Claims:1. A Switchgear Vacuum Circuit Breaker (VCB) racking mechanism for racking operation, comprising:
a breaker housing (1); a stand (4);
a cradle assembly (2) adapted to accommodate the mechanical and motorized racking mechanism;
a lead screw (11);
(a) the mechanical racking mechanism comprising:
(i) a locking channel assembly (3) comprising:
a locking bracket (5);
a spacer (6) and a spring (7) positioned below the locking bracket (5);
a handle adapted to rotate the lead screw (11) to change the position of the breaker to test or service condition.
(b) the motorized racking mechanism comprising:
(i) a motor and a gear assembly comprising:
a motor mounting bracket (18) adapted to mount the gear assembly;
a gear key (17); a motor gear (14) consisting a motor gear bearing 1 (15) and a motor gear bearing 2 (16); a motor (12) and a motor shaft (13) adapted to drive the motor gear (14);
(ii) a cage nut assembly mounted over the lead screw (11) and connected to the motor gear (14) comprising:
a cage nut gear (20); a cage nut gear key; at least two cage nut support bracket (22, 23);
a spacer (24) adapted to provide a gap between the cage nut support bracket (22, 23);
a threaded brass bush (19) adapted to rotate over the lead screw (11) to change the position of the breaker to test or service condition;
wherein during the motorized racking operations the position of the mechanical racking mechanism remains unchanged and vice-versa.

2. The switchgear VCB racking mechanism as claimed in claim 1, wherein the locking bracket (5) is adapted to lock the rotation of the lead screw (11).

3. The switchgear VCB racking mechanism as claimed in claim 1, wherein the locking channel assembly (3) comprises a plurality of dowel pin adapted to hold the lead screw (11) with the locking channel assembly (3).

4. The switchgear VCB racking mechanism as claimed in claim 1, wherein during the mechanical racking operation, the lead screw (11) transfers the motion to the cage nut assembly.

5. The switchgear VCB racking mechanism as claimed in claim 1, wherein the lead screw (11) comprises a lead screw lock bracket 1 (8) and a lead screw lock bracket 2 (10).

6. The switchgear VCB racking mechanism as claimed in claim 1, wherein the handle is inserted through a flap on the front door of the panel of the switchgear VCB.

7. The switchgear VCB racking mechanism as claimed in claim 1, wherein the lead screw (11) comprises a lead screw lock bracket 1 (8) and a lead screw lock bracket 2 (10).

8. The switchgear VCB racking mechanism as claimed in claim 1, wherein the locking bracket (5) is pressed against the spring (7) to allow the lead screw (11) rotation.

9. The switchgear VCB racking mechanism as claimed in claim 1, wherein the mechanical racking operation is carried out in closed door condition.

10. The VCB racking mechanism as claimed in claim 1, wherein the lead screw (11) makes an angle of 90 degrees with the locking channel assembly (3).

11. The switchgear VCB racking mechanism as claimed in any of the preceding claims is motor operated or manual.
, Description:TECHNICAL FIELD OF THE INVENTION
The present invention relates to circuit breaker racking mechanism and more particularly, to mechanical arrangement for motorized as well as mechanical racking operation of the Medium Voltage (MV) switchgear breaker from test to service condition and vice-versa.

BACKGROUND OF THE INVENTION
In most uses of large circuit breakers, the breaker is housed within a suitably dimensioned cubicle. For obvious safety reasons the breaker main conductors extend from the rear of the circuit breaker whereby they may be electrically connected to associated main external conductors which pass through the-rear wall of the cubicle. To fulfil basic operating, testing, and servicing requirements, it is normally required that the circuit breaker be -able to fulfil three electrical conditions and in addition thereto, the circuit breaker must be capable of being quickly and easily withdrawn from connected to disconnected position & vice versa in its cubicle or housing.

The three electrical conditions correspond to a connected or service position in which the breaker main and secondary conductors are electrically connected to their respective external main and secondary conductors; a test position in which the breaker main conductors are electrically isolated from their respective external main conductors, while the breaker secondary conductors(auxiliary wires) or selected ones thereof remain electrically connected to their respective external secondary conductors and the isolated condition in which both the breaker main and secondary conductors are electrically isolated from their respective external main and secondary conductors. As noted above, a final requirement for the breaker, although not electrical in nature, is that the breaker may be easily withdrawn from service to test & vice versa in its cubicle.

Present means for establishing the various electrical circuit breaker conditions and for withdrawing the breaker from service to test position comprise racking apparatus for physically moving the circuit breaker along with its main conductors away from their associated external main conductors whereby the necessary clearance is established between the breaker conductors and external conductors, respectively. Thus, in a normal operating connected position the breaker occupies its most rearward position within its cubicle such that the breaker main conductors are electrically connected to their respective external conductors. Initial operation of the racking mechanism moves the circuit breaker forward within its cubicle such that the main breaker conductors, but not the secondary breaker conductors, are of sufficient distance from their associated external main conductors so that electrical clearance is established therebetween. The breaker now occupies the test position.

The document US1676420A, relates to cradles and particularly by electric power,and has for its object to provide a simple and inexpensive means whereby the said cradle may be operated. Another object is to provide a cradle of the type described which shall be readily collapsible for storage or convertible for use as a crib.

The document US10141129B2, discloses (Remote control and racking device for medium-voltage circuit breakers). It relates in general to electrical switchgear servicing equipment and more particularly to a remotely operated system for circuit breaker operation and for racking circuit breakers into and out of engagement with the primary and secondary disconnects terminals within the electric switchgear.

The document US7612988B2, discloses (Switchgear with movable user interface module) a switchgear installation has a cubicle with a door to provide access there into, and a low voltage circuit breaker is mounted therein and accessible through the door. Coupled to the circuit breaker is a logic module, and a portable user interface module is releasably mounted on the exterior of the cubicle and operatively connected to the logic module to display information concerning the operation of the breaker and to provide an interface for the user to interact with the logic module and thereby with the breaker. The user interface module includes a battery providing the required power for setting and monitoring the functions of the breaker.

The document US5477017A, (Electric racking device for racking circuit breakers into switchgear) relates generally to racking devices for racking large circuit breakers into switchgear cells and, more specifically, to remote controlled electric racking devices having an anti-rotation assembly that prevents the racking devices from rotating.

The document US6951990B1 discloses, (Apparatus for racking circuit breakers into and out ofswitchgear). It relates generally to an apparatus for racking circuitbreakers into and out of switchgear, and particularly to a motorized racking operator and the document FR2773648B1 discloses, (Device for locking a mechanism to connect and disconnect a breaker).

The above described prior art system suffers from many disadvantages, which the instant invention effectively eliminates. Specifically, for safety reasons, it is desirable to move the circuit breaker with the panel door closed and from a remote location that is the operating personnel is not required to be around the panel during the racking mechanism. Further, the existing racking shield of known switchgear is a relatively complex mechanism which does not provide a safe racking mechanism. Also there is no such existing system which is providing electrical as well as manual racking operation of the switchgear VCB. The risk involved during the existing racking mechanisms is very high.

For this reason, there is a dire need to provide an improved VCB racking mechanism which will eliminate the above mentioned drawbacks of the conventional mechanisms.

SUMMARY OF THE INVENTION
The following disclosure 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.

An object of the present invention is to overcome the problems of prior art.

An object of the present invention is to provide the service-test movement of the MV switchgear Breaker with distinguished mechanical arrangement which can operate the breaker both mechanically and electrically.

An object of the present invention to provide a MV switchgear VCB racking mechanism where the breaker’s service and test position movement is done by a distinguished mechanical arrangement which can be used for both manual as well as motorised racking operation, mounted on a VCB cradle base containing necessary interlock options.

Yet another object of the present invention is to provide a MV switchgear VCB racking mechanism which provides less wear and tear due to movement during mechanical racking operation.

Yet another object of the present invention is to provide a racking mechanism which ensures the safety of the operator during racking operation.

One aspect of the present disclosure is to provide an operating technique for Medium Voltage (MV) switchgear racking mechanism. It discloses a distinguished mechanical arrangement for electrical as well as mechanical racking operation of the medium voltage switchgear breaker from test to service condition and vice-versa. During its electrical racking operations the mechanism provides protection and increases safety factor of human life as personnel is not required to stand in front of the panel during the power contact engagement. This disclosure provides an unique arrangement of lead screw, gears, threaded bush and motor, in which the parts (Gear, motor & Threaded bush) which are idle during manual racking operation becomes moving during motorized racking operation and parts (lead screw) which are idle during motorized racking operation becomes moving during manual racking operation.

In one implementation, the present invention provides a Switchgear Vacuum Circuit Breaker (VCB) racking mechanism for motorized and manual racking operation which comprises breaker housing, a stand, a cradle assembly adapted to accommodate the mechanical and motorized racking mechanism and a lead screw.

In one implementation, the present invention provides a Switchgear Vacuum Circuit Breaker (VCB) racking mechanism which comprises a mechanical racking mechanism comprises a locking channel assembly which further comprises a locking bracket, a spacer and a spring positioned below the locking bracket and a handle adapted to rotate the lead screw to change the position of the breaker to test or service condition.

In one implementation, the present invention provides a Switchgear Vacuum Circuit Breaker (VCB) racking mechanism which comprises a motorized racking mechanism comprises a motor and a gear assembly further comprises a motor mounting bracket adapted to mount the gear assembly, a gear key, a motor gear consisting a motor gear bearing 1 and a motor gear bearing 2, a motor and a motor shaft adapted to drive the motor gear.

In one implementation, the present invention provides a Switchgear Vacuum Circuit Breaker (VCB) racking mechanism which comprises a cage nut assembly mounted over the lead screw and connected to the motor gear comprising a cage nut gear , a cage nut gear key, at least two cage nut support bracket, a spacer adapted to provide a gap between the cage nut support bracket, a threaded brass bush adapted to rotate over the lead screw to change the position of the breaker to test or service condition wherein during the motorized racking operations the position of the mechanical racking mechanism remains unchanged and vice-versa.

In one implementation, the present invention provides a switchgear VCB racking mechanism in which the locking bracket is adapted to lock the rotation of the lead screw.

In one implementation, the present invention provides a racking mechanism where the locking channel assembly comprises a plurality of dowel pin adapted to hold the lead screw with the locking channel assembly.

In one implementation, the present invention provides a racking mechanism where during the mechanical racking operation; the lead screw transfers the motion to the cage nut assembly.

In one implementation, the present invention provides a racking mechanism in which the handle is inserted through a flap on the front door of the switchgear panel into the VCB and the lead screw comprises a lead screw lock bracket 1 and a lead screw lock bracket 2.

In one implementation, the present invention provides a racking mechanism where the mechanical racking operation is carried out in closed door condition and the lead screw makes an angle of 90 degrees with the locking channel assembly.

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 ACCOMPANYING DRAWINGS
The above and other aspects, features and advantages of the embodiments of the present disclosure will be more apparent in the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 illustrates the schematic view of the MV switchgear Panel assembly with breaker in test condition, according to one of the embodiments of the present invention.

Figure 2 illustrates the schematic view of the of the MV switchgear Panel assembly with breaker in service condition, according to one of the embodiments of the present invention.

Figure 3illustrates the schematic view of the MV switchgear breaker, according to one of the embodiments of the present invention.

Figure 4 (a) illustrates the schematic view of the locking channel assembly in idle condition, according to one of the embodiments of the present invention.

Figure 4 (b) illustrates the schematic exploded view of the locking channel assembly, according to one of the embodiments of the present invention.

Figure 5 (a)illustrates the schematic view of the locking channel with lead screw in idle condition, according to one of the embodiments of the present invention.

Figure 5 (b) illustrates the schematic cross-section view of the lead screw in lock condition, according to one of the embodiments of the present invention.

Figure 5 (c) illustrates the schematic cross-section view of the lead screw in free condition, according to one of the embodiments of the present invention.

Figure 6 illustrates the schematic view of MV switchgear breaker cradle during ideal condition, according to one of the embodiments of the present invention.

Figure 7 (a) illustrates the schematic view of motor and gear assembly, according to one of the embodiments of the present invention.

Figure 7 (b) illustrates the schematic exploded view of motor and gear assembly, according to one of the embodiments of the present invention.

Figure 8 (a) illustrates the schematic view of the cage nut assembly, according to one of the embodiments of the present invention.

Figure 8 (b) illustrates the schematic exploded view of the cage nut assembly, according to one of the embodiments of the present invention.

Figure 9 illustrates the schematic view of the arrangement of the cage nut & lead screw, according to one of the embodiments of the present invention.

Figure 10 (a) illustrates the schematic view of the bottom view of cradle assembly, according to one of the embodiments of the present invention.

Figure 10 (b) illustrates the schematic detail view of motor, gears and lead screw assembly according to one of the embodiments of the present invention.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may not have 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
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding, but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

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 present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

The present invention provides an operating technique for Medium Voltage (MV) switchgear racking mechanism. It discloses a distinguished mechanical arrangement for electrical as well as mechanical racking operation of the medium voltage switchgear breaker from test to service condition and vice-versa. During its electrical operations the mechanism provides protection and increases safety factor of human life as personnel is not required to stand in front of the panel during the power contact engagement. This disclosure provides an unique arrangement of lead screw, gears, threaded bush and motor, in which the parts (Gear, motor & Threaded bush) which are idle during manual racking operation becomes moving during motorized racking operation and parts (lead screw) which are idle during motorized racking operation becomes moving during manual racking operation.

It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, a reference to "a component surface" includes a reference to one or more of such surfaces.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments belong. Further, the meaning of terms or words used in the specification and the claims should not be limited to the literal or commonly employed sense, but should be construed in accordance with the spirit of the disclosure to most properly describe the present disclosure.

The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof. Also, Expressions such as "at least one of," when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

The present disclosure will now be described more fully with reference to the accompanying drawings, in which various embodiments of the present disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the various embodiments set forth herein, rather, these various embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the present disclosure. Furthermore, a detailed description of other parts will not be provided not to make the present disclosure unclear. Like reference numerals in the drawings refer to like elements throughout.

The arrangement is in such a way that while doing the mechanical racking operation, the handle rotates the lead screw and the breaker is put to test or service condition. The racking mechanism assembly of the circuit breaker in the panel is an independent assembly itself, which need to be fixed below the circuit breaker housing assembly (1). The cradle assembly (2) and locking channel (3) engulf both the electrical and mechanical aspect of the invention. There is a locking provision for locking the lead screw (11). The locking provision is on locking channel assembly (3) (fig 4). The locking provision consists of locking bracket (5) and spring (7). In idle condition the locking bracket (5) locks the lead screw (11) rotation [Figure 5 (a)]. The electrical rack in/out operations is taken out in lead screw (11) lock condition. For mechanical racking operation the lead screw (11) is allowed to rotate. To allow the lead screw (11) rotation the locking bracket (5) is pressed against the spring (7) as shown [figure 5 (c)].

Mechanical rack in-out operations will be carried out in closed door condition with the help of racking handle having key way provision for easy insertion. The handle is inserted through the lap on the door of the front panel. The handle then pushes the locking bracket (5) against the spring (7) (in idle condition the locking bracket locks the lead screw to arrest mechanical operation) to free the rotation of the lead screw (11) of the circuit breaker. During mechanical operation the motor and the gear arrangement remain idle (no movement in motor shaft & gear). The lead screw transfers the motion to cage nut assembly (Figure 8). As the cage nut assembly, motor & gear assembly (figure 7) are fixed to the cradle assembly (2). So all the assemblies act as a single body and moves back and forth depending upon the direction of rotation of the lead screw (11).

On the other hand while going for the electrical operation the motor (12) drives the gear (14) arrangement which is connected to the cage nut assembly (figure 8). The cage nut assembly is mounted over the lead screw (Figure 9). The cage nut consists of a threaded brass bush (19) which rotates over the stationary lead screw (11). Hence, movement of threaded bush on lead screw (11) moves whole VCB in test-service position, keeping the lead screw idle [no movement in lead screw (11)].

In one implementation, the present invention provides a Switchgear Vacuum Circuit Breaker (VCB) racking mechanism for motorized and manual racking operation which comprises a breaker housing (1), a stand (4), a cradle assembly (2) adapted to accommodate the mechanical and motorized racking mechanism and a lead screw (11).

In one implementation, the present invention provides a Switchgear Vacuum Circuit Breaker (VCB) racking mechanism which comprises a mechanical racking mechanism comprises a locking channel assembly (3) which further comprises a locking bracket (5), a spacer (6) and a spring (7) positioned below the locking bracket (5) and a handle adapted to rotate the lead screw (11) to change the position of the breaker to test or service condition.

In one implementation, the present invention provides a Switchgear Vacuum Circuit Breaker (VCB) racking mechanism which comprises a motorized racking mechanism comprises a motor and a gear assembly further comprises a motor mounting bracket (18) adapted to mount the gear assembly, a gear key (17), a motor gear (14) consisting a motor gear bearing 1 (15) and a motor gear bearing 2 (16), a motor (12) and a motor shaft (13) adapted to drive the motor gear (14).

In one implementation, the present invention provides a Switchgear Vacuum Circuit Breaker (VCB) racking mechanism which comprises a cage nut assembly mounted over the lead screw (11) and connected to the motor gear (14) comprising a cage nut gear (20), a cage nut gear key, at least two cage nut support bracket (22, 23), a spacer (24) adapted to provide a gap between the cage nut support bracket (22, 23), a threaded brass bush (19) adapted to rotate over the lead screw (11) to change the position of the breaker to test or service condition wherein during the motorized racking operations the position of the mechanical racking mechanism remains unchanged and vice-versa.

In one implementation, the present invention provides a switchgear VCB racking mechanism in which the locking bracket (5) is adapted to lock the rotation of the lead screw (11).

In one implementation, the present invention provides a racking mechanism where the locking channel assembly (3) comprises a plurality of dowel pin adapted to hold the lead screw (11) with the locking channel assembly (3).

In one implementation, the present invention provides a racking mechanism where during the mechanical racking operation; the lead screw (11) transfers the motion to the cage nut assembly.

In one implementation, the present invention provides a racking mechanismin which the lead screw (11) comprises a lead screw lock bracket 1 (8) and a lead screw lock bracket 2 (10).

In one implementation, the present invention provides a racking mechanism in which the handle is inserted through a flap on the front door of the panel of the switchgear VCB and the lead screw (11) comprises a lead screw lock bracket 1 (8) and a lead screw lock bracket 2 (10).

In one implementation, the present invention provides a racking mechanism in which the locking bracket (5) is pressed against the spring (7) to allow the lead screw (11) rotation.

In one implementation, the present invention provides a racking mechanism where the mechanical racking operation is carried out in closed door condition and the lead screw (11) makes an angle of 90 degrees with the locking channel assembly (3).

Stages of Development:
In switchgear industries. Few points are dealt with care: safety, reliability, ease of assembly, time saving etc. This invention encircles almost all these points. All of the above said features are covered by the following ways:
1. Close door rack in and rack out.
2. No need for the operator to be around the panel.
3. Less parts require for this invention, which guarantee reliability.
4. Less complicated parts ensure ease of assembly and time savings.
Thus, the idea is developed to add these valuable features to the switchgear.

Some of the non-limiting advantages of the present invention are as follows:
1. The arrangement of lead screw, gears, threaded bush and motor are unique, in which the parts (Gear, motor & threaded bush) which are idle during manual racking operation becomes moving during motorized operation and parts (Lead screw) which are idle during motorized racking operation becomes moving during manual racking operation.

2. Breaker’s service and test position, movement by a distinguished mechanical arrangement which can be used for both manual as well as motorised racking operation, mounted on a VCB cradle base containing necessary interlock options also.

3. This arrangement keeps the motor and gear ideal during the mechanical operation, Hence reduces wear and tear due to movement during mechanical racking operation.

4. Reduce human effort to manually rack in-out VCB, hence reduces chances of error or mis- operation.

5. Protection of personnel from internal arc fault in the breaker compartment during racking operation.