Claims:1. A withdrawable type circuit breaker, comprising:
a fixed cradle compartment having plurality of jaw contacts; and
a moving switching module racked into said fixed cradle compartment;
wherein, said moving switching module comprises:
plurality of fixed conductor assemblies; and
plurality of moving conductor assemblies;
plurality of intermediate connecting adaptors to facilitate connection of said fixed and moving conductor assemblies with said plurality of jaw contacts;
characterized in that,
said intermediate connecting adaptors includes a ‘tapered’ or a ‘transverse’ or a ‘slant’ profile with progressive change of contact area over its insertion surface.

2. The withdrawable type circuit breaker as claimed in claim 1, wherein said jaw contacts are spring-loaded conductors.

3. The withdrawable type circuit breaker as claimed in claim 2, wherein both ends of said intermediate connecting adaptors slides over said spring-loaded conductors sequentially one after another.

4. The withdrawable type circuit breaker as claimed in claim 3, wherein said spring-loaded conductors are actuated sequentially due to sequential insertion of said intermediate connecting adaptors.

5. A withdrawable type circuit breaker, comprising:
a fixed cradle compartment having plurality of jaw contacts; and
a moving switching module racked into said fixed cradle compartment;
wherein, said moving switching module comprises:
plurality of fixed conductor assemblies; and
plurality of moving conductor assemblies;
plurality of intermediate connecting adaptors to facilitate connection of said fixed and moving conductor assemblies with said plurality of jaw contacts;
characterized in that,
said intermediate connecting adaptors includes a ‘tapered’ or a ‘transverse’ or a ‘slant’ profile with progressive change of contact area over its insertion surface; and
said intermediate connecting adaptors provisions an ‘optimized entry radius’ on said insertion surface.
, Description:TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to switching devices such as circuit breakers, and particularly, withdrawable type of air circuit breakers. More particularly, the invention relates to a conductor profile for efficient racking of withdrawable air circuit breakers.

BACKGROUND

[002] Electrical transmission and distribution systems employ an equipment known as ‘Circuit breaker’, a kind of which known as “Air Circuit breaker” is customarily used in low voltage power distribution systems. It is used to carry, make & break current in low-voltage applications. Air Circuit breakers are usually classified into two sub-categories viz. ‘fixed’ type and ‘withdrawable’ or ‘draw-out’ type. The latter, i.e. withdrawable or draw-out type of air circuit breakers usually comprises of a fixed compartment, often referred to as ‘cradle’ or ‘chassis’ and a moving switching module, often referred to as a ‘breaker’. The supply from source is fed by connection of busbars to the ‘cradle’. Moving switching module, i.e. breaker is a separable component and is inserted into the fixed cradle compartment through translational motion, often referred to as ‘racking’. The major advantage that draw-out circuit breakers have over fixed types is that the breaker can be isolated from the electrical circuit without disturbing the termination busbars which are electrically live. Breaker isolation may be required when maintenance activities are to be done. The purpose of a withdrawable air circuit breaker is served once the electrical connection between the moving module, i.e. ‘breaker’ & fixed compartment, ‘cradle’, is adequately established, which occurs only once the moving module, i.e. the breaker is completely inserted or ‘racked-in’ as termed popularly, into the fixed compartment, i.e. the ‘cradle’ or ‘chassis’.

[003] The moving module portion of a withdrawable circuit breaker (‘breaker’ as aforementioned) comprises of fixed & moving conductor assemblies, both of which are encompassed inside a housing. The fixed cradle compartment consists of spring-loaded conductors, often known as ‘jaw clusters’ or ‘jaw contacts’ which are mounted on a component known as ‘cradle terminal’ or ‘chassis terminal’. Usually, the number of jaw contacts are in direct proportion to rating of the product, and tend to increase with increase in the ampere rating and/or the breaking capacity of the product. An intermediate connecting conductor, often referred to as ‘adaptor’ is provided to facilitate connection of the housing-mounted conductor assemblies (fixed and moving as aforementioned) of the moving switching module with the jaw clusters of the fixed cradle compartment.

[004] The process of translational insertion of moving module (breaker as referred earlier) inside the fixed compartment (‘cradle’ as referred earlier) is termed as ‘racking’. During this process, to establish an electrical connection, the connecting adaptor of the moving module slides over the spring-loaded jaw clusters of the fixed compartment, thereby actuating the springs from external sliding over surface of jaw contacts. The process of racking is executed thru’ a racking mechanism which converts rotational motion (actuated and controlled by the user) into translational motion of the moving module, i.e. ‘breaker’ & guides it inside the fixed compartment, i.e. ‘cradle’. Since rotational motion is involved in the process of racking as aforementioned, a ‘torque’ is involved by which the breaker gets inside the cradle, known as ‘racking torque’. Since the process of racking involves sliding of adaptor onto the spring-loaded jaw contacts, the racking torque is largely dependent on the number of jaw clusters & thus in direct proportion to the amount of spring actuation. It is required that the racking torque remains within stipulated limits (which in turn depends upon the type and rating of circuit breaker). In case the racking torque increases beyond a specific limit, there are adverse effects on the racking mechanism due to mechanical stresses & may consequently lead to wear & tear of the crucial components of the racking mechanism, thereby affecting the product performance at large. Hence, for best performance of product, it is always desirable to have minimum racking torque.

[005] Conventional connecting adaptors have a straight profile such that, during racking operation, when it slides over the jaw clusters, the entire contact surface of adaptor slides over the jaw clusters at the same time. Therefore, all springs of jaw contacts are actuated simultaneously.

[006] Reference is made to figure 3a & 3b, in conventional adaptors, the profile of contact surface is of straight type at both ends of the adaptor (4) & (5). When the connecting adaptor (3) with conventional profile (4) & (5) slides over the jaw clusters (2), both ends of the adaptor (4) and (5) inserts simultaneously over the jaw clusters (2). Since jaw clusters are spring-loaded as explained earlier in the article, all springs are actuated simultaneously. Consequently, since the racking torque is in direct proportion to the amount of spring actuation, the racking torque in conventional adaptors is due to all springs’ simultaneous compression.

[007] Conventional connecting adaptors have a flat surface or a chamfer on its entry surface. During racking process, when the connecting adaptor slides over the spring-loaded jaw clusters, the jaw clusters’ conductors are pushed inside owing to the entry chamfer present on the connecting adaptor.

[008] Thus, there exists a dire need for an improved conductor profile and an optimized entry radius instead of a chamfer which facilitates in reduction of insertion force of adaptor externally onto the jaw clusters and thereby reducing the racking torque.

SUMMARY OF THE INVENTION

[009] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[0010] An objective of the present invention is to provide an adaptor having a ‘slant’ or a ‘transverse’ or a ‘tapered’ conductor profile for withdrawable air circuit breakers.

[0011] Another objective of the present invention is to provide an adaptor having optimized ‘entry radius’ on its insertion area leading to reduced insertion force when it slides externally onto the jaw clusters of withdrawable air circuit breakers.

[0012] Yet another objective of the present invention is to provide sequential insertion of different ends of the adaptor externally onto jaw-clusters or jaw-contacts and not simultaneous insertion.

[0013] Still another objective of the present invention is to facilitate distributed exertion of spring force of Jaw clusters’ springs over different sections of the adaptor’s surface.

[0014] Accordingly to one aspect, the present invention provides a withdrawable type circuit breaker, comprising:
a fixed cradle compartment having plurality of jaw contacts; and
a moving switching module racked into said fixed cradle compartment;
wherein, said moving switching module comprises:
plurality of fixed conductor assemblies; and
plurality of moving conductor assemblies;
plurality of intermediate connecting adaptors to facilitate connection of said plurality of fixed and moving conductor assemblies with said plurality of jaw contacts;
characterized in that,
said intermediate connecting adaptors includes a ‘tapered’ or a ‘transverse’ or a ‘slant’ profile with progressive change of contact area over its insertion region.

[0015] In another aspect, the present invention provides a withdrawable type circuit breaker, comprising:
a fixed cradle compartment having plurality of jaw contacts; and
a moving switching module racked into said fixed cradle compartment;
wherein, said moving switching module comprises:
plurality of fixed conductor assemblies; and
plurality of moving conductor assemblies;
plurality of intermediate connecting adaptors to facilitate connection of said plurality of fixed and moving conductor assemblies with said plurality of jaw contacts;
characterized in that,
said intermediate connecting adaptors includes a ‘tapered’ or a ‘transverse’ or a ‘slant’ profile with progressive change of contact area over its insertion region; and
said intermediate connecting adaptors provisions an ‘optimized entry radius’ on said insertion surface.

[0016] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0017] Figure 1(a) and (b) illustrates different types of the ‘cradle terminals’ which are mounted on the fixed compartment, i.e. cradle or chassis, spring-loaded jaw contacts and the connecting adaptor, in the condition when the moving module is racked out, according to one implementation of the present invention.

[0018] Figure 2 shows the condition of a completely racked-in condition or ‘service condition’ or ‘connected position’ of the device, according to one implementation of the present invention.

[0019] Figure 3(a) and 3(b) illustrates another view wherein the position of connecting adaptor is the one which is just before its insertion over the spring-loaded jaw contacts starts, according to the prior art. Figure 3(c) and 3(d) illustrates the view wherein the position of connecting adaptor is the one which is just before its insertion over the spring-loaded jaw contacts starts, according to one implementation of the present invention.

[0020] Figure 4(a) and (b) illustrates the position of connecting adaptor when it just begins to slide over the jaw contacts. Figure 4(a) depicts conventional adaptors which has a flat surface or an entry chamfer on its insertion area whereas figure 4(b) depicts the present invention with an optimized entry radius on the insertion area of the connecting adaptor.

[0021] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0022] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0023] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0024] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0025] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0026] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0027] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0028] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0029] It is also to be understood that the term “module” is used in the specification to indicate an apparatus, unit, component and the like. The term “means” when used in the specification is taken to specify the mode by which desired result is achieved.

[0030] The present invention can be implemented with an electrical switching system that may include but not limited to, circuit breakers or thermo-magnetic breaker, molded case circuit breaker (MCCB) residual circuit breaker (RCB), earth leakage circuit breaker (ELCB) and the like.

[0031] In one implementation, the present invention relates to a ‘transverse’ or ‘slanted’ or ‘angular’ or ‘tapered’ profile of the connecting adaptor. This is designed such that during racking operation, a part of the adaptor’s contact surface slides over the jaw contacts at one point of time and the remaining part slides slightly later. Thus, a sequential spring actuation arrangement is created. Owing to this sequential actuation arrangement, the total spring force exerted onto the adaptor is distributed into different instants & hence racking torque is considerably reduced, which is in direct proportion to the amount of spring actuation.

[0032] In another implementation, the present invention relates to provision of optimized ‘entry radius’ on the connecting adaptor which facilitates in reduction of insertion force of adaptor externally onto the jaw clusters and thereby reducing the racking torque.

[0033] In one implementation, figure 1 illustrates the different types of the ‘cradle terminals’ which are mounted on the fixed compartment, i.e. cradle or chassis, spring-loaded jaw contacts and the connecting adaptor, in the condition when the moving module is racked out.

[0034] In one implementation, figure 2 shows the condition of a completely racked-in condition or ‘service condition’ or ‘connected position’ of the device.

[0035] In the implementation, in figures 1 and 2, (1) shows the ‘cradle terminals’ which can be mounted on the fixed compartment, i.e. cradle or chassis. They may be of different types as depicted in the images depending on the rating of the product. Spring loaded jaw contacts (2) are connected with the cradle terminals (1) and thus, are a part of the fixed portion of the withdrawable product. A connecting adaptor (3) is a part of the moving module, i.e. the breaker which is racked-in/out of the fixed compartment as mentioned earlier in the article. Position depicted in figure-1 shows the condition when the moving module is racked out, i.e. the adaptor is not in contact with the jaw contacts & product is not in operating condition. During the process of racking, the moving module (‘breaker’ as stated earlier), moves translationally inside the fixed part, (‘cradle’ or ‘chassis’), during which, the connecting adaptor (3) slides over the spring-loaded jaw contacts (2) externally and actuates the springs, thereby establishing an electrical connection as shown in figure-2 which depicts condition of a completely racked-in condition or ‘service condition’ or ‘connected position’ of the device.

[0036] In one implementation, 3(c) and 3(d) illustrates the view wherein the position of connecting adaptor is the one which is just before its insertion over the spring-loaded jaw contacts starts, according to one implementation of the present invention.

[0037] In the implementation, as shown in figures 3(c) and (d), the unique design of the adaptor includes a ‘slant’ or ‘transverse’ or ‘tapered’ profile (6) and (7) with progressive change of contact area over its length. Hence, for the present invention, when the adaptor with said invention having transverse or tapered profile (6) and (7) slides over the jaw clusters (2), both ends of the adaptor (6) and (7) inserts sequentially one after another and not simultaneously as in conventional adaptors. Due to sequential insertion of adaptors, the springs of the jaw clusters (2) are actuated sequentially and not simultaneously. Hence, the spring force exerted onto the adaptor surface is distributed into different instants.

[0038] The figure 4(a) and (b) illustrates Figure 4(a) and (b) illustrates the position of connecting adaptor (3) when it just begins to slide over the jaw contacts. Figure 4(a) depicts conventional adaptors which has a flat surface or an entry chamfer (8) on its insertion area whereas figure 4(b) depicts the present invention with an optimized entry radius (9) on the insertion area of the connecting adaptor.

[0039] In the prior art as shown in figure 4, in conventional systems, the connecting adaptor (3) has a flat surface or ‘chamfer’ (8) at the entry portion of the breaker adaptor’s contact surface. During the racking process, when the adaptor (3) inserts over the jaw contacts (2), the contact surface of adaptor (3) pushes against the surface of jaw contacts (2) and actuates its springs.

[0040] In one implementation, there is a provision of an optimized ‘entry radius’ (9) such that during racking process when the adaptor (3) inserts over the jaw contacts (2), the entry radius (9) helps in easy actuation of the jaw contacts’ springs, thereby lesser insertion force.

[0041] Consequently, with the present inventions as listed above, the racking torque is reduced and is on lower side as compared to conventional adaptors (which has simultaneous insertion onto the jaw-clusters & a flat or chamfered entry contact surface). Since the racking torque is reduced, issues that can arise due to high racking torque like wear & tear of components associated with the racking mechanism are reduced considerably. Moreover, since possibilities of wear out of racking mechanism are reduced, the life of racking mechanism is improved, thereby making it customer friendly.

[0042] Therefore, some of the non-limiting advantages of the present invention, are mentioned below:
• Reduced racking torque of the product.
• Efficient racking process.
• Prevent issues that can arise due to high racking torque like wear & tear of components associated with the racking mechanism.
• With the present invention, due to reduction in racking torque, possibilities of wear out of racking mechanism are reduced and hence improving the life of racking mechanism, thereby making it customer friendly.
• Due to reduction in racking torque, the force experienced by the user to rack-in the breaker is also reduced, hence making it ergonomically better.

[0043] Although an intermediate connecting adaptor for efficient racking of withdrawable air circuit breakers have been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations of the intermediate connecting adaptors for efficient racking of withdrawable air circuit breakers.