MXPA00002745A - Circuit breaker handle block - Google Patents

Abstract

A circuit breaker having a crank (12) for coupling a switching mechanism to the contact pole structure (15) is presented. The crank (12) has a pair of cam surfaces (12U, 12L) which cooperate with a blocking lever (14) to restrict movement of the operating handle (20) when the contacts of the circuit breaker are welded. The blocking lever (14) is arranged such that it does not interfere with the handle (20) under normal operating conditions.

Description

CIRCUIT SWITCH HANDLE BLOCK Field of the Invention The present invention relates generally to circuit breakers and more particularly to circuit breaker operating mechanisms having a handle locking means to restrict the movement of the handle when the contacts carrying current are welded. BACKGROUND OF THE INVENTION Molded case current limiting circuit interrupters are well known in the art. Circuit breakers of this type have a manual operation handle to switch the circuit breaker between the on and off states. The operation of turning on and off is done through a mechanism spring that connects the operation handle with a swivel articulation. The pivoting joint is in turn connected to a contact carrier assembly that performs the operation of connecting and interrupting the flow of current to a protected circuit. When the operating handle is moved from the on position to the off position, the direction of the force applied by the mechanism spring changes as the spring rotates with the handle. At some point during the movement, the direction of the force changes from one side of a pivot of the swinging joint to the other. This causes the tilting joint to collapse and the contact carrier assembly g i re. The circuit breaker generally provides a visual indication as to the position of the contact carrier assembly. However, in extreme and rare occasions, the contacts of the circuit breaker can be soldered. In this case, if the operating handle were allowed to return to the off position, it would give the operator a false indication that the protected circuit has been disconnected from the power source. Some regulatory agencies such as the International Electrotechnical Commission (I EC) require that the operating handle be blocked from moving to the off position when the contacts are soldered. These regulatory agencies also require that the circuit breaker indicate the position of the contacts. In many circuit breakers when the contacts are soldered, the handle automatically returns to the on position. This not only provides a correct visual indication of the status of the contacts, but also provides the operator with an indication that there is some improper functioning. A circuit breaker of the type mentioned herein having a mechanism with the tilting type articulation is described in United States Patent No. Serial No. 5,200, 724. In this circuit breaker, the movement of the handle it is blocked by projections extending from the upper link and the lower link of the pivoting joint. The upper link projection interacts with a crossbar assembly to prevent rotation of the swingarm. Additionally, U.S. Patent Number 5,543,595 discloses a circuit breaker, which uses reversing levers that are attached to a cradle. The reversing levers interact with a top link and the handle to prevent rotation of the handle to a position where the pivot joint can rotate if the contacts are soldered. BRIEF DESCRIPTION OF THE INVENTION In an exemplary embodiment of the present invention, a molded case circuit breaker includes a mechanism having a handle, movable between an on and off position, with the handle having a locking projection extending from the same to restrict the movement of the handle when the contacts of the circuit breaker are soldered or otherwise fixed in the ON position and prevented from opening. The circuit breaker also has a movable contact arm between a closed position and an open position in response to the movement of the handle. A crank is coupled to the handle and the contact arm so that when the handle is moved from the on position to the off position, the crank moves the contact arm from the closed position to the open position. A locking lever having a first projection is arranged to cooperate with the crank so that when the contact arm is fixed in the ON position, the locking projection of the handle interacts with the first projection of the locking lever for Prevent the handle from being moved to the 5 off position. Brief Description of the Drawings Figure 1 is a perspective view of a circuit breaker in accordance with the present invention; Figure 2 is a perspective view of a mechanism for use with circuit breakers in accordance with the present invention; Figure 3 is a front plan view of the mechanism of Figure 1 in the ON position; Figure 4 is a front plan view of the mechanism of Figure 1, in transition from the ON position to the OFF position; Figure 5 is a front plan view of the mechanism of Figure 1 in the OFF position; Figure 6 is a front plan view of the mechanism of Figure 1 wherein the handle is blocked due to welded contacts; and Figure 7 is a front plan view of a mechanism for a simple interruption contact system in accordance with an alternative embodiment of the present invention. 25 Description of the Preferred Modality lftfllM ^ Mri3iifiiiM? éritt) -_ With reference to Figure 1, a molded case circuit breaker 9 is generally shown. Circuit breakers of this type have an insulated box 11 which houses the components of the circuit breaker. A handle 20 extending through the box 11 provides the operator with the ability to "turn on" the circuit breaker by energizing the protected circuit, "turning off" the circuit breaker, disconnecting the protected circuit or "resetting" the circuit breaker after a failure. Two series of bands 34, 35 also extend through the box 11 to connect the circuit breaker 9 to the protected circuit wires. The circuit breaker in Figure 1 shows a typical configuration of three phases; however, the present invention is not limited to this configuration but can be applied to other configurations, such as circuit breakers typical of one, two or four phases. The handle 20 is attached to an internal mechanism 10 as shown in Figure 2. The handle 20 is attached to a yoke of the handle 22 which rotates on a leg 22P in the side structure 16. There would commonly be two side structures 16, but only one of they are shown in Figure 2 for clarity. The yoke of the handle 22 consists of a main body 22M and a projection 22A, a cut 22C is formed between the projection 22A and the main body 22M. The remaining internal components of the circuit breaker are shown in Figure 3. The handle 20 is attached to a spring of mechanism 24 joining at its opposite end to a tilting leg tftatfil ^ M ^ 52. The pivoting leg 52 connects the pivoting joint 35, 37 to the mechanism spring 24. As will be described herein, the force generated by the movement of the handle 20 will cause the pivoting joint 35, 37 to extends or collapses, which in turn causes the circuit breaker to turn on or off depending on the movement of the handle 20. The upper link 35 of the pivoting joint is attached to a cradle 39. The lower link 37 joins the crank 12 via the leg 19. The crank 12 rotates in the leg 17 unit to the side structures 16 and connects to a multi-pole rotary contact system 15 via the leg 13. The rotary contact system operates in substantially the same manner as the one described in the co-pending "U.S. Patent Application of the United States of America" entitled "Circuit Breaker Mechanism for a Rotating Contact Assembly" S / N 09/196706 filed November 20, 1998 which is incorporated herein by reference. Adjoining the leg 13, the crank 12 interacts with a locking lever 14 that rotates in a leg 18 unit to the lateral structures 16. The interaction of the crank 12 with the fixing lever 14 will be clarified herein. The clamping lever 14 has a first and second surface 14A, 14B which are adjacent to the upper and lower surfaces 12 U, 12 L of the crank 12. Adjacent to the first surface of the clamping lever 14A, there is a third surface 14C. Under certain operations, the third surface of the clamping lever 14C will contact a crank transition surface 33 that connects the upper surface of the crank 12U to the lower surface of the crank 12L. The clamping lever 14 also has a lever projection 14D that interacts with a handle yoke projection 22A. The importance of the interaction between the lever projection 14D and the handle yoke projection 22A will be clarified herein. The rotary contact system 15 includes a rotor 1 1 connecting the crank 12 via the leg 13. A contact arm 28 connects with the rotor 1 1 for the purposes of opening and closing the circuit breaker. The contact arm 28 has a pair of movable contacts 30, 31 which electrically connect to a pair of stationary contacts 32., 33, respectively. The stationary contacts 32, 33 are attached to the bands 34, 35 respectively, which allows the electric current to flow from the power source through the circuit breaker to the protected circuit. Under normal operating conditions, when the circuit breaker is in the on position, the mechanism 0 and the rotary contact system 15 will be oriented as shown in Figure 3. In this orientation, the movable contacts 30, 31 are coupled with the stationary contacts 32, 33 to allow current to flow through the circuit breaker. In this position, the first surface of the clamping lever 14A rests against the lower crank surface 12L and the second surface of the clamping lever 14B makes contact with the upper crank surface 12U. When the users rotate the handle 20 to the off position (counterclockwise as directed in Figures 2-7) the line of force generated by the mechanism spring 24 on the swinging leg 52 rotates with the handle . At the point where the line of force generated by the mechanism spring 24 crosses the leg of the upper link 38, the pivoting joint 35, 37 will collapse as shown in Figure 4. This collapse of the pivoting joint 35, 37 rotates the crank 12 counterclockwise separating the movable contacts 30, 31 from the stationary contacts 32, 33. When the contacts 30, 31, 32, 33 are separated, the flow of the electric current through is interrupted. of the circuit breaker and the protected circuit is disconnected from the power source. As the crank 12 continues to rotate at an angle A, the transition surface 12T contacts the third surface of the locking lever 14C which biases the locking lever to rotate in the clockwise direction. As at this point the second surface of the clamping lever 14B is no longer in contact with the crank, the clamping lever 14 is free to rotate thus allowing the projection 14D to extend into the cutting of the yoke of the handle 22C shown in FIG. Figure 5. As the projection 14D is not interfering with the handle yoke projection 22A, the user can rotate the handle 20 to the full off position shown in Figure 5.

Under certain conditions, the contacts 30, 32, or 31, 33 can be welded together. This welding condition prevents the mechanism from separating the contacts 30, 32 and 31, 33 as mentioned above to disconnect the protected circuit. Certain quasi-regulatory agencies such as the International Electrotechnical Commission (IEC) require that the handle of the mechanism 22 be prevented from moving to the off position while the contacts 30, 32, 31, 33 are welded. To achieve this, the present invention provides a projection 14D on the clamping lever 14 to interfere with the projection of the yoke of the handle 14A to prevent the handle 22 from being placed in the off position and if the handle 22 is moved, automatically it will return to the on position when the handle 22 is released. When the contacts 30, 32, 31, 33 are welded, the handle 12 will remain in the closed position shown in Figure 6. If the user attempts to reset the switch, the yoke of the handle 22 rotates until the yoke projection 22A contacts the projection of the lever 14D. Unlike the previous situation, when the polarization in the clamping lever 14 allowed the clamping lever 14 to rotate out of the yoke path of the handle 22, the first and second surfaces of the clamping lever 14A, 14B are both in contact with the crank 12. Thus, it is prevented that the fixing lever 14 rotates clockwise by the surface 14B, or counterclockwise by the surface 14A. once the yoke of the handle 22A is interfered with the projection of the locking lever 14D, additional rotation in the counterclockwise direction of the handle 20 is avoided. It should be appreciated that once the handle 20 is released by the user, the line of force 36 on the handle 20 of the mechanism spring 24 will cause the yoke of the handle 22 and the handle 20 to rotate clockwise in the yoke pivot of the handle 22P until that reaches the ignition position. With reference to Figure 7, an alternative embodiment is shown in which the clamping lever is incorporated into a traditional simple switch contact system. In this embodiment, the contact arm assembly 40 consists of the contact arm 42 having a movable contact 44 at one end and a copper braid 48 at the other. The movable contact 44 engages with the stationary contact 32 to form an electrical connection with the aforementioned line band 34. The copper braid 48 is connected at one end to the contact arm 42 and to a load band 50 at the other. The copper braid 48 can be connected to the contact arm 42 and the band 50 by other suitable means to create an electrical connection, including a welded or screwed joint. The contact arm 42 is connected to the mechanism 10 by a carrier 46 and the leg 13 extending between the crank 12 and the carrier 46. The operation of the contact arm assembly 40 is well known, and is similar to that described in FIG. Patent of the United States of America Serial number 4,732,921 BdtMH MMa ^^^^ which is incorporated herein by reference. Although a preferred embodiment of this invention has been described in a rotary double contact switch system, it is within the scope of the present invention that this invention can be applied to any traditional circuit breaker mechanism having a single contact and several Modifications and variations will be apparent to those skilled in the art. Therefore, it is preferred that the present invention be limited not by the specific description but only by the appended claims. 10 ^ j = ¡U

Claims (9)

1. CLAIMS l. A circuit breaker comprising: a handle having a locking projection extending therefrom, said handle being movable between an ignition position and an off position; a contact arm that supports at least one contact, said contact arm can be moved between a closed position and an open position; a crank operably coupled to said handle and such contact arm for moving said contact arm from the closed position to the open position when said handle moves from the on position to the off position; a locking lever having a first projection extending therefrom, such a first projection interacts with said locking projection of said handle to prevent said handle being moved to the off position when said contact arm is fixed in the closed position.
2. 2. The circuit breaker of claim 1, wherein: said crank further comprises first and second cam surface; and such clamping lever further comprises second and third projections extending therefrom, said second and third projections cooperate with such first and second cam surfaces to rotate such clamping lever when such a contact arm moves between closed positions and open, without such first projection or said locking lever interacting with said locking projection of the handle of said handle.
3. The circuit breaker of claim 2, wherein: said crank further includes a transition surface between said first and second cam surfaces, said transition surface interacts with such a second projection of such a locking lever to rotate said aforementioned locking lever when such contact arm moves between its closed and open positions, without such first projection or said locking lever interacting with said locking projection or said handle.
4. The circuit breaker of claim 3, wherein: said crank further comprises a resetting surface adjacent to said second camming surface, said restarting surface interacting with said third projection or said locking lever for rotating said lever of fixing when said contact arm moves between the open and closed positions.
5. 5. The circuit breaker of claim 1, wherein said at least one contact comprises a contact located at one end thereof.
6. 6. The circuit breaker of claim 1, wherein said at least one contact comprises a pair of contacts, each of said contacts is located at an opposite end of said contact arm. - '- * - * • "* < -»
7. 7. The circuit breaker of claim 1, further comprising: a cradle; a tilting hinge having a top link and a bottom link, said top link is pivotally attached to said cradle at one end and a pivot pivot at an opposite end, such a bottom link is pivotally attached to such a pivot pivot at a end and said crank at an opposite end; and - a spring connected between such pivoting pivot and said handle for biasing said crank in a direction to move said contact arm to an open position when said handle moves from an off position to an ignition position, said spring is biased .
8. The circuit breaker of claim 7, wherein: said crank is coupled to said lower link on a first crank pivot and said crank is coupled to said contact arm by a leg.
9. 9. The circuit breaker of claim 8, wherein said leg is diametrically opposite said first pivot.