US2881285A - Time delay device for circuit breakers - Google Patents

Description

' Ap 1959 'r. G. BANK 7 2,881,285

TIME DELAY DEVICE FOR CIRCUIT BREAKERS 7 Filed- June 24, '1954- 2 Sheets-Sheet 1 April 7, 1959 T. G. BANK 2,881,285 I 7 TIME: DELAY DEVICE FOR CIRCUIT BREAKERS Filed June 24. 1954- 2 Shee ts-Sheet 2 1 /6 1 69 4/6 & wwbo a Z 5392 United States Patent 2,881,285 TIME DELAY DEVICE FOR CIRCUIT BREAKERS Thor G. Bank, West Allis, Wis., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Application June 24, 1954, Serial No. 438,982 2 Claims. (Cl. 200-97) This invention relates generally to circuit breakers for interrupting an electrical circuit and more particularly to a new and improved time delay device used in combina tion therewith for improving the combination.

Time delay devices are defined as those devices which when combined with a relay are capable of selectively delaying interrupting action of a circuit breaker. The delay device has an inverse time delay action wherein the reaction time of the device becomes shorter as overload currents increase. Therefore, the greater the overload current the shorter the time of reaction of the de vice.

Prior art time delay devices are known which employ orifices or constricted openings through which a fluid is forced to provide the time delay. These orifices often clogged as a result of impurities in the fluid, thus disabling the device. Further, erosion would enlarge the orifice opening and upset the time delay constant of the device. The amount of adjustment to provide a varied range of operation was also rather limited.

The present invention overcomes these disadvantages and offers a structure in which the time delay action is provided by forcing a fluid through a porous filter which has a given delay constant. The filter persents a large working area and is therefore unafiected by minor impurities in the fluid. As the filter is rather impervious to erosion, it will retain its designed time delay indefinitely. The filter is incorporated into a delay device which is readily adjustable over a substantial time delay range. Adjustment of the time delay can be effected by a variety of changeable or interchangeable parts and settings.

- The instant invention accordingly provides a new and improved time delay device in combination with a circuit breaker. The breaker incorporates a relay having an armature responsive to current changes in the circuit employing the breaker. The delay device, being associated with the armature, delays armature closing re sponse in accordance with a predetermined time delay. The device generally includes a pair of sealed fluid con-- fining compartments each of which is provided with at least one movable wall. A midsection is positioned intermediate the compartments and isolates one from the Positioned in the midsection is a porous material filter. The filter communicates the compartments with each other. The armature is structurally associated with one of the movable walls in one of the compartments. Therefore, when an overload current causes the relay to build up suflicient magnetic flux to pick up the armature, :he armature is delayed in closing by the delay device mtil transmitted armature force against the movable vall has caused the fluid in the one of the compartments vo be displaced through the filter to the other of the com- :artments. Upon release of the armature, the force tgainst the movable wall is released and the fluid is re :urned to the one of the compartments through a uniiirectional passageway, thus restoring the delay device. An object of the presentinvention is to provide a new and improved time delay device which is readily adjustable to a variety of armature pickup ratings, and to a variety of trip coil current or potential ratings.

Another object of this invention is to provide a circuit breaker with a time relay device for improving the circuit breaker operation, further, providing an improved combination.

Another object of this invention is to provide a new and improved inverse time delay device which is readily adjustable for operation at predetermined current values with predetermined periods of time delay.

Another object of this invention is to provide a time delay device which is insensitive to impurities present in the fluid utilized.

Another object of this invention is to provide a timedelay device which is impervious to erosion and will retain a stable time delay.

Another object of this invention is to provide a new and improved delayed action device with multiple inverse time relationships which are readily adjustable in accordance with predetermined calibrations.

Other objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is a side view in elevation of a circuit breaker embodying the invention, portions of the breaker are broken away to show greater detail;

Fig. 2 is an enlarged side view in elevation showing the series trip coil and its relation to the time delay device wherein the delay device has a cover portion removed and is shown in section;

Fig. 3 is a plan view of the structure shown in Fig. 2;

Fig. 4 is a view in section taken along line IVIV of the structure shown in Fig. 2; and

Figs. 5 and 6 are further modifications of the time delay device and are shown in section.

Referring more particularly to the drawing, Fig. 1 shows a circuit breaker 10 for protecting a circuit (not shown). Breaker 10 may be connected in series with the circuit and must therefore be made large enough to interrupt the maximum currents to be carried by such circuit. Circuit breaker 10 and its component parts are primary fingers 13 which connect breaker 10 with the cir cuit. Upper and lower contact blocks 14, 15 are of like construction, with the lower block 15 being mounted on back panel 11 in a position as viewed in Fig. 1 of the drawing, to the position of upper contact block 14. The bar stud 12 is firmly aflixed to upper contact ner to a trip coil 21. A main finger block 14 to permit limited arcuate movement of main finmanent closing bias for main finger 18. A contact arm 20 1s pivotally mounted on contact block 15 and mechanically and electrically engages main finger 18. Trip coil 21 at one of the coil This current path may be designated as the primary current path which carries substantially full circuit current,

which current is conducted through the breaker from primary fingers 13 to bar stud 12 to contact block 14, through main finger 18 and contact arm 20 to contact block 15 and through the trip coil 21, the bar stud16 and the primary fingers 13, thus completing the primary current path through breaker 10.

A secondary or arcing current path includes an arcing contact arm 24 which is pivotally carried by and mounted on contact arm 20 at a pivot 25. Arcing contact arm 24 may be extruded from a good conducting material, such as copper. An arcing contact 26 is brazed to arcing contact arm 24. The arcing contact 26 is preferably made of silver tungsten alloy which is capable of withstanding high arcing temperatures and currents. A complementary arcing contact 27, which extends into an arc runner 28 is similar in material to arcing contact 26, and is atfixed to and carried by contact block 14.

When breaker 10 is in a closed position (as shown in Fig. l) arcing contact 26 of arcing contact arm 24 is biased by a spring 29 carried by contact arm 20, against arcing contact 27 carried by contact block 14. The contact arm 20 which is integral at its top part 33 is cut apart at its bottom part 34 forming two legs physically and electrically insulated from each other by an insulating washer 35. The secondary or arcing current path receives its current from contact block 14 through arcing contacts 26, 27 flowing down arcing contact arm 24 through the pivot and up a leg of contact arm 20 from the lower part 34 to the upper part 33 thence down contact arm 20 to contact block 15, aiding the primary current path. This secondary current path aids to hold arcing contact arm 24 and contact arm 20 in a closed position because of the electromagnetic force created by the loop type current path.

The spring 19 provided intermediate the main finger and the contact block biases main finger 18 against contact arm 20 when breaker 10 is closed. Another spring 29 exerts force on arcing contact arm 24 to bias arcing contacts 26, 27 in a closed position. An insulating disk 36 is provided intermediate spring 29 and arcing contact arm 24 to electrically insulate one from the other. Another such insulating disk 37 is provided on the arcing contact arm 24 opposing disk 36 to cushion and insulate the opening of contact arm 20.

The series trip coil 21 is shown as part of an overcurrent trip relay 40 which in turn is part of a breaker tripping mechanism 41 of the breaker 10. Trip coil 21 is illustrated as series connected with the circuit and may may also be parallelly connected with the circuit to provide potential responsiveness for breaker operation, as is well known in the art. The trip relay 40 comprises a magnetizable core 42 with trip coil 21 mounted thereon and magnetically coupled therewith. An armature 45, part of relay 40, is pivotally carried by core 42 at pivot 46 and is responsive to electrical changes, either current or voltage, in the circuit. The armature 45 is limited in its open position by a stop pin 47 carried by breaker 10.

Tripping mechanism 41 further includes a time delay device 50 for delaying closing of armature 45. Time delay device 50 is shown in detail in Figs. 2 and 3 and is pivotally carried at pivots 51 by supports 52. The supports 52 are mounted on the breaker 10. Delay device 50 comprises in addition to a casing 53, first and second sealed fluid confining compartments 54, 55 partially defined by casing 53. Each of compartments 54, 5 is provided with at least one movable wall which is shown in the preferred embodiment as resilient diaphragms 56, 57 mounted in the casing and in first and second compartments 54, 55, respectively. A midsection 60 is positioned within the casing 53 intermediate the compartments 5 4, 55, to isolate these compartments from each other. The midsection 60 may be formed in any known manner but is shown formed integral with casing 53. The midsection 60 may be provided with two conduits or passages 61, 62 which connect compartments 54, 55 with each other. A porous filter 63 is disposed in one of the passages 61 in midsection 60. Filter 63 may be made of any known porous material .and is shown in the preferred embodiment as being made of porous metal. The porosity, cross sectional area and length of filter 63 determines the time delay of device 50. Filter 63 may be constructed with various porosities, cross sectional areas and lengths, thereby permitting change of the time delay by changing to a filter of different physical characteristics. In addition, changing of fluid viscosities will permit further changing of time delay.

A means connecting armature 45 with first compartment 54 is shown as a plunger 64 reciprocatingly mounted through casing 53. One end of plunger 64 abuts diaphragm 56 mounted in first compartment 54 and the other end thereof is pivoted at pivot 65 to a cam in an arcuately slotted portion 68 of the armature 45. To provide more positive response of diaphragm 56 to the reciprocation of plunger 64, it has been found advantageous to aflix plunger 64 to diaphragm 56 by any known means. The end of the plunger 64 may be selectively adjusted along the slotted portion 68 to vary the desired time delay.

A means which is operable in one direction only and contained in midsection 60 for returning the fluid from second compartment 55 to first compartment 54 is shown as a ball check valve 69 in passage 62. The ball check valve 69 permits return of fluid through passage 62 only after the pressure is released on plunger 64 by armature 45. Figs. 5 and 6 show, respectively, the use of a more porous filter 63 and a plain passage 62 for return of the fluid, both, however, having a resilient check valve 70 mounted in the first compartment 54.

Armature 45 is biased by a spring 71, against pickup, one end of which engages a knob 72 on the armature 45 and the other end of which is carried by a pickup adjusting structure 75. The pickup adjusting structure 75 is carried by breaker 10 and includes an adjusting member 76 to adjust the spring tension of spring, 71 for increasing or decreasing the amount of flux in the relay 40 needed to pick up armature 45. Moving with and carried by adjusting member 76 is a visual indicator 77 which may be calibrated to indicate the pickup ratings of armature 45 or the amount of tension spring 71 is exerting on armature 45.

A delay device adjusting means 78 is provided to.

aflect movement of plunger 64 along slotted portion 68 of the armature 45. The delay device adjusting means 78 (shown in detail in Fig. 2) includes a handle part 80v which is aflixed to casing 53 of delay device 50 and a slotted adjusting rod 81 which loosely carries handle part 80. A nut 82 is used to adjust initial tension against a rubber washer 83 which is adjacent the handle part 80. A plane surface 84 is carried by adjusting rod 81. Handle part 80 rides upon the plane surface 84. Adjusting rod 81 may be adjusted vertically and is fixed in a selected vertical position by a thumb screw 87 having a captive nut 88 (shown in detail in Fig. 4) both of which are carried by breaker 10 for fixing the adjusting rod 81 in the selected position.

In operation, therefore, when it is desired to selectively vary the time delay, thumb screw 87 is loosened along with captive nut 88, adjusting rod 81 is moved up or down in a vertical direction as viewed in Figs. 1 and 2, thereby pivoting delay device 50 in its supports 52 and repositioning the other end of plunger 64 in slotted portion 68 of armature 45. The thumb screw 87 is thentightened, thereby locking captive nut 88 to breaker 10 when the desired time delay is set.

Armature 45 has. mounted thereon an adjustable screwtripping hammer 90 which initiates operation of tripping mechanism 41 or the means acted upon by the armature for breaking the circuit. Tripping mechanism 41 includes a block 91 which is mounted on a trip shaft 92- journaled in breaker 10. The block 91 is fixed to trip shaft 92 causing the trip shaft to rotate when the block 91 is rotated. A Y-shaped star wheel 93 is pivotally carried by breaker 10. A roller 94 is mounted come of the legs of the star wheel 93 and is in engagement with block 91. A trip rocker 97, having a first and a second rocker arm 98, 99 is pivotally carried by breaker at a pivot 100. Pivotally mounted on first rocker arm 98 is a roller 102 which engages one of the legs of the star wheel 93 in endwise engagement. The second rocker arm 99 has an outer surface 103 eccentrically ground with its geometric center within the rocker 97 but above its pivot 100. Therefore pressure exerted on the outer surface 103 of the second rocker arm 99 will produce a clockwise turning torque (as viewed in Fig. 1) on the rocker 97 about its pivot 100. A cam plate 104 having an arcuate inner cam opening 105 is mounted on breaker 10 and is adjacent rocker 97. An operating arm 106 having a first end 107 and a second end 108, has its first end 107 mounted adjacent cam plate 104. The first end 107 also carries a pin 111 which projects through the cam plate 104 at the inner cam opening 105. The pin 111 has a roller 112 journaled thereon which roller 112 is free to rotate but is firmly held against axial movement by pin 111 and operating arm 106. The roller 112 abuts and engages the outer surface 103 of the second rocker arm 99. A trip latch 113 having a cam surface 121, is pivotally carried by the operating arm 106 at its pin 111. The second end 108 mounts a pivot element 115 for pivotally attaching an insulating arm 116 and a first indicator link 119.

Operating arm 106 has a changing pivot point which shifts from a center point 120 intermediate the ends 107, 108 when the contacts are opened to a point coinciding with the pin 111 of the first end 107 when the contacts are reclosed. A trip pin 114 is mounted on a trip latch bar 122 and engages cam surface 121 of a trip latch 113. Trip latch bar 122 is pivotally mounted on a shaft 123. A cam rider 126 is carried by trip latch bar 122. A spring 127, biasing the trip latch bar 122 and its trip pin 114 against cam surface 121 of trip latch 113, is connected at one end thereof to breaker 10 and the other end thereof is connected to the operating arm 106 intermediate the center point 120 and the second end 108.

A manual reclosing mechanism 130 comprises a handle 131 mounted on a shaft 132 journaled in breaker 10. A closing cam 133 is affixed to shaft 132 and rotates therewith upon rotation of handle 131. Handle 131 is spring biased by a torsion spring 134 which returns the handle 131 to a normal reset position upon release. Cam rider 126 slidingly engages closing cam 133 when the breaker has tripped and the contacts are open. Reclosing is efi'ected by rotating handle 131 whereupon the cam rider 126 follows closing cam 133 and counteracts the bias of the spring 134 to resent the trip pin 114 against cam surface 121, thereby resetting trip latch bar 122.

Insulated arm 116, which is pivotally attached to the second end 108 of operating arm 106, is also pivotally attached at its opposite extremity to contact arm 20 at pivot 135. First indicator link 119 is pivoted at pivot 137 and has a second indicator link 138 pivotally attached at pivot 139. The second indicator link 138 is attached to an open-closed breaker indicator 140 pivotally mounted on pivot 141 carried by breaker 10.

A phase trip indicator 145, shown in Fig. 3 and dotted in Fig. 2, is aflixed to an indicator trip shaft 146 journaled by breaker 10. Phase trip indicator 145 has a latch portion 147 which engages a phase indicator trip pin 148. The phase indicator trip pin 148 is mounted on a phase indicator trip bar 149. As the armature 45 closes, it engages the phase indicator trip pin 148 and disengages the phase indicator trip pin 148 from latch portion 147 freeing phase trip indicator 145. Phase trip indicator 145 is caused to rotate clockwise by its own weight and is aided by a torsion spring 150 mounted on indicator trip shaft 146. The clockwise rotation of phase tripindicator 145 is also aided by a spring 151 (shown in Fig. 3) which also exerts a positive turning action on phase trip indicator 145. A phase trip indicator reset button 155 (Fig. l) is mounted in breaker 10 and for indicating the tripped phase by popping out on tripping and for resetting the indicator 145 by rotating shaft 146. Manual pressure is applied to button 155 and is translated into rotary motion exerted on shaft 146 by links 156, 157 and 158.

The opening of breaker 10 (shown in Fig. 1 in a closed position) which operation is hereafter explained, occurs when overload currents cause the circuit it is protecting to be interrupted.

As a prolonged overload current or a short circuit condition is presented to breaker 10, trip coil 21 presents an increased magnetic flux to relay 40. This increased magnetic flux attracts armature 45 for pickup. However, armature 45 is restrained from pickup by spring 71. Therefore, when the overload current through trip coil 21 is great enough, armature 45 will overcome the tension of spring 71 and pick up. As the armature 45 starts to close it pivots at pivot 46, and exerts a force on the delay device 50. The plunger 64 accepts this force and transmits it to resilient diaphragm 56 in the fluid filled first compartment 54. Diaphragm 56 transmits the force to the fluid which absorbs a part thereof by filtering through porous filter 63 in midsection 60 and into second compartment 55. The time required to force the fluid to pass through porous filter 63 furnishes a time delay in closing of armature 45. When the time delay has been effected and the fluid is in second compartment 55 closing of the armature 45 is completed.

As the armature 45 approaches closing, it engages the phase indicator pin 148 causing it to be dislodged from latch portion 147, thereby dropping phase trip indicator 145 into tripped indicating position.

As pickup of armature 45 is effected, it also causes tripping hammer of armature 45 to engage block 91 and cause block 91 to be rotated counterclockwise a portion of a revolution. The counterclockwise rotation of block 91 causes roller 94 of one of the legs of star wheel 93 to transmit a clockwise rotation to the star wheel 93. As the star wheel 93 rotates clockwise, roller 102 mounted on first rocker arm 98, which roller 102 endwise engages one of the legs of star wheel 93, drops from endwise engagement therewith freeing rocker arm 97 for clockwise rotation about its pivot 100. Roller 112 of operating arm 106 exerts the forces of spring 127 and breaker contact springs 19, 29 against outer surface 103 of rocker arm 97 and further causes a positive clockwise rotation of rocker arm 97. Roller 112 of operating arm 106 becomes disengaged from outer surface 103, thus permitting pin 111 carried by the first end 107 of operating arm 103 to follow the cam opening in cam plate 104. This movement of first end 107 of operating arm 106 permits about the center point 120.

are drawn in the opening of arcing contacts 26, 27 travels upwards toward an arc 7 plates 162 and the addition of a magnetic iron core 164 adjacent the underside of arc runner 28, in combination with the thermal and magnetic conditions caused by the arc, all aid in its extinguishment.

At the same time insulating arm 116 is drawn back to open breaker 10, the first indicator link 119 pivots clockwise about pivot 137 which causes link 119 to act on second indicator link 138 to pivot the open-closed breaker indicator 140 about pivot 141 indicating the open condition of the contacts of breaker 10.

A clockwise rotation of handle 131 of manual reclosing mechanism 130 after pushing the phase trip indicator reset button 155, will restore breaker 10 to a closed position.

The particular embodiment of the invention illustrated and described herein is illustrative only and the invention includes such other modifications and equivalents as may readily appear to those skilled in the art, within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a circuit breaker, a relay having an armature responsive. to current flowing in said relay, a time delay device for said armature comprising a pair of sealed compartments, a fluid in a first of said compartments, a midsection separating said compartments, a nondeforrnable porous. element in said midsection providing restricted communication for said fluid between said compartments, plunger means for forcing said fluid from said first compartment through said porous element to the other of said compartments, means attaching said armature to said plunger to transmit the armature force to said plunger throughout the closing of said armature, means in said midsection blocking communication from said first compartment to said other compartment and providing unrestricted communication from said other compartment to said first compartment, resilient means biasing said armature toward the nonoperated position for determining the magnitude of said current which causes said armature to close.

2. In a circuit breaker, a relay having an armature responsive to current flowing in said relay, a time delay device for said armature comprising a pair of sealed compartments, a fluid in a first of said compartments, a midsection separating said compartments, means including aporous metal element in said midsection providing continuous restricted communication for said fluid between said compartments, plunger means for forcing said fluid from said first compartment through said porous element to the other of said compartments, means adjustably attaching said plunger to said armature to continuously control movement of said armature, separate means in said midsection blocking communication from said first compartment to said other compartment and providing unrestricted communication from said other compartment to said first compartment, resilient means biasing said armature toward the nonoperated position for determining the magnitude of said current which causes said armature to close.

References Cited in the file of this patent UNITED STATES PATENTS 894,910 Scott Aug. 4, 1908 1,138,800 Scott May 11, 1915 1,389,140 Hodgkins Aug. 30, 1921 1,449,025 Wilms Mar. 20, 1923 2,103,378 Oestnaes et a1 Dec. 28, 1937 2,579,334 Plank Dec. 18, 1951 2,702,398 Marcus Feb. 22, 1955 2,740,074 Grifies et al Mar. 27, 1956 FOREIGN PATENTS 642,711 France May 6, 1928 255,872 Great Britain Feb. 10, 1927

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