US2840662A - Contactors - Google Patents

Description

June 24, 1958 RD. JESSEE CONTACTORS Filed Nov. 25, 1955 2 Sheets-Sheet 1 WITNESSES m Fig. 2-.

INVENTQR Ralph D. Jessee.

ATTORNEY June 24, 1958 R. D. JESSEE 2,840,662

CONTACTORS Filed Nov. 25, 1955 I 2 Sheets-Sheet 2 I 14 so 2| o 59 I9 23 54 54 53 6 22 lo 52 Q 75 7? 58 Fig 3.

Jo Generator 4B 7 Load Bus 52 2 To Proud": Relays To Protective Relays nited States Patent Ofifice 2,840,662 Patented June 24, 1958 CONTACTORS Ralph D. Jessee, Lima, Ohio, assiguor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 25, 1955, Serial No. 549,026 7 Claims. (Cl. 200-406) My invention relates, generally, to contactors and, more particularly, to a contactor suitable for utilization in a system for controlling and protecting a direct-current generator which operates in parallel with other generators such as, for example, contactors of the type described in a copending application of B. 0. Austin, Serial No. 411,469, filed February 19, 1954, now Patent No. 2,821,666, issued January 28, 1958.

The contactor described in the aforesaid copending application has contact members which are actuated to the closed position by a closing magnet and held in the closed position by a holding magnet. The aforesaid contactor also has tripping means for releasing the contact actuating element of the contactor independently of the holding coil to effect opening of the contacts in a shorter time than is required for the contacts to be opened by deenergization of the holding magnet.

An object of my invention is to improve the operation of a contactor of the type described in the aforesaid copending application.

A more specific object of my invention is to prevent chattering of the contactor during closing of the contact members.

Other objects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of my invention, the closing lever and the holding lever of a contactor of the type referred to above are made of different lengths and the pivot points for these levers are so located that the arcs of movement of the levers intersect. Thus, the latch, which is carried by the closing lever to lock it to the holding lever when both levers are in their closed position, is disengaged when the levers are moving toward their open position, so that the holding lever returns to its closed position and is held there by a spring, while the closing lever continues to the open position. When the contactor is to be closed, the closing coil and the holding coils are energized. The closing coil moves the closing lever to closed position and the latch engages the holding lever to hold the contactor closed. Once the contactor is latched in, it stays latched until it is either tripped out by a trip magnet or released by deenergizing the holding coil.

For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure l is a view, in plan, of a contactor embodying the principal features of the invention;

Fig. 2 is a view, partly in side elevation and partly in section, of the contactor;

Fig. 3 is a view, in section, taken along the line Ill-4H in Fig. 2; and

Fig. 4 is a diagrammatic view of the contactor and a portion of a control system in which it may be utilized.

Referring to the drawings, and particularly to Figs. 1, 2 and 3, the contactor shown therein comprises an insulating base on which a closing lever assembly 11 and a holding lever assembly 12 are pivotally mounted. The closing lever assembly 11 is pivoted on vertical supports 13 by means of a pivot pin 14 which extends through the spaced supports 13. The assembly 11 comprises two spaced side members 15 which are joined by cross members 16 and 17. A compression spring 18 is disposed between the cross member 16 and a horizontal support 19. The spring 18 biases the lever assembly 11 in a counterclockwise direction about the pivot pin 14.

The holding lever assembly 12 comprises two spaced side arms 21 which are pivoted on horizontally extending bracket arms 22 by means of pivot pins 23. The side arms 22 are joined together by a transverse member 24. T he arms 21 have laterally extending projections 25 thereon. An angular latch bar 26 is mounted between the ends of the arms 21 on the transverse member 24. Armature members 27 are slidably mounted on pins 28 which extend through the extensions 25. A compression spring 29 is disposed between each armature member 27 and the extension 25. A guide pin 31 also extends through the extension 25 into the armature member 27. The springs 29 provide a cushion for the armature members 27 upon closing of the holding lever 12. They also provide a means for positioning the holding magnet armatures 27 so that they will lie flat on holding magnet pole pieces 32 and 33.

A latch member 35 is pivotally mounted between the side members 15 on a pivot pin 36. The latch member 35 is positioned to engage the latch bar 26 under predetermined conditions to latch the lever assemblies 11 and 12 together. A tension spring 37 has one end connected to the latch bar 26 and the other end connected to a bracket 38 which is attached to the base 10. The spring 37 functions to normally retain the holding lever assembly 12 in the closed position, as will be explained more fully hereinafter. v

The contactor is actuated to closed position by means of a closing coil 40 contained in a housing 41 on the base 10. The coil 40 has a stationary core 42 and a movable armature 43 attached to a plunger 44 which extends through a central passage in the core 42. A spring 45 may be provided to adjust the force required to actuate the armature. A cap 46 is placed on the upper end of the plunger 4 in position to engage a platform 47 extending between the ends of the side members 15 of the lever assembly 11. It will be seen that when the coil 40 is energized the armature 43 is drawn towards it and raises the plunger 44 and cap 46, thereby moving the lever assembly 11 in a clockwise direction about the pivot 14 to actuate the contactor to closed position against the opposing force of the spring 18. The latch 35 engages the latch bar 26 when the lever assembly 11 is in the fully closed position.

The contactor is held in closed position by means of a holding coil 48 which is preferably divided into two series-connected coils 48 and 48' carried on the pole pieces 32 and 33 on opposite sides of the lever assembly 12 to cooperate with the armature members 27. Thus, when the holding coils are energized, the contactor is held in its closed position and the closing coil 40 can be deenergized.

A trip coil 49 is mounted on the platform 47 to actuate the latch member 35. Any suitable means may be utilized for this purpose and, as shown in the drawings, a rod 50 is provided which is connected to the latch member 35 and moved longitudinally when the coil 49 is energized. A compression spring 51 is placed on the rod 50 to normally hold the latch in the position shown in Fig. 2 where it will engage the latch bar 26 when the lever assembly 11 is actuated to its closed position.

It will be seen that when the coil 49 is energized, the rod 50 is moved longitudinally against the force of g the spring 51 to move the latch 35 about its pivot and release the lever assembly 11 from the lever assembly 12, so that the lever assembly 11 is moved by the spring 18 to the open or tripped position of the contactor even though the holding lever 12 is still held in the closed position by the holding coil 48 as shown in Fig. 2.

The contactor has two identical sets of main contacts mounted on the base It on opposite sides of the lever assembly 12. As shown most clearly in Figs. 2 and 3, each set of main contacts comprises a stationary contact 52 mounted on the base and a cooperating movable contact 53. The movable contact 53 is mounted on a conducting clamping member 54 and a heavy flexible conductor 56 which may, for example, be braided copper, is clamped between the clamping members 54 and an upper clamping member 55. The clamping members 54 and 55 with the conductor 56 clamped between them are movably mounted on guide pins 57 on the base 10 and are supported on springs 58 which bias the contacts apart. The upper clamping member 55 is molded of insulating material and has a central hollow projection 59 which contains a contact actuating button 60 supported on a spring 61. The button 60 is preferably composed of insulating material.

The contacts 53 are actuated to closed position by means of buttons 63 carried on a transverse member 64 on the lever assembly 11. When the lever assembly 11 is moved clockwise about the pivot pin 14 by energization of the coil 40, the buttons 63 engage the contact actuating buttons 60 and move the main contacts 52 and 53 into engagement. The movable contacts 53 of the two sets of main contacts are connected in series by'the conductor 56 which extends across the base 10. p

In order to provide for the interruption of relatively heavy currents, arcing tips 66 are provided on the extreme end of the lever arms 15, preferably being mounted on the lever by springs 65. The arcing tips 66 are dis posed to engage fixed contacts 67 on the base 10 and are disposed within arc boxes 68 of any desired type. The arcing tips 66 and contacts 67 are electrically connected in parallel-circuit relation with the main contacts. Thus, when-the main contacts are separated, the current is transferred to the arcing tips and interrupted in the arc boxes 68. This arrangement makes it possible to construct the contactor in the manner shown in the drawings with a very short travel for the main contacts, which permits the use of high operating forces for the main contacts to minimize contact resistance when the contacts are closed and to prevent freezing of the contacts. However, the arcing tips have relatively long travel, thereby providing considerable spacing between the arcing contacts to facilitate interrupting arcs and, consequently, high currents are readily interrupted.

As previously described, the contactor is closed by energizing the closing coil 40 which moves the lever assembly 11 to actuate both sets of contacts 52 and 53 to closed position. The contactor is held in this position by energizing the holding coil 48 which holds the lever assembly 12 in its closed position after the closing coil 40 is deenergized. As previously explained, the latch 35 engages the latch bar 26 when the lever assembly 11 is actuated to its closed position to lock the two lever assemblies together. The main contacts are opened by deenergizing the holding coil 48 to permit the spring 1% to move both lever assemblies 11 and 12 in a counterclockwise direction. The main contacts may also be opened by energizing the trip coil 49 to release the latch 35 and permit the lever assembly 11 to move in a counterclockwise direction to its open position independently of the lever assembly 12. The holding coil 48 is pref erably so designed that it has a relatively high time constant as compared with the coil 49 so that the contacts are opened much more rapidly by energization of the trip, coil 49 thanthey are. by deenergization of the coil 48 and substantially instantaneous tripping is thereby obtained.

The contactor is also provided with auxiliary contacts 69 and 76 which may be mounted on opposite sides of the housing 41 of the closing coil, as shown most clearly in Fig. l. The auxiliary contacts may be of any suitable type and have not been shown in detail. The auxiliary contacts are actuated by contact buttons 71 disposed to be engaged by actuating buttons 72 carried by the platform 47. Therefore, the auxiliary contacts are actuated whenever the contactor is opened or closed. When the contactor is to be used in the manner disclosed in the above-mentioned copending application, the auxiliary contacts are so arranged that the contact 69 is a normally open contact and the contact is a normally closed contact, as indicated in Fig. 4. However, it will be understood that any suitable contact arrangement may be used.

A polarized relay 75 is mounted on the base 10 in a central recess 76 formed in the base. The polarized relay 75 may be of any suitable type and is shown as comprising a magnetic circuit 77 and an operating coil 78 with a contact assembly generally indicated at 79. The relay 75 is mounted on the base 10 between the two main contact assemblies, and the flexible conductor 56, which connects the movable contacts, passes through the magnetic circuit 77 of the relay and is arranged to cooperate with it so that the relay may be actuated by current flowing in the conductor 56. The relay 75 is preferably so adjusted that it responds to a higher value of current in the conductor 56 than in the main operating coil 78, when the relay is to be used as part of a control system for the contactor as shown in Fig. 4.

It has been found that operation of contactors of this general type, as described in the aforesaid copending application, may be somewhat impaired by failure of the holding magnets to hold the main contacts in the closed position when the contactor is operated at some voltages within its operating range, resulting in chattering of the contactor. In the structure of the previous application, when the contactor was almost closed the circuit for the closing coil 40 was opened by auxiliary contacts 70 and at the same time the holding magnet armature closed the holding magnet air gap, thereby increasing the inductance of the circuit for the holding coil 48. This increase in inductance reduced the holding coil current, which reduced the holding magnet force at the time that the force was required to seal in the contacts of the contactor. The return spring 18, therefore, began to open the main contacts, and auxiliary contact 70 reclosed, beginning the cycle once more, thereby causing the chattering of the contactor.

In order to overcome the foregoing deficiency, I have provided a means for preventing the cycling operation. As previously explained, in the present structure, the holding lever assembly 12 is normally in the closed position and is retained in this position by the spring 37. The pivot point 23 for the lever assembly 12 is separated from the pivot of the lever 11 and is positioned near the midpoint of the lever arms 21 and below a line joining the pivot point 14 and the latching point 26 when the contactor is closed.

As shown by the arcs 11' and 12 in Fig. 2, the radius of movement of the lever 12 is shorter than the radius of movement of the lever 11. Furthermore, the pivot points for these levers are so located that the arcs of movement intersect. Therefore, the latch 35 is disengaged from the latch bar 26 at substantially the point of intersection of the arcs of movement when the two lever assemblies are moving together toward the opened position. The disengagement of the latch 35 from the latch bar 26 permits the holding lever 12 to return to the closed position while the closing lever 11 continues to its fully opened position. As previously explained, the holding lever 12 is biased to its closed position by the spring 37.

When voltage is applied to the contactor circuit, which may be done from a line 87 by means of a contact 88 of the polarized relay 75, as shown diagrammatically in Fig. 4, the closing coil 40 and the coil 48 are both energized. The closing magnet 40 closes the contactor and the latch engages the latch bar 26. Since the holding magnet is already in its closed position, there is no change in the inductance of the holding coil circuit and there is no change in the holding coil current when the contactor closes. Consequently, there is no decrease in the force of the holding magnet. Therefore, once the contactor latches in it stays latched in until it is either tripped out by the trip coil 49 or released by deenergizing the holding coil 48.

As previously explained, the trip mechanism disengages the latch 35' while the holding magnet remains closed, thereby permitting the main contacts of the contactor to open. Removal of contactor circuit voltage releases the holding magnet, permitting both lever assemblies to move toward the open position. As previously explained, the lever assembly 12 rotates on a shorter radius than does the lever assembly 11 and the latch 35 is disengaged from the latch bar 26 at the point of intersection of the arcs of movement of the two lever systems. The lever assembly 12 returns to its closed position and the contactor is ready for its closing operation.

The contactor described herein is especially adapted for connecting a generator to a load bus, as shown in Fig. 4, and numerous protective relays are provided in the control system, as shown in the above-mentioned copending application, to control the operation of the contactor to protect the generator and the system from faults and other abnormal conditions. In the interest of simplicity, these relays are not shown in the present application. The contactor shown and described in this application functions under the control of these relays in the manner described in the aforesaid application.

From the foregoing description, it is apparent that I have provided an improved contactor which is particularly suitable for utilization in aircraft electrical systems. However, the present contactor is not necessarily limited to utilization in such systems and it may be utilized in other electrical systems.

Since numerous changes may be made in the abovedescribed construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a contactor, in combination, a base, a closing lever pivotally mounted on the base, contact means actuated to the closed position by movement of said lever, a closing coil for actuating said lever in a direction to close said contact means, spring means for biasing the lever in the other direction, a holding lever pivotally mounted on the base, latch means for latching said levers together when the latch means engages the holding lever, a holding coil for retaining both levers in the closed position when the latch means is engaged, said spring means actuating both levers toward the open position when both coils are'deenergized, and the pivot point for the holding lever being located substantially midway between the pivot for the closing lever and the latching point so that the latch means is disengaged during movement of said levers toward the open position.

2. In a contactor, in combination, a base, a closing lever pivotally mounted on the base, contact means actuated to the closed position by movement of said lever, a closing coil for actuating said lever in a direction to close said contact means, spring means for biasing the lever in the other direction, a holding lever pivotally mounted on the base, latch means for latching said levers together when the latch means engages the holding lever,

a holding coil for retaining both levers in the closed position when the latch means is engaged, said spring means actuating both levers toward the open position when both coils are deenergized, and the pivot point for the holding lever being located substantially midway between the pivot for the closing lever and the latching point so that their arcs of movement intersect to cause the latch means to be disengaged during movement of said levers toward the open position.

3. In a contactor, in combination, a base, a closing lever pivotally mounted on the base, contact means actuated to the closed position by movement of said lever, a closing coil for actuating said lever in a direction to close said contact means, spring means for biasing the lever in the other direction, a holding lever pivotally mounted on the base, latch means for latching said levers together when the latch means engages the holding lever, a holding coil for retaining both levers in the closed position when the latch means is engaged, said spring means actuating both levers toward the open position when both coils are deenergized, the pivot point for the holding lever being located substantially midway between the pivot for the closing lever and the latching point so that the latch means is disengaged during movement of said levers toward the open position, and a spring for returning the holding lever to the closed position after the latch means is disengaged.

4. In a contactor, in combination, a base, a closing lever pivotally mounted on the base, contact means actuated to the closed position by movement of said lever, a closing coil for actuating said lever in a direction to close said contact means, spring means for biasing the lever in the other direction, a holding lever pivotally mounted on the base, said levers having different radii of movement, latch means for latching said levers together when the latch means engages the holding lever, a hold ing coil for retaining both levers in the closed position when the latch means is engaged, said spring means actuating both levers toward the-open position when both coils are deenergized, and the pivot point for the holding lever being located substantially midway between the pivot for the closing lever and the latching point so that the latch means is disengaged during movement of said levers toward the open position.

5. In a contactor, in combination, a base, a closing lever pivotally mounted on the base, contact means actuated to the closed position by movement of said lever, a closing coil for actuating said lever in a direction to close said contact means, spring means for biasing the lever in the other direction, a holding lever pivotally mounted on the base, latch means for latching said levers together when the latch means engages the holding lever, a holding coil for retaining both levers in the closed position when the latch means is engaged, said spring means actuating both levers toward the open position when both coils are deenergized, the pivot point for the holding lever being located substantially midway between the pivot for the closing lever and the latching point and so disposed that the latch means is disengaged during movement of said lever toward the open position, and a spring for biasing the holding lever toward the closed position.

6. In a contactor, in combination, a base, a closing lever pivotally mounted on the base, contact means actuated to the closed position by movement of said lever, a closing coil for actuating said lever in a direction to close said contact means, spring means for biasing the lever in the other direction, a holding lever pivotally mounted on the base, latch means carried by the closing lever for latching said levers together when the latch means engages the holding lever, a holding coil for retaining both levers in the closed position when the latch means is engaged, said spring means actuating both levers toward the open position when both coils are deenergized, and the pivot points for said levers being so located that 7 the latch means is disengaged during movement of said levers toward the open position.

7. In a contactor, in combination, a base, a closing lever pivotally mounted on the base, contact means actuated to the closed position by movement of said lever, a closing coil for actuating said lever in a direction to close said contact means, spring means for biasing the lever in the other direction, a holding lever pivotally mounted on the base, latch means carried by the closing lever for latching said levers together when the latch means engages the holding lever, a holding coil for retaining both levers in the closed position when the latch means is engaged, said spring means actuating both levers toward the open position when both coils are deenergized, the pivot points for said levers being so located that the latch means is disengaged during movement of said levers toward the open position, tripping means for releasing said latch means to permit the closing lever to move to the open position independently of the holding lever, and a spring for retaining the holding lever in the closed position.

References Cited in the file of this patent UNITED STATES PATENTS 872,400 Andersen Dec. 3, 1907 1,286,101 Randall et al Nov. 26, 1918 2,543,398 Bohn Feb. 27, 1951 FOREIGN PATENTS 457,174 Germany Mar. 9, 1928 665,040 Germany Sept. 14, 1938

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