US3288964A - Spring trip multi-phase overload relay having a u-shaped bimetal with a pivot pin at its web portion - Google Patents

Description

Nov. 29, 1966 J. B. CATALDO ET AL 3,23

SPRING TRIP MULTI-PHASE OVERLOAD RELAY HAVING A U-SHAPED I BIMETAL WITH A PIVOT PIN AT ITS WEB PORTION Filed June 1. 1965 5 Sheets-Sheet 1 Nov. 29, 1966 J. B. CATALDO ET AL S PRING TRIP MULTI-PHASE OVERLOAD RELAY HAVING A U-SHAPED BIMETAL WITH A PIVOT PIN AT ITS WEB PORTION 5 Sheets-Sheet 2 Filed June 1, 1965 Nov. 29, 1966 J. B. CATALDO ET 3,283,954

SPRING TRIP MULTI-PHASE OVERLQAD RELAY HAVING A U-SHAPED BIMETAL WITH A PIVOT PIN AT ITS WEB PORTION Filed June 1, 1965 5 Sheets-Sheet 5 Nov. 29, 1966 J. B. CATALDO ET 3,

SPRING TRIP MULTI-PHASE OVERLOAD RELAY HAVING A U-SHAPED BIMETAL WITH A PIVOT PIN AT ITS WEB PORTIQN Filed June 1, 1965 5 Sheets-Sheet 4 Nov. 29, 1966 J. B. CATALDO ET L 3,238,964

SPRING TRIP MULTI-PHASE OVERLOAD RELAY HAVING A U-SHAPED BIMETAL WITH A PIVOT PIN AT ITS WEB PORTION Filed June 1, 1965 5 Sheets-Sheet 5 United States Patent f SPRING TRIP MULTl-PHASE OVERLOAD RELAY HAVING A U-SHAPED BlMETAL WITH A PIVOT PIN AT ITS WEB PORTIUN John B. Cataldo, Bloomfield Hills, Elwood T. Platz, Grosse Pointe, Frank W. Kussy, Birmingham, and Bernard Di Marco, Lincoln Park, Mich, assignors to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed .lune 1, 1965, Ser. No. 460,204 15 Claims. (Cl. 200-116) In general the instant invention relates generally to overload relays of the type combined with electro-magnetic contactors to form motor controllers and in particular relates to a multi-phase overload relay of this type having spring trip means for separating the cooperating contacts of the coil energizing circuit upon the occurrence of overload conditions in any of the phases.

Copending application Serial No. 225,044 filed September 20, 1962, entitled Overload Relay for Motor Starters with Robert W. Thomas et al. as inventors and assigned to the assignee of the instant invention, discloses a single phase overload relay. For multi phase operation two or more such single phase relays are combined with an electro-magnetic contactor. It often happens that for multi phase applications, rather than utilizing a plurality of single phase overload relays it has been found advantageous to utilize a single so-called block-type relay.

In essence, a block type overload relay is a unit providing individual bimetal elements for detecting fault conditions in two or more of the phases to be protected. The block type overload relay is so constructed that upon the occurrence of an overload in any of the phases the bimetal of that particular phase will operate to open a pair of cooperating contacts in the energizing circuit of the contactor coil thereby deene-rgizing the contactor.

Prior art block type overload relay constructions have either been unduly complicated and/or the bimetals of each phase were unduly influenced by the heaters of the other phases. To overcome these disadvantages of the prior art the instant invention provides a relatively simple construction in which the influence between the heaters of different phases is reduced by placing the bimetal for each phase in a separate pocket and separating the pockets from one another by air spaces. The undesirable effects of heating in adjacent spaces is further reduced by mounting the bimetals in a manner such that they are in minimum surface engagement with the housing so as to avoid heat conduction. 'Bimetal heating influence between phases is still further reduced by having each bimetal actuate its own over-center spring with the latter operating upon a common trip bar.

Accordingly, a primary object of the instant invention is to provide a novel construction for a so-called block type multi-phase overload relay.

Another object is to provide an overload relay of this type in which the affects of heating in one phase are reduced in the other phase.

Still another object is to provide an overload relay of this type having a common adjusting bar and a common trip bar.

A further object is to provide a novel overload relay of this type in which each pole is in line with the corresponding load terminal of the contactor so that a mechanical connect-ion from the overload relay to the contactor straps automatically becomes an electrical connection.

A still further object is to provide a novel overload relay of this type which requires no more than two parts to form the housing for all phases together as well as the switching and resetting elements.

These as well as other objects of this invention shall 3,288,964 Patented Nov. 29, 1966 become readily apparent after read-ing the following description of the accompanying drawings in which:

FIGURE 1 is a perspective of a block type overload relay constructed in accordance with the teachings of the instant invention.

FIGURE 2 is a front elevation of the overload relay of FIGURE 1.

FIGURE 3 is an end view of the overload relay of FIGURE 1.

FIGURES 4, '4, 6, and 7 are cross-sections taken through the respective lines 4-4, 55, 66 and 77 of FIGURE 2 looking in the directions of the respective arrows. In this group of figures only the structural elements being described in detail are shown, the other elements having been removed to avoid confusion.

FIGURE 8 is a perspective of a tripping spring and its mounting member together with the element engageable with this spring for tripping thereof.

FIGURE 9 is a perspective of the common adjusting bar.

FIGURE 10 is a perspective of the common trip bar.

FIGURE 11 is a perspective show-ing the front of the housing cover and the elements mounted thereto.

Now referring to the figures. Block type overload relay 15 is a three phase unit typically of such a size as to be used in conjunction with contactor 16, partially shown in FIGURES 4 and 7, to form a motor starter. For a detailed description of contactor 16 reference is made to the Cataldo et al. copending application Serial No. 189,915 filed April 24, 1962, entitled Electrical Device and assigned to the assignee of the instant invention.

Overload relay 15 is provided with a housing consisting of hollow base 17 and plate-like rear cover 18 mated along line 19 and secured together by means of screws (not shown). Essentially base 17 is divided into a series of parallel compartments. That is, there are three main compartments, one for each of the current carrying phases of overload relay 15 The main compartments are separated by two narrower compartments which house the automatic reset lock element 21 and the manual reset plunger 22 respectively. It is noted that extensive portions below these narrow compartments are void of mechanism so as to provide dead air spaces between the main compartments thereby reducing the heat transfer between these main compartments. The right side of base 17 with respect to FIGURE 2 is formed as a narrow short compartment 23 which houses the main and signalling contacts 51, 54, 56.

Since the current carrying elements of all three phases are identical, only those current carrying elements associated with phase A (the left of FIGURE 2) will be described. This current path consists of line terminal strap 25, U-shaped bimetal heater 26, load terminal strap 27 and wire grip 27a. Line terminal strap 25 is a generally L-shaped member having a vertical leg riveted or otherwise suitably secured to the front side of cover 18 and positioned between the upwardly protruding barriers 28a, 2%. Screw 29 removably secures one leg of bimetal heater 26 to the horizontal leg of line terminal 25 while screw 38 secures the other leg of bimetal heater 26 to a generally horizontal portion of load terminal 27. Rivets 31 (FIGURE 2) secure a vertical portion of load terminal 27 to the front surface of base 17.

Heater 26 is positioned between the arms of U-shaped bimetal 33 which is pivotally mounted to base 17 by means of pin 34. The ends of pin 34 extend beyond the sides of bimetal 33 and are received in pivot defining apertures in the arms of U-shaped retaining member 35. The latter is received by suitable formations of base 17 and retained in operative position by forward protrusion 36 of cover 18 which engages the web portion of member 35 (FIGURE 4). The free end of bimetal calibrating leg 33a abuts the rear end of calibration screw 37 with the latter being threadably mounted to the downward radial extension 38a of common adjusting bar 49. The head of screw 37a is aligned with front aperture 39a of base 17 so as to be accessible for adjustment of bimetal 33.

The free end of bimetal tripping leg 33b is positioned to engage the forward edge of member 41. More particularly, when heater 26 is subjected to overload current the heat generated thereby causes the free ends of the bimetal legs to diverge. Movement of calibrating leg 33a is restricted by calibration screw 37 so that movement is limited to tripping leg 33b with the latter moving to the left with respect to FIGURE 4 thereby moving member 41 in a generally horizontal path defined by slots in base 17. When member 41 engages center leg 42a of bistable spring trip member 43 the latter is movable from the solid to dotted line position of FIGURE 4. Leg 42a is positioned between legs 42b and 42c. The latter two legs are riveted near the free end thereof to the forwardly offset leg of mounting member 45 with member 45 being fixedly secured to the forward surface of cover 18.

In a manner well known to the art, as legs 42b and 420 are secured to member 45 appropriate stresses are set up in member 43 to permit the latter to be operated between two bistable positions. That is, when leg 42a is moved to the left, in a counter-clockwise direction with respect to FIGURE 4, as leg 42a moves just slightly to the left of legs 42b and 420 the bistable characteristics of spring member 43 causes leg 42a and the upward extension 43a thereof to move with a snap action in the clockwise direction with respect to FIGURE 4.

As this movement takes place extension 43a engages radial projection 47a of common trip bar 50 thereby pivoting bar 50 in a clockwise direction with respect to FIGURE 4 and a counter-clockwise direction with respect to FIGURE 7. This motion of common trip bar 50 is effective to move its radial switch arm 51 from its solid line position of FIGURE 7 to the dotted line position thereof. The free end of switch arm 51 mounts contact member 99 which is connected at its upper end to current carrying spring member 52 extending downwardly from U-shaped terminal member 53. In the solid line position switch arm 51, contact 98 carried by member 99 is in engagement with main contact 54 secured to the lower leg of Z-shaped terminal member 55 while in the dotted line position for switch arm 51, contact 97 carried by member 99 is in engagement with signalling contact 56 mounted to the lower end of offset terminal strap 57. As illustrated in FIGURE 7, with switch arm 51 in its solid line position the contactor coil energizing circuit is completed through the electrical connection provided by L-shaped conducting strap 58 connecting terminal strap 55 to coil terminal 59 of contactor 16. With switch arm 51 in the dotted line position of FIGURE 7 it may be utilized to control a signalling circuit which indicates that tripping has taken place.

In a manner well known to the art, common trip bar 50 extends through all phases A-C of overload relay 15 and is positioned by means of appropriate recesses in the partitions defining the chambers in base 17 in cooperation with forward projections 61 of cover 18. Similarly, adjusting bar 40 extends through the three main compartments and is positioned by cut-outs in the walls of base 17 defining these compartments. Insulating cover strip 62, retained in position by the overlapping vertical portions of terminal member 27, prevents forward movement of common adjusting bar 40. Wire spring 63 (FIGURE biases bar 40 in a counter-clockwise direction with respect to FIGURES 4 and 5 so that the long radial extension 3811 of bar 40 remains firmly seated against the rear end of adjusting screw 65.

In order to calibrate overload relay the head of adjusting screw 65 is positioned with the protrusion thereof pointing to 100 as seen in FIGURE 2. Thereafter, the calibration screws 37 for each of the phases A, B and C are individually adjusted so that the respective bimetals 33 are positioned to bring about tripping under predetermined overload conditions. Apertures 39 are then blocked by sealing compound so that calibrating screws 37 may not be tampered with in the field. Field adjustment for overload relay 15 takes place by means of adjusting screw 65 which is limited to a rotation of slightly less than one revolution because of the engagement of head protrusion 65a with base surfaces 66a, 6612.

After tripping has taken place reset slide 22 is utilized for manually operating one or more of the spring trip members 43 to their solid line positions illustrated in FIGURE 4. That is, the lower edge of reset slide 22 is provided with inclined surface 22a which, upon downward movement of reset slide 22, engages common trip bar radial projection 67 causing the latter to move to the left with respect to FIGURE 5 and in so doing rotating common trip bar 50 in a counter-clockwise direction. This brings trip bar projection 4711 into engagement with spring member projection 43a causing the latter to rotate in a counter-clockwise direction with respect to FIGURE 4 thereby operating leg 42 to the solid line position illustrated in FIGURE 4. Spring 68, retained by screw 69, urges reset slide 22 to its upper position illustrated in FIGURE 5.

Automatic reset member lock 21, as best seen in FIG- URES 2 and 6, is selectively positioned in one of two setting member 22.

positions depending on which bulge in slot 21a screw 70 extends through. With lock 21 in its lower position as illustrated automatic reset member 72 is disposed so that overload relay 15 will automatically reset after tripping. That is, lock 21 acts to hold member 72 against the force of its biasing spring 73 to the position shown in FIGURE 6. This positions member 72 in the path of common tripping bar projection 74 to limit pivotal movement of tripping bar 50 to a position such that spring trip member 43 does not move over center in the tripping direction. Accordingly, after a tripping operation has taken place, as bimetal 33 cools trip member 43 will automatically move to its solid line position illustrated in FIG- URE 4 thereby permitting contact arm 51 to engage main contact 54 without the necessity of utilizing manual re- Obviously, with reset member lock 21 raised, spring 73 moves member 72 to the right with respect to FIGURE 6 to a position clear of projection 74 so that trip members 43 are free to snap over center to the trip position.

It is noted that the line terminals 25 of overload relay 15 are positioned substantially in line with the load terminals of contactor 16. Thus, terminals 25 may readily be mechanically and electrically connected to the load terminals of contactor 16 by utilizing three offset straps 99 (FIGURE 4). Further, by simply utilizing L-shaped strap 58 the terminal member 55, carrying main contact 54, may readily be connected to terminal 59 extending from one of the terminals of the contactor coil.

Thus, this invention provides an improved block type overload relay of relatively simple construction. This relay is provided with a generally U-shaped bimetal pivotally mounted at the web of the U with one of the U- arms being utilized for calibrating purposes and the other U-arm being utilized to actuate a spring trip means. Individual calibrating means are provided for each phase while a common adjusting bar is utilized for field adjustments. Further, a common tripping bar is utilized so that only a single set of contacts connected in the contactor coil circuit are necessary.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. An overload protective device including an electric heater, a generally U-shaped bimetal element having spaced arms connected by a Web portion, said bimetal element mounted in spaced relation with respect to said heater and in close proximity thereto so that heat generated by current fiow through said heater heats said bimetal element causing said arms to diverge, pin means pivotally mounting said bimetal element at said web portion, calibrating means engageable with one of said arms, overcenter means, the other of said arms, upon predetermined deflection thereof engaging and thereby actuating said overcenter means, and contact means operable by said overcenter means upon actuation thereof.

2. A multiphase overload protective device including for each of said phases an electric heater, a generally U- shaped bimetal element having spaced arms connected by a web portion, said element mounted in spaced relation with respect to said heater and in close proximity thereto so that heat generated by current flow through said heater heats said bimetal element causing said arms to diverge, pin means pivotally mounting said bimetal element at said Web portion, calibrating means engageable with one of said arms; a common adjusting member, said calibrating means of all phases mounted to said common adjusting member; main contact means; a common tripping member connected to said contact means for operation thereof; the other arm of each of said elements being connected for operation of said tripping member upon the occurrence of predetermined heating of any of said bimetal elements.

3. A device as set forth in claim 1 in which the heater extends between the arms of said element.

4. A device as set forth in claim 3 in which the heater is a generally U-shaped member whose arms are positioned generally parallel to the arms of said element.

5. A device as set forth in claim 2 also including an insulating housing having partition means defining an individual main compartment for each of said phases, each of said main compartments having disclosed therein an individual one of said heaters and an individual one of said bimetal elements, said main compartments being separated from one another by air spaces so as to reduce heat conduction between phases.

6. A device as set forth in claim 5 also including a manual resetting means positioned between a first and a second of said main compartments and an automatic resetting means positioned between said second main compartment and a third of said main compartments.

'7. A device as set forth in claim 6 in which the housing also defines another compartment wherein said contact means is disposed.

8. A device as set forth in claim 5 in which the housing is constituted by a rear cover and a hollow base having a generally closed front and an open back, an adjusting element for selectively positioning said adjusting mem ber, said adjusting element positioned so as to be accessible for operation from the front of said base.

9. A device as set forth in claim 5 in which said adjusting member is a pivotally mounted rod having an individual radial extension projecting into each of said main compartments, each of said calibrating means mounted to an individual one of said extensions.

10. A device as set forth in claim 5 in which for each of said phases there also is a spring trip means interposed between said other arm of said bimetal element and said common tripping member.

11. A device as set forth in claim 10 in which each of the spring trip means includes a bistable overcenter mechanism.

12. A device as set forth in claim 11 in which said tripping member is a pivotally mounted rod having an individual radial projection engageable by an individual one of said spring trip means, said rod also having an additional projection for operating said contact means.

13. A device as set forth in claim 12 in which said adjusting member is another pivotally mounted rod, each of said calibrating means mounted to an individual radial extension of said another rod.

14. A device as set forth in claim 13 also including biasing means urging said another rod to pivot in a first direction and an adjusting element positioned to limit movement of said another rod in said first direction.

15. A device as set forth in claim 14 also including an insulating housing having partition means defining an individual main compartment for each of said phases, each of said main compartments having disposed therein an individual one of said heaters and an individual one of said bimetal elements, said main compartments being separated from one another by air spaces so as to reduce heat conduction between phases.

No references cited.

BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWITTER, Assistant Examiner.

Claims (1)

1. AN OVERLOAD PROTECTIVE DEVICE INCLUDING AN ELECTRIC HEATER, A GENERALLY U-SHAPED BIMETAL ELEMENT HAVING SPACED ARMS CONNECTED BY A WEB PORITON, SAID BIMETAL ELEMENT MOUNTED IN SPACED RELATION WITH RESPECT TO SAID HEATER AND IN CLOSE PROXIMITY THERETO SO THAT HEAT GENERATED BY CURRENT FLOW THROUGH SAID HEATER HEATS SAID BIMETAL ELEMENT CAUSING SAID ARMS TO DIVERGE, PIN MEANS PIVOTALLY MOUNTING SAID BIMETAL ELEMENT AT SAID WEB PORTION, CALIBRATING MEANS ENGAGEABLE WITH ONE OF SAID ARMS, OVERCENTER MEANS, THE OTHER OF SAID ARMS, UPON PREDETERMINED DEFLECTION THEREOF ENGAGING AND THEREBY ACTUATING SAID OVERCENTER MEANS, AND CONTACT MEANS OPERABLE BY SAID OVERCENTER MEANS UPON ACTUATION THEREOF.

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