FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"AN INTERLOCKING SYSTEM"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO LIMITED,
L&T House, Ballard Estate, P. O. Box: 278, Mumbai 400 001, India
" 3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

AN INTERLOCKING SYSTEM
FIELD OF INVENTION
The present invention relates to the field of circuit breakers, and more particularly, the present invention relates to a system for interlocking and regulating actuation of adjacently disposed Moulded Case Circuit Breakers (MCCBs).
BACKGROUND OF THE INVENTION
Generally, circuit breakers are used for isolating a faulty power distribution network or circuit in an event of a possible electrical fault, such as short-circuits, overload, and earth faults from the remaining power distribution network or circuit, thereby protecting the remaining power distribution network or circuit of a power distribution system against damages caused by short-circuiting or overloading. However, the circuit breakers can also be used for isolating an electrical circuit for selectively disrupting power supply from or to that electrical circuit, thereby selectively regulating the flow of electrical current through an electrical distribution system of which the electrical circuit is a part. of.
Various types of circuit breakers such as Miniature Circuit Breakers (MCBs), Air Circuit Breaker, Vacuum circuit breakers, Residual Current Circuit Breaker (RCCBs) and Moulded Case Circuit Breakers (MCCBs) are conventionally known. The MCCBs are circuit breakers that can withstand rated current and the trip current in case of MCCBs faults like overload or over current. Further, the MCCBs have thermal or thermal-magnetic mode of operation. There are electrical power distribution systems that rely on different sources of electrical power supply and that can derive electrical power from the different power sources. In case of such electrical power distribution schemes, while certain feeder circuit associated with a source of electrical power is required to be

switched ON to facilitate deriving electrical power from that source, the other feeder circuit associated with another source of electrical power should not be switched ON and vice versa. If by any means both the sources of the electrical power supply are connected to each other, i.e. both sources are supplying electrical power, excessive circulating currents may result that may damage the source. Therefore, it is imperative not to connect both sources at same time.
In such electrical power distribution systems that can derive electrical power from the different power sources to meet the electrical load requirements, the MCCBs are generally used, wherein the MCCBs are adjacently placed to define a MCCB set. The MCCB set utilizes an interlocking system that interlocks the circuit breakers (MCCBs) controlling the sources of electrical power supply so that at a given moment, only pre-determined circuit breakers (MCCBs) are actuated to supply power from only the pre-determined source(s) of electrical power. The interlocking of the circuit breakers (MCCBs) of the set permits selective switching ON/OFF of the circuit breakers when other circuit breakers of the set are actuated.
The conventionally known interlocking systems for interlocking the MCCBs are complicated and sometimes ineffective. Further, the conventionally known interlocking systems for interlocking the MCCBs are bulky, complex and have more number of parts. As the conventionally known interlocking systems for interlocking the MCCBs require more number of parts, the conventionally known interlocking systems are prone to frequent failures, are less reliable and require regular maintenance. Most of the conventionally known interlocking systems are difficult to access once installed and are therefore difficult to service.
Accordingly, there is a need for an interlocking system for interlocking MCCBs of a MCCB set for accurately controlling switching ON/OFF of the adjacently disposed MCCBs upon actuation of certain MCCBs to permit selective

connecting of the power distribution system to different power sources and ensure safety. There is a need for an interlocking system for interlocking MCCBs that effectively regulates the actuation of the adjacent MCCBs, even if the MCCBs are too close to interfere with each other. Further, there is a need for an interlocking system for interlocking MCCBs that is customizable by changing operation logic to meet different customer requirements. Further, there is a need for an interlocking system for interlocking MCCBs that safeguard against unintentional switching ON/OFF of the MCCBs. Still further, there is a need for an interlocking system for interlocking the MCCBs that is simple in construction and convenient to- use. Furthermore, there is a need for an interlocking system for interlocking the MCCBs that is compact and involves less number of parts. Still further there is a need for an interlocking system for interlocking the MCCBs that is reliable. Furthermore, there is a need for an interlocking system for interlocking the MCCBs that require less maintenance. Further, there is a need for an interlocking system for interlocking the MCCBs that is easily accessible once installed and therefore is convenient to service. Further, there is a need for an interlocking system for interlocking the MCCBs that can be retrofitted on MCCB set of any type or configuration. There is a need for an interlocking system for interlocking the MCCBs that ensures safety of the power distribution system.
OBJECTS OF THE INVENTION
Some of the objects of the present invention are described herein below:
It is an object of the present invention to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present invention is to provide an interlocking system for interlocking MCCBs of a MCCB set for accurately controlling switching ON/OFF of the adjacently disposed MCCBs upon actuation of certain MCCBs

to permit selective connecting of the power distribution system to different power sources/
Another object of the present invention is to provide an interlocking system for interlocking MCCBs that effectively regulates the actuation of the adjacent MCCBs,.
Yet another object of the present invention is to provide an interlocking system for interlocking MCCBs that safeguard against unintentional switching ON/OFF of the MCCBs.
Still another object of the present invention is to provide an interlocking system for interlocking the MCCBs that is simple in construction and convenient to use.
Yet another object of the present invention is to provide an interlocking system for interlocking the MCCBs that is compact and involves less number of parts.
Still another object of the present invention is to provide an interlocking system for interlocking the MCCBs that is reliable.
Yet another object of the present invention is to provide an interlocking system for interlocking the MCCBs that require less maintenance.
Another object of the present invention is to provide an interlocking system for interlocking the MCCBs that is easily accessible once installed and therefore is convenient to service.
Still another object of the present invention is to provide an interlocking system for interlocking the MCCBs that can be retrofitted on MCCB set of any type or configuration.

Another object of the present invention is to provide an interlocking system for interlocking three MCCBs at a time so that it ensures safety & reliability of the power distribution system.
Another object of the present invention is to provide an interlocking system for interlocking the MCCBs that ensures safety of the power distribution system.
SUMMARY OF THE INVENTION
An interlocking system for interlocking circuit breakers of a set of circuit breakers is disclosed in accordance with an embodiment of the present disclosure. The interlocking system includes an actuation sub-system corresponding to each circuit breaker of the set of circuit breakers. The actuation sub-system is functionally coupled to the remaining actuation sub-systems corresponding to the remaining circuit breakers, wherein each actuation subsystem regulates a corresponding circuit breaker based on actuation statuses of the remaining actuation systems. Each actuation sub-system includes an actuation switch and a block arrangement. The actuation switch is displaceable between an "ON" configuration and an "OFF" configuration for defining actuation status of a corresponding actuation sub-system. The block arrangement is functionally coupled to the actuation switch of the actuation sub-system, at least one actuation switch corresponding to any of the remaining actuation subsystems and a circuit breaker corresponding to the actuation sub-system. The block arrangement regulates tripping of the circuit breaker based on actuation status of the actuation sub-system and actuation statuses of the remaining actuation sub-systems. The block arrangement includes housing, a plunger slidably received inside the housing and a spring element. The plunger projects outside the housing under action of urging forces for facilitating tripping of the circuit breaker, wherein the urging forces act based on actuation status of the actuation sub-system and actuation statuses of the remaining actuation subsystems. The spring element is functionally coupled to the plunger and restores

the plunger inside the housing upon failure to maintain the urging forces, thereby facilitating resetting the tripped circuit breaker.
Typically, the interlocking system further includes linkages to transmit displacement of the actuation switch of an actuation sub-system and at least one actuation switch corresponding to any of the remaining actuation sub-systems to transmitting elements received inside the block arrangement, wherein the transmitting elements apply urging forces on the plunger.
Generally, the plunger further includes a centrally supported lever that swivels about the plunger under action of the urging forces acting based on actuation status of the actuation sub-system and actuation statuses of the remaining actuation sub-systems.
Alternatively, the centrally supported lever presses the plunger in an operative downward direction under action of the urging forces acting on the lever based on actuation status of the actuation sub-system and actuation statuses of the remaining actuation sub-systems.
In accordance with an embodiment, the set of circuit breakers includes three circuit breakers and the mechanical interlocking system permits flow of electrical current only through any two of the circuit breakers at any point of time by tripping any one of the circuit breakers in-case actuation status of an actuation sub-system corresponding to the circuit breaker and one of the remaining actuation sub-systems corresponding to the remaining circuit breakers is "ON" and the third actuation sub-system corresponding to third circuit breaker is also turned "ON", thereby preventing turning "ON" of all three actuation sub-system at one time.
BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a set of three Moulded Case Circuit Breakers (MCCBs) interlocked by a mechanical interlocking system in accordance with an embodiment of the present invention;
Figure 2 illustrates an exploded view of the mechanical interlocking system of Figure 1 used for interlocking the set of three Moulded Case Circuit Breakers (MCCBs);
Figure 3 illustrates another exploded view of the mechanical interlocking system of Figure 1 used for interlocking the set of three Moulded Case Circuit Breakers (MCCBs), wherein the mechanical interlocking system permits flow of electrical current only through any two of the Moulded Case Circuit Breakers (MCCBs) at any point of time by tripping any one of the Moulded Case Circuit Breakers (MCCBs) if current flow through the remaining Moulded Case Circuit Breakers (MCCBs) is also actuated; and
Figure 4a illustrates an assembled view of a block arrangement of the mechanical interlocking system of Figure 1, wherein the block arrangement regulates tripping of a circuit breaker based on actuation status of the Moulded Case Circuit Breakers (MCCBs);
Figure 4b illustrates an exploded view of the block arrangement of Figure 4a;
Figure 5 illustrates an assembled view of a mechanical interlocking system of Figure 1;
Figure 6 illustrates an assembled view of a mechanical interlocking system of Figure 1 with actuation switches of the actuation sub-systems corresponding to any two circuit breakers out of the set of three circuit breakers in an "ON" configuration; and

Figure 7 illustrates an assembled view of a mechanical interlocking system of Figure 1 with an actuation switch of an actuation sub-system corresponding to a circuit breaker out of the set of three circuit breakers in an "ON" configuration and a block arrangement corresponding to the actuation sub-system is in a configuration that facilitates tripping of the corresponding circuit breaker.
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the

purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The electrical power distribution systems that can derive electrical power from the different power sources to meet the electrical load requirements generally use circuit breakers, particularly, MCCBs. The MCCBs are adjacently placed to define a MCCB set. The MCCB set utilizes an interlocking system that interlocks the circuit breakers (MCCBs) controlling the sources of electrical power supply so that at a given moment, only pre-determined circuit breakers (MCCBs) are actuated to supply power from only the pre-determined source(s) of electrical power. The interlocking of the circuit breakers (MCCBs) of the set permits selective switching ON/OFF of the circuit breakers when other circuit breakers of the set are actuated.
However, most of the conventionally known interlocking systems used for interlocking the two MCCBs only for properly control switching ON/OFF of the adjacently disposed MCCBs upon actuation of certain MCCBs to permit selective connecting of the power distribution system to different power sources and ensure safety. The conventionally known interlocking systems may be ineffective in regulating the actuation system with three MCCBs,. The conventionally known interlocking systems for interlocking the MCCBs are complicated and sometimes ineffective. Further, the conventionally known interlocking systems for interlocking the MCCBs are bulky, complex and have more number of parts. As the conventionally known interlocking systems for interlocking the MCCBs require more number of parts, the conventionally known interlocking systems are prone to frequent failures, are less reliable and require regular maintenance. Most of the conventionally known interlocking systems are difficult to access once installed and are therefore difficult to service.

The present invention envisages an interlocking system, particularly, a mechanical interlocking system for interlocking MCCBs of a MCCB set of three MCCBs for accurately controlling switching ON/OFF of the adjacently disposed MCCBs upon actuation of certain MCCBs to permit selective connecting of the power distribution system to different power sources. The mechanical interlocking system for interlocking MCCBs permits flow of electrical current only through any two of the Moulded Case Circuit Breakers (MCCBs) at any point of time by tripping any one of the Moulded Case Circuit Breakers (MCCBs) if current flow through the remaining Moulded Case Circuit Breakers (MCCBs) is also actuated. More specifically, the mechanical interlocking system regulates actuation of the MCCBs of the set of MCCBs based on actuation status of the remaining MCCBs.
Figure 1 illustrates a set of three Moulded Case Circuit Breakers (MCCBs) interlocked by a mechanical interlocking system (100). The Figure 1 illustrates the plan view of mechanically interlocked MCCBs placed adjacent to each other. The MCCBs, referred to as Ml (1), M2 (2) and M3 (3) are connected by a plurality of mounting plates (27), (28) and (29). More specifically, each of the mounting plate is connected to a cover of a corresponding MCCB by screws of suitable size. For example, the mounting plate (27) is mounted on the MCCB Ml (1).
The interlocking system (100) for interlocking circuit breakers, particularly, the MCCBs, Ml (1), M2 (2) and M3 (3) of a set of circuit breakers includes a plurality of actuation sub-systems, wherein there is an actuation sub-system corresponding to each circuit breaker or MCCB of the set of circuit breakers or MCCBs. For example, there is an actuation sub-system corresponding to the MCCB Ml (1), there is a separate actuation sub-system corresponding to MCCB M2 (2) and another actuation sub-system corresponding to the MCCB M3 (3). The actuation sub-system corresponding to MCCB Ml (1) is functionally

coupled to the remaining actuation sub-systems corresponding to the remaining MCCBs M2 (2) and M3 (3). Similarly, actuation sub-system corresponding to MCCB M2 (2) is functionally coupled to the remaining actuation sub-systems corresponding to the remaining MCCBs Ml (1) and M3 (3) and the actuation sub-system corresponding to MCCB M3 (3) is functionally coupled to the remaining actuation sub-systems corresponding to the remaining MCCBs M2 (2) and Ml (1). Each actuation sub-system regulates a corresponding MCCB based on actuation statuses of the remaining actuation sub-systems. For example, the actuation sub-system corresponding to the MCCB Ml (1) regulates the MCCB Ml (1) based on the actuation statuses of the remaining actuation sub-systems corresponding to MCCB's M2 (2) and M3 (3). Each of the actuation sub-system includes an actuation switch and a block arrangement. For example, the actuation sub-system corresponding to the MCCB Ml (1) includes an actuation switch (4) and a block arrangement (13). Similarly, the actuation sub-system corresponding to the MCCB M2 (2) includes an actuation switch (5) and a block arrangement (14) and the actuation sub-system corresponding to the MCCB M3 (3) includes an actuation switch (6) and a block arrangement (15).
Figure 2 illustrates an exploded view of the mechanical interlocking system (100) used for interlocking the set of three Moulded Case Circuit Breakers (MCCBs), referred to as Ml (1), M2 (2) and M3 (3). Figure 3 illustrates another exploded view of the mechanical interlocking system (100) used for interlocking the set of three Moulded Case Circuit Breakers (MCCBs) Ml (1), M2 (2) and M3 (3), wherein the mechanical interlocking system (100) permits flow of electrical current only through any two of the Moulded Case Circuit Breakers (MCCBs) at any point of time by tripping any one of the Moulded Case Circuit Breakers (MCCBs) if current flow through the remaining Moulded Case Circuit Breakers (MCCBs) is also actuated. For example, if at any point of time MI (1) and M2 (2) are actuated and electrical current is passing through Ml (1) and M2 (2), thereafter M3 (3) is also actuated, then either of Ml (1) or

M2 (2) will get tripped so that at any point of time only two out of the three MCCBs are permitting flow of electric current there-through.
Referring to Figure 2 of the accompanying drawings, on each mounting plate corresponding to each MCCB there are mounted a pair of actuators. For example, the actuators (19) and (21) are disposed on the mounting plate (27). The actuators (23) and (25) are disposed on the mounting plate (28) and the actuators (44) and (46) are disposed on the mounting plate (29). The actuators are actuated by the respective actuation switches of the actuation sub-systems corresponding to the MCCBs (4), (5) and (6). For example, the actuators (19) and (21) are actuated by the actuation switch (4) of the actuation sub-systems corresponding to the MCCB Ml (1). Similarly, the actuators (23) and (25) are actuated by the actuation switch (5) of the actuation sub-systems corresponding to the MCCB M2 (2) and the actuators (44) and (46) are actuated by the actuation switch (6) of the actuation sub-systems corresponding to the MCCB M3 (3). The actuators (19), (21), (23), (25), (44) and (46) are connected to transmitting elements or transmitters (20), (22), (24), (26), (45) and (47) respectively that are received inside the block arrangements (13), (14) and (15) by means of linkages such as clutch cables (7), (8), (9), (10), (11) and (12). More specifically, the first end of clutch cable (7), (8), (9), (10), (11) and (12) are connected to actuators (19), (21), (23), (25), (46) and (44). The other end of clutch cables (7), (8), (9), (10), (11) and (12) are connected to transmitters (20), (22), (24), (26), (45) and (47). The clutch cable (7) connects the actuator (19) to the transmitting element (20) received in the block arrangement (15), the clutch cable (8) connects the actuator (21) to transmitter (22) received in the block arrangement (14), the clutch cable (9) connects the actuator (23) to the transmitter (24) received in the block arrangement (13). Similarly, the clutch cable (10) connects the actuator (25) to the transmitter (26), the clutch cable (11) connects the actuator (44) to the transmitter (45) and the clutch cable (12) connects the actuator (46) to the transmitter (47). More specifically, the clutch cables transmits displacement of an actuation switch of an actuation sub-system

and at least one actuation switch corresponding to any of the remaining actuation sub-systems to the transmitting elements received inside a block arrangement. For example, the clutch cable (12) and clutch cable (9) transmits displacement of the actuation switch (6) and actuation switch (5) to the block arrangement (13). Similarly, the clutch cable (10) and clutch cable (7) transmits displacement of the actuation switch (5) and actuation switch (4) to the block arrangements (15) and the clutch cable (11) and clutch cable (8) transmits displacement of the actuation switch (6) and actuation switch (4) to the block arrangements (14). The clutch cables (7), (8), (9), (10), (11) and (12) transmit the motion of actuators to the other end. The transmitters (20), (22), (24), (26), (45) and (47) are terminated in the block arrangements (13) (14) and (15).
Each of the block arrangement includes housing, a plunger slidably received inside the housing and a spring element. Figure 4a illustrates an assembled view of a block arrangement (15) of the mechanical interlocking system (100), wherein the block arrangement (15) regulates tripping of a corresponding circuit breaker, particularly, MCCB M3 (3) based on actuation status of the other Moulded Case Circuit Breakers (MCCBs) M2 (2) and Ml (1). Figure 4b illustrates an exploded view of the block arrangement (15).
Referring to Figure 4a and Figure 4b, the block arrangement (15) includes a main body or housing (48), a plunger (49), a spring element (50), a hinge or a centrally supported lever (51) and a pin (52). The housing or the main body (48) includes two holes (54) configured on an operative top side thereof and one extruded hole (55) configured on an operative bottom side thereof. The hinge or the centrally supported lever (51) has a hole (56) in the centre for facilitating pivotable connection of the centrally supported lever (51) with the plunger (49). The spring element (50) is assembled on the plunger (49), the hinge or the centrally supported lever (51) is assembled on the pivot (53) of the plunger (49) by aligning holes on pivot (53) and centrally supported lever or hinge (51) and assembling the hinge or centrally supported lever (51) with the pivot (53) of the

plunger (49) by using a pin (52). The hinge or the centrally supported lever (51) is pivotable with respect to the plunger (49) and acts like a see-saw. The other end of the plunger (49) passes co-centrically through hole (55) configured on main body or the housing (48). The other end of the plunger (49) projects outside the housing (48) as illustrated in Figure 4a under action of urging forces for facilitating tripping of the corresponding circuit breaker, particularly, the MCCB M3 (3). The urging forces acting for facilitating tripping of the circuit breaker are based on actuation status of the actuation sub-system and actuation statuses of the remaining actuation sub-systems. When one of the sides of the hinge or the centrally supported lever (51) is pressed by the transmitters, the corresponding side of hinge (51) moves down wards or in other words hinge acts as see-saw. When both sides of the hinge (51) are pressed by the transmitters, the plunger (49) moves down wards to cause tripping of the circuit breaker. More specifically, as the plunger (49) moves down wards, the other end of the plunger (49) is aligned to the push a trip button (18) of MCCB M3 (3). More specifically, when the other end of the plunger (49) moves, it pushes the trip button (18) thereby, tripping the corresponding MCCB M3 (3). Similarly, the block arrangement (14) can be used to actuate a trip button (17) corresponding to the MCCB M2 (2) and the block arrangement (13) can be used to actuate trip button (16) corresponding to the MCCB Ml (1).
The transmitters (20), (22), (24), (26), (45) and (47) are received in the corresponding block arrangements (13), (14) and (15) to cause pressing of the trip buttons (16), (17) and (18) respectively, that in turn cause the tripping of the MCCBs Ml (1), M2 (2) and M3 (3) respectively. More specifically, the transmitters (26) and (20) are received in the holes (54) of the main body or housing (48) of the block arrangement (15) as illustrated in Figure 2. When the actuation switch (4) of MCCB Ml (1) is actuated, the actuator (19) and (21) will be pushed or displaced, the actuators (19) and (21) are connected clutch cables (7) and (8) so that the motion of actuators (19) and (21) due to actuation of the actuation switch (4) is transmitted to the other end of the clutch cable (7) and (8)

i.e. to the transmitters (20) and (22). The transmitter (20) is received in the block arrangement (15) which in turn is placed on MCCB M3 (3). The transmitter (20) pushes the corresponding side of the hinge or the centrally supported lever (51) of the block arrangement (14). Similarly, actuation of any other actuation switch (5) or (6) causes the transmitter (26) received in the block arrangement (15) to push corresponding side of the hinge or the centrally supported lever (51).
When both the transmitters (20) and (26) received in the block arrangement are displaced, the hinge or the centrally supported lever (51) gets depressed, and the plunger (49) gets pressed downwards and projects out of the block arrangement (15), thereby pressing the trip button (18) of MCCB M3 (3) thus tripping the MCCB M3 (3). So long as both the transmitters (20) and (26) remain displaced and the plunger (49) remains pressed, the trip button (18) remains actuated for causing tripping of the MCCB M3 (3) hence de-latching of MCCB M3 (3) from the other two MCCBs M l (I) and M(2). In such configuration, even if the user tries to reset the MCCB M3 (3), the user will not be able to reset the MCCB M3 (3) which ensure the interlocking.
When any of the transmitters (20) or (26) return back to original position thereof, by changing the state of the actuation switch (4) or actuation switch (5), the plunger (49) will move upward due to spring element (50), thereby releasing the pushing force acting on the trip button (18) and causing resetting of the MCCB M3 (3). During this time one of the transmitters out of (20) and (26) is pressing the hinge or centrally supported lever (51) while the other transmitter one is not pressing against the hinge or the centrally supported lever (51) and accordingly the centrally supported lever (51) again swivels about the pivot (53). In such configuration, the hinge or the centrally supported lever (51) remains in tilted condition as shown in Figure 6.
The operation of the mechanical interlock (100) can be explained by operation of one entire cycle for one pair of MCCBs. For remaining combinations, the

corresponding operation remains same. Supposing a circuit requires that the MCCB Ml (1) and MCCB M3 (3) to remain ON and while MCCB Ml (1) and MCCB M3 (3) remains ON, the MCCB M2 (2) cannot be made ON by the operator.
Initially all the MCCBs i.e. MCCB Ml (1), MCCB M2 (2) and MCCB M3 (3) are in OFF state as shown in Figure 5. While the MCCBs are in off state, the actuators (19), (21), (23), (25), (44) and (46) are in released state. So the transmitters (20) (22) (24) (26) (45) and (47) which are connected to the actuators (19), (21), (23), (25), (44) and (46) and are terminated in the block arrangements (13), (14) and (15) also remain in released state. So the plungers (33) (37) and (49) remain in released state. So the push to trip buttons (16), (17) and (18) corresponding to the MCCB Ml (1), MCCB M2 (2) and MCCB M3 (3) respectively are in reset state and the MCCBs can permit flow of electric current there-through.
When the actuation switch (4) corresponding to the actuation system for actuating the MCCB Ml (1) is operated, the MCCB Ml (1) is made ON as illustrated in Figure 6. The turning "on" of the actuation switch (4) causes displacement of the actuators (19) and (21). The actuators (19) and (21) are connected at one end of clutch cables (7) and (8), wherein on other end of clutch cables (7) and (8), transmitters (20) and (22) respectively are connected. The displacement of the actuators (19) and (21) due to actuation of the actuation switch (4) is transmitted to the transmitters (20) and (22), to cause displacement of the transmitters (20) and (22), thereby causing pressing the hinges (51) and (39) respectively. Accordingly, the hinges (51) and (39) get tilted as shown in Figure 6.
As shown in Figure 7, while keeping MCCB Ml (1) in ON condition, when MCCB M3 (3) is put ON, the actuation switch (6) displaces the actuators (44) and (46). The actuators (44) and (46) that are connected to the one end of clutch

cables (12) and (11). The other end of clutch cables (12) and (11) are connected to the transmitters (45) and (47) that are received inside the block arrangements (14) and (13) respectively. The transmitters (45) and (47) get displaced to cause pressing of the hinges (39) and (35) respectively. The hinge (39) is already actuated by transmitter (22) and therefore was tilted, when the transmitter (45) gets displaced, the motion of transmitter (45) is transmitted to hinge (39) so the plunger (37) along with spring (38) gets pressed. The plunger (37) pushes the hinge (39) in downward direction and the plunger (37) projects out of the block arrangement (14) to cause pressing of trip button (17) of MCCB M2 (2), thereby causing tripping of the MCCB M2 (2). So long as the MCCB Ml (1) and MCCB M3 (3) remain ON, the transmitters (45) and (47) will act on the hinge (39) and will continue pushing the hinge (39), thereby causing the plunger (37) will continue pushing the trip button (17) of MCCB M2 (2) for maintaining the MCCB M2 (2) in tripped condition. While trip button (17) corresponding to the MCCB M2 (2) remains pressed, the resetting of the MCCB M2 (2) is not possible even if the operator tries to reset the MCCB M2 (2) and hence the MCCB M2 (2) cannot be made ON while MCCB Ml (1) and MCCB M2 (2) are ON, thereby interlocking is achieved.
When all three MCCBs M l (1), M2 (2) and M3 (3) are tried to be switched on simultaneously from off position, actuation switches (4), (5) and (6) actuate actuators (19), (21), (23), (25), (44) and (46) simultaneously. The simultaneous movement of actuators (19), (21), (23), (25), (44) and (46) causes the movement of transmitters (20), (22), (24), (26), (45) and (47). The transmitters push hinges (35) (39) and (51) simultaneously, so the hinges (35) (39) and (51) push the plungers (33) (37) and (49) simultaneously. The movement of the plungers (35) (39) and (49) causes pressing of the trip buttons (16), (17) and (18) corresponding to the respective MCCBs Ml (1), M2 (2) and M3 (3) simultaneously. This happens before all the MCCBs Ml (1), M2 (2) and M3 (3) reach their dead centre. Thus all the MCCBs Ml (1), M2 (2) and M3 (3) trip

simultaneously so the actuation switches (4), (5) and (6) of MCCBs Ml (1), M2 (2) and M3 (3) return back to trip position.
ADA VANTAGES OF THE INVENTION
The interlocking system in accordance with the present invention for interlocking MCCBs of a MCCB set has several technical advantages including but not limited to the realization of:
• an interlocking system for interlocking MCCBs of a MCCB set for accurately controlling switching ON/OFF of the adjacently disposed MCCBs upon actuation of certain MCCBs to permit selective connecting of the power distribution system to different power sources;
• an interlocking system for interlocking MCCBs that is customizable by changing operation logic to meet different customer requirements of interlocking upto three MCCBs at a time;
• an interlocking system for interlocking MCCBs that effectively regulates the actuation of the adjacent MCCBs, even if the MCCBs are too close to interfere with each other;
• an interlocking system for interlocking MCCBs that safeguard against unintentional switching ON/OFF of the MCCBs;
• an interlocking system for interlocking the MCCBs that is simple in construction and convenient to use;
• an interlocking system for interlocking the MCCBs that is compact and involves less number of parts;
• an interlocking system for interlocking the MCCBs that is reliable;
• an interlocking system for interlocking the MCCBs that require less maintenance;
• an interlocking system for interlocking the MCCBs that is easily accessible once installed and therefore is convenient to service;

• an interlocking system for interlocking the MCCBs that can be retrofitted on MCCB set of any type or configuration; and
• an interlocking system for interlocking the MCCBs that ensures safety & reliability of the power distribution system.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities; as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the invention. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the invention as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the invention, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has-been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features

can be added and that many changes can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We Claim:
1. An interlocking system for interlocking circuit breakers of a set of circuit breakers, said interlocking system comprising an actuation subsystem corresponding to each circuit breaker of the set of circuit breakers, said actuation sub-system functionally coupled to the remaining actuation sub-systems corresponding to the remaining circuit breakers, wherein each actuation sub-system adapted to regulate a corresponding circuit breaker based on actuation statuses of the remaining actuation sub-systems, each actuation sub-system comprising:
an actuation switch adapted to be displaceable between an "ON" configuration and an "OFF" configuration for defining actuation status of a corresponding actuation sub-system; a block arrangement functionally coupled to said actuation switch of said actuation sub-system, at least one actuation switch corresponding to any of the remaining actuation sub-systems and a circuit breaker corresponding to said actuation sub-system, said block arrangement adapted to regulate tripping of said circuit breaker based on actuation status of said actuation sub-system and actuation statuses of the remaining actuation sub-systems, said block arrangement comprising: housing;
a plunger adapted to be slidably received inside said housing, said plunger adapted to project outside said housing under action of urging forces for facilitating tripping of said circuit breaker, wherein said urging forces act based on actuation status of said actuation sub-system and actuation statuses of the remaining actuation subsystems; and
a spring element functionally coupled to said plunger and adapted to restore said plunger inside said housing upon

failure to maintain said urging forces, thereby facilitating resetting said tripped circuit breaker.
2. The interlocking system as claimed in claim 1, further comprising linkages adapted to transmit displacement of said actuation switch of an actuation sub-system and at least one actuation switch corresponding to any of the remaining actuation sub-systems to transmitting elements received inside said block arrangement, wherein said transmitting elements are adapted to apply urging forces on said plunger.
3. The interlocking system as claimed in claim 1, wherein said plunger further comprising a centrally supported lever that is adapted to swivel about said plunger under action of said urging forces acting based on actuation status of said actuation sub-system and actuation statuses of the remaining actuation sub-systems.
4. The interlocking system as claimed in claim 3, wherein said centrally supported lever adapted to press said plunger in an operative downward direction under action of said urging forces acting on said lever based on actuation status of said actuation sub-system and actuation statuses of the remaining actuation sub-systems.
5. The interlocking system as claimed in claim 1, wherein said set of circuit breakers comprises three circuit breakers and a circuit breaker trips in-case actuation status of an actuation sub-system corresponding to said circuit breaker and one of the remaining actuation sub-systems corresponding to the remaining circuit breakers is "ON" and the third actuation sub-system corresponding to third circuit breaker is also turned "ON", thereby preventing turning "ON" of all three actuation system at one time.