is mounted in a thermally conductive relationship with a FTC-resistor 12 which is arranged electrically in parallel with the series connection of the series resistor 6 and the starting switch 7.
  • the ferrite plate 11 possess the property of losing its magnetic permeance when it is heated beyond the Curie point.
  • the main switch 3 When the main switch 3 is closed the full short circuit current flows through the main winding 4. A starting current flows through the starting winding 5, which is largely determined by the resistance of the starting winding and the series resistor 6. At the same time, current flows through the PTC- resistor 12, so that it is heated and with it the ferrite plate 11. After some time, which depends upon the particular characteristics of the ferromagnetic material and the particular construction,. the temperature of the plate 11 rises above the Curie point and the switch 7 opens, since-the leaf spring 9 is no longer held in an attracted condition by. the magnet system. Thus, the starting operation or period terminates and the starting current drops to a very low value, which is mainly determined by the thermal resistance of the FTC-resistor 12. Only a small starting current flows, therefore, but this suffices to keep the magnetic system 10, 11 in a nonmagnetic condition.
  • a movable contact on said switch a magnetic system comprising a permanent magnet releasably closing said switch mounted on said movable contact, said movable contact being magnetically actuated by said magnet to a switch-closing position and automatically operable to a switch-opening position when magnetic system attraction of said magnet is reduced sufficiently to allow said contact to open said switch, a stationary magnetizable member cooperating with said magnet to define a magnetic circuit for causing said magnet to close said switch, and means to reduce the permeance of said magnetizable member thereby to reduce magnetic attraction by said magnetic system to cause said magnet to effect release of said movable contact and determine said starting period.
  • a starting circuit for a single-phase asynchronous motor according to claim 1, in which said magnetizable member comprises a ferrite.
  • said means electrically. .en'e'r gized comprise a positive temperature coefficient resistor in series with said main winding and in parallel with the starting winding heating said member above the Curie point thereof.

Abstract

A synchronous motor and a starting circuit therefore in which a switch in series with the motor winding determines the starting period during which the starting winding is electrically energized. The switch has a leaf-spring movable contact tending toward opening the starting circuit kept in a circuit-closing position by a magnetic system which has a ferromagnetic member therein rendered nonmagnetic by heat applied by a PTC-resistor in series with the motor starting winding so that the ferromagnetic member releases a magnet on the movable contact closing the switch and the motor starting period is thus determined.

Description

United States Patent [72] Inventor Erik Kurt Poulsen Egelykke, Vollerup, Denmark [21] Appl. No. 762,757 [22] Filed Sept. 26, 1968 [45] Patented Feb. 23, 1971 [73] Assignee Danfoss A/S Nordborg, Denmark [32] Priority Oct. 7, 1967 1 Germany [31] Pl588139.7
[54] MAGNETIC CIRCUIT OPENING AND CLOSING MOTOR STARTING SWITCH IN RESPONSE TO HEAT VARYING MAGNETIC PERMEANCE 4 Claims, 1 Drawing Fig.
[52] U.S.Cl 318/221; 335/146 '51] mcr ..I-I02k 17/08 [50] FieldofSearch 318/221, 221.6,221.8,221.9;335/146 [56] References Cited v UNITED STATES PATENTS 2,261,250 11/1941 l-laddad 172/278 2,668,884 2/1954 Jacobs 335/146 2,751,483 6/1956 Keen et al.... 335/146 3,284,736 ll/l966 Vance 335/146 3,430,166 2/1969 Gambill... 335/146 2,117,123 5/1938 Werner 318/2216 2,588,257 3/1952 Lewus 3l8/22l.8
Primary Examiner-Cris L. Rader Assistant Examiner-K. L. Crosson Attorney-Wayne B. Easton MAGNETIC CIRCUIT OPENING AND CLOSING MOTOR STARTING SWITCH IN RESPONSE TO BEAT VARYING MAGNETIC PERMEANCE This invention relates generally, to single-phase asynchronous motors and more particularly to a starting switch for a single-phase motor in the starting branch circuit thereof.
A starting switch for single-phase asynchronous motors is known which is actuated electromagnetically by the main winding of the motor in dependence upon the current and opens when this current falls below a certain value. Also there is known a starting switch having a temperature-dependent component, eg a bimetallic element which is heated during the starting operation, so that the switch opens some time after the commencement of the starting operation. A starting switch is also known wherein only a FTC-resistor, i.e. a resistor, the resistance of which increases with temperature, is connected in the starting branch circuit. This is heated by the starting current and consequently assumes a resistance of a magnitude such that the current through the starting winding is negligible small. However, whereas the actuation of the two first-named switches calls for considerable expense (the provision of a magnet winding or heating winding), in the case of the last-mentioned switching deviceit is notalways possible to keep the cold resistance of the FTC-resistor so low that a sufficiently high starting current can flow in the starting circuit.
According to the invention a starting switch is kept closed by means of a magnetic system which consists of a permanent magnet and a yoke which bridges its poles and is made of a ferromagnetic material that loses its magnetic conductivity and is rendered nonmagnetic upon being heated. The yoke is heated by a'PTC-resistor, which is connected in parallel with the switch and a resistor arranged in series therewith. When the ferromagnetic materialis rendered nonmagnetic the starting switch opens.
In this arrangement, the starting switch comprises a movable contact kept closed by the fully effective magnet. Consequently, the starting current is limited only by the series resistor in series with the starting switch. The value or rating of the series resistor can be selected asrequired, and, of course,
the starting current is affected by the resistance of the starting winding itself. However, when the motor is started current also flows through thebridging FTC-resistor. The PTC-resistor heats the yoke of the magnetic system. When the Curie point of the ferromagnetic yoke is reached, it is rendered nonmagnetic and the switch opens. r e v The length of the starting period of the motor can be influenced by various factors, for example by the choice of different ferrites having different Curie points, by the choice of the FTC-resistor material, by the choice ofthe thermal capacity of the heating resistor and the yoke, by the nature of the heat transfer, and so forth. it is particularly advantageous if the yoke and the FTC-resistor are interconnected in a thermally conductive or best heat-transfer manner, since then the smallest possible amount of heat suffices to bring the yoke to the Curie point. j A very simple construction of the starting switch is obtained if the moving contact of the switch is a'pretensioned leaf spring. The spring force should be such'that the magnet, in the cold condition, or deenergized condition of the motor is able to close the'switch and to keep it closed. In a preferred embodiment of theiinvention the permanent magnet is disposed on the movable contact of the switch and the yoke/PTC-resistor combination is stationary. I
Other features and advantages of the starting circuit in accordance with the present invention will be better understood as described in the following specification and appended claims in conjunction with the sole drawingconstituting a schematic of amotor provided with a starting circuit according to the invention.
According to the drawing a main winding 4 is connected by a main switch 3 to two supply terminals 1 and 2, and a starting starting switch 7 are connected in series with the motor starting winding. A contact 8 of the starting switch is attached to an upwardly pretensioned spring 9 jointly forming therewith the movable contact of the switch. Apermanent magnet 10 is attached to the leaf spring 9. I
This magnet together with a ferromagnetic member comprising a ferrite plate 11, form a magnetic system. The ferrite plate 11 is mounted in a thermally conductive relationship with a FTC-resistor 12 which is arranged electrically in parallel with the series connection of the series resistor 6 and the starting switch 7. The ferrite plate 11 possess the property of losing its magnetic permeance when it is heated beyond the Curie point.
When the main switch 3 is closed the full short circuit current flows through the main winding 4. A starting current flows through the starting winding 5, which is largely determined by the resistance of the starting winding and the series resistor 6. At the same time, current flows through the PTC- resistor 12, so that it is heated and with it the ferrite plate 11. After some time, which depends upon the particular characteristics of the ferromagnetic material and the particular construction,. the temperature of the plate 11 rises above the Curie point and the switch 7 opens, since-the leaf spring 9 is no longer held in an attracted condition by. the magnet system. Thus, the starting operation or period terminates and the starting current drops to a very low value, which is mainly determined by the thermal resistance of the FTC-resistor 12. Only a small starting current flows, therefore, but this suffices to keep the magnetic system 10, 11 in a nonmagnetic condition.
While a preferred embodiment of the invention has been shown and described it will be understood that'many modifitrically disconnectsaid starting winding upon completion of said starting period, a movable contact on said switch, a magnetic system comprising a permanent magnet releasably closing said switch mounted on said movable contact, said movable contact being magnetically actuated by said magnet to a switch-closing position and automatically operable to a switch-opening position when magnetic system attraction of said magnet is reduced sufficiently to allow said contact to open said switch, a stationary magnetizable member cooperating with said magnet to define a magnetic circuit for causing said magnet to close said switch, and means to reduce the permeance of said magnetizable member thereby to reduce magnetic attraction by said magnetic system to cause said magnet to effect release of said movable contact and determine said starting period.
2. A starting circuit for a single-phase asynchronous motor according to claim 1, in which said magnetizable member comprises a ferrite.
according to claim 3, in which said means electrically. .en'e'r gized comprise a positive temperature coefficient resistor in series with said main winding and in parallel with the starting winding heating said member above the Curie point thereof.-

Claims (4)

1. A starting circuit for a single-phase asynchronous motor having a main winding and a starting winding, said starting circuit comprising means for electrically energizing said starting winding and said main winding, a switch in series with said starting winding for keeping said starting circuit closed and said starting winding in circuit during a predetermined starting period and subsequently opening said starting circuit to electrically disconnect said starting winding upon completion of said starting period, a movable contact on said switch, a magnetic system comprising a permanent magnet releasably closing said switCh mounted on said movable contact, said movable contact being magnetically actuated by said magnet to a switch-closing position and automatically operable to a switch-opening position when magnetic system attraction of said magnet is reduced sufficiently to allow said contact to open said switch, a stationary magnetizable member cooperating with said magnet to define a magnetic circuit for causing said magnet to close said switch, and means to reduce the permeance of said magnetizable member thereby to reduce magnetic attraction by said magnetic system to cause said magnet to effect release of said movable contact and determine said starting period.
2. A starting circuit for a single-phase asynchronous motor according to claim 1, in which said magnetizable member comprises a ferrite.
3. A starting circuit for a single-phase asynchronous motor according to claim 1, in which said means to reduce the permeance of said member comprises means electrically energized heating said member.
4. A starting circuit for a single-phase asynchronous motor according to claim 3, in which said means electrically energized comprise a positive temperature coefficient resistor in series with said main winding and in parallel with the starting winding heating said member above the Curie point thereof.
US762757A 1967-10-07 1968-09-26 Magnetic circuit opening and closing motor starting switch in response to heat varying macnetic permeance Expired - Lifetime US3566225A (en)

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DE19671588139 DE1588139B1 (en) 1967-10-07 1967-10-07 Starting circuit for a single-phase motor

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BE (1) BE721828A (en)
DK (1) DK131528B (en)
ES (1) ES358872A1 (en)
FR (1) FR1587425A (en)
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SE (1) SE355907B (en)

Cited By (19)

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US3760310A (en) * 1971-08-06 1973-09-18 Honeywell Inc Thermoferrite switch with ptc resistor temperature compensation
US3852648A (en) * 1971-05-25 1974-12-03 Carrier Corp Control circuit
US4745385A (en) * 1984-12-04 1988-05-17 Ranco Incorporated Switching relays
US20050007062A1 (en) * 2003-07-09 2005-01-13 Mehlhorn William L. Switch assembly, electric machine having the switch assembly, and method of controlling the same
US9328727B2 (en) 2003-12-08 2016-05-03 Pentair Water Pool And Spa, Inc. Pump controller system and method
US9404500B2 (en) 2004-08-26 2016-08-02 Pentair Water Pool And Spa, Inc. Control algorithm of variable speed pumping system
US9551344B2 (en) 2004-08-26 2017-01-24 Pentair Water Pool And Spa, Inc. Anti-entrapment and anti-dead head function
US9556874B2 (en) 2009-06-09 2017-01-31 Pentair Flow Technologies, Llc Method of controlling a pump and motor
US9568005B2 (en) 2010-12-08 2017-02-14 Pentair Water Pool And Spa, Inc. Discharge vacuum relief valve for safety vacuum release system
US9726184B2 (en) 2008-10-06 2017-08-08 Pentair Water Pool And Spa, Inc. Safety vacuum release system
US9777733B2 (en) 2004-08-26 2017-10-03 Pentair Water Pool And Spa, Inc. Flow control
US9885360B2 (en) 2012-10-25 2018-02-06 Pentair Flow Technologies, Llc Battery backup sump pump systems and methods
US9932984B2 (en) 2004-08-26 2018-04-03 Pentair Water Pool And Spa, Inc. Pumping system with power optimization
US10240606B2 (en) 2004-08-26 2019-03-26 Pentair Water Pool And Spa, Inc. Pumping system with two way communication
US10465676B2 (en) 2011-11-01 2019-11-05 Pentair Water Pool And Spa, Inc. Flow locking system and method
US10731655B2 (en) 2004-08-26 2020-08-04 Pentair Water Pool And Spa, Inc. Priming protection
US10871001B2 (en) 2004-08-26 2020-12-22 Pentair Water Pool And Spa, Inc. Filter loading
US10916395B2 (en) * 2017-07-28 2021-02-09 Maggma Group Ip Limited Switch
US10947981B2 (en) 2004-08-26 2021-03-16 Pentair Water Pool And Spa, Inc. Variable speed pumping system and method

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FR2486729A1 (en) * 1980-07-11 1982-01-15 Electro Hydraulique Seh SINGLE PHASE ASYNCHRONOUS MOTOR AND DEVICE FOR CONTROLLING SUCH A MOTOR

Cited By (46)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3852648A (en) * 1971-05-25 1974-12-03 Carrier Corp Control circuit
US3760310A (en) * 1971-08-06 1973-09-18 Honeywell Inc Thermoferrite switch with ptc resistor temperature compensation
US4745385A (en) * 1984-12-04 1988-05-17 Ranco Incorporated Switching relays
US7183741B2 (en) 2003-07-09 2007-02-27 A. O. Smith Corporation Switch assembly, electric machine having the switch assembly, and method of controlling the same
US7427844B2 (en) 2003-07-09 2008-09-23 A. O. Smith Corporation Switch assembly, electric machine having the switch assembly, and method of controlling the same
US20050158177A1 (en) * 2003-07-09 2005-07-21 A.O. Smith Corporation Switch assembly, electric machine having the switch assembly, and method of controlling the same
US6989649B2 (en) 2003-07-09 2006-01-24 A. O. Smith Corporation Switch assembly, electric machine having the switch assembly, and method of controlling the same
US7042192B2 (en) 2003-07-09 2006-05-09 A.O. Smith Corporation Switch assembly, electric machine having the switch assembly, and method of controlling the same
US20050007062A1 (en) * 2003-07-09 2005-01-13 Mehlhorn William L. Switch assembly, electric machine having the switch assembly, and method of controlling the same
US20070113647A1 (en) * 2003-07-09 2007-05-24 A.O. Smith Corporation Switch assembly, electric machine having the switch assembly, and method of controlling the same
US20050156557A1 (en) * 2003-07-09 2005-07-21 A. O. Smith Corporation Switch assembly, electric machine having the switch assembly, and method of controlling the same
US9328727B2 (en) 2003-12-08 2016-05-03 Pentair Water Pool And Spa, Inc. Pump controller system and method
US9371829B2 (en) 2003-12-08 2016-06-21 Pentair Water Pool And Spa, Inc. Pump controller system and method
US9399992B2 (en) 2003-12-08 2016-07-26 Pentair Water Pool And Spa, Inc. Pump controller system and method
US10642287B2 (en) 2003-12-08 2020-05-05 Pentair Water Pool And Spa, Inc. Pump controller system and method
US10416690B2 (en) 2003-12-08 2019-09-17 Pentair Water Pool And Spa, Inc. Pump controller system and method
US10409299B2 (en) 2003-12-08 2019-09-10 Pentair Water Pool And Spa, Inc. Pump controller system and method
US10289129B2 (en) 2003-12-08 2019-05-14 Pentair Water Pool And Spa, Inc. Pump controller system and method
US10241524B2 (en) 2003-12-08 2019-03-26 Pentair Water Pool And Spa, Inc. Pump controller system and method
US9932984B2 (en) 2004-08-26 2018-04-03 Pentair Water Pool And Spa, Inc. Pumping system with power optimization
US10871163B2 (en) 2004-08-26 2020-12-22 Pentair Water Pool And Spa, Inc. Pumping system and method having an independent controller
US11391281B2 (en) 2004-08-26 2022-07-19 Pentair Water Pool And Spa, Inc. Priming protection
US11073155B2 (en) 2004-08-26 2021-07-27 Pentair Water Pool And Spa, Inc. Pumping system with power optimization
US9605680B2 (en) 2004-08-26 2017-03-28 Pentair Water Pool And Spa, Inc. Control algorithm of variable speed pumping system
US10240606B2 (en) 2004-08-26 2019-03-26 Pentair Water Pool And Spa, Inc. Pumping system with two way communication
US10240604B2 (en) 2004-08-26 2019-03-26 Pentair Water Pool And Spa, Inc. Pumping system with housing and user interface
US10947981B2 (en) 2004-08-26 2021-03-16 Pentair Water Pool And Spa, Inc. Variable speed pumping system and method
US10871001B2 (en) 2004-08-26 2020-12-22 Pentair Water Pool And Spa, Inc. Filter loading
US10415569B2 (en) 2004-08-26 2019-09-17 Pentair Water Pool And Spa, Inc. Flow control
US9551344B2 (en) 2004-08-26 2017-01-24 Pentair Water Pool And Spa, Inc. Anti-entrapment and anti-dead head function
US9777733B2 (en) 2004-08-26 2017-10-03 Pentair Water Pool And Spa, Inc. Flow control
US10480516B2 (en) 2004-08-26 2019-11-19 Pentair Water Pool And Spa, Inc. Anti-entrapment and anti-deadhead function
US10502203B2 (en) 2004-08-26 2019-12-10 Pentair Water Pool And Spa, Inc. Speed control
US10527042B2 (en) 2004-08-26 2020-01-07 Pentair Water Pool And Spa, Inc. Speed control
US10731655B2 (en) 2004-08-26 2020-08-04 Pentair Water Pool And Spa, Inc. Priming protection
US9404500B2 (en) 2004-08-26 2016-08-02 Pentair Water Pool And Spa, Inc. Control algorithm of variable speed pumping system
US10724263B2 (en) 2008-10-06 2020-07-28 Pentair Water Pool And Spa, Inc. Safety vacuum release system
US9726184B2 (en) 2008-10-06 2017-08-08 Pentair Water Pool And Spa, Inc. Safety vacuum release system
US10590926B2 (en) 2009-06-09 2020-03-17 Pentair Flow Technologies, Llc Method of controlling a pump and motor
US9556874B2 (en) 2009-06-09 2017-01-31 Pentair Flow Technologies, Llc Method of controlling a pump and motor
US11493034B2 (en) 2009-06-09 2022-11-08 Pentair Flow Technologies, Llc Method of controlling a pump and motor
US9568005B2 (en) 2010-12-08 2017-02-14 Pentair Water Pool And Spa, Inc. Discharge vacuum relief valve for safety vacuum release system
US10465676B2 (en) 2011-11-01 2019-11-05 Pentair Water Pool And Spa, Inc. Flow locking system and method
US10883489B2 (en) 2011-11-01 2021-01-05 Pentair Water Pool And Spa, Inc. Flow locking system and method
US9885360B2 (en) 2012-10-25 2018-02-06 Pentair Flow Technologies, Llc Battery backup sump pump systems and methods
US10916395B2 (en) * 2017-07-28 2021-02-09 Maggma Group Ip Limited Switch

Also Published As

Publication number Publication date
FR1587425A (en) 1970-03-20
GB1180354A (en) 1970-02-04
DK131528C (en) 1975-12-15
DK131528B (en) 1975-07-28
SE355907B (en) 1973-05-07
BE721828A (en) 1969-03-14
ES358872A1 (en) 1970-05-16

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