DESC:TECHNICAL FIELD
[0001] The present disclosure relates to the field of protection devices used in low and medium voltage power supply systems. In particular, the present disclosure relates to a telescopic arrangement for rails of cradle for draw out type circuit breakers.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Circuit breakers are incorporated in a power supply circuit for protection against potential damage that may be caused to electrical circuit and connected load by potentially damaging occurrences such as but not limited to overvoltage, short-circuit etc. Circuit breakers are designed to detect such potentially dangerous conditions and operate to disconnect the load automatically. After a fault has been diagnosed and rectified, circuit breaker can be either manually or remotely reset and power supply circuit can resume its normal operations/ functioning. They can also be used to isolate the connected load from power supply that may become necessary for various reasons such as maintenance.
[0004] Circuit breakers are designed according to their operating environment and intended purpose. They come in many different sizes and shapes. Circuit breakers are also of many different types such as Withdrawal type or Fixed type of Circuit Breakers. Fixed type of Circuit Breakers are standalone and need no external enclosure for their operations. In extractable or withdrawal type of Circuit Breakers, which the present disclosure relates to, the circuit breaker is housed inside an external frame or enclosure that encases the circuit breaker in such a way that the circuit breaker can be switched off and extracted from within the enclosure for maintenance without removing the termination of bus bars. In extractable/ withdrawal type of circuit breakers, electrical connection between the circuit breaker and external enclosure is maintained with the help of array of movable and flexible contacts. Array of flexible contacts are fixed to the enclosure and remain energized even when the breaker is disconnected and is in withdrawn position. Thus, flexible contacts carry the system potential.
[0005] Withdrawal type or extractable circuit breaker systems typically incorporate a cradle arrangement that besides enabling withdrawal of the circuit breaker, is configured for establishing and removing connection with the bus bar system. Cradle consists of a racking mechanism, a rail system along with a locking arrangement and a contact system.
[0006] Existing cradles for withdrawal type circuit breakers typically incorporate an extended rail arrangement with complicated features that are difficult to operate. Such arrangements are different for circuit breakers having different ratings. Furthermore, manufacturing of these rails requires special processes, wherein, for instance, complex locking systems lead to frequent failures in the rail system.
[0007] There is therefore a need in the art for an improved railing system that is simple to manufacture, easy to operate and maintain, and is not susceptible to frequent failures.
[0008] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0009] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0010] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0011] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0012] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

OBJECTS OF THE INVENTION
[0013] An object of the present disclosure is to provide a railing system for cradle of a withdrawal type circuit breaker that incorporates telescopic rails.
[0014] Another object of the present disclosure is to provide telescopic rails that incorporate interlocking to ensure their smooth functioning.
[0015] Yet another object of the present disclosure is to provide a railing system for cradle that is simple to manufacture.
[0016] Still another object of the present disclosure is to provide a railing system for cradle that is not susceptible to frequent failures.

SUMMARY
[0017] Aspects of the present disclosure relate to the railing system and its locking arrangement for cradle of a withdrawal type circuit breaker. In an aspect, the disclosed railing system incorporates telescopic rails that result in increased travel distance thus providing ease of maintenance for the circuit breaker.
[0018] In an aspect, the telescopic rails can be a two stage arrangement comprising a set of inner rails (also referred to as breaker rail as they support the circuit breaker, and the two terms used interchangeably hereinafter) and a set of outer rails (also referred to as cradle rail as it is configured on cradle side, and the two terms used interchangeably hereinafter) with the set of outer rails configured to move telescopically within and relative to the set of inner rails.
[0019] In an aspect, each of the breaker rails rest on the respective cradle rail with help of two guiding pins through a slot provided on the breaker rail. The length of the slot determines extent of movement of the telescopic arrangement of the two rails.
[0020] In an aspect, each of the cradle rails can be slidably configured with corresponding cradle side plate with help of a top rail guide and a bottom rail guide. Thus the movement of the cradle rail relative to the cradle side plate and movement of the breaker rail relative to the cradle rail constitute the two stages of the railing movement.
[0021] In another aspect, the telescopic rails incorporate an interlocking such that only one of the two stages moves at a time. The interlocking arrangement can be configured such that during withdrawal operation, movement of the breaker rails relative to corresponding cradle rails is prevented till the cradle rail is fully out of the cradle. Likewise during return operation, movement of the cradle rails is prevented till the breaker rails are in fully home position. Thereafter, the cradle rails are free to move to take the breaker to fully home position.
[0022] In another aspect, the means for interlocking can comprise a latching mechanism between the two telescopic rails. The latch can be gravity operated latch and operate under action of gravitational force to lock (also referred to as latch and the two terms used interchangeably hereinafter) relative motion of telescopic arrangement between the respective breaker rails and cradle rails in distinct/desired positions.
[0023] In another aspect, there can be two distinct positions in which the latching mechanism latches the relative motion of telescopic arrangement. The two positions can correspond to fully extended position and fully collapsed position of the telescopic arrangement of the two rails. In an aspect, the latching of the rails in these two positions can prevent movement of the breaker rail relative to cradle rail (keeping the telescopic arrangement in fully collapsed condition) till the cradle rail is fully extended/out during withdrawal operation. Further it prevents relative movement of the two (keeping the telescopic arrangement in fully extended condition) till the cradle rail is fully home during return operation.
[0024] In another aspect, the latching mechanism between the breaker rails and respective cradle rails can incorporate means to unlock/unlatch the respective breaker rail and cradle rail. The unlocking/unlatching means can be a manually operated mechanism.
[0025] In another aspect, the means for interlocking can further comprise a cradle rail lock configured to prevent travel of the cradle rail after it is in fully extended/out position. Unlocking of the cradle rail lock can get actuated by the breaker rail after the breaker rail is fully home within the cradle rail (telescopic arrangement fully collapsed). This arrangement prevents travel of the cradle rail till the breaker rail is fully home. Thus the interlocking ensures that only one of the two stages of the rails operate at a time providing smooth withdrawal and return operations.
[0026] In another aspect, the disclosure provides a service latch arrangement in the proposed railing system that enables locking of the circuit breaker in service position.
[0027] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components

BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0029] FIG. 1 illustrates an exemplary schematic diagram of telescopic rail arrangement in accordance with embodiments of the present disclosure.
[0030] FIG. 2 illustrates an exemplary schematic diagram of breaker rail and latching mechanism in its latched position of in accordance with an embodiment of the present disclosure.
[0031] FIG. 3 illustrates an exemplary schematic diagram of latching mechanism in its de-latched position in accordance with an embodiment of the present disclosure.
[0032] FIG. 4 illustrates an exemplary schematic diagram indicating de-latched condition of the two rails in accordance with an embodiment of the present disclosure.
[0033] FIG. 5 illustrates an exemplary schematic diagram indicating latched condition of the two rails in accordance with an embodiment of the present disclosure.
[0034] FIG. 6 illustrates an exemplary schematic diagram indicating service latch arrangement in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0035] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0036] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0037] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0038] Embodiments of the present disclosure relate to railing system and its locking arrangement for cradle of a withdrawal type circuit breaker. In an aspect, the disclosed railing system incorporates telescopic arrangement which can be a two stage arrangement comprising a set of breaker rails and a set of cradle rails with the breaker rails configured to move telescopically relative to the respective cradle rail. Each of the cradle rails can be slidably configured with corresponding cradle side plate with help of a top rail guide and a bottom rail guide.
[0039] In an aspect, combination of sliding movement of the cradle rail relative to cradle side plate and that of the breaker rail relative to the cradle results in increased travel distance thus providing ease of maintenance for the circuit breaker breaker that is mounted on the breaker rails.
[0040] In an embodiment, each of the breaker rails rest on the respective cradle rail with help of guiding pins through a slot provided on the breaker rail. The configuration of the guiding pins and the slot can determine extent of movement of the telescopic arrangement of the two rails.
[0041] In an embodiment, the telescopic rails incorporate an interlocking such that only one of the two stages moves at a time. The interlocking arrangement can be configured such that during withdrawal operation, movement of the breaker rails relative to corresponding cradle rails is prevented till the cradle rail is fully out of the cradle. Likewise during return operation, movement of the cradle rails is prevented till the breaker rails are fully in home position. Thereafter, the cradle rails are free to move to take the breaker to fully home position.
[0042] In another aspect, the means for interlocking can comprise a latching mechanism between the two telescopic rails. The latch can be gravity operated latch and operate under action of gravitational force to lock (also referred to as latch and the two terms used interchangeably hereinafter) relative motion of telescopic arrangement between the respective breaker rails and cradle rails in distinct/desired positions.
[0043] In another aspect, there can be two distinct positions in which the latching mechanism latches the relative motion of telescopic arrangement. The two positions can correspond to fully extended position and fully collapsed position of the telescopic arrangement of the two rails. In an aspect, the latching of the rails in these two positions can prevent movement of the breaker rail relative to cradle rail (keeping the telescopic arrangement in fully collapsed condition) till the cradle rail is fully extended/out during withdrawal operation. Further it prevents relative movement of the two (keeping the telescopic arrangement in fully extended condition) till the cradle rail is fully home during return operation.
[0044] In another aspect, the latching mechanism between the breaker rails and respective cradle rails can incorporate means to unlock/unlatch the respective breaker rail and cradle rail. The unlocking/unlatching means can be a manually operated mechanism.
[0045] In another aspect, the means for interlocking can further comprise a cradle rail lock configured to prevent travel of the cradle rail after it is in fully extended/out position. Unlocking of the cradle rail lock can get actuated by the breaker rail after the breaker rail is fully home within the cradle rail (telescopic arrangement fully collapsed). This arrangement prevents travel of the cradle rail till the breaker rail is fully home. Thus the interlocking ensures that only one of the two stages of the rails operate at a time providing smooth withdrawal and return operations.
[0046] In another aspect, the disclosure provides a service latch arrangement in the proposed railing system that enables locking of the circuit breaker in service position.
[0047] Referring to FIG. 1, where a schematic diagram of the proposed telescopic rails in accordance with an embodiment is disclosed. A telescopic rail arrangement 100 can comprise a breaker rail 110 and a cradle rail 108 with the breaker rail 110 configured to move telescopically relative to the cradle rail 108. The cradle rail 108 can be slidably configured with corresponding cradle side plate 102 with help of a top rail guide 104 and a bottom rail guide 106 wherein the top rail guide 104 and the bottom rail guide 106 are fixed on the cradle side plate 102. The movement of the cradle rail 108 relative to the cradle side plate 102 and movement of the breaker rail 110 relative to the cradle rail 108 constitute the two stages of the railing movement.
[0048] In an embodiment of implementation there can be more than one breaker rails 110 and corresponding number of cradle rails 108 in a circuit breaker cradle with one breaker rail 110 and one cradle rail 108 forming one telescopic rail and one or more telescopic rails configured on cradle side walls such as left side wall and right side wall with help of corresponding numbers of top rail guides 104 and bottom rail guides 106 so as to provide adequate support to the circuit breaker mounted on the breaker rail(s) 110.
[0049] In an aspect, combination of sliding movement of the cradle rail 108 relative to cradle side plate 102 and that of the breaker rail 110 relative to the cradle rail 108 results in increased travel distance thus providing ease of maintenance for the circuit breaker breaker that is mounted on the breaker rails 110.
[0050] In an embodiment, each of the breaker rails 110 can rest on the respective cradle rail 108 with help of guiding pins 112 through a slot provided on the breaker rail. The exemplary illustration in FIG. 1 shows two such pins however it is possible to The configuration of the guiding pins and the slot can determine extent of telescopic movement of the two rails.
[0051] Furthermore, FIG. 1 illustrates the breaker rail 110 in a position that is farthest outside the cradle corresponding to isolated position of the circuit breaker resting on the slots provided in the breaker rail 110. As is evident, additional travel of the breaker rail 110 relative to cradle rail 108 results in extra travel of the breaker resulting in a position that is farther from the electrical system.
[0052] In an embodiment, the telescopic rails arrangement can incorporate an interlocking such that only one of the two stages moves at a time. The interlocking arrangement can be configured such that during withdrawal operation, movement of the breaker rails 110 relative to corresponding cradle rails 108 is prevented till the cradle rail 108 is fully out of the cradle. Likewise during return operation, movement of the cradle rails 108 is prevented till the breaker rails 110 are fully in home position. Thereafter, the cradle rails 108 are free to move to take the breaker to fully home position.
[0053] In another aspect, the means for interlocking can comprise a latching mechanism between the two telescopic rails (108 and 110) and a cradle rail lock configured to prevent travel of the cradle rail 108 after it is in fully extended/out position relative to the cradle side plate 102. Both the latching mechanism and the cradle rail lock can be gravity operated configured to provide latching/locking of the respective members in their desired positions under action of gravitational force without any intervention.
[0054] FIG. 1 also illustrates the latching mechanism configured to provide latching between the the breaker rail 110 and corresponding cradle rails 108 to prevent telescopic movement between the two. The latching mechanism can be a coupling pin 114 configured with the cradle rail 108 with freedom to move in single direction which for example can be achieved by slot provided in cradle side rail 108. The direction of movement of the coupling pin 114 can be vertical so that it falls under gravity in a notch configured alongside the slot that accommodates the guiding pins 112. This can happen when the coupling pin 114 aligns with the notch. Engagement of the coupling pin 114 with the notch can latch the breaker rail 110 and corresponding cradle rails 108 together to prevent any telescopic movement between them.
[0055] In another aspect, there can be two distinct positions in which the latching mechanism latches the relative motion of telescopic arrangement and these distinct positions can be facilitated by providing two notches at appropriate positions as shown in FIG. 1. The two positions can correspond to fully extended position and fully collapsed position of the telescopic arrangement of the two rails. In an aspect, the latching of the rails in these two positions can prevent movement of the breaker rail relative to cradle rail (keeping the telescopic arrangement in fully collapsed condition) till the cradle rail is fully extended/out during withdrawal operation. Further it prevents relative movement of the two (keeping the telescopic arrangement in fully extended condition) till the cradle rail is fully home during return operation.
[0056] In another aspect, the latching mechanism between the breaker rails and respective cradle rails can incorporate means to unlock/unlatch the respective breaker rail 110 and cradle rail 108. The unlocking/unlatching means can be a manually operated mechanism.
[0057] FIG. 2 illustrates an exemplary schematic arrangement of the latching and de-latching arrangement between cradle rail 108 and breaker rail 110. As shown the coupling pin 114 can incorporate a cam follower and the cam follower can on engagement with a com configured on an actuating member, unlatch the rails by pushing the coupling pin 114 vertically up out of the notch. The actuating member can be part of a sliding actuator 116 with the sliding actuator 116 biased by a spring 122 to keep the actuating member disengaged from the cam on the coupling pin 114. There can be provision for a user to push the sliding actuator 116 which can enable the actuating member to engage with the cam follower of the coupling pin 114 and shift the coupling pin 114 up to dislodge the coupling pin 114 out of the notch to unlatch the rails.
[0058] FIG. 2 illustrates the latching mechanism with the cradle rail 108 and the breaker rail 110 in latched condition and FIG. 3 illustrates the latching mechanism with the cradle rail 108 and the breaker rail 110 in unlatched condition where the coupling pin 114 has been dislodged from the notch freeing the cradle rail 108 and the breaker rail 110 to have telescopic movement.
[0059] FIG. 1 and FIG. 3 also illustrate the other constituent part of the interlocking arrangement i.e. cradle rail lock 120 that is configured to prevent travel of the cradle rail 108 after it is in fully extended/out position. The cradle rail lock 120 can be pivotally attached to the cradle rail 108 by suitable means such as rivet 118. It can also be actuated by gravity to drop down and block the return path of the cradle rail 108 after the cradle rail 108 has come out fully. Unlocking of the cradle rail lock 120 can get actuated by a projection provided in the breaker rail 110 after the breaker rail is fully home within the cradle rail (telescopic arrangement fully collapsed). This arrangement prevents travel of the cradle rail till the breaker rail 110 is fully home. FIG. 1 shows the latched condition of the cradle rail latch 120 where the cradle rail latch 120 engages with the bottom rail guides 106 preventing the cradle rail 108 from moving in. In this condition the breaker rail 110 can be moved in without movement of the cradle rail 108. After the breaker rail 110 is fully home with cradle rail 108, the end of the breaker rail 110 can dislodge the cradle rail lock 120 from its lock position making the cradle rail 108 free to move in. Thus the interlocking by means of the latching arrangement and the cradle rail lock 120 ensures that only one of the two stages of the telescopic rails operate at a time providing smooth withdrawal and return operations.
[0060] After the cradle rail 108 has been pushed fully in, the rails can take position as shown in FIG. 4. In this position, breaker rail 110 is in latched condition with cradle rail 108 and racking pin 124 has just touched the cradle shaft cam 126. In this position the racking pin 124 can be actuated using cradle shaft cam 126 and rail system moves to service/connected position as shown in FIG. 5.
[0061] In another aspect, the disclosure provides a service latch arrangement in the proposed railing system that enables locking of the circuit breaker in service/connected position. FIG. 6 illustrates another view of the cradle with the breaker in service/connected position showing the service latch arrangement. In the service position, service latch actuator 128 will slide into service latch 130 which is connected to cradle side rail 108, thereby locking the movement of both the rail.
[0062] The present disclosure solves the issue regarding breaker fitment in cradle of circuit breaker, which is among the most tedious jobs during installation. The present disclosure also solves the interlocking issue that is not available in the known cradle systems. In yet another aspect, construction of the present invention enables automated actuation of interlocking of the rail arrangement. Furthermore, telescopic arrangement is rigidly mounted on the cradle side plate to enable stress distribution to take place uniformly, which improves mechanical life of the system.
[0063] The proposed disclosure enables increased breaker movement in a cradle, making it easy to inspect or service the cradle part without removing breaker. Furthermore, independent mechanism gives more accuracy and reliability in operation. Furthermore, interlocking feature helps avoid errors and delivers foolproof system.
[0064] In an aspect, the proposed mechanism has an interlock system in rail, which is auto actuated. Furthermore, interlocking is provided using a cam follower arrangement. Furthermore, gravity based interlocking is provided, which eliminates complicated spring arrangement. Furthermore, the proposed disclosure has lesser number of moving parts, which leads to better mechanical life and more strength of system.
[0065] In an aspect, in the present disclosure, double stage telescopic rail system provides ease of maintenance due to increased travel distance of rail. Locking system with minimal number of components ensures error free and failure free operation of telescopic rail system. Furthermore, the present disclosure provides more extension with rigid mounting and is easy to operate.
[0066] The proposed disclosure uses cam-follower and gravity based system for 3 stage locking arrangement and avoids complex spring based mechanisms giving a more robust system. Latching and de-latching mechanism also has better ergonomics.
[0067] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art

ADVANTAGES OF THE INVENTION
[0068] The present disclosure provides a railing system for cradle of a withdrawal type circuit breaker that incorporates telescopic rails.
[0069] The present disclosure provides telescopic rails that incorporate interlocking to ensure their smooth functioning.
[0070] The present disclosure provides a railing system for cradle that is simple to manufacture.
[0071] The present disclosure provides a railing system for cradle that is not susceptible to frequent failures.
,CLAIMS:We claim –
1. A railing system for cradle of a withdrawal type circuit breaker, the railing system comprising:
at least one cradle rail slidably configured on a cradle wall by means of one or more rail guides providing first stage of sliding rail movement;
at least one breaker rail configured with the at least one cradle rail in slidable telescopic arrangement providing second stage of sliding rail movement; and
interlocking arrangement wherein the interlocking arrangement is configured to allow movement of either the first stage or the second stage depending on position of withdrawal or insertion of the circuit breaker.
2. The railing system of claim 1, wherein the at least one breaker rail is configured in slidable telescopic arrangement with the at least one cradle rail by means of pins and slot.
3. The railing system of claim 1, wherein the interlocking arrangement is configured to allow sequential movement in the first stage and thereafter in the second stage during withdrawal of the circuit breaker; and allow sequential movement in the second stage and thereafter in the first stage during insertion of the circuit breaker.
4. The railing system of claim 1, wherein the interlocking arrangement comprises:
at least one latching arrangement configured between the at least one cradle rail and the at least one breaker rail configured to latch telescopic movement between the at least one cradle rail and the at least one breaker rail;
at least one cradle lock configured to lock movement of the at least one cradle rail.
5. The railing system of claim 4, wherein the at least one latching arrangement latches the at least one cradle rail and the at least one breaker rail in their fully collapsed condition and in their fully extended condition.
6. The railing system of claim 4, wherein the at least one cradle rail lock locks movement of the at least one cradle rail in its fully out position.
7. The railing system of claim 4, wherein the at least one latching arrangement and the at least one cradle lock are gravity actuated to latch the respective parts.
8. The railing system of claim 4, wherein the at least one latching arrangement is unlatched manually.
9. The railing system of claim 4, wherein the at least one cradle lock is unlatched by the at least one breaker rail when it is in fully collapsed condition in relation to the at least one cradle rail.
10. The railing system of claim 1, wherein the railing system further comprises a service latch configured to lock movement of both of the at least one cradle rail and the at least one breaker rail in service position of the circuit breaker.