A safety shutter arrangement of an air circuit breaker (ACB)
Patent Information
- Application Number
- PCT/IN2026/050291
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-21
- Filing Date
- 2026-02-19
- Publication Date
- 2026-08-27
Smart Images
Figure IN2026050291_27082026_PF_FP_ABST
Abstract
Description
[0001] A SAFETY SHUTTER ARRANGEMENT OF AN AIR CIRCUIT BREAKER (ACB) TECHNICAL FIELD
[0002] The present invention generally relates to the field of circuit breakers. More particularly, the present invention relates to a safety shutter arrangement of an Air Circuit Breaker (ACB).
[0003] BACKGROUND
[0004] This section is intended to provide information relating to the field of the invention and thus, any approach or functionality described below should not be assumed to be qualified as prior art merely by its inclusion in this section.
[0005] Circuit Breakers are electro-mechanical switching devices capable of carrying and interrupting a flow of current in an electrical circuit and are also commonly known as over current protective devices. Under normal circuit conditions, a circuit breaker closes the electrical circuit and thereby allows the flow of current from a line side (i.e., power supply side) to a load side (i.e., output load connection side), and breaks the electrical circuit under some abnormal circuit conditions i.e., fault conditions. In simpler words, the circuit breaker is an equipment which can open or close the electrical circuit, under all conditions viz. no load, full load, and fault conditions. Low voltage circuit breakers are commonly known to be deployed for low voltage applications, for example 1000 Volt or lower.
[0006] Various examples of low voltage circuit breakers are known, for example, a miniature circuit breaker (MCB), a moulded case circuit breaker (MCCB), a residual current circuit breaker (RCCB), an air circuit breaker (ACB), and the like. Notably, the ACB is used in applications of withstanding current rating ranging between 65 kA (kiloampere) to 100 kA, nominal current ranging between 800 A (Ampere) to 10 kA, and voltage rating below 450V. The ACB is commonly known to be deployed in distribution panels, particularly, upstream the other overcurrent protective devices such as, the MCB, the MCCB, and the like.
[0007] The air circuit breaker, as its name suggests, employs ‘air’ as a dielectric medium for quenching and / or extinguishing arc formed therein, in the event of a fault condition. The fault condition includes, but is not limited to, over-current fault condition, short-circuit fault condition, and the like. Further, in the event of a short-circuit fault condition, contrary to the functioning of MCB, MCCB, and other similar circuit breakers, the air circuit breaker is capable of ‘withstanding’ a fault current for a maximum time span of 1 second. Air circuit breakers are largely classified intotwo broad types, namely, a fixed-type air circuit breaker and a withdrawable-type air circuit breaker. Essentially, the withdrawable-type air circuit breaker comprises a fixed cradle unit and a withdrawable drawer unit, wherein the withdrawable drawer unit is capable of being slidably withdrawn from the fixed cradle unit. General details of the air circuit breaker, irrespective of its type, are provided hereunder for ease of understanding of a reader.
[0008] A typical air circuit breaker (ACB) is capable of being operated amongst two stable states, namely, an ON (CLOSED) state and an OFF / TRIP (OPEN) state. The ACB comprises a frame member, a plurality of pole assemblies housed and supported within the frame member, an operating mechanism installed onto the plurality of pole assemblies, and a control panel unit adapted to fittingly attach with the frame member, to protect various components of the ACB against any extraneous matter and also safeguard users from coming into contact with a current path established within the ACB during its operation.
[0009] In the typical ACB, the plurality of pole assemblies is operated together amongst the ON state and the OFF / TRIP state, by means of the operating mechanism. Particularly, the operating mechanism of the ACB employs a charging spring arrangement capable of being adjusted between a CHARGED state and a DISCHARGED state. As is commonly known, the ACB can be switched to an ON state only if the said charging spring arrangement is in the CHARGED STATE, and the charging spring arrangement is automatically adjusted to a DISCHARGED state, once the ACB is in the ON state. To adjust the charging spring arrangement back to the CHARGED state, a charging lever member is provided in the control panel unit.
[0010] In the withdrawable-type air circuit breaker, the fixed cradle unit includes a chassis, a plurality of female contact units, and a plurality of bus bar units. The chassis is adapted to hold and support the plurality of female contact units, and the plurality of bus bar units are connected to the plurality of female contact units at one end thereof. On the other hand, the withdrawable drawer unit comprises various vital components of the ACB, wherein one such vital component is a plurality of male contact units adapted to attach to the plurality of female contact units of the fixed cradle unit.
[0011] Conventionally a safety shutter arrangement is generally provided within the fixed cradle unit to prevent exposure of the plurality of female contact units to the surroundings, when the withdrawable drawer unit is disconnected and ejected from the fixed cradle unit. The conventional safety shutter arrangement comprises at least one safety shutter, a safety shutter spring, a shutter plunger, and a shutter front cover attached to the chassis of the fixed cradle unit.Particularly, the at least one safety shutter of the safety shutter arrangement automatically slides and cuts off access to the plurality of female contact units once the withdrawable drawer unit is in either of a disconnected position or is altogether ejected from the fixed cradle unit.
[0012] Conventionally, the front cover of the safety shutter arrangement is screwed into the chassis of the fixed cradle unit to secure thereof to the chassis. During routine maintenance, the shutter front cover is unscrewed, thus allowing removal of the shutter plunger, the shutter spring and the at least one safety shutter to gain access to the plurality of female contact terminals, allowing cleaning thereof. The repeated screwing and unscrewing of the shutter front cover causes threads of the chassis to wear off, thus loosely fitting the shutter front cover onto the chassis. Due to wearing-off of the threads, the shutter front cover fails to lock the shutter plunger against a force exerted by the shutter spring in an extended state, thus causing failure in operation of the safety shutter arrangement. Further, in the extended state, the force of the spring causes the screws of the shutter front cover to rip off thus, cutting threads in the chassis. Further, the chassis needs to be replaced to now screw in a new shutter front cover, leading to wastage of resources, time and effort.
[0013] Accordingly, in light of the aforementioned drawbacks and several other inherent in the existing art, there is a well-felt need to provide an improved and reliable safety shutter arrangement, which the present disclosure aims to address.
[0014] SUMMARY OF THE INVENTION
[0015] This section is intended to introduce certain aspects of the disclosed system in a simplified form and is not intended to identify the key advantages or features of the present disclosure.
[0016] The present disclosure relates to a safety shutter arrangement of an Air Circuit Breaker (ACB). The ACB comprises a fixed cradle unit that comprises a chassis defining L-shaped slots. The safety shutter arrangement comprises a shutter plunger resiliently and slidably installed against the chassis of the fixed cradle unit, along a horizontal axis. Further, the safety shutter arrangement comprises a shutter front cover that defines a central plate portion, and a pair of L-shaped locking protrusions extending from opposite ends of the central plate portion, such that the locking protrusions extends through the L-shaped slots of the chassis of the fixed cradle unit, wherein the central plate portion restricts the sliding movement of the shutter plunger beyond a limit.
[0017] According to an aspect of the present disclosure, the central plate portion further defines a cavity,and at least one grip extension, such that the at least one grip extension is adapted to enable a technician to hold thereof to push the shutter front cover downwards from a top of the chassis of the fixed cradle unit, and into the L-shaped slots of the chassis, to lock the shutter front cover to the chassis of the fixed cradle unit.
[0018] According to another aspect of the present disclosure, the ACB further comprises a withdrawable drawer unit that includes a plurality of male contact units, the fixed cradle unit comprises the plurality of female contact units, such that the withdrawable drawer unit is operable amongst a disconnected position, a test position, a connected position, and an ejected position.
[0019] According to yet another aspect of the present disclosure, the safety shutter arrangement further comprises at least one safety shutter, and a safety shutter spring, such that the shutter front cover movably locks the shutter plunger, the safety shutter spring and the at least one safety shutter against the chassis of the fixed cradle unit.
[0020] According to yet another aspect of the present disclosure, the shutter plunger defines a plurality of lands, a protrusion and at least one extension leg, wherein the shutter plunger is configured to be manipulated between a retracted state and an extended state.
[0021] According to yet another aspect of the present disclosure, the protrusion is adapted to attach the safety shutter spring thereon, the safety shutter spring exerts force on the shutter front cover, thereby firmly attaching the shutter front cover to the chassis even in the extended state of the shutter plunger.
[0022] According to yet another aspect of the present disclosure, the extension leg is adapted to abut with the central plate portion of the shutter front cover in an extended state, to lock and limit travel of the shutter plunger therein, such that the extension leg prevents the shutter plunger from falling through the cavity of the central plate portion.
[0023] According to yet another aspect of the present disclosure, the at least one safety shutter is slidably attached to the chassis of the fixed cradle unit, and the at least one safety shutter defines a plurality of grooves, wherein each of the plurality of grooves are adapted to engage with each of the plurality of lands of the shutter plunger such that each of the plurality of lands impart a slidable motion to each of the plurality of grooves of the at least one safety shutter, to slidably adjust the at least one safety shutter between an open and a closed position, during the retracted and extended state of the shutter plunger respectively.
[0024] According to yet another aspect of the present disclosure, the withdrawable drawer unit is ineither of the ejected position or the disconnected position, the shutter plunger is in the extended state, such that the at least one safety shutter is in the closed position, such that access to the plurality of female contact units is restricted, and when the withdrawable drawer unit is in either of the connected position or the test position, the shutter plunger is in the retracted state, such that the at least one safety shutter is in the open position, such that plurality of female contact units are accessible.
[0025] BRIEF DESCRIPTION OF DRAWINGS
[0026] In order to explain the technical solution in the embodiments of the present application more clearly, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the application. For those skilled in the art, without any creative work, other drawings can be obtained based on these drawings.
[0027] Figure 1 illustrates a front perspective view of an Air Circuit Breaker (ACB), in accordance with the concepts of the present disclosure.
[0028] Figure 2 illustrates a rear perspective view of the ACB, in accordance with the concepts of the present disclosure.
[0029] Figure 3 illustrates a side sectional view of a withdrawable drawer unit of the ACB of Figure 1, in accordance with the concepts of the present disclosure.
[0030] Figure 4 illustrates a side sectional view of a fixed cradle unit of the ACB of Figure 1, in accordance with the concepts of the present disclosure.
[0031] Figure 5 illustrates a side sectional view of the ACB of Figure 1, in a disconnected position, in accordance with the concepts of the present disclosure.
[0032] Figure 6 illustrates a side sectional view of the ACB of Figure 1, in a test position, in accordance with the concepts of the present disclosure.
[0033] Figure 7 illustrates a side sectional view of the ACB of Figure 1, in a connected position, in accordance with the concepts of the present disclosure.
[0034] Figure 8 illustrates a side sectional view of an arrangement of an operating mechanism and a plurality of pole assemblies of the ACB of Figure 1, in an ON position corresponding to a CLOSED state of the ACB, in accordance with the concepts of the present disclosure.Figure 9 illustrates a side sectional view of the arrangement of Figure 8, in an OFF / TRIP position corresponding to an OPEN state of the ACB of Figure 1, in accordance with the concepts of the present disclosure.
[0035] Figure 10 illustrates an assembled perspective view of a safety shutter arrangement installed relative to a chassis of the withdrawable-type air circuit breaker, in accordance with the concepts of the present disclosure.
[0036] Figure 11 illustrates an exploded perspective view of the safety shutter arrangement relative to the chassis of the withdrawable-type air circuit breaker, in accordance with the concepts of the present disclosure.
[0037] Figure 12a illustrates a close-up view of a shutter front cover of the safety shutter arrangement installed relative to the chassis, depicting a shutter plunger in a retracted state, in accordance with the concepts of the present disclosure.
[0038] Figure 12b illustrates a close-up view of the shutter front cover of the safety shutter arrangement installed relative to the chassis, depicting the shutter plunger in an extended state, in accordance with the concepts of the present disclosure.
[0039] Figure 13 illustrates a perspective view of the shutter front cover of the safety shutter arrangement of the withdrawable type air circuit breaker, in accordance with the concepts of the present disclosure.
[0040] Figure 14 illustrates an assembly of the shutter front cover relative to the chassis of the withdrawable type air circuit breaker, in accordance with the concepts of the present disclosure.
[0041] Figure 15 illustrates a perspective view of a relative arrangement between the shutter plunger and a safety shutter spring of the safety shutter arrangement, in accordance with the concepts of the present disclosure.
[0042] Figure 16 illustrates a perspective view of the shutter plunger the safety shutter arrangement, in accordance with the concepts of the present disclosure.
[0043] DETAILED DESCRIPTION OF THE INVENTION
[0044] In the following description, for the purposes of explanation, various specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent, however, that embodiments of the present invention may be practiced without thesespecific details. Several features described hereafter can each be used independently of one another or with any combination of other features. An individual feature may not address any of the problems discussed above or might address only one of the problems discussed above. Some of the problems discussed above might not be fully addressed by any of the features described herein. Exemplified embodiments of the present invention are described below, as illustrated in various drawings in which, like reference numerals refer to the same parts throughout the different drawings.
[0045] Figure 1 illustrates a front perspective view of an Air Circuit Breaker (ACB)
[0100] , in accordance with the concepts of the present disclosure. Figure 2 illustrates a rear perspective view of the ACB
[0100] , in accordance with the concepts of the present disclosure. Figure 3 illustrates a side sectional view of a withdrawable drawer unit
[0116] of the ACB
[0100] of Figure 1, in accordance with the concepts of the present disclosure. Figure 4 illustrates a side sectional view of a fixed cradle unit
[0114] of the ACB of Figure 1, in accordance with the concepts of the present disclosure. Figure 5 illustrates a side sectional view of the ACB
[0100] of Figure 1, in a disconnected position, in accordance with the concepts of the present disclosure. Figure 6 illustrates a side sectional view of the ACB
[0100] of Figure 1, in a test position, in accordance with the concepts of the present disclosure. Figure 7 illustrates a side sectional view of the ACB
[0100] of Figure 1, in a connected position, in accordance with the concepts of the present disclosure. Figure 8 illustrates a side sectional view of an operating mechanism
[0102] of the ACB
[0100] of Figure 1, in an ON position corresponding to a CLOSED state of the ACB, in accordance with the concepts of the present disclosure. Figure 9 illustrates a side sectional view of the arrangement of Figure 8, in an OFF / TRIP position corresponding to an OPEN state of the ACB
[0100] of Figure 1, in accordance with the concepts of the present disclosure. Figures 1 to 9 are to be viewed in conjunction with each other, in order to appreciate the scope of the present invention. For ease of reference and understanding, different embodiments relating to the structure and arrangement of the air circuit breaker is elucidated hereunder, with reference to the aforementioned accompanying drawings.
[0046] The ACB
[0100] is capable of being operated amongst three states, namely, an ON state, an OFF state, and a TRIP state. The ACB
[0100] comprises a frame member (not shown), the plurality of pole assemblies
[0104] housed and supported within the frame member, the operating mechanism
[0102] installed onto the plurality of pole assemblies
[0104] , and a control panel unit
[0108] adapted to fittingly attach with the frame member, to protect various components of the ACB
[0100] against any extraneous matter and also safeguard users from coming into contact with a current path established within the ACB
[0100] during its operation.In the ACB
[0100] , the plurality of pole assemblies
[0104] is operated together between the ON state and the OFF / TRIP state, by means of the operating mechanism
[0102] , Particularly, the operating mechanism
[0102] of the ACB
[0100] employs a charging spring arrangement (not shown) capable of being adjusted / manipulated between a CHARGED state and a DISCHARGED state. As is commonly known, the ACB
[0100] can be switched to the ON state only if the said charging spring arrangement is in the CHARGED STATE, and the charging spring arrangement is automatically adjusted to a DISCHARGED state, once the ACB
[0100] is in the ON state. To adjust the charging spring arrangement back to the CHARGED state, a charging lever member
[0106] is provided in the control panel unit
[0108] , In the ‘ON’ position, the ACB
[0100] allows a flow of current from a line side (i.e., input supply side) to a load side (i.e., output side), whereas, in each of the ‘OFF’ position and the ‘TRIP’ position, the ACB
[0100] restricts the flow of current therethrough. The ACB can be broadly classified into two categories, namely, a fixed-type ACB
[0100] and a withdrawable-type ACB
[0100] ,
[0047] The withdrawable-type ACB
[0100] is a two-part circuit breaker comprising a fixed cradle unit
[0114] and a withdrawable drawer unit
[0116] , wherein the withdrawable drawer unit
[0116] is detachably installed within the fixed cradle unit
[0114] , preferably, in a slidable manner, either vertically or horizontally. The fixed cradle unit
[0114] employs a terminal device
[0118] connected to the line side, while the withdrawable drawer unit
[0116] comprises various components and / or units described hereinabove. The withdrawable drawer unit
[0116] is operable relative to the fixed cradle unit
[0114] amongst the disconnected position, the test position, the connected position, and an ejected position.
[0048] The frame member is a housing structure that provides a mounting base and support structure for holding and supporting each of the plurality of pole assemblies
[0104] therein. In particular, the frame member defines pole holding cavities (not shown) to mount and support each of the plurality of pole assemblies
[0104] therein. Notably, each of the plurality of pole assemblies
[0104] are fixedly attached within the pole holding cavities defined by the frame member. An attachment means for attaching the plurality of pole assemblies
[0104] within the pole holding cavities defined by the frame member includes, but is not limited to, a bolt attachment means, a screw attachment means, a rivet attachment means, an adhesive attachment means, a fit attachment means, a weld attachment means, and the like. The structure and arrangement of the control panel unit
[0108] will be elucidated hereafter.
[0049] The control panel unit
[0108] is fittingly mounted on the frame member, to cover various components of the ACB
[0100] housed within the frame member. The control panel unit
[0108] hasvarious portions to define electrical parameters related to ACB
[0100] , The control panel unit
[0108] also has various visual indicators for indicating the real-time status of at least one of the charging spring arrangement, the plurality of pole assemblies
[0104] , and other such similar arrangements and / or units.
[0050] Referring to figures 5 to 7, each of the plurality of pole assemblies
[0104] includes a pole housing
[0120] , a stationary contact unit
[0122] , a moving contact unit
[0124] , and an arc chute unit
[0126] , More particularly, a number of the plurality of pole assemblies
[0104] , in combination, define a number of electrical connection poles of the ACB
[0100] , The stationary contact unit
[0122] is an electric contact plate-like structure that may be positioned within a defined portion in the casing unit
[0120] , The stationary contact unit
[0122] is provided to connect to electrical wires from the line side. In particular, in complete assembly of the ACB
[0100] , the electrical wires from the line side are usually connected to the stationary contact unit
[0122] ,
[0051] On the other hand, the moving contact unit
[0124] is a moving structure that engages / di sengages with the stationary contact unit
[0122] , to allow / restrict the flow of electric current therethrough. The moving contact unit
[0124] is rotatably positioned within a defined portion in the pole housing
[0120] , and is further connected to electrical wires on the load side. In particular, in complete assembly of the ACB
[0100] , the electrical wires from the line side are usually connected to the stationary contact unit
[0122] , Further, the moving contact unit
[0124] is pivotally adjusted while being positioned within the pole housing
[0120] , to make and release a contact relative to the stationary contact unit
[0122] , in order to allow and restrict the flow of electric current therebetween, respectively. Notably, the moving contact unit
[0124] ‘makes’ a contact relative to the stationary contact unit
[0122] to allow the flow of electric current (the ‘ON’ position), while the rotary contact unit ‘releases’ a contact relative to the stationary contact unit
[0122] , to restrict the flow of electric current (the ‘OFF’ position and the ‘TRIP’ position).
[0052] Referring to figures 8 and 9, the moving contact unit
[0124] is commonly known to comprise a moving contact carrier [124a], a plurality of contact fingers [124b] adapted to be affixed within the moving contact carrier [124a], and a carrier frame (not shown) adapted to pivotally connect the moving contact unit
[0124] relative to a pole shaft [102a] of the operating mechanism
[0102] , Notably, the plurality of contact fingers [124b] is known to be made up of a combination of two elements, for example, silver and copper. Such a structure enables each of the plurality of contact fingers [124b] to function as a pair of contacts, namely, a main contact and an arcing contact. Essentially, the plurality of contact fingers [124b] are affixed relative to the moving contact carrier [124a] in a resiliently pivotal manner, such that upon tripping, as soon as the movingcontact unit
[0124] disengages from the stationary contact unit
[0122] , the arcing contact rapidly engages with the same, preferably, in a tip-to-toe manner, thereby safeguarding the ACB
[0100] against nuisance arcing.
[0053] The arc chute unit
[0126] is positioned within the arc chute unit portion [120a] of the pole housing
[0120] and comprises of a two-wall shaped arc chute holder member [126a] and an arc chute member [126b], The arc chute holder member [126a] and the arc chute member [126a] are arranged together to vent out gases generated by an arc caused due to engagement / disengagement of the moving contact unit
[0124] relative to the stationary contact unit
[0122] through a vent channel defined by the arc chute holder member.
[0054] The fixed-cradle unit
[0114] comprises a chassis
[0128] , a plurality of female contact units
[0130] , and a plurality of bus bar units
[0110] , The chassis
[0128] is adapted to hold and support the plurality of female contact units
[0130] , and the plurality of bus bar units
[0110] are connected to the plurality of female contact units
[0130] at one end thereof. The chassis
[0128] defines L-shaped slots [128a] to facilitate attachment thereon a shutter front cover
[0208] of a safety shutter arrangement
[0200] , The withdrawable drawer unit
[0116] comprises the ACB
[0100] , wherein the ACB
[0100] comprises a plurality of male contact units
[0132] adapted to attach to the plurality of female contact units
[0130] of the fixed cradle unit
[0114] ,
[0055] Figure 10 illustrates an assembled perspective view of the safety shutter arrangement
[0200] installed relative to the chassis
[0128] of the withdrawable-type air circuit breaker, in accordance with the concepts of the present disclosure. Figure 11 illustrates an exploded perspective view of the safety shutter arrangement
[0200] relative to the chassis
[0128] of the withdrawable-type air circuit breaker, in accordance with the concepts of the present disclosure. Figure 12a illustrates a close-up view of a shutter front cover
[0208] of the safety shutter arrangement
[0200] installed relative to the chassis
[0128] , depicting a shutter plunger
[0206] in a retracted state, in accordance with the concepts of the present disclosure. Figure 12b illustrates a close-up view of the shutter front cover
[0208] of the safety shutter arrangement
[0200] installed relative to the chassis
[0128] , depicting the shutter plunger
[0206] in an extended state, in accordance with the concepts of the present disclosure. Figure 13 illustrates a perspective view of the shutter front cover
[0208] of the safety shutter arrangement
[0200] of the withdrawable type air circuit breaker, in accordance with the concepts of the present disclosure. Figure 14 illustrates an assembly of the shutter front cover
[0208] relative to the chassis
[0128] of the withdrawable type air circuit breaker, in accordance with the concepts of the present disclosure. Figure 15 illustrates a perspective view of a relative arrangement between the shutter plunger
[0206] and a safety shutter spring
[0204] of the safetyshutter arrangement
[0200] , in accordance with the concepts of the present disclosure. Figure 16 illustrates a perspective view of the shutter plunger
[0206] the safety shutter arrangement
[0200] , in accordance with the concepts of the present disclosure.
[0056] Referring to figures 10 and 11, the ACB
[0100] comprises the safety shutter arrangement
[0200] , The safety shutter arrangement
[0200] comprises at least one safety shutter
[0202] , the safety shutter spring
[0204] , the shutter plunger
[0206] and the shutter front cover
[0208] , wherein the shutter plunger
[0206] is operable between the extended state and the retracted state, and the shutter front cover
[0208] movably locks the shutter plunger
[0206] , the safety shutter spring
[0204] and the at least one safety shutter
[0202] against the chassis
[0128] of the fixed cradle unit
[0114] , The safety shutter arrangement is employed to selectively provide and restrict access to the plurality of female contact units
[0130] , When the withdrawable drawer unit
[0116] of the ACB
[0100] is in either of the ejected or disconnected position, the shutter plunger
[0206] is in the extended state, such that the at least one safety shutter
[0202] is in the closed position, such that access to the plurality of female contact units
[0130] of the fixed cradle unit
[0114] is restricted, and when the withdrawable drawer unit
[0116] is in either of the connected position or the test position, the shutter plunger
[0206] is in the retracted state, such that the at least one safety shutter
[0202] is in the open position, such that plurality of female contact units
[0130] are accessible.
[0057] Referring to figures 10, and 12a to 13, the shutter front cover
[0208] defines a central plate portion [208a], a cavity [208b], a pair of L-shaped locking protrusions [208c], and at least one grip extension [208d], The pair of L-shaped locking protrusions [208c] extend from opposite ends of the central plate portion [208a], such that the locking protrusions [208c] extends through the L-shaped slots [128a] of the chassis
[0128] of the fixed cradle unit
[0114] , and the at least one grip extension [208d] enable a technician to hold the shutter front cover
[0208] to push the shutter front cover
[0208] downwards from a top of the chassis
[0128] of the fixed cradle unit
[0114] , and into the L-shaped slots [128a] of the chassis
[0128] , to lock the shutter front cover
[0208] to the chassis
[0128] of the fixed cradle unit
[0114] , The shutter plunger
[0206] is resiliently and slidably installed against the chassis
[0128] by means of the safety shutter spring
[0204] , along a horizontal axis thereof, such that the central plate portion [208a] of the shutter front cover
[0208] restricts the sliding movement of the shutter plunger
[0206] beyond a predetermined limit. Further, the shutter plunger
[0206] is configured to be manipulated between a retracted state and an extended state.
[0058] Referring to figures 10, and 14 to 16, the shutter plunger
[0206] defines a plurality of lands [206a], a protrusion [206b] and at least one extension leg [206c], The protrusion [206b] is adapted to attach one end of the safety shutter spring
[0204] thereon, and other end of the safetyshutter spring
[0204] is attached in the chassis
[0128] of the fixed cradle unit
[0114] , The extension leg [206c] is adapted to abut with the central plate portion [208a] of the shutter front cover
[0208] in an extended state, to lock and limit travel of the shutter plunger
[0206] therein, such that the extension leg [206c] prevents the shutter plunger
[0206] from falling through the cavity [208b] of the central plate portion [208a], In the extended state of the shutter spring
[0204] , such that the safety shutter spring
[0204] exerts force on the shutter front cover
[0208] , thereby firmly attaching the shutter front cover
[0208] to the chassis
[0128] even in the extended state of the shutter plunger
[0206] ,
[0059] Referring to figures 10, 11 and 15, the at least one safety shutter
[0202] of the safety shutter arrangement
[0200] is slidably attached to the chassis
[0128] of the fixed cradle unit
[0114] , The at least one safety shutter
[0202] defines a plurality of grooves [202a], wherein each of the plurality of grooves [202a], are adapted to engage with each of the plurality of lands [206a] of the shutter plunger
[0206] , The plurality of lands [206a] impart a slidable motion to each of the plurality of grooves [202a] thereby slidably adjusting the at least one safety shutter
[0202] between an open and a closed position, during the retracted state and the extended state of the shutter plunger
[0206] respectively.
[0060] OPERATION
[0061] During a rack-in operation, the withdrawable drawer unit
[0116] slides inwards, and into the fixed cradle unit
[0114] from the disconnected position to the test position or the connected position. The shutter plunger
[0206] abuts against the withdrawable drawer unit
[0116] , and as the withdrawable drawer unit
[0116] slides inwards, and into the fixed cradle unit
[0114] , the safety shutter spring
[0204] compresses corresponding to a compressed state, such that the shutter plunger
[0206] is adjusted from the extended state to the retracted state. The adjustment of the shutter plunger
[0206] from the extended state to the retracted state causes each of the plurality of grooves [202a] to engage with each of the plurality of lands [206a], thereby slidably adjusting the at least one safety shutter
[0202] to the open position from the closed position, thereby slidably adjusting the at least one safety shutter
[0202] to the open position from the closed position, thereby allowing access to the plurality of female contact units
[0130] of the fixed cradle unit
[0114] , In a rack-out operation, the withdrawable drawer unit
[0116] slides outwards from the fixed cradle unit
[0114] , from the test position or the connected position to the disconnected position, such that the shutter plunger
[0206] is adjusted from the retracted state to the extended state, and the safety shutter spring
[0204] corresponds to the extended state, such that the each of the plurality of grooves [202a] engage with each of the plurality of lands [206a], thereby slidablyadjusting the at least one safety shutter
[0202] to the closed position from the open position, thereby restricting access to the plurality of female contact units
[0130] of the fixed cradle unit [H4].
[0062] Various advantages of the presently disclosed safety shutter arrangement
[0200] of the ACB
[0100] exist. Firstly, the shutter front cover
[0208] of the safety shutter arrangement
[0200] comprising the L - shaped locking protrusions [208c] are adapted to lock with the L - shaped slots [128a] of the chassis
[0128] without the need for any additional securing means to attach the shutter front cover
[0208] to the chassis
[0128] of the fixed cradle unit
[0114] , Secondly, the technician can easily install the shutter front cover
[0208] on a job site without requiring any specialised tools. Thirdly in case of breakage of the shutter front cover
[0208] , only the front cover
[0208] needs replacement, whereas the chassis remains untainted, thus saving a user significant replacement costs. Fourth, the central plate portion [208a] restricts the sliding movement of the shutter plunger
[0206] beyond a limit, without requiring any additional hardware. It may be understood that the above listed advantages are merely illustrative and not exhaustive. Those skilled in the art may contemplate additional advantages not described herein above, in light of the concepts of the present disclosure.
[0063] While the preferred embodiments of the present invention have been described hereinabove, it should be understood that various changes, adaptations, and modifications may be made therein without departing from the concepts of the present invention. It will be obvious to a person skilled in the art that the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive.
[0064] LIST OF COMPONENTS
[0065] 100 - Air circuit breaker
[0066] 102 - Operating mechanism
[0067] 102a - Pole shaft
[0068] 104 - Pole assembly
[0069] 106 - Charging lever member
[0070] 108 - Control panel unit
[0071] 110 - Bus bar units
[0072] 114 - Fixed cradle unit116 - Withdrawable drawer unit 118 - Terminal device
[0073] 120 - Pole housing
[0074] 120a - Arc chute unit portion
[0075] 122 - Stationary contact unit
[0076] 124 - Moving contact unit
[0077] 124a - Moving contact carrier
[0078] 124b - Plurality of contact fingers 126 - Arc chute unit
[0079] 126a - Arc chute holder member 126b - Arc chute member
[0080] 128 - Chassis
[0081] 128a - L - shaped Slots
[0082] 130 - Female contact units
[0083] 132 - Male contact units
[0084] 200 - Safety shutter arrangement 202 - Safety shutter
[0085] 202a - Groove
[0086] 204 - Safety shutter spring
[0087] 206 - Shutter plunger
[0088] 206a - Land
[0089] 206b - Protrusion
[0090] 206c - Extension leg
[0091] 208 - Shutter front cover
[0092] 208a - Central plate portion
[0093] 208b - Cavity
[0094] 208c - L - shaped locking protrusions208d - Grip extension
Claims
We Claim1. A safety shutter arrangement [200] of an Air Circuit Breaker (ACB) [100], the ACB [100] comprising a fixed cradle unit [114] that comprises a chassis [128] defining L- shaped slots [128a], the safety shutter arrangement [200] comprising:a shutter plunger [206] resiliently and slidably installed against the chassis [128] of the fixed cradle unit [114], along a horizontal axis; anda shutter front cover [208] defining a central plate portion [208a], and a pair of L- shaped locking protrusions [208c] extending from opposite ends of the central plate portion [208a], such that the locking protrusions [208c] extends through the L-shaped slots [128a] of the chassis [128] of the fixed cradle unit [114],wherein the central plate portion [208a] restricts the sliding movement of the shutter plunger [206] beyond a limit.
2. The safety shutter arrangement [200] as claimed in claim 1, wherein, the central plate portion [208a] further defines a cavity [208b] and at least one grip extension [208d], such that the at least one grip extension [208d] is adapted to enable a technician to hold thereof to push the shutter front cover [208] downwards from a top of the chassis [128] of the fixed cradle unit [114], and into the L-shaped slots [128a] of the chassis [128], to lock the shutter front cover [208] to the chassis [128] of the fixed cradle unit [114],3. The safety shutter arrangement [200] as claimed in claim 1, wherein, the ACB [100] further comprising a withdrawable drawer unit [116] that includes a plurality of male contact units [132], the fixed cradle unit [114] comprising the plurality of female contact units [130], such that the withdrawable drawer unit [116] is operable amongst a disconnected position, a test position, a connected position, and an ejected position.
4. The safety shutter arrangement [200] as claimed in claim 1, further comprising at least one safety shutter [202], and a safety shutter spring [204], such that the shutter front cover [208] movably locks the shutter plunger [206], the safety shutter spring [204] and the at least one safety shutter [202] against the chassis [128] of the fixed cradle unit [H4].
5. The safety shutter arrangement [200] as claimed in claim 1, the shutter plunger [206] defines a plurality of lands [206a], a protrusion [206b] and at least one extension leg [206c], wherein the shutter plunger [206] is configured to be manipulated between a retracted state and an extended state.
6. The safety shutter arrangement [200] as claimed in claims 1, 2 and 5, wherein the protrusion [206b] is adapted to attach the safety shutter spring [204] thereon, the safety shutter spring [204] exerts force on the shutter front cover [208], thereby firmly attaching the shutter front cover [208] to the chassis [128] even in the extended state of the shutter plunger [206],7. The safety shutter arrangement [200] as claimed in claims 1, 2 and 5, the extension leg [206c] is adapted to abut with the central plate portion [208a] of the shutter front cover [208] in an extended state, to lock and limit travel of the shutter plunger [206] therein, such that the extension leg [206c] prevents the shutter plunger [206] from falling through the cavity [208b] of the central plate portion [208a],8. The safety shutter arrangement [200] as claimed in claims 1 to 7, wherein the at least one safety shutter [202] is slidably attached to the chassis [128] of the fixed cradle unit [114], and the at least one safety shutter [202] defines a plurality of grooves [202a], wherein each of the plurality of grooves [202a] are adapted to engage with each of the plurality of lands [206a] of the shutter plunger [206] such that each of the plurality of lands [206a] impart a slidable motion to each of the plurality of grooves [202a] of the at least one safety shutter [202], to slidably adjust the at least one safety shutter [202] between an open and a closed position, during the retracted and extended state of the shutter plunger [206] respectively.
9. The safety shutter arrangement [200] as claimed in claims 1 to 8, wherein the withdrawable drawer unit [116] is in either of the ejected position or the disconnected position, the shutter plunger [206] is in the extended state, such that the at least one safety shutter [202] is in the closed position, such that access to the plurality of female contact units [130] is restricted, and when the withdrawable drawer unit [116] is in either of the connected position or the test position, the shutter plunger [206] is in the retracted state,such that the at least one safety shutter [202] is in the open position, such that plurality of female contact units [130] are accessible.