US2658175A - Electrical apparatus - Google Patents

Electrical apparatus Download PDF

Info

Publication number
US2658175A
US2658175A US302777A US30277752A US2658175A US 2658175 A US2658175 A US 2658175A US 302777 A US302777 A US 302777A US 30277752 A US30277752 A US 30277752A US 2658175 A US2658175 A US 2658175A
Authority
US
United States
Prior art keywords
bimetal
strip
starting
control
winding
Prior art date
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
US302777A
Other languages
English (en)
Inventor
Harry F Clark
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.)
Motors Liquidation Co
Original Assignee
Motors Liquidation 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 Motors Liquidation Co filed Critical Motors Liquidation Co
Priority to US302777A priority Critical patent/US2658175A/en
Priority to GB20311/53A priority patent/GB724628A/en
Priority to DEG12390A priority patent/DE947908C/de
Application granted granted Critical
Publication of US2658175A publication Critical patent/US2658175A/en
Priority to FR1086547A priority patent/FR1086547A/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H61/00—Electrothermal relays
    • H01H61/002—Structural combination of a time delay electrothermal relay with an electrothermal protective relay, e.g. a start relay

Definitions

  • This invention relatesto an electrical apparatus and more particularlyto an electrothermal starting control for split phase electric motors.
  • Electrothermal starting controls for electric motors are a success. However, they have one particular disadvantage in comparison to electromagnetic s-tarting controls. Simple electromagnetic starting controls do not terminate the start ing period until the main winding current drops below a certain value. This provides a starting period which increases in length as the motor load increases and particularly the starting period increases in lengthas the motor accelerates more quickly. Electrothermal starting controls have provided a substantially uniform starting time regardless of the rate of motor acceleration and regardless of the load upon the motor. Consequently, the starting Period is made long enough for maximum loads and this is longer than necessary for lighter loads. The unnecessary prolonged Starting eriod for lighter loads causes an audible motor hum near the end of the starting period. g
  • bimetal strip is ihth startingposition when motor acceleration isslow' and the load is heavy
  • a second bimetal which has an arm normally in engagement with the starting bimetal strip.
  • This second bimetal is made of more active bimetal material than the starting bimetal strip.
  • This second bimetal is connected in series with the main winding and under heavy loads and heavy acceleration it will be heated to a higher temperature to oppose in greater amounts the movement of the starting bimetal strip from the starting position to the running position.
  • the control normally returns to the starting position during the off cycle but if the motor is energized before resetting is accomplished, this second bimetal since it is made of more active bimetal than the starting bimetal switch will reset the starting bimetal strip immediately so that a successful start can be accomplished.
  • Figure 1 is a horizontal sectional view taken along the line l"-
  • Figure 2 is a sectional View taken along the line 2- 2 of Figure 1';
  • Figure 3 is a sectional view taken along the line 3--3 of Figure 1;
  • Figure 4 is a sectional view taken along the line 4-4 of Figure 1;'
  • Figure 5 is a fragmentary sectional view similar to the upper'portion of Figure 1 showing the starting control in the running position;
  • Figure 6 is a perspective view of the starting bimetal strip and its resetting control.
  • an electric motor circuit including an electric motor 20 having a main or running winding 22 and a phase or starting winding 24.
  • the common junction ofthe main and phase-windings is connected by a line switch 28 to the supply conductor 30.
  • a capacitor 32' may be connected in series with the phase-winding 24 if desired but many starting controls will operate equally well Without this capacitor and it may be omitted where an ample starting torque can be obtained without its use;
  • phase-winding control The phase-winding 24 and the capacitor 32 are connected by' the conductor ,34 to the L-shaped starting contact and terminal 36 the horizontal portion of which is beneath the base 38 and is connected thereto by the use of an upwardly extruded eyelet rivet which is internally threaded to receive a binding screw 39.
  • the base 38 is made of a suitable mounted electrically insulated material and carries an integral U-shaped rib of the same material which supports the moving parts of the control.
  • the base 38 may also be provided with additional stiffening ribs which are not shown.
  • U-shaped bimetal member 55 Fastened to the rib :32 by the rivets 44 and 59 is a U-shaped bimetal member 55 having one leg 46 forming the starting cantilever bimetal strip portion having its high expansion side facing outwardly away from the center of the base 38.
  • the high expansion side of the yoke portion of the U-shaped bimetal member 65 lies directly against the U'shaped rib Q2.
  • the movable end portion of the cantilever strip portion 66 carries a movable starting contact 41 shown in engagement with the L-shaped station ary contact 36.
  • the strip 46 is thereby connected in series with the phase-winding 24 and carries and is self-heated by the starting or phase-winding current.
  • the outer face of the rib t2 carries a hook-shaped tempera ture compensating bimetal strip as also having its high expansion side iacin outwardly from the center of the base 38 and having its low expansion side lying against the outside oi the rib d2. It is fastened to the rib by two rivets ill.
  • This compensating strip 48 has the same ehective length as the cantil ver strip portion id but is preferably much wider and somewhat thicker as shown in Figure 2.
  • the geometrical arrangement and the adjustment of the setscrew is such that when the starting bimetal strip portion it and its contact ll are in either the open or closed position the toggle spring 55! is at such an angle that when the strip 43 is cool it will move to or remain in the starting or closed position.
  • the bimetal strip 45 Since the bimetal strip 45 is connected in series with the phasewinding 24 it will receive a flow of current as soon as the line switch 23 is closed.
  • the cumulative heating efiect of this current through the starting bimetal strip portion 48 causes it to bow downwardly and move from the starting position, shown in Figure 1, to the running position shown in Figure 5 to open the phase-winding circuit. In this running position, its further movement is stopped by the island 58 formed as a part of the base 38.
  • the starting period is almost the same length at all times. This has made it necessary to adjust the setscrew 52 so that the starting time is sufficiently long to cause the motor to start properly under the most severe starting conditions which might be encountered. Therefore, when the starting conditions are normal, the phase-wind ing circuit has remained energized for a longer period than is necessary.
  • the speed at which it is desired to deenergize the phase-winding is termed the balancing speed. For a motor having normal running speed of 1750 R. P. M., this balancing speed occurs at between about 1400 and 1600 R. P. M.
  • I provide a reset bimetal member 5i having its lower end anchored in cantilever fashion to the L-shaped main winding terminal member 60.
  • This terminal member 69 is connected by a binding screw 4%] threaded into the eyelet portion of the terminal 6% to the conductor 62 connecting with the second terminal of the main winding 22.
  • the bimetal 5? has its upper portion I51 bent at right angles and provided with a U-shaped portion having an arm t3 extending toward and engaging the portion of the bimetal strip 46 on the opposite side from the contact 41.
  • the arm 63 may be provided with a bent over tip I63.
  • the strip i5 is provided with a localized coating MS of an electrical insulating material.
  • the reset bimetal is made of a more active bimetal material than the starting bimetal strip portion
  • the reset bimetal 51 is connected in series with the main winding through the riveting of its base to the main winding terminal by the to the running position in Figure 5.
  • This bimetal 51 is used to prolong the starting period of the motor. It is arranged so that its high expansion side faces the center of the base Since the high expanding side of the bimetal 57 faces the center of the base 38 and the high side or" the bimetal strip portion 4% is away from the center of the base 38 the bimetals it and 57 when heated simultaneously will bow or deflect toward each other.
  • the motor As long as the motor 20 is rotating at a low speed there will be a heavy flow of current thorugh the main winding 22 and through the main reset bimetal 51.
  • the motor accelerates rapidly under normal or light load, heavy current will quickly diminish and the heating effect upon the reset bimetal 51 will be small. Consequently, the reset bimetal 51 will generate a relatively low force opposing the movement of the starting bimetal strip portion 46 from the starting position shown in Figure l to the running position shown in Figure 5. This movement will therefore take place at the minimum time after the motor 20 is energized.
  • This heater -64 is connected in series with the main winding 22 by-any suitable arrangement.
  • the heater 164 not-only supplies suflicient heat to the starting bimetal-strip portion 46 during the running period of the motor to keep the contact 41 in the runningposition after the end of the starting period, butit-also controls the resetting of the contact 47 to the starting position as shown inEigure :1.
  • the heater 64- As wellas the bimetallic cool off and when they have become sufficiently e001 the to gle l-springafio will move the bimetal strip 46 and the contact-41 from the-running position shown in Fi ure 5 to the starting position shown in Figure 1.
  • the heater 64 and the reset bimetal-5.! are conveniently combined in a reset control by connecting the upper end .of the heater -46 to the bent portion I51 of the reset bimetal ,5] at the point designated by the reference character 164.
  • the projection 63 maintains the upper portion of the heater 64 properly spaced from the starting bimetal strip 46 so that the desired limited amount of heat transfer between the heater 64 and thestrip portion .46 is provided.
  • the heater .64 slowly :heats the bimetal strip portion 46 so that its heating efiect-does not-become pronounced However, in a prolonged starting attempt it does bimetal '65.
  • the reset bimetal-51 has asecond function. litheidleperiodof themotor 20 is not su'flici'ently long for the startingbimetal strip portion 46 :to .cool off andreturnfrom the running position shown in Figure-5 'to'the starting position .shown in ' Figure' 1, the motor 2 0wil1 not start and a heavy 'current'will flow through the main winding :circuit from the supply conductor 35 through the line switch 28 and the main winding 22 the conductor 62, the main winding terminal '60, the reset bimetal 6-1, the heater 64, to the other side 'ofthe line.
  • the compensating bimetal 48 is -provided with a stiffening rib 49l which controls itsmovement under changes in ambient temperature.
  • the overload protector The main winding current is conducted through the resettingrbimetal 5'! and the-electric heater'ee to the yoke .portion of the U-shaped The phase wi-miing current is also conducted by the starting bimetal strip portion to the yoke portion of the U-shaped bimetal member 55.
  • the lower portion'of this U-shaped bimetal member is provided with acantilever overload bimetal strip portion 66. This portion 66 carries a movable contact it which normally makes contact with theL-shaped stationary contact and terminal member "[2 connecting with the second supply conductor 33.
  • a hook-shaped overload compensating bimetal strip ifi is fastened byrivets to the adjacent outer face ofthe rib '42.
  • This overload compensating bimetal strip 16 andithew'overload bimetal strip portion 66 both have their high expansion sides turned outwardly relative to the center of the base 38.
  • the end portion of the overload compensating bimetal strip 16 is-notched.
  • the movable end portion of the over-load bimetalstrip portion 66 is provided witha rectangular aper- *ture.
  • the overload bimetal strip portion 66 is self-heated by the current flowing from the yoke portion of the 'U-shaped bimetal member 65 through the overload contacts Hi, 12 to the second supply conductor 13.
  • the strip portion 66 When the strip portion 66 is self-heated sufficiently it will trip to the open position into contact with the adjacent part of the island 68.
  • the tripping point of the overload strip portion 66 is adjusted by bending the vertical contact portion of the terminal l2 toward or away from the strip portion 66 in order to reduce or increase the current value to which the overload portion 66 trips to the open position.
  • the reclosing of the overload por ion 66 is adjusted by the setscrew 80 which bears against the base of the overload bimetal strip portion 66 to adjust its position.
  • This ceramic heater GEES will apply sufficient heat to the overload bimetal 16 that it will deflect upwardly after a period of time and insure the reclosing of the bimetal at.
  • a U-shaped wire spring I36 extending between the screws 52 and 80 so as to apply sufficient friction upon them to prevent movement under such conditions.
  • a control including a bimetal strip means, a control means connected to and operated by the movement a portion of said bimetal strip means, means including a first heating circuit under the control of said control means for heating said bimetal strip means, a resetting control including a bimetal support extending near to and generally parallel to said strip means and having its high expanding side away from said bimetal strip means to cause it to bow toward the strip means when heated, said resetting con trol also including an electric heater supported by said bimetal support alongside and adjacent to said strip means, a second heating circuit portion connected to said electric heater and said support in parallel circuit relationship with the first heating circuit to normally energize said heater to heat said strip means and for heating said bimetal support abnormally during abnormally high current flow to cause said support to bow toward the strip means, said support being provided with a resetting, extension for engaging and moving said strip means under abnormally high current conditions.
  • a control including a bimetal strip means, a control means connected to and operated by the movement of said strip means from a first position to a second position and return, a snap acting means cooperating with said strip means to provide a limited force to hold the strip means and the control means in said first position,-
  • a resetting control including a bimetal support located in opposite relationship to the strip means so that they deflect toward each other if heated simultaneously, said bimetal support having an extension for engaging and moving said strip means and said control means from the second position to the first position, said resetting control also including an electric heater supported in heating relationship to said bimetal strip means and a second heating circuit portion connected to energize said heater and said bimetal support for heating said bimetal strip means to hold said strip means in the second position during normal current flow in said second heating circuit portion and for heating said bimetal support during abnormally high current flow in said second circuit portion to insure resetting of said bimetal strip means and said control means to the first position.
  • a control including a bimetal strip means, a control means connected to and operated by the movement of said strip means from a first position to a second position and return, a snap acting cooperating with said strip means to provide a limited force to hold the strip means and the control means in said first position, means including a first heating circuit under control or said control means for heating said strip means sufficiently to cause its bimetal action to overcome the restraining force of the snap acting means to move the strip means and the control means from the first position to the second position, a resetting control including a bimetal support located in opposite relationship to the strip means so that they deflect toward each other if heated simultaneously, said bimetal support having an extension for engaging and moving said strip means and said control means from the second position to the first position, said resetting control also including an electric heater supported in heating relationship to said bimetal strip means and a second heating circuit portion connected in series with said heater and said bi metal support for heating said bimetal strip means to hold said strip means in the second position during normal current flow in said second heating circuit portion
  • a control including a bimetal strip means, a control means connected to and operated by the movement of said strip means from a first position to a second position and return, a snap acting means cooperating with said strip means to provide a limited force to hold the strip means and the control means in said first position, means including a first heating circuit under control of said control means for heating said strip means sufficiently to cause its bimetal action to overcome the restraining force of the snap .9. acting means to move the strip means and the control means from the first position to the sec-- ond position, a resetting control including a bimetal support located in opposite relationship to the strip means so that they deflect toward each other if heated simultaneously, said resetting control also including an electric heater supported.
  • said bimetal support alongside said strip means for heating the strip means to hold the strip means and the control means in the second position
  • said bimetal support having an extension extending into engagement with said strip means for maintaining said heater properly spaced from said strip means and for moving said strip means and control means from the second position to the first position
  • a second heating circuit portion connected to energize said heater and said bimetal support for heating said bimetal strip means to hold said strip means in the second position during normal current flow in said second heating circuit portion and for heating said bimetal support during abnormally high current flow in said second circuit portion to insure resetting of said bimetal strip means and said control means to the first position.
  • a control for an electric motor having main and phase-windings including a bimetal strip means and a switch means connected in series with said phase-winding for controlling the energization of the phase-winding, said switch means being connected to and operated by said strip means from a first position to a second position and return in response to changes in temperature of said strip means, a snap acting means cooperating with said strip means to provide a limited force to hold the strip means and switch means in the first position, a resetting control including a bimetal support located in opposite relationship to the strip means so that they defiect toward each other if heated simultaneously, said bimetal support having an extension for engaging and moving said strip means and said switch means for the second position to the first position, said resetting control also including an electric heater supported in heating relationship to said bimetal strip means, said bimetal support and said heater being connected in series with said main winding so that the heater is energized during the running period to heat and hold the bimetal strip means and the switch means in the second position during the running period and
  • a control for an electric motor having main and phase-windings including a bimetal strip means and a switch means connected in series with said phase-winding for controlling the energization of the phase-winding, said switch means being connected to and operated by said strip means from a first position to a second position and return in response to changes in temperature of said strip means, a snap acting means cooperating with said strip means to provide a limited force to hold the strip means and switch means in the first position, a resetting control including a bimetal support located in opposite relationship to the strip means so that they deflect toward each other if heated simultaneously, said resetting control also including an electric heater supported by said bimetal support alongside said strip means for heating the strip means to hold the strip means and the switch means in the second position, said bimetal 10 support having an extension extending into engagement with said strip means for maintaining said heater properly spaced from said strip means and for moving said strip means and switch means from the second position to the first position, said bimetal support and said heater being connected in series with said main Winding,
  • a control for an electric motor having main and phase-windings including a bimetal strip means and a switch means connected in series with said phase-winding, a snap acting means cooperating with said strip means to provide a limited force to hold the strip means and the switch means in the starting position, said switch means being connected to and operated by said strip means when heated by the phase-winding current from the starting position to the running position, an electric heater energized coincidentally to the energization of said main winding and located in heating relationship to said strip means for holding the strip means and the switch means in the running position during the running period of the motor, and electrically operated means connected in series with said main winding having opposing means engaging said strip means when in starting position for retarding the movement of the strip means to the running position in accordance with the main winding current.
  • a control for an electric motor having main and phase-windings including a bimetal strip means and a switch means connected in series with said phase-winding, a snap acting means cooperating with said strip means to provide a limited force to hold the strip means and the switch means in the starting position, said switch means being connected to and operated by said strip means when heated by the phase-winding current from the starting position to the running position, an electric heater energized coincidentally to the energization of said main winding and located in heating relationship to said strip means for holding the strip means and the switch means in the running position during the running period of the motor, a bimetal opposing means having an extension extending into engagement with said strip means and having its high expansion side located so that as it is heated it will oppose with increasing force the movement of the strip means and the switch means from the starting position to the running position, said bimetal opposing means being connected in series with the main winding to increase the length of the starting period as long as the heavy main winding current continues.
  • a control for an electric motor having main and phase-windings including a bimetal strip means and a switch means connected in series with said phase-winding, a snap acting means cooperating with said strip means to provide a limited force to hold the strip means and the switch means in the starting position, said switch means being connected to and operated by said strip means when heated by the phase-winding current from the starting position to the running position, and electrically operated means connected in series with said main winding having opposing means engaging said strip means when in starting position for retarding the movement of the strip means to the running position in accordance with the main winding current.
  • a control for an electric motor having main and phase-windings including an electrothermal means and a switch means connected in series with the phase-winding, said switch means being connected to and operated by said electrothermal means when heated by the phase-winding current from the starting position to the running position, an electric heater energized coincidentally to the energization of said main winding and located in heating relationship to said electrothermal means for holding said electrothermal means and the switch means in the running position during the running period of the motor, and electrically operated means connected in series with said main winding having opposing means operating upon said switch means for retarding the movement of said switch means to the running position in accordance with the main winding current.

Landscapes

  • Thermally Actuated Switches (AREA)
  • Protection Of Generators And Motors (AREA)
US302777A 1952-08-05 1952-08-05 Electrical apparatus Expired - Lifetime US2658175A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US302777A US2658175A (en) 1952-08-05 1952-08-05 Electrical apparatus
GB20311/53A GB724628A (en) 1952-08-05 1953-07-22 Improvements in control switches for electric motors
DEG12390A DE947908C (de) 1952-08-05 1953-08-05 Elektrothermischer Bimetall-Steuerschalter
FR1086547A FR1086547A (xx) 1952-08-05 1954-08-11

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US302777A US2658175A (en) 1952-08-05 1952-08-05 Electrical apparatus

Publications (1)

Publication Number Publication Date
US2658175A true US2658175A (en) 1953-11-03

Family

ID=23169162

Family Applications (1)

Application Number Title Priority Date Filing Date
US302777A Expired - Lifetime US2658175A (en) 1952-08-05 1952-08-05 Electrical apparatus

Country Status (4)

Country Link
US (1) US2658175A (xx)
DE (1) DE947908C (xx)
FR (1) FR1086547A (xx)
GB (1) GB724628A (xx)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2788413A (en) * 1957-04-09 Electrical apparatus
US3453577A (en) * 1966-12-15 1969-07-01 Texas Instruments Inc Compact thermostatic snap switch with heater for protection of motor windings and the like
US3718879A (en) * 1971-05-19 1973-02-27 Texas Instruments Inc Apparatus for starting and protecting of electrical motors
US3852695A (en) * 1973-04-09 1974-12-03 L Northrup Electrical switching system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1141006B (de) * 1957-10-25 1962-12-13 Licentia Gmbh Thermisch wirkendes Zeitrelais zur Steuerung von zwei oder mehreren Stromkreisen

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2593268A (en) * 1948-07-20 1952-04-15 Gen Motors Corp Single-phase motor control

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2788413A (en) * 1957-04-09 Electrical apparatus
US3453577A (en) * 1966-12-15 1969-07-01 Texas Instruments Inc Compact thermostatic snap switch with heater for protection of motor windings and the like
US3718879A (en) * 1971-05-19 1973-02-27 Texas Instruments Inc Apparatus for starting and protecting of electrical motors
US3852695A (en) * 1973-04-09 1974-12-03 L Northrup Electrical switching system

Also Published As

Publication number Publication date
DE947908C (de) 1956-09-13
FR1086547A (xx) 1955-02-14
GB724628A (en) 1955-02-23

Similar Documents

Publication Publication Date Title
US2338474A (en) Thermostat
US2417912A (en) Split-phase motor thermal starting switch
US2175032A (en) Single phase motor control
US2573404A (en) Thermal control means for induction motors
US2658175A (en) Electrical apparatus
US2786171A (en) Starting and overload control for split-phase electric motor
US2311048A (en) Electric switch
US2618721A (en) Control with column loaded strip
US2137073A (en) Thermostatic control system
US2304018A (en) Control apparatus
US2340877A (en) Thermal responsive circuit controller
US2805302A (en) Thermostatic control mechanism
US2312915A (en) Protective circuit
US2993976A (en) Heater control
US2158288A (en) Thermally controlled switch
US2447488A (en) Single-phase motor control
US2926233A (en) Electric heater control apparatus
US2090526A (en) Circuit controlling device
US2629034A (en) Electrical apparatus
US2252444A (en) Thermal relay
US2313969A (en) Control apparatus
US2158850A (en) Temperature control device
US2984722A (en) Motor starter switch
US3562688A (en) Quick trip overload relay heaters
US3240906A (en) Thermostatic dual switch with improved manual control