US3497838A - Circuit breaker having inertial delay - Google Patents

Circuit breaker having inertial delay Download PDF

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Publication number
US3497838A
US3497838A US729486*A US3497838DA US3497838A US 3497838 A US3497838 A US 3497838A US 3497838D A US3497838D A US 3497838DA US 3497838 A US3497838 A US 3497838A
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US
United States
Prior art keywords
circuit breaker
pin
armature
breaker
bell crank
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Expired - Lifetime
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US729486*A
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English (en)
Inventor
Lyal N Merriken
George S Harper
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.)
Airpax Electronics Inc
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Airpax Electronics Inc
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Publication date
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Publication of US3497838A publication Critical patent/US3497838A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H73/00—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism
    • H01H73/36—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism having electromagnetic release and no other automatic release
    • H01H73/38—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism having electromagnetic release and no other automatic release reset by lever
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10—Operating or release mechanisms
    • H01H71/12—Automatic release mechanisms with or without manual release
    • H01H71/44—Automatic release mechanisms with or without manual release having means for introducing a predetermined time delay
    • H01H71/446—Automatic release mechanisms with or without manual release having means for introducing a predetermined time delay making use of an inertia mass

Definitions

  • the present invention is directed to an improved electromagnetic circuit breaker which will not trip out when subjected to high amplitude current for a short time.
  • the circuit breaker incorporates a balanced inertia wheel for effectively increasing the inertia of the circuit breaker armature to introduce a time delay before the breaker trips out when subjected to very high overload currents.
  • circuit breakers are used in numerous devices where it is desired to protect electrical equipment against overload. Important advantages include the fact that the conventional electromagnetic circuit breaker is resettable and may be tripped repeatedly without any necessity for replacement or repair. However, one of the disadvantages of the electromagnetic circuit breakers is that they have a tendency to trip out when subjected to high amplitude current for a short time. This is often referred to as nuisance tripping and occurs in some cases in conjunction with the starting of certain types of electrical motors and inductive and capacitive loads.
  • the present invention provides a device for overcoming this nuisance tripping so that the circuit breaker is substantially insensitive to very high amplitude currents which last for only a short time.
  • the device of the present invention preserves the other advantageous features of the more conventional circuit breaker including its response to small overloads and to large overloads of long duration. This is accomplished by introducing into the circuit breaker in a simple and inexpensive manner, an increased mechanical delay which only has a significant effect for overloads in excess of about 400% of rated current for the breaker. As the result, the breaker has the capacity to take electrical pulses of higher amplitude and/or longer electrical pulse duration before tripping.
  • the increase in capacity is achieved through the provision of an inertial wheel in the breaker to introduce an additional time delay. That is, a certain predetermined amount of force is required to move the armature, operate the mechanism, and open the contacts in a conventional circuit breaker.
  • the provision of a balanced inertia wheel in the circuit breaker increases the dynamic mass of the breaker mechanism but does not change the amount 3,497,838 Patented Feb. 24, 1970 ice of force required to operate the breaker.
  • the force required to operate the mechanism is essentially the same with or without the inertia wheel, but the dynamic mass of the mechanism is increased by the mass of the inertia wheel, the acceleration is decreased.
  • the circuit breaker of the present invention When subjected to overload currents at or below about 400% of the rated current, the circuit breaker of the present invention maintains the specified calibration of a circuit breaker not having an inertia wheel. This is because the inertia wheel is balanced and does not exert any appreciable force on the armature. It is only at currents above 400% of rated current that the inertia wheel begins to have a significant affect on the trip time of the breaker.
  • Another object of the present invention is to provide a circuit breaker having increased capacity to take electrical pulses of higher amplitude and/or longer electrical duration, as compared with similar conventional circuit breakers.
  • Another object of the present invention is to provide a circuit breaker having an increased time delay for overload currents in excess of about 400% of rated current.
  • Another object of the present invention is to provide a simplified and inexpensive arrangement for incorporating, in a circuit breaker, an additional mechanical time delay without at the same time significantly modifying the amount of force required to trip the breaker.
  • Another object of the present invention is to provide a circuit breaker with a balanced inertia wheel coupled to the breaker armature, thereby effectively increasing the dynamic mass of the armature.
  • FIGURE 1 is a perspective view of a circuit breaker in its housing constructed in accordance with the present invention
  • FIGURE 2 is a side view of the breaker of FIGURE 1 with the housing removed, showing the breaker mechanism in relatched open position with the contacts open;
  • FIGURE 3 is a partial sectional view similar to that of FIGURE 2, showing the mechanism in a position where the contacts are closed;
  • FIGURE 4 is a partial sectional view similar to FIG- URES 2 and 3, showing the mechanism in an intermediate or tripped open position;
  • FIGURE 5 is a vertical cross section taken along line 55 of FIGURE 2;
  • FIGURE 6 is an enlarged section taken along lines 6-6 of FIGURE 2, but showing the threaded ferrule in place;
  • FIGURE 7 is an enlarged perspective view showing the detail of the sear pin and striker bar assembly
  • FIGURE 8 is a detailed view showing engagement of the sear pin and striker bar assembly with the forked lever of the breaker of FIGURE 1;
  • FIGURE 9 is an enlarged perspective view of the electro magnet armature bell crank assembly
  • FIGURE 10 is an enlarged view of the inertia wheel mounted on its support.
  • FIGURE 11 is an exploded view showing the details of the inertia wheel and axle rivet on which it rotates.
  • the novel circuit breaker of the present invention illustrated in FIGURE 1, comprises a housing 10, which is formed of a molded plastic having good electrical insulating properties. Supported in the housing is a frame 11 upon which is mounted the operating elements of the circuit breaker to move a movable contact 12 into and out of engagement with a fired contact 13.
  • Movable contact 12 is secured to a lever 14 pivotally and slidably mounted on the frame by a pin 15 passing through an elongated opening 16 in the lever.
  • Pin 15 is mounted on the frame 11, intermediate its ends while the ends extend beyond the frame and fit snugly into cooperating recesses 17, molded in the housing halves 10 and 10 as seen in FIGURE 5.
  • a spring 18 is wound around pin 15 and is provided with a biasing arm 19 hearing against the lever 14 and with a reaction arm 20 bearing against the frame 11. Portions of the frame 11 are omitted in FIGURES 3 and 4 for the sake of clarity. The entire frame 11 is illustrated in FIGURE 2.
  • An actuating lever 21 is pivotally mounted on the frame 11 by a pin 22.
  • the pin 22 is mounted in the frame intermediate its ends while the ends extend beyond the frame and fit snugly into cooperating recesses 22' molded in the housing 10 as best seen in FIGURE 5.
  • a spring 23 is wound around the pin 22 and has a biasing arm 24 bearing against a pin 25 and also a reaction arm 26 bearing against the frame 11.
  • Pivotally mounted on pin 25 is an L-shaped link 27 and this link is pivotally connected to a spaced pair of links 28 by pin 29.
  • the links 28 are pivotally connected by a pin 30 to straddle the lever 14.
  • Rotatably supported in link 27 at the bend of the L is the shaft of a sear pin 31 which sear pin is provided with a reduced section 32 between the links which is provided by grinding a fiat sufrace 32 on the shaft 31 (FIGURE 7) which acts as a sear for edge 42 of a forked cam lever 40.
  • An arm or striker bar 33 is mounted rigidly and non-rotatably on shaft 31 and carries a tab 34 bent up from the end of the arm.
  • One end of shaft 31 is square to accommodate the square hole in arm 33. After assembly, the end of shaft 31 is peened tight against arm 33, permanently keying the shaft and arm together.
  • a spring 35 is wound around shaft 31 and is provided with arms 36 and 37 bearing respectively against a stop 38 integral with one arm of link 27 and against an extension 39 of arm 33. The spring is wound to urge extension 39 against the stop.
  • Forked lever 40 is pivotally mounted on pin 25 between the parallel arms of link 27.
  • One leg 41 of the fork is provided with an edge portion 42 for engagement with the sear portion 32 of shaft 31, and the other leg 43 of the fork is provided with a curved cam section 44 for engagement with a pin 45 carried by links 28.
  • a locking recess 46 is between the legs at the end of cam section 44.
  • Frame 11 is provided with a shelf 47 on which is mounted an electromagnet 48 having a winding, one end of which is connected in series with a terminal 49 and the other end in series with a braided flexible copper wire 50 secured to lever 14, for completing a circuit through movable contact 12, fixed contact 13, and contact support 51 to terminal 52.
  • An armature 53 is pivotally mounted on the frame by a pin 54 and is secured to an armature lever 55 to form therewith a bell crank '56 shown in detail in FIGURE 9.
  • a spring 57 is mounted on pin 54 to bias the bell crank 56 toward the position shown in FIGURE 2.
  • the free end of the armature lever forms an arcuate trigger cam surface 58. In the closed contact position, the linkage is in the position shown in FIGURE 3 with the tab portion 34 adjacent the arcuate trigger cam surface 58 at the end of armature lever 55.
  • the armature bell crank 56 pivots about pin 54 secured to frame 11.
  • Slot 84 in the bell crank receives a projection or pin 83 mounted on a brass inertia wheel 82.
  • Wheel 82 is mounted for rotation on an axle rivet 81 which pases through a central aperture 86 in the wheel and through a suitable aperture in a flat support plate soldered or otherwise rigidly attached to frame 11.
  • Wheel 82 is preferably balanced about its rotational axis 87 and is cut away as at 88 and 89 so that the bell crank 56 acts through the center of the wheel. In this way, the wheel is completely balanced so that it can be rotated by the bell crank without exerting any substantial retarding force on the crank, other than that due to rotary inertia of the wheel.
  • the housing is formed of two mirror image sections 10 and 10' (FIGURES 1 and 5) which are secured together by rivets 62 passing through openings in the housing.
  • One of the sections, such as section 10 is provided with an elongated groove 70 and the other section is provided with an elongated tongue which is snugly received in the groove.
  • This tongue-in-groove arrangement is for the purpose of accurately aligning the housing sections in assembly.
  • Each housing section is provided with recesses 63 molded in the meeting faces.
  • the recesses 63 are provided with an enlarged portion 64.
  • the recesses 63 combine to provide openings which receive threaded metal ferrules 65 (FIGURE 6) with hexagonal heads by which the assembly is secured to a support.
  • the recesses 66 combined to provide openings for the reception of the threaded terminals 49 and 52.
  • the electromagnet 48 In operation, on overload, the electromagnet 48 is energized to a point where it attracts armature 53 and causes the bell crank 56 to rotate counterclockwise about pin 54. Slot 84 in the leg of the bell crank shown in FIGURE 9, engages with crank pin 83 of the inertia wheel 82.
  • the inertia wheel 82 is attached to the support plate 80 by axle rivet 1 but freely rotates about the rivet.
  • the armature 53 Before the armature 53 can rotate to a point where it will trip the breaker mechanism, it has to rotate the balanced inertia wheel 82 in a clockwise direction in FIG- URE 10. Under conditions of high current overload through the electromagnet 48, the inertia wheel 82 increases the length of time it takes to rotate the armature 53 as compared to a circuit breaker not having an inertia wheel. However, under conditions of low cuirent overload, the inertia wheel 82 does not restrict the travel of armature 53 via the bell crank and the time required for the armature 53 to rotate is substantially the same as a similar breaker not having an inertia wheel.
  • the present invention provides an improved circuit breaker, particularly insensitive to short duration high overloads.
  • the inertia device of this invention is of relatively simple and inexpensive construction and requires no modification of the basic circuit breaker mechanism. At the same time, it substantially increases the capacity of the breaker to resist overload currents and substantially reduces the so-called nuisance tripping previously encountered in conventional circuit breakers.
  • a bell crank pivoted adjacent said electromagnet including a first portion forming an armature for said electromagnet, said bell crank including a second portion for actuating said trip mechanism after a predetermined amount of movement of said crank, and pivotally mounted balanced inertia means coupled to said bell crank for efiectively increasing its dynamic mass to overload currents in excess of about 400% of the rated current through said electromagnet.
  • inertia means comprises a balanced inertia wheel mounted for is rotatably mounted in the pivotal plane of said bell crank.
  • a circuit breaker for protecting against electrical overloads comprising an electromagnet, a pair of contacts, a toggle mechanism coupled to one of said contacts for moving said one contact away from the other of said contacts, an armature pivoted adjacent said electromagnet and including means for tripping said toggle mechanism, and pivotally mounted balanced inertia means coupled to said armature for increasing the trip time of said breaker for currents through said electromagnet in excess of approximately 400% of its rate current.
  • inertia means comprises a balanced inertia wheel mounted for rotation about a fixed axis adjacent said armature.
  • a circuit breaker comprising an electrically insulating housing, an electromagnet mounted in said housing,
  • toggle mechanism in said housing for moving one of said contacts away from the other, said toggle mechanism including a sear, a bell crank pivoted adjacent said electromagnet for tripping said sear, a portion of said bell crank forming an armature for said electromagnet, a balanced inertia wheel mounted for rotation about a fixed axis in said housing, and means coupling said bell crank to said inertia wheel whereby pivotal movement of said bell crank causes said inertia wheel to rotate.
  • a circuit breaker according to claim 8 wherein said wheel carries a projection, said bell crank having a slot slidably received in said projection.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Breakers (AREA)
US729486*A 1968-04-22 1968-04-22 Circuit breaker having inertial delay Expired - Lifetime US3497838A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US72948668A 1968-04-22 1968-04-22

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US (1) US3497838A (enrdf_load_stackoverflow)
JP (1) JPS521106B1 (enrdf_load_stackoverflow)
DE (1) DE1920175A1 (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3749873A (en) * 1971-08-18 1973-07-31 Airpax Electronics Circuit breaker housing
US3959755A (en) * 1974-12-13 1976-05-25 Airpax Electronics Incorporated Circuit breaker with improved delay
US4117285A (en) * 1977-08-19 1978-09-26 Airpax Electronics Incorporated Snap action circuit breaker
US4237436A (en) * 1979-01-15 1980-12-02 Heinemann Electric Company Circuit breaker having a modified armature for time delays at high transient currents
USRE31690E (en) * 1977-08-19 1984-10-02 No. American Philips Corp. Snap action circuit breaker
US4882557A (en) * 1987-11-13 1989-11-21 Airpax Corporation Multipole circuit breaker system with differential pole operation
US4885558A (en) * 1983-04-20 1989-12-05 Airpax Corporation Circuit breaker
US4926157A (en) * 1983-04-20 1990-05-15 Airpax Circuit breaker
US6034586A (en) * 1998-10-21 2000-03-07 Airpax Corporation, Llc Parallel contact circuit breaker
US6853274B2 (en) 2001-06-20 2005-02-08 Airpax Corporation, Llc Circuit breaker

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52141309U (enrdf_load_stackoverflow) * 1976-04-20 1977-10-26
DE9113965U1 (de) * 1991-11-09 1992-01-16 Stewing Beton- Und Fertigteilwerk Gmbh & Co Kg, 4270 Dorsten Bausatz zum Erstellen einer Haltestellenüberdachung
FR2772981B1 (fr) * 1997-12-24 2000-01-21 Schneider Electric Sa Dispositif de declenchement selectif pour disjoncteur

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US898649A (en) * 1908-03-17 1908-09-15 Monnosuke Higuchi Electric clock.
US1554652A (en) * 1920-11-22 1925-09-22 Gen Electric Time-element device
US1774966A (en) * 1926-05-15 1930-09-02 Gen Electric Time-element device
US2064657A (en) * 1935-02-28 1936-12-15 Gen Electric Control device
CH259580A (de) * 1946-10-02 1949-01-31 Karl Bollschweiler Hans Elektromagnetisch gesteuerter Schalter.

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US898649A (en) * 1908-03-17 1908-09-15 Monnosuke Higuchi Electric clock.
US1554652A (en) * 1920-11-22 1925-09-22 Gen Electric Time-element device
US1774966A (en) * 1926-05-15 1930-09-02 Gen Electric Time-element device
US2064657A (en) * 1935-02-28 1936-12-15 Gen Electric Control device
CH259580A (de) * 1946-10-02 1949-01-31 Karl Bollschweiler Hans Elektromagnetisch gesteuerter Schalter.

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3749873A (en) * 1971-08-18 1973-07-31 Airpax Electronics Circuit breaker housing
US3959755A (en) * 1974-12-13 1976-05-25 Airpax Electronics Incorporated Circuit breaker with improved delay
US4117285A (en) * 1977-08-19 1978-09-26 Airpax Electronics Incorporated Snap action circuit breaker
USRE31690E (en) * 1977-08-19 1984-10-02 No. American Philips Corp. Snap action circuit breaker
US4237436A (en) * 1979-01-15 1980-12-02 Heinemann Electric Company Circuit breaker having a modified armature for time delays at high transient currents
US4885558A (en) * 1983-04-20 1989-12-05 Airpax Corporation Circuit breaker
US4926157A (en) * 1983-04-20 1990-05-15 Airpax Circuit breaker
US4882557A (en) * 1987-11-13 1989-11-21 Airpax Corporation Multipole circuit breaker system with differential pole operation
US6034586A (en) * 1998-10-21 2000-03-07 Airpax Corporation, Llc Parallel contact circuit breaker
US6420948B1 (en) * 1998-10-21 2002-07-16 Airpax Corporation, Inc. Parallel contact circuit breaker
US6853274B2 (en) 2001-06-20 2005-02-08 Airpax Corporation, Llc Circuit breaker

Also Published As

Publication number Publication date
JPS521106B1 (enrdf_load_stackoverflow) 1977-01-12
DE1920175A1 (de) 1969-11-06

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