CLIAMS:We Claim

1. A winding handle (100) for draw out type circuit breaker, the winding handle comprising:
a first arm (10) having a female slot (12) at front portion thereof for inserting into a protrusion (110a) of a racking mechanism (110) of a cradle compartment (200);
a second arm (20) rotatabaly joined to the first arm (10) on rear side thereof;
a third arm (30) rotatabaly joined to the second arm (20) on rear portion thereof, and
a rear arm (40) slidably mounted over the third arm (30) for providing extension, the rear arm (30) having diametrically opposite slots (40a) configured thereon for engaging with counter protrusions (120) of the cradle compartment (200) to provide locking during storage inside cradle compartment,
wherein upon inserting the first arm (10) into the racking mechanism (110) through the slot (12) and rotating the first arm (10) and the second arms (20) about the joint, and rotating the second arm (20) and the third arm (30) about the joint such that the first arm (10) and the second arm (20) are at a non-perpendicular angle (A) and the second arm (20) and the third arm (30) are at a non-perpendicular angle (B), ensures that the winding handle (100) does not touch the circuit breaker facia at any stage of the racking process.

2. The winding handle as claimed in claim 1, wherein the first arm (10) and the second arm (20) are joined together with a riveted joint (10a) such that the first arm (10) and the second arm (20) have only rotational degree of freedom about the axis of the riveted joint (10a).

3. The winding handle as claimed in claim 1, wherein the second arm (20) and the third arm (30) are joined together with a riveted joint (20a) such that the second arm (20) and the third arm (30) have only rotational degree of freedom about the axis of the riveted joint (20a).
,TagSPECI:Field of the invention

The present invention relates to circuit breakers, and more particularly to extendable winding handle of withdrawable or draw out type of circuit breakers.

Background of the invention

Electrical transmission and distribution employs a device known as switching device or a circuit breaker. One kind of the circuit breaker is known as “Air Circuit breaker” is customarily used in low voltage power distribution systems. The air circuit breaker is used to carry, make and break current in low-voltage applications.

The air circuit breaker is generally categorized broadly into two categories viz. fixed type and withdrawable or draw out type circuit breaker. The draw out type air circuit breakers usually employ a fixed compartment or a cradle which is connected to mains supply. The air circuit breaker is a separable component and needs to be inserted into the cradle compartment during normal operating conditions without which electrical path would not be complete. Also, the air circuit breaker needs to be removed from the cradle during maintenance or as and when the need arises.

In a switching modular device like air circuit breaker, the moving switching module can have a translational motion in and out of the fixed body or cradle compartment. For connection between the moving switching module and the fixed conductor of the cradle, interfacing electrical contacts often referred to as jaws are used. The transitional motion of the moving switching module in draw-out air circuit breaker is generally called racking of air circuit breaker and the mechanism used to perform the aforesaid function is known as racking assembly mechanism.

The racking process is actuated externally with the help of a winding handle. The winding handle is engaged with the racking mechanism for racking of air circuit breaker. An external force is applied on the winding handle which transforms the externally applied rotational motion into linear motion of the air circuit breaker inside the cradle compartment. The winding handle in general is stored inside the cradle compartment.

High ampere rated air circuit breakers incorporate large number of interfacing electrical contacts on the cradle often referred to as jaws. The racking force that needs to be applied externally on the winding handle is in direct proportion to the number of interfacing electrical contacts present in the cradle and hence is higher for higher ampere rated air circuit breakers. When racking is performed with the help of conventional winding handles, the process may lead to excessively high applied force on the handle, which, if not used properly, may further lead to development of unwanted mechanical stresses in the system and may cause wear and tear of the rack and other components of the racking mechanism.

Further, conventional winding handles contain male type of solid protrusion on the handle and female type of slot inside the racking mechanism such that when the protrusion of the handle is inserted into the slot of the racking mechanism, the protrusion gets engaged with the female type of slot and racking process can be initiated. Since the applied force is higher for high ampere rated air circuit breakers and may cause damage to the racking system as explained above, there is a chance that the racking mechanism gets damaged prior to the winding handle owing to the female type of slot having lesser mechanical strength present on racking mechanism and solid mass present on the winding handle. In such cases, the entire racking mechanism or at least the rack would need replacement which becomes a cumbersome and is a less feasible process.

Furthermore, in case of conventional winding handles, front most and second arm of the winding handle are perpendicular to each other as well as the second and rear arms are perpendicular to each other. In this case, while racking in the breaker inside the cradle compartment, the handle has a tendency to touch the breaker facia present just above it and damaging it.

Accordingly, there exists a need to provide a winding handle for draw out type circuit breaker which overcomes abovementioned drawbacks.

Objects of the invention

An object of the present invention is to reduce wear and tear of the rack and other components of the racking mechanism of the cradle compartment of the draw out type circuit breaker.

Another object of the present invention is to avoid replacement of the racking mechanism of the cradle compartment which becomes a cumbersome and is a less feasible process.

Summary of the invention

Accordingly, the present invention provides a winding handle (100) for draw out type circuit breaker. The winding handle (100) includes a first arm (10) having a slot (12) at front portion thereof for inserting into a protrusion (110a) of a racking mechanism (110) of a cradle compartment (200), a second arm (20) rotatabaly joined to the first arm (10) on rear side thereof, and a third arm (30) rotatabaly joined to the second arm (20) on rear portion thereof. The winding handle (100) further includes a rear arm (40) slidably mounted on the third arm (30) for providing extension. The rear arm (40) includes diametrically opposite slots (40a) configured thereon for engaging with counter protrusions (120) of the cradle compartment (200). Wherein upon inserting the first arm (10) into the racking mechanism (110) through the slot (12), the first arm (10) and the second arms (20) respectively are rotated about the joint and the second arm (20) and the third arm (30) are rotated about the joint such that the first arm (10) and the second arm (20) are at a non-perpendicular angle (A) and the second arm (20) and the third arm (30) are at a non-perpendicular angle (B) thereby ensuring that the winding handle (100) does not touch the circuit breaker facia at any stage of the racking process.

Brief description of the drawings

Other features as well as the advantages of the invention will be clear from the following description.
In the appended drawings:

Figure 1, 2 and 3 shows a winding handle for draw out type circuit breaker in various positions, in accordance with the present invention;

Figure 4 shows the winding handle of figure 1 and a racking mechanism of the circuit breaker;

Figure 5 shows the winding handle of figure 1 inserted in the racking mechanism of the circuit breaker; and

Figure 6 depicts the shows the winding handle inserted into a cradle compartment of the circuit breaker for storage purpose.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The present invention provides winding handle with a female slot & non-perpendicular arms having a distinct locking arrangement of the draw out type circuit breaker. The winding handle with increased the working arm length thereby reduces the possibility of the wear and tear of the racking mechanism. Further, the winding handle (100) prevents contact with the circuit breaker facia during the racking process. In addition to above, the invention provides a non-specific rotation direction of the handle.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.

Referring to figures 1, 2 and 3, there is shown, a winding handle (100) for circuit breaker in various positions, in accordance with the present invention. The circuit breaker explained herein is withdrawable or draw out type of air circuit breaker. The winding handle (100) includes a first arm (10), a second arm (20), a third arm (30) and a rear arm (40).

The first arm (10) includes a slot (12) configured at front portion thereof. In an embodiment, the slot (12) is hexagonal type female slot. The slot (12) provides for inserting into a protrusion (110a) configured on a racking mechanism (110) of a cradle compartment (200). Specifically, the protrusion (110a) is a male type hexagonal protrusion which fits into the slot (12) when inserted. The first arm (10) is connected to the second arm (20).

Specifically, the second arm (20) is rotatabaly joined to the first arm (10) on rear side thereof. More specifically, the first arm (10) and the second arm (20) are joined together with a riveted joint (10a) such that the first arm (10) and the second arm (20) have only rotational degree of freedom about the axis of the riveted joint (10a). The second arm (20) defines working length of the winding handle (100). The second arm (20) is further connected to the third arm (30).

The third arm (30) is rotatabaly joined to the second arm (20) on rear portion thereof. More specifically, the second arm (20) and the third arm (30) are joined together with a riveted joint (20a) such that the second arm (20) and the third arm (30) have only rotational degree of freedom about the axis of the riveted joint (20a). The rotational degree of freedom about the axis of the riveted joints (10a, 20a) provides flexibility to users of the winding handle (100) to rotate the arms (10, 20, and 30) in any direction as per their convenience before initiation of the racking process. Thus, there is no restriction to rotate the arm in only a particular direction prior to initiating the racking process.

Specifically, the third arm (30) includes the rear arm (40) slidably mounted thereon for providing extension to the winding handle (100). The extension of the winding handle (100) by means of the rear arm (40) increases length of the winding handle (100). The extendable winding handle (100) can be maintained in same storage space inside the cradle compartment (200) which ensures compactness of the winding handle (100). Specifically, figure 2 shows the winding handle (100) in its extended position.

The rear arm (40) includes diametrically opposite slots (40a) configured thereon for engaging with counter protrusions (120) of the cradle compartment (200). The rear arm (40) is used to hold the winding handle (100) and rotate it.

In an operation, upon inserting the first arm (10) into the racking mechanism (110) through the slot (12), the first arm (10) and the second arm (20) respectively are rotated about axis of the riveted joint (10a). Further, the second arm (20) and the third arm (30) are rotated about the axis of the riveted joint (20a) to form an assembly as shown in figure 3. In this position, the first arm (10) and the second arm (20) are at a non-perpendicular angle (A) and the second arm (20) and the third arm (30) are at a non-perpendicular angle (B). When the first arm (10) is inserted into the racking mechanism (110) as shown in figure 4 through the slot (12), the non-perpendicularity of the arms (10, 20, and 30) ensures that the winding handle (100) does not touch the circuit breaker facia at any stage of the racking process. This prevents damage to the circuit breaker’s facia.

As shown in figure 6, the winding handle (100) is inserted into the cradle compartment (200) for storage purpose. The winding handle (100) is provided with a distinct locking arrangement as described earlier. The winding handle (100) includes diametrically opposite slots (40a) (as shown in figure 1) on the rear arm (40) for locking purpose. When the winding handle (100) is inserted into the cradle compartment (200) for storage, the slots (40a) get engaged with their counter protrusions (120) present on the cradle compartment (200) thereby forming a locked assembly. To remove the winding handle (100) from the cradle compartment (200), the winding handle (100) has to be rotated by holding the grip (42) provided on the rear arm (40) in either direction about the axis of the winding handle (100) and then pulled out translationally.
Advantages of the invention

1. The winding handle (100) prevents damage to the circuit breaker facia during racking process due to non-perpendicular arms.
2. The winding handle (100) requires reduced applied force by operator because of increased working arm length.
3. The winding handle (100) is operator friendly by ensuring ease in racking high ampere breakers.
4. The winding handle (100) requires no change in storage length of the handle inside the cradle compartment.
5. The winding handle has a female slot in itself instead of a male solid protrusion which reduces possibility of damage to racking arrangement prior to damaging the handle.
6. The winding handle provides a distinct locking arrangement which prevents un-skilled removal of handle from the cradle compartment.
7. The winding handle arms has a rotational degree of freedom and hence the user has the flexibility to rotate the arms in either direction prior to initiate the racking process.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.