DESC:TECHNICAL FIELD

The present subject matter described herein, in general relates to circuit breakers and more particularly, to a draw out type circuit breaker arrangement, and to the electrical indication of distinct positions of draw out type of circuit breakers.

BACKGROUND

An electrical circuit breaker may be defined as a unit designed to carry, make and break current and protect the equipments connected in the electrical circuit from abnormal conditions like overload, under-voltage or short circuit etc. A circuit breaker is commonly used as an electrical switching device.

There are two popular versions of circuit breakers namely, Fixed and Draw-Out Type. In Draw out type, the breaker can be removed without dismantling the terminals, in order to facilitate maintenance and secure stability. Unlike fixed breakers, draw out breakers are housed inside the cradle or cassette. They can be racked-in and out from cradle.

In a Draw out type of circuit breaker, positions of breaker with respect to cradle are normally defined as 'Disconnected/ Isolated', 'Test' and 'Connected/ Service'. In a Draw out type of breaker, the breaker can be racked in by use of detachable crank; from 'Disconnected' position to ‘Test position’ and then to 'Connected' position and racked out in the reverse order.

When breaker is racked in to ‘Test’ position, control circuit contacts of breaker and cradle get connected and when it is completely racked in i.e. to 'Connected' position, breaker terminals are in contact with cradle terminals through jaws. In this condition, both Power (main) circuit and control circuit are connected. When breaker is completely racked out i.e. to 'Disconnected' position, both main circuit and control circuit are disconnected. In the 'Test’ position, Power (main) circuit is not connected but control circuit is connected.

Based on position of circuit breaker, i.e. whether breaker is in Isolated, Test or Connected position, further circuit logic is built up for downstream electrical appliances. To build up this logic, electrical signal as an input to further circuit is required. This invention discloses an arrangement that describes design which facilitates electrical indication to obtain based on positions of circuit breaker.

Traditionally in the art, though indications were dependent on breaker travel, micro-switches were not interlinked electrically. Also, there were more than two micro-switches required for electrical indications in all positions. Further, it was possible to have undesired band overlap between indications of two different positions.

In spite of so many techniques available in the prior-art, the existing electrical indication provides continuous type of indication which is not precise. It can introduce error while building electrical logic interlinked with electrical circuit.

Thus, there was an efficient solution required to avoid the drawbacks mentioned in the prior-art.

SUMMARY

This summary is provided to introduce concepts related to an electrical indication of positions in a draw out type of circuit breakers. This summary is not intended to identify essential features of the subject matter nor is it intended for use in determining or limiting the scope of the subject matter.

In one implementation, the present invention relates to an arrangement that describes design which facilitates electrical indication to obtain based on positions of circuit breaker.

In one implementation, in the present invention an electrical indication is obtained based on state of both micro-switches.

In one implementation, the present invention achieves all four position indications i.e., for 'Disconnected/ Isolated', 'Test', ‘Maintenance Position’ and 'Connected/ Service', with use of only two micro-switches.

In one implementation, the present invention avoids the undesired band overlap between indications of two different positions.

In one implementation, the present invention relates generally to circuit breakers. More particularly, the present invention relates to a draw out type circuit breaker arrangement. This invention relates to the electrical indication of distinct positions of draw out type of circuit breakers. Disclosed invention presents design and assembly for electrical indication for Connected, Test and Isolated positions of circuit breakers.

In one implementation, the design for electrical indication of positions in draw out type of circuit breakers is disclosed.

Accordingly, in one implementation, a circuit breaker (17) is disclosed. The circuit breaker (17) comprises of a racking mechanism for performing racking operation by racking-in and racking-out said circuit breaker (17) into a cradle (18), characterized in that a position of said circuit breaker (17) in said cradle (18) is indicated by position indicator by the use of an electrical indication. The racking mechanism further comprises of a micro switch mounting plate (11) with two micro switches (12); and a micro switch actuating plate (14) with at least one hump (13) for actuation of said micro-switches (12).

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1illustrates a cradle mounted plate showing schematic representation of micro-switches S1and S2is shown, in accordance with an embodiment of the present subject matter.

Figure 2 illustrates a breaker mounted plate showing schematic representation of four non linear humps is shown, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates an isolated position of breaker: only one micro-switch is actuated is shown, in accordance with an embodiment of the present subject matter.

Figure 4 illustrates a test position of breaker: Both micro-switches are actuated is shown, in accordance with an embodiment of the present subject matter.

Figure 5 illustrates a Connected position of breaker: 2nd micro-switch (right) is actuated is shown, in accordance with an embodiment of the present subject matter.

Figure 6 illustrates a Circuit Diagram: Maintenance position (No micro-switch is pressed by hump) is shown, in accordance with an embodiment of the present subject matter.

Figure 7 illustrates a Circuit Diagram: Isolated position (1st micro-switch is pressed by hump; another in 'NO' state) is shown, in accordance with an embodiment of the present subject matter.

Figure 8 illustrates a Circuit Diagram: Test Position (Both micro-switches are pressed by hump; changing their state to 'close') is shown, in accordance with an embodiment of the present subject matter.

Figure 9 illustrates a Circuit Diagram: Connected position (2nd micro-switch is pressed by hump; 1st one is returned in 'NO' state is shown, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION

Preferred embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

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

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

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

In one implementation, the present invention relates to the design for electrical indication of positions in draw out type of circuit breakers is disclosed.

In one implementation, a circuit breaker (17) is disclosed. The circuit breaker (17) comprises of a racking mechanism for performing racking operation by racking-in and racking-out said circuit breaker (17) into a cradle (18), characterized in that a position of said circuit breaker (17) in said cradle (18) is indicated by position indicator by the use of an electrical indication. The racking mechanism further comprises of a micro switch mounting plate (11) with two micro switches (12); and a micro switch actuating plate (14) with at least one hump (13) for actuation of said micro-switches (12).

In one implementation, said micro switch mounting plate (11) is characterized in that a flat link is attached to a cradle assembly (19) side plate from inner side.

In one implementation, said two micro switches (12) are selected from a group comprising a NO-C, a NC- O type of switches mounted on said flat link or micro switch mounting plate (11).

In one implementation, said micro switches (12) gets actuated when said circuit breaker (17) mounted said micro switch actuating plate (14) presses said micro-switches (12).

In one implementation, based on at least one combination of states of said micro switch actuating plate (14) presses said micro-switches (12) an output signal is obtained.
In one implementation, the output signal is electrical signal which is to be used to build further electrical logic in the circuitry. Else this signal is used to get indication of breaker position. This output is in series with other electrical circuits to build electrical logic.

In one implementation, said micro-switch actuating plate (14) travels as said circuit breaker (17) travels during rack-in or rack-out operation, thereby actuates micro-switch (12) based on actual travel of said circuit breaker (17) and thus eliminates possibility of any lag.

In one implementation, said at least one hump (13) presses said micro-switches (12) at different instances during racking operation.

In one implementation, preferably four humps (13) are mounted on said a micro switch actuating plate (14) are non linear enabling different combinations of humps function in different distinct positions to actuate said micro-switches (12).

In one implementation, said at least one hump (13) actuate said micro-switches (12) when said circuit breaker (17) is in a position selected from a group comprising of a maintenance position, an isolated position, a test position, a connected position, and combination thereof.

In one implementation, the breaker mounted link travels as breaker is racked-in or out of cradle. Humps provided on link actuate micro-switches in different positions as mentioned below:

The breaker has four different positions:
1. Maintenance
2. Isolated
3. Test
4. Connected

Maintenance Position: When breaker taken into maintenance position, both micro-switches remain in 'NO' (Normally open) position. Humps present on breaker mounted plate don't actuate any of micro-switch. Circuit gets completed as shown in Figure 1 and thus electrical indication is obtained.

Isolated Position: In this position 1st micro-switch is pressed by a hump present on actuating link. Thus 'NO' contact of 1st micro-switch gets closed and other micro-switch remains 'NO' state. Thus another electrical indication for isolated position of breaker is obtained as shown in figure 2.
On further travel this hump moves forward.

Test Position: On further racking of breaker, breaker reaches to Test position. In this position, two separate humps press each micro-switch and both micro-switch change to 'close' state. As shown in figure 3, circuit is completed and Test position's electrical indication is obtained.

Connected position: When breaker reaches connected position, only 2nd micro-switch is pressed by one hump present on actuating plate. In this position, 1st micro switch is in NO and other in 'closed' state giving another combination and thus a different indication corresponding to connected position is obtained as shown in figure 4.

In one implementation, the present invention consists of the following components
1. The cradle mounted plate used for mounting of two micro-switches
2. The breaker mounted plate with four non linear humps. These humps form different combinations to actuate micro-switches in different breaker position.

In one implementation, a Draw out type of circuit breaker is disclosed. The breaker is supported on rail assembly, which is an integral part of a cradle assembly (19). The cradle assembly (19) consists of a base plate, a racking assembly, at least one side plate and a rail assembly. The racking operation is accomplished by the racking assembly mounted on the base plate. The rotation of the racking handle causes the racking screw to rotate which, in turn moves the rack inside or outside depending upon whether it is a rack-in or rack out operation. When a racking handle is rotated in the clockwise direction, the breaker is racked in any of the positions selected from a group of position comprising a disconnected position, a test position and/or a connected position and on the other hand, when rotated in counter clock wise direction, the breaker is racked-out in any of the positions selected from a group of position comprising a disconnected position, a test position and/or a connected position.

While performing rack-in operation racking a breaker (17) into a cradle (18), the position of the breaker (17) in the cradle (18) is indicated by at least one position Indicator. The present invention discloses obtaining of additional at least one position indication by electrical indication.

In the disclosed invention, entire assembly consists of the following components:
1. At least one micro switch mounting plate (11) with two micro switches (12)
2. The at least one micro switch actuating plate (14) mounted on the breaker housing. It has distinct humps (13) for actuation of micro-switch (12).

The micro switch mounting plate (11) with two micro switches (12): A flat link is attached to cradle (19) side plate from inner side. Two micro switches (12) generally with NO-C or NC- O type of switches are mounted on this link or plate (11).

These micro switches (12) get actuated when breaker mounted plate / link (14) presses micro switches. Based on their combinations of states, output signal is obtained.

The micro-switch actuating plate (14) mounted on breaker housing (17): It travels as breaker travels during rack-in or rack-out operation. As it is connected to breaker housing (17), it actuates micro-switch (12) based on actual travel of breaker and thus eliminates possibility of any lag.

It has four humps (13). These humps (13) press micro-switches (12) at different instances during racking operation. These four humps (13) mounted on plate are non linear and thus different combinations of humps function in different distinct positions to actuate micro-switches.

Working of the invention is disclosed below with reference to figures:

Maintenance Position: When breaker taken into maintenance position, both micro-switches remain in 'NO' (Normally open) position. Refer figure 6 for electrical connections. Humps (13) present on breaker mounted plate (14) don't actuate any of micro-switch (12). Circuit gets completed as shown in figure 6 and thus electrical indication is obtained.

Isolated Position: In this position 1stmicro-switch (S1) is pressed by a hump (refer 15 for combination of hump and micro-switch) present on actuating link (14). Thus 'NO' contact of 1st micro-switch gets closed and other micro-switch remains 'NO' state. Thus another electrical indication for isolated position of breaker is obtained as shown in figure 7.

Test Position: On further racking of breaker, breaker reaches to Test position. In this position, two separate humps press each micro-switch and both micro-switch change to 'close' state. (Refer (16) for combination of hump and micro-switch) As shown in figure 8, circuit is completed and Test position's electrical indication is obtained.

Connected position: When breaker reaches connected position, only 2nd micro-switch (S2) is pressed by one hump present on actuating plate. In this position, 1st micro switch is in NO and other in 'closed' state (refer 18 for combination of hump and micro-switch) giving another combination and thus a different indication corresponding to Connected position is obtained as shown in figure 9.

Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features:

One feature of the invention is that, the present invention discloses an arrangement that describes design which facilitates electrical indication to obtain based on positions of circuit breaker.

Another feature of the invention is that, using the present invention an electrical indication is obtained based on state of both micro-switches.

Another feature of the invention it that, all four position indications may be achieved with use of only two micro-switches.

Yet another feature of the invention it that, an undesired band overlap between indications of two different positions is avoided.

Apart from above mentioned features, the disclosed invention has below mentioned features:
1. A simple design of breaker housing mounted plate which has four humps to actuate micro-switches at different instances is proposed.
2. The design and assembly of cradle mounted plate on which two micro-switches are placed is disclosed.
3. The actuation of 1 micro-switch in isolated position through non obvious hump; while other micro-switch remains in its non-actuated position is disclosed.
4. The actuation of both micro-switches simultaneously in Test position through two different non obvious non linear humps is disclosed.
5. The actuation of another micro-switch through one hump to provide connected position indication; while 1stremaining in its normal position is disclosed.
6. The combination of four humps to actuate two micro-switches through disclosed four combinations is achieved and disclosed.
7. An electrical design having two micro-switches to achieve four different outputs for the use of electrical logic purpose is disclosed.

Further, the proposed invention has various advantages apart from the above disclosed features:

1. Simple design facilitates the use of minimum components to actuate micro-switches.
2. The design arrangement ensures no two positions are displayed simultaneously by electrical indication.
3. It provides use of only two micro-switches to achieve four electrical position indications.
4. Micro-switches are interlinked which ensure no false electrical indication while displaying position of breaker.
5. Compact, modular design and ease of assembly.

Although an electrical indication of positions in a draw out type of circuit breakers has been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations an electrical indication of positions in a draw out type of circuit breakers.
,CLAIMS:1. A circuit breaker (17) comprising:
a racking mechanism for performing racking operation by racking-in and racking-out said circuit breaker (17) into a cradle (18), characterized in that a position of said circuit breaker (17) in said cradle (18) is indicated by position indicator by the use of an electrical indication comprises:
a micro switch mounting plate (11) with two micro switches (12); and
a micro switch actuating plate (14) with at least one hump (13) for actuation of said micro-switches (12).

2. The circuit breaker (17) as claimed in claim 1, wherein said micro switch mounting plate (11) is characterized in that a flat link is attached to a cradle assembly (19) side plate from inner side.

3. The circuit breaker (17) as claimed in claims 1 and 2, wherein said two micro switches (12) are selected from a group comprising a NO-C, a NC- O type of switches mounted on said flat link or micro switch mounting plate (11).

4. The circuit breaker (17) as claimed in claims 1 to 3, wherein said micro switches (12) gets actuated when said circuit breaker (17) mounted said micro switch actuating plate (14) presses said micro-switches (12).

5. The circuit breaker (17) as claimed in claims 1 to 4, wherein based on at least one combination of states of said micro switch actuating plate (14) presses said micro-switches (12) an output signal is obtained.

6. The circuit breaker (17) as claimed in claims 1 to 5, wherein said micro-switch actuating plate (14) travels as said circuit breaker (17) travels during rack-in or rack-out operation, thereby actuates micro-switch (12) based on actual travel of said circuit breaker (17) and thus eliminates possibility of any lag.

7. The circuit breaker (17) as claimed in claims 1 to 6, wherein said at least one hump (13) presses said micro-switches (12) at different instances during racking operation.

8. The circuit breaker (17) as claimed in claims 1 to 7, wherein preferably four humps (13) are mounted on said a micro switch actuating plate (14) are non linear enabling different combinations of humps function in different distinct positions to actuate said micro-switches (12).

9. The circuit breaker (17) as claimed in claims 1 to 8, wherein said at least one hump (13)actuate said micro-switches (12) when said circuit breaker (17) is in a position selected from a group comprising of a maintenance position, an isolated position, a test position, a connected position, and combination thereof.