Claims:WE CLAIM:

1. An isolation mechanism module (31) for use in earth leakage module for molded case circuit breakers of different frame size, wherein said isolation mechanism module (31) comprising:
a base casing (26);
a top casing (27), wherein said base casing (26) is hinged with said top casing (27) and said top casing (27) assembled over said base casing (26);
an electronic circuit board (28) housed in said base casing (26), wherein said electronic circuit board (28) carrying two sets of tapping points 28(a) and 28(b);
a switching flapper component (29);
at least one set of electrical contacts (30) arranged on said switching flapper component (29), wherein when said switching flapper (30) is closed, said set of electrical contacts (30) completes the electric circuit path between said two set of tappings (28a) & (28b);
wherein, when performing high voltage test on said circuit breaker, said switching flapper (29) is opened up, said electrical contacts (30) disengages with said two set of tapping (27a & 27b), electrically isolating said two set of tapping, to provide required clearances and creepage.

2) The isolation mechanism module (31) as claimed in claim 1, wherein said two set of tappings put into an array pattern on said electronic circuit board for meeting clearance and creepage requirements during line and test conditions.
3) The isolation mechanism module (31) as claimed in claim 1, wherein one set of said two sets of tapping points includes the power tappings taken from line conductors of said circuit breaker through voltage tapping means which includes arrangement of leaf spring in various shapes.
4) The isolation mechanism module (31) as claimed in claim 3, wherein other set of said two sets of tapping points include the tappings taken from another set of points arranged along the first set of points on said electronic circuit board (28) to a microprocessor card and electronic circuits connected in conjunction with said microprocessor card for providing current settings or time settings or trip indication or any combinations thereof.
5) The isolation mechanism module (31) as claimed in claim 2, wherein said electronic circuit board (28) comprises plurality of grooves cut along said array of two set of tappings.
6) The isolation mechanism module (31) as claimed in claim 5, wherein said top casing (27) are provided with thin walled structures built in a pattern to get accommodated in said grooves cut in said electronic circuit board (28) and then into cut features provided in said base casing (26).
7) The isolation mechanism module (31) as claimed in claim 1, wherein said set of electrical contacts (30) made of phosphor bronze alloy.
8) The isolation mechanism module (31) as claimed in claim 6, wherein said wall structures of the top casing accommodates in said grooves cut in said electronic circuit board (28) and base casing (26) to provide required clearances and creepage between said two set of tapping points terminated on said electronic circuit board.
9) The isolation mechanism module (31) as claimed in claims 1-8, wherein during normal working conditions, when said switching flapper component (29) is closed, the voltage tapped from said line conductors of the circuit breaker are fed to power up said microprocessor card and said electronic circuits.
10) The isolation mechanism module (31) as claimed in claim 9, wherein while performing Dielectric voltage withstand test on said circuit breaker, the Switching Flapper (29) is opened up, electrically isolating said circuit breaker under test and microprocessor card and relays which are in conjunction with the microprocessor card.
11) The isolation mechanism module (31) as claimed in claim 1, is screwed joined to the isolation-box module, in case of Modular L-shaped four pole earth leakage module for a four pole circuit breaker.
12) The isolation mechanism module (31) as claimed in claim 1, is screwed joined to a CBCT Housing module (5), in case of Modular L-shaped three pole earth leakage module for a three pole circuit breaker.

13) The isolation mechanism module (31) as claimed in claims 1-12, wherein during a dielectric voltage withstand test, the Switching Flapper (29) is opened around a hinge and stay intact with said Top cover for a Modular L-shaped three pole earth leakage module / four pole earth leakage module.
14) The isolation mechanism module (31) as claimed in claims 1-12, wherein said modular L-shaped earth leakage (3,4) module consists of :
a. CBCT Housing module (5)
b. Card housing module (6)
c. Isolation-box module (7)
d. Core balanced current transformer (8)
e. Sub assembly of (6) card housing module & (7) isolation-box module. (23)
f. Sub-assembly of (6) card housing module, (7) isolation-box module and CBCT housing module (5).
g. Sub assembly of (6) card housing module & (7) CBCT housing module (5).

Dated this 02nd day of April 2018

Abhishek Sen
Of S. MAJUMDAR & CO.
(Applicant’s Agent)
, Description:TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to isolation mechanism module for use in earth leakage add-on module for a molded case circuit breaker for protection during dielectric tests.

BACKGROUND OF THE INVENTION

[002] Circuit breakers are devices that are employed in electrical system or network for switching operations as well as protection from electrical fault conditions such as overload, short circuits and under voltage conditions. These are widely used in domestic, commercial & light industrial applications.

[003] A circuit breaker is an automatically operated electric switch designed to detect fault condition and immediately interrupt the current flow, either instantaneously or with time-delay, usually of few milliseconds. Unlike a fuse, a circuit breaker can be reset (either manually or automatically) to resume normal operation.

[004] Circuit breakers come in various frame sizes ranging from small ones that are used to protect individual house hold appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.

[005] In addition to fault conditions as mentioned above, there can also be stray voltages on metal enclosures of electrical equipment causing leakage currents to flow through parts which are actually not meant to be live, which can be fatal to human life, commonly called as electrical shock and even result in electrocution.

[006] Earth leakage modules are designed to disconnect the circuit, if there is any leakage current. Earth leakage modules can detect leakage current typically from setting as low as 30 milliamperes to several amperes.

[007] There are earth leakage modules which can detect leakage currents typically 5-30 milliamperes & disconnect quickly in time much lesser than 25-40 milliseconds, and thus preventing electrocution. There are earth leakage modules with low sensitivities and intentionally slower responses designed to protect equipment or avoid risk of electric fires, but not disconnect unnecessarily the equipment with greater leakage currents in normal operation.

[008] Generally, electrical safety testing is done to ensure safe operating standards, when the electrical equipment including switchgear devices are installed in various applications. Various governments & agencies have developed stringent requirements & standards set up by various safety & standard agencies for electrical products that are sold world-wide. To conform to such standards, the products must pass safety tests such as Insulation resistance test, Ground Bond & Ground continuity test, Leakage current/Line leakage test and High voltage / Dielectric voltage withstand test / High potential test.

[009] The High voltage / Dielectric voltage withstand test / High potential test is an integral part of the product safety evaluation of electrical & electronic devices. It is carried out by applying a significantly higher than operating voltage to the device under test. The applied dielectric voltage is usually much higher to accommodate transient over voltages & provides safety margin for production variations & aging of the material.

[0010] If the insulation breaks down and allows the current to flow, the insulation is determined to be insufficient as it might pose a shock hazard to the end-users. The test is done to determine the effectiveness of its insulation. This test is a means to qualify a device's ability to operate safely during rated electrical conditions. The current during dielectric test is performed at much higher voltage and hence not evaluated against device leakage current limits.

[0011] A dielectric withstand test may be done as a factory test on new equipment to identify material and workmanship defects, or may be done on apparatus already in service as a routine maintenance test.

[0012] Typically, the earth leakage module basically consist of core balanced current transformer. The earth leakage module is connected such that all the phase conductors of the circuit breaker will pass through core balanced current transformer. In case of fault free system, the flux induced by each of the phase conductor will cancel each other, and the net resultant magnetic flux induced will be nil. As, such there will no secondary voltage induced across the secondary of the CBCT. In case of any residual current flowing through the conductor, the residual flux present in the CBCT will induce a secondary voltage across its secondary.

[0013] The voltage is tapped from line conductors of the circuit breaker on the line side. The voltage tapped is then fed for powering up of the microprocessor card. The microprocessor card includes settings like current settings, time settings, trip indication and the like.

[0014] Typically when High voltage / Dielectric voltage withstand test / High potential test is performed on the circuit breaker, there is mechanism devised in the earth leakage module generally referred to as ‘isolation mechanism’, to disconnect as well as isolate the main circuit (that of the circuit breaker under test) and the microprocessor card & relays, so that the high voltage does not appear at the points of microprocessor card, which is fatal to the life of the microprocessor card and similar electronic circuits in conjunction with the microprocessor card.

[0015] The earth leakage modules are currently available as integrated as well as add-on modules.

[0016] The integrated earth leakage modules have the detection, evaluation and actuating means of interruption means integrated inside the circuit breaker module. The circuit breaker with integrated earth leakage protection thus will provide basic circuit breaker functions like protection against overloads, short circuit and under voltage in addition to earth leakage protection. These modules will be compact in size as compared to add-on module, but will provide lesser features.

[0017] The add-on modules are separate modules housing the detection, evaluation and some parts of actuating means of interruption which are mounted in conjunction with the circuit breaker. Add-on earth leakage modules are available in different configurations.

[0018] The bottom mounted configuration is the one which is mounted just below the circuit breaker in vertically mounted condition. The bottom mounted configuration has the best advantage of catering to all the termination types as that of the basic circuit breaker.

[0019] The side mounted configuration will have the earth leakage add-on module mounted next to the associated circuit breaker along its height in mounted condition. The side mounted will also have advantage of catering to maximum of the termination types as that of the basic circuit breaker. Also, the setting will be visible when mounted in distribution boards.

[0020] The L-shaped add-on configuration will typically have L-shape and when mounted in conjunction with the circuit breaker will have one limb along the height of the breaker and the other limb below the breaker in vertically mounted condition. This module has the best advantage of setting visibility when mounted in distribution boards and better than side mounted configuration.

[0021] The conventional design of a typical add-on earth leakage module demands separate earth leakage modules for a three pole breaker and a four pole breaker for a given frame size. The isolation mechanism also typically varies from one frame size to another.

[0022] This increases the number of components and hence increasing the tooling cost and making inventory management difficult in the assembly line.

[0023] Reference is made to EP 1261005 A1, which discloses a mechanism, for an enclosed residual current-operated circuit breaker, has a relay provided with a piston adapted to act on a tripping mechanism, a handle for resetting the tripping mechanism and for acting on the piston of the relay in order to return it to the normal operating condition, a pre-adjusted elastic member arranged between the handle and the piston so that the force applied to the piston is set by means of the elastic member and does not depend on the force applied to the handle.
[0024] Reference is further made to CN 102243957 B, which relates to a residual current protection with a moulded case circuit breaker, the device includes a base, contact interrupter module group, operating mechanism, residual current release, lid assembly, partitions, thermal magnetic release group, insulation, zero-sequence current transformer, leakage control unit, said contact interrupter module group fixed to the base, the operating mechanism fixed to the base and contact interrupter module group, the remaining current release mounted on the contact interrupter module group, and the drain is connected via a wire control assembly, the thermal-magnetic release set by each phase zero-sequence current transformer located in contact interrupter module group and base Take electric wire holder, the leakage control assembly disposed between the thermal-magnetic release set and zero-sequence current transformer, the leakage control components are connected to three-phase thermal magnetic release group, the said cover assembly is mounted on the base.
[0025] However, the conventional isolation mechanism consist of mechanically engaging & disengaging the two sets of contacts, one set from the main circuit and other set to the microprocessor card. The conventional layout of isolation mechanism consists of a third set of contacts mounted on plastic plate. This plastic plate carrying the set of contacts is screwed to the earth leakage module and remains fixed along with the earth leakage module when mounted with the circuit breaker.
[0026] However during the dielectric withstand test at installation site, the plastic plate carrying set of contacts is then physically removed by removing the screws. This causes inconvenience to end users in installations as misplacing the plastic plate & screws at the installation site can lead to non-functioning of earth leakage module in normal running conditions.
[0027] Also, this conventional kind of layout demands different mechanism modules in case of a three pole breaker and a four pole breaker and from one frame size to another.
[0028] This increases the variety of components required for three pole as well as four pole circuit breaker and through all the frame sizes. So, it will in turn increase the tooling cost incurred separately for earth leakage module for a three pole as well as four pole circuit breaker and for different frame sizes. The inventory management becomes difficult in the assembly line.

[0029] Accordingly, there is a dire need to meet the limitations of the prior art.

SUMMARY OF THE INVENTION

[0030] The following 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.

[0031] An objective of the present invention is to provide a modular isolation mechanism which will ensure that this module can be used across all frame sizes alike and irrespective of whether the add-on module will go along with a three pole breaker or a four pole breaker.

[0032] Another objective of the present invention is to ensures commonisation of components to both three pole as well as for pole circuit breaker. This helps us in minimising inventory.

[0033] Accordingly, in one implementation, the present invention discloses an isolation mechanism module for use in earth leakage module for molded case circuit breakers of different frame size, wherein said isolation mechanism module comprising: a base casing; a top casing, wherein said base casing is hinged with said top casing and said top casing assembled over said base casing; an electronic circuit board housed in said base casing, wherein said electronic circuit board carrying two sets of tapping points; a switching flapper component; at least one set of electrical contacts arranged on said switching flapper component, wherein when said switching flapper is closed, said set of electrical contacts completes the electric circuit path between said two set of tappings; wherein, when performing high voltage test on said circuit breaker, said switching flapper is opened up, said electrical contacts disengages with said two set of tapping, electrically isolating said two set of tapping, to provide required clearances and creepage.

[0034] 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 THE ACCOMPANYING DRAWINGS

[0035] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0036] Figure 1 shows the Figure 1 shows an isolation mechanism module, according to one implementation of the present invention.

[0037] Figure 2 shows the shows a modular L-shaped three pole earth leakage module and modular L-shaped four pole earth leakage module, according to one implementation of the present invention.

[0038] Figure 3 shows the exploded view of a modular L-shaped four pole earth leakage module, according to one implementation of the present invention.

[0039] Figure 4 shows the exploded view of a modular L-shaped three pole earth leakage module, according to one implementation of the present invention.

[0040] Figure 5 shows the exploded view of isolation mechanism module, according to one implementation of the present invention.

[0041] Figure 6 shows the two sets of tappings are brought to an array pattern on electronic circuit board, according to one implementation of the present invention.

[0042] Figure 7 shows housing of the electronic circuit board in the base casing and the top casing being hinged on the base casing, according to one implementation of the present invention.

[0043] Figure 8 shows the isolation mechanism module top casing is assembled over the isolation mechanism module base casing, according to one implementation of the present invention.

[0044] Figures 9-12 shows details of the CBCT housing module and its various components, according to one implementation of the present invention.

[0045] Figure 13 shows the the microprocessor card with its slots, according to one implementation of the present invention.

[0046] Figure 14 shows the detailed view of card housing module and its features, according to one implementation of the present invention.

[0047] Figure 15 shows the detailed view of a card cover and its components, according to one implementation of the present invention.

[0048] Figure 16 shows an isolation-box module, according to one implementation of the present invention.

[0049] Figure 17 shows the inverted L-shaped feature of the isolation-box module, according to one implementation of the present invention

[0050] Figure 18 shows the top cover which are different for earth leakage modules for both three pole as well as four pole circuit breaker, according to one implementation of the present invention

[0051] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not 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

[0052] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0053] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0054] 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 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 as defined by the appended claims and their equivalents.

[0055] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0056] 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.

[0057] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0058] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0059] The present invention makes use of modular construction of ‘Isolation Mechanism’ commonly used in a typical add-on earth leakage module.

[0060] The modular construction of the ‘isolation mechanism’ allows the use of the same module to be used in all the earth leakage modules, irrespective of the frame size or the number of poles in the circuit breaker along which the add-on module will be assembled.

[0061] In one implementation, the present invention consists of the following:
a. Isolation Mechanism module Base casing
b. Isolation Mechanism module Top casing
c. Electronic circuit board carrying two sets of tapping points 28(a) & 28(b).
d. Switching Flapper
e. Phosphor bronze contacts

[0062] In one implementation, figure 1 shows an isolation mechanism module (31). Figure 2 shows a modular L-shaped three pole earth leakage module (3) and modular L-shaped four pole earth leakage module (4).

[0063] In one implementation, the construction of a three pole or four pole L-shaped modular earth leakage module consists of the following:
1) A three pole circuit breaker
2) A four pole circuit breaker (of the same frame size as that of the three pole circuit breaker).
3) Modular L-shaped three pole earth leakage module
4) Modular L-shaped four pole earth leakage module
5) CBCT Housing module
6) Card Housing module
7) Isolation-box module
8) Core balanced current transformer assembly
9) Line conductors of a three/four pole circuit breaker
10) Voltage tapping means
11) Microprocessor card
12) Current settings & Time settings
13) Trip indication
14) Setting flapper
15) Isolation box
16) Plastic casing
17) Card cover
18) Self-tapping mechanical joining screw
19) Top cover for Modular L-shaped three pole earth leakage module
20) Top cover for Modular L-shaped four pole earth leakage module
21) Flapper for Modular L-shaped three pole earth leakage module
22) Flapper for Modular L-shaped four pole earth leakage module
23) Sub assembly of (6) card housing module & (7) isolation-box module.
24) Sub-assembly of (6) card housing module, (7) isolation-box module & CBCT housing module (5).
25) Sub assembly of (6) card housing module & (7) CBCT housing module (5).

[0064] In one implementation, the modular construction of a modular L-shaped four pole earth leakage module (4) configuration basically consists of three main modules, namely the CBCT housing module (5), card housing module (6) and isolation-box module (7). Figure 3 shows the exploded view of a modular L-shaped four pole earth leakage module (4). Figure 4 shows the exploded view of a modular L-shaped three pole earth leakage module (3).

[0065] In the implementation, the CBCT housing module (5) houses the core balanced current transformer assembly (8). In addition, it also encloses the voltage tapping means (10) from the line conductors (9) for powering up of the microprocessor card (11). The voltage is tapped from the line conductors (9) of the circuit breaker on the line side of the L-shaped earth leakage module (3, 4). The card housing module (6) houses the microprocessor card (11) which includes settings like current settings (12), time settings (13), trip indication(14) and the like.

[0066] In one implementation, figure 5 shows the exploded view of isolation mechanism module (31). The isolation-box module (7) houses the isolation mechanism module (31). The isolation mechanism module (31) houses the ‘isolation mechanism’. The isolation mechanism consists of two set of tappings (28a) & (28b) & one set of electrical contacts (30). The two sets of tappings (28a) & (28b) are brought to an array pattern on electronic circuit board (28) as shown in Figure 6.

[0067] In the implementation, one set of tappings includes power tappings (28a) from the line conductors of the circuit breaker (1, 2). The tappings (28a) are taken from the line conductors via voltage tapping means which includes arrangement of leaf spring in various shapes. The tappings (28a) are then terminated on set of specified points on an electronic circuit board (28). The other set of tappings include the tappings (28b) taken from another set of points arranged along the first set of points on electronic circuit board (28) to the microprocessor card (11) & electronic circuits connected in conjunction with the microprocessor card (28) for the purpose of current settings (12a), time settings (12b), trip indication (13) etc.

[0068] In one implementation, The isolation mechanism module base casing (26) has grooves cut as shown in Figure 5. The electronic circuit board (28) also have grooves cut along in similar fashion as in isolation mechanism module base casing (26). The grooves are cut along the set of tapping points (28a), where the tapping taken from the line conductors of a circuit breaker (1, 2) are terminated.

[0069] Similarly, grooves are cut along tapping points (28b), where the tapping are taken from another set of points arranged along the first set of points on electronic circuit board (28) to the microprocessor card (11) & electronic circuits connected in conjunction with the microprocessor card (28) for the purpose of current settings (12a), time settings (12b), trip indication (13) etc.

[0070] In one implementation, the isolation mechanism module top casing (27) are provided with thin walled structures as shown in Figure 5. These walls are built in a pattern to get accommodated in the grooves cut in the electronic circuit board (28) and then into the cut features provided in isolation mechanism module base casing (26). The electronic circuit board (28) is then housed in the Isolation Mechanism module Base casing (26). The Isolation Mechanism module Base casing (26) is hinged with the Isolation Mechanism module Top casing (27).

[0071] In one implementation, the isolation mechanism module top casing is assembled over the isolation mechanism module base casing (26) as shown in Figure 8. Now, when the isolation mechanism module base casing (26) & top casing (27) are assembled together, the wall structures of the isolation mechanism top casing (27) accommodates in grooves cut in electronic circuit board (28) and isolation mechanism module base casing (26) and provides the required clearances (through-air space requirements between live conductors) and creepage (over-surface space requirements between live conductors) that are to be provided between the two set of tapping (28a & 28b) terminated on the electronic circuit board (28).

[0072] In one implementation, there is a set of electrical contacts (30) made of phosphor bronze alloy arranged on a switching flapper component (29). The switching flapper (29) with electrical contacts arrangement (30) is hinged around the isolation mechanism casing assembly as shown in Figure 8.

[0073] In one implementation, in normal working conditions, when the switching flapper (30) is closed, the set of electrical contacts (30) made of phosphor bronze alloy (30) completes the electric circuit path between the two set of tappings (28a) & (28b). The voltage tapped from the line conductors of the circuit breaker (1,2) are basically fed to power up the microprocessor card (11) & electronic circuits connected in conjunction with the microprocessor card for the purpose of current settings (12a), time settings (12b), trip indication (13) etc. In live conditions, the required clearances & creepage distances are met by the isolation mechanism module.

[0074] In the implementation, while performing High voltage / Dielectric voltage withstand test / High potential test on the circuit breaker (1, 2), which is critical for electrical safety testing, the circuit breaker (1,2) is subjected to a significantly higher voltage than the operating voltage of the circuit breaker (1,2). As a result, high voltage appears at the points of microprocessor card (11), which is fatal to the life of the microprocessor card (11) and similar electronic circuits in conjunction with the microprocessor card (11).

[0075] So, when performing high voltage test on the circuit breaker (1, 2), the switching flapper (29) is opened up, thus the electrical contacts (30) disengages with two set of tapping (27a & 27b), thus electrically isolating the two, that is the main circuit (that of the circuit breaker under test) and the microprocessor card (11) & relays which are in conjunction with the microprocessor card (11). Under test conditions, the required clearances & creepage are still met by the isolation mechanism module.

[0076] In one implementation, the switching flapper (29) is hinged & will stay intact with the Top cover (19, 20) for Modular L-shaped three pole earth leakage module / four pole earth leakage module during the dielectric voltage withstand test. The switching flapper (29) design is such that it ensures that there is only electrical isolation and no physical isolation of contacts, which is the case in conventional earth leakage modules (3, 4). This ensures that there is no inconvenience to the end-user at the installation site.

[0077] In one implementation, in modular L-shaped earth leakage module, the CBCT housing module (5), the isolation-box module (7) and the card housing module (6) are designed in such a manner that using the same modules, the earth leakage module(3,4) can be configured for both three pole (1)as well as four pole circuit breaker(2). In case of Modular L-shaped four pole earth leakage module (4) for a four pole circuit breaker(2), the CBCT housing module (5), the card housing module (6) and the isolation-box module (7) are integrated by means of slide fit and screw joining. In case of Modular L-shaped three pole earth leakage module (3) for a three pole circuit breaker(1), the CBCT housing module (5) & the card housing module (6) are integrated by means of slide fit & screw joining. The isolation-box module (7) will not be included. In this case, the isolation mechanism module will be arranged in the CBCT housing module (5).

[0078] In one implementation, figures 9-12 shows details of the CBCT housing module (5).

[0079] In the implementation, as seen in Figure 9, the CBCT housing module (5) has provision of voltage tapping (10) from the line conductors (9) of the circuit breaker (1, 2) on the line side of earth leakage module (3, 4) in mounted condition. The voltage tapping means (10) are provided in the feature (5a). The module (5) has an elongated feature (5b) along its depth so as to engage with the circuit breaker. This serves as mechanical joining between the earth leakage module (3, 4) as well as the circuit breaker (1, 2) respectively. Also, it helps in meeting the necessary clearance & creepage requirements as per the standards. This elongated feature also has T-provision (5c) on its upper end, which locks the earth leakage module (3, 4) in position & prevents its translational motion along height direction of a circuit breaker (1, 2). In addition to this, the module (5) also has a hexagonal feature (5d) as seen in Figure 10 which engages with the slot in the circuit breaker (1, 2). This again helps in preventing the translational motion along height direction of a circuit breaker (1, 2).

[0080] In the implementation, the CBCT housing module (5) also has provision (5e) of keeping the voltage tapping wires (10) or conductors or strips whichever used, intact and shielded by means of plastic casing (16). This plastic casing (16) also ensures that the customer termination does not interfere with the voltage tapping wires (10). The CBCT housing module (5) has slot (5f) as seen in Figure 11 to accommodate the core balanced current transformer (8).

[0081] In one implementation, the core balanced current transformer (8) is designed considering termination required for a four pole circuit breaker (2). The same core balanced current transformer (8) is being used in Modular L-shaped three pole earth leakage module (3) for a three pole circuit breaker (1) as shown in Figure 3 and 4.

[0082] In the implementation, the CBCT housing module (5) has knockout feature (5g) as shown in the Figure 10. In case of Modular L-shaped four pole earth leakage module(4) for a four pole circuit breaker (2), the feature (5g) will be knocked out before the assembly, as shown in Figure 12 so as to integrate the internal elements in the CBCT housing module (5), card housing module (6) as well as isolation-box module (7). In case of an Modular L-shaped three pole earth leakage module (3) for a three pole circuit breaker (1), the CBCT housing module (5) will be used as it is, with the feature (5g) intact and secured by some means, say like factory seal, label, sticker etc. as this will be the part of the outside facia of Modular L-shaped three pole earth leakage module (3).

[0083] In the implementation, whenever Modular L-shaped three pole earth leakage module (3) will be configured for a three pole circuit breaker (1), the voltage tapping means (10) for the fourth pole will not be assembled in the CBCT housing module (5). Also, the hexagonal feature (5d) given in the fourth pole of CBCT housing module (5) will be accommodated inside the card housing module (6).

[0084] In the implementation, the card housing module (6) houses the microprocessor card (11). The microprocessor card (11) as seen in Figure 13 has a slot (11a) and is placed vertically in the card housing module (6) and is constrained in the breaker’s (1,2) width-height direction at the bottom side by means of locking feature (6a) given in the card housing module (6) as seen in Figure 14. On the top side too, the microprocessor card (11) has a slot (11b), which gets locked by means of feature (17a) given in the card cover (17) as seen in Figure 13. This constrains the microprocessor card (11) along the depth of the breaker (1, 2).

[0085] In one implementation, the card housing module (6) has features (6b) & (6c) as shown in detailed view in Figure 14.

[0086] In one implementation, in case of Modular L-shaped four pole earth leakage module (4),the feature (6b) of card housing module (6) slides through the feature (7a) of the isolation-box module (7) and gets locked by T-shaped feature given in the feature (6c) of the card housing module (6).

[0087] In the implementation, on sliding the isolation-box module (7) over the card housing module (6), the feature (6d) of card housing module (6) will come under the feature (7b) given in the isolation-box module (7). Then the hole-feature (6d) in card housing module (6) will lie in the same axis as that of the hole-feature (7c) of the isolation-box module (7). Now, a sub-assembly (23) of card housing module (6) and isolation-box module (7) will be formed.

[0088] Then the inverted L-shaped feature (7d) & (7d’) of the isolation-box module as seen in Figure 17 will be clamped over the walls of the CBCT housing module (5) and the subassembly (24) consisting of (6) card housing module, (7) isolation-box module & CBCT housing module (5) will be formed. Now, the card cover (17) will be assembled over the card housing module (6) with the feature (17c) lying axially with (6d) of card housing module and (7c) of isolation-box module (7). Self-tapping mechanical joining screw (18) is provided through features (17b) & (6e) to engage respectively the card cover (17) & card housing module (6). Now, top cover for Modular L-shaped four pole earth leakage module (20) will be assembled over the above assembly. A self-tapping mechanical joining screw (18) is provided to engage the top cover (20), card housing module (6), card cover (17) and isolation-box module (7).

[0089] In one implementation, the isolation-box module (7), as seen in Figure 16 houses the isolation box (15) only in case of Modular L-shaped four pole earth leakage module (4) for a four pole circuit breaker (2) which was described previously. The isolation-box module (15) is cot connected in case of a Modular L-shaped three pole earth leakage module (3) for a three pole circuit breaker (1).

[0090] In one implementation, in case of Modular L-shaped three pole earth leakage module (3) for three pole circuit breaker (1) , the features (7a) as shown by in isolation-box module (7) will be given by (5h) in the CBCT housing module (5) as shown by in Figure 11. Similarly, features (7b) & (7c) of isolation-box module (7) as shown in Figures 16 and 17 respectively will be provided by (5j) & (5k) of the CBCT housing module (5) as seen in Figure 11. The features (5h), (5j) & (5k) however will not serve any purpose only in case of Modular L-shaped four pole earth leakage module (4) for four pole circuit breaker (2) as shown in Figure 3.Now, the feature (6b) of card housing module (6) slides through the feature (5h) of the CBCT housing module (5) and gets locked by T-shaped feature given in the feature (6c) of the card housing module (6).

[0091] In the implementation, on sliding the CBCT housing module (5) over the card housing module (6), the feature (6d) of card housing module (6) will come under the feature (5j) given in CBCT housing module (5). Then the hole-feature (6d) in card housing module (6) will lie in the same axis as that of the hole-feature (5k) of the CBCT housing module (5). Now, a sub-assembly (25) of card housing module (6) and CBCT housing module (5) will be formed. Now, the card cover (17) will be assembled over the card housing module (6) with the feature (17c) lying axially with (6d) of card housing module and (5k) of CBCT housing module (5) .Self-tapping mechanical joining screw (18) is provided through features (17b) & (6e) to engage respectively the card cover (17) & card housing module (6).

[0092] In one implementation, top cover for Modular L-shaped three pole earth leakage module (19) will be assembled over the above assembly. A self-tapping mechanical joining screw (18) is provided to engage the top cover (20), card housing module (6), card cover (17) and CBCT housing module (5).

[0093] In one implementation, the card cover (17) is same for earth leakage modules (3, 4) for both three pole (1) as well as four pole circuit breaker (2).

[0094] In one implementation, figure 18 shows the top cover (19, 20) which are different for earth leakage modules (3, 4) for both three pole (1) as well as four pole circuit breaker (2).

[0095] In one implementation, the top cover (20), as one can see has window (20a) which has a flapper (22) as shown .The purpose of the window (20a) given in top cover (20) is to have better view while terminating cables at customer end. The isolation mechanism module (31) can be accessed through the window shown by (20b). Similarly, top cover (19), as one can see has window (19a) which has a flapper (21) as shown .The purpose of the window (19a) given in top cover (19) is to have better view while terminating cables at customer end. The isolation mechanism module (31) can be accessed through the window shown by (19b).

[0096] In one implementation, the isolation mechanism module (31) will be screwed joined to the isolation-box module (7), in case of Modular L-shaped four pole earth leakage module (4) for a four pole circuit breaker (2).

[0097] In one implementation, the isolation mechanism module (31) will be screwed joined to the CBCT housing module (5), in case of Modular L-shaped three pole earth leakage module (3) for three pole circuit breaker (1)

[0098] In one implementation, the switching flapper (29) is hinged and will stay intact with the isolation mechanism module (31). So, during the dielectric test, the switching flapper has to be opened around the hinge given in isolation mechanism module (31). The switching flapper will be accessed through the window shown by (19b) in top cover (19) & (20b) in top cover (20).

[0099] Some of the noteworthy features of the present invention are as follows:
• The modular construction of ‘Isolation Mechanism’ module (31) consists of :
Isolation Mechanism module Base casing (26)
Isolation Mechanism module Top casing (27)
Electronic circuit board (28) carrying two sets of tapping points 28(a) & 28(b).
Switching Flapper (29)
Phosphor bronze contacts (30)
• There are two set of tappings put into an array like pattern on electronic circuit board.
• One set of tappings includes the power tappings taken from the line conductors of the circuit breaker via voltage tapping means which includes arrangement of leaf spring in various shapes. These tappings are then terminated on set of specified points on the electronic circuit board.
• The other set of tappings include the tappings taken from another set of points arranged along the first set of points on Electronic circuit board (28) to the microprocessor card & electronic circuits connected in conjunction with the microprocessor card for the purpose of current settings, time settings, trip indication etc.
• The Electronic circuit board (28) also have grooves cut along the array of two set of tappings given for meeting clearance & creepage requirements during line and test conditions.
• The Isolation mechanism module Base casing (26) has grooves cut in similar fashion as in electronic circuit board.
• The Isolation Mechanism module Top casing (27) are provided with thin walled structures. These walls are built in a pattern to get accommodated in the grooves cut in the Electronic circuit board (28) & then into the cut features provided in Isolation Mechanism module Base casing (26).
• The Electronic circuit board (28) is housed in the Isolation Mechanism module Base casing (26).
• The Isolation Mechanism module Base casing (26) is hinged with the Isolation Mechanism module Top casing (27) & is assembled over the Isolation Mechanism module Base casing (26).
• A set of electrical contacts (30) made of phosphor bronze alloy is arranged on a Switching Flapper (29) component.
• The Switching Flapper (29) with electrical contacts (30) arrangement is hinged around the isolation mechanism casing assembly & will stay intact with the isolation mechanism module
• When the Isolation Mechanism module Base casing (26) & top casing are assembled together, the wall structures of the isolation mechanism top casing accommodates in grooves cut in Electronic circuit board (28) & Isolation Mechanism module Base casing (26) and provides the required clearances and creepage that are to be provided between the two set of tapping terminated on the electronic circuit board.
• In normal working conditions, when the Switching Flapper (29) is closed, the set of electrical contacts (30) made of phosphor bronze alloy completes the electric circuit path between the two set of tappings. The voltage tapped from the line conductors of the circuit breaker are basically fed to power up the microprocessor card & electronic circuits connected in conjunction with the microprocessor card for the purpose of current settings, time settings, trip indication etc.
• While performing Dielectric voltage withstand test on the circuit breaker critical for electrical safety testing, the Switching Flapper (29) is opened up, thus the electrical contacts (30) disengages with two set of tapping, thus electrically isolating the two, that is the circuit breaker under test & microprocessor card & relays which are in conjunction with the microprocessor card.
• The construction of the isolation mechanism module (31) is such that the required clearances & creepage are met both under live and test conditions.
• The isolation mechanism module (31) will be screwed joined to the isolation-box module, in case of Modular L-shaped four pole earth leakage module for a four pole circuit breaker.
• The isolation mechanism module (31) will be screwed joined to the CBCT Housing module (5), in case of Modular L-shaped three pole earth leakage module for three pole circuit breaker.
• The Switching Flapper (29) of the isolation mechanism module (31) will be accessed through the window given in top cover.
• The Switching Flapper (29) is hinged & will stay intact with the isolation mechanism module. During the dielectric test, the Switching Flapper (29) has to be opened around the hinge given in isolation mechanism module (31)&& will stay intact with the Top cover for Modular L-shaped three pole earth leakage module / four pole earth leakage module during the dielectric voltage withstand test.
• The present invention involves use of modular isolation mechanism which will ensure that the Switching Flapper (29) carrying third set of contacts have to just be opened around the hinge axis on isolation mechanism module (31) and thus will stay physically along with the circuit breaker in mounted condition.
• There will be no misplacement of any of the plastic component carrying contacts or mechanical joining hardware & hence ensures smooth testing & functioning of the circuit breaker along with the earth leakage module.
• The present invention of modular construction of the isolation mechanism module (31) also ensures that this module can be used across all frame sizes alike & irrespective of the whether the add-on module will go along with a three pole or a four pole circuit breaker. So, it will in turn minimize the tooling cost which could have been incurred separately for earth leakage module for a three pole as well as four pole circuit breaker & for different frame sizes.The inventory management will be easier in the assembly line.
• The modular L-shaped earth leakage (3,4) module consists of :
CBCT Housing module (5)
Card housing module (6)
Isolation-box module (7)
Core balanced current transformer (8)
Sub assembly of (6) card housing module & (7) isolation-box module. (23)
Sub-assembly of (6) card housing module, (7) isolation-box module & CBCT housing module (5).
Sub assembly of (6) card housing module & (7) CBCT housing module (5).
• The three pole Modular L-shaped earth leakage module (7) can be assembled by assembling:
CBCT Housing module (5)
Card housing module (6)
Core balanced current transformer (8)
Sub assembly of (6) card housing module & (7) CBCT housing module (5)
Here, the isolation-box module (7) will be assembled inside the CBCT hosing module (5).
• The four pole Modular L-shaped earth leakage module (8) can be assembled by assembling:
CBCT Housing module (5)
Card housing module (6)
Isolation-box module (7)
Core balanced current transformer (8)
Sub assembly of (6) card housing module & (7) isolation-box module. (23)
Sub-assembly of (6) card housing module, (7) isolation-box module & CBCT housing module (5).
Sub assembly of (6) card housing module & (7) CBCT housing module (5).
• The elongated protrusion features given in the card housing module (6) are used to slide through similar groove cut feature given in the CBCT housing module (5) in case of assembly of three pole Modular L-shaped earth leakage module (7).
• The elongated protrusion features given in the card housing module (6) are used to slide through similar groove cut feature given in the Isolation-box module (7) in case of assembly of four pole Modular L-shaped earth leakage module (8).
• There is interlocking feature given in the elongated protrusions of the card housing module (6) as mentioned in Claim 4, which ensures that the CBCT housing module (5) in case of assembly of three pole Modular L-shaped earth leakage module (7) will remain secured in its final assembled position and prevent the CBCT housing module (5) from falling apart.
• There is interlocking feature given in the elongated protrusions of the card housing module (6) as mentioned in Claim 5, which ensures that the Isolation-box module (7) in case of assembly of four pole Modular L-shaped earth leakage module (8) will remain secured in its final assembled position and prevent the Isolation-box module (7) from falling apart.
• The wedge feature given in the Isolation-box module (7) is used to clamp on the walls of the CBCT housing module (5) in case of assembly of four pole Modular L-shaped earth leakage module (8).
• The CBCT housing (5) has knock out feature which will be knocked out, in case four pole Modular L-shaped earth leakage module (8) is being assembled so as to integrate the internal elements in the CBCT housing module (5), card housing module (6) as well as isolation-box module (7).
• The CBCT housing (5) has knock out feature which will remain secure amd intact by some means like factory seal, label, sticker, etc. in of three pole Modular L-shaped earth leakage module (7) is being assembled as this will be the part of the outside facia of Modular L-shaped three pole earth leakage module (3).
• The card housing module (6) has features on its bottom surface to secure the microprocessor card (11) at the bottom.
• The card cover (17) will have features to secure the microprocessor card (11) at the top.
• The top cover (19, 20) for three pole and four pole Modular L-shaped earth leakage module (7), (8) respectively has window which has a flapper .The purpose of the window given in top cover is to have better view while terminating cables at customer end.
• The isolation box will be accessed through the window given in top cover (19, 20) for three pole and four pole Modular L-shaped earth leakage module (7), (8) respectively.

[00100] Some of the non-limiting advantages of the present invention are:
• The use of modular isolation mechanism which will ensure that the switching flapper carrying third set of contacts have to just be opened around the hinge axis on isolation mechanism module (31) and thus will stay physically along with the circuit breaker (1,2) in mounted condition. So, there will be no misplacement of any of the component & hence ensures smooth testing & functioning of the circuit breaker (1,2) along with the earth leakage module (3,4).
• The present invention of modular construction of the isolation mechanism module (31) also ensures that this module can be used across all frame sizes alike & irrespective of the whether the add-on module will go along with a three pole or a four pole circuit breaker.
• This ensures the commonisation of components to both three pole as well as four pole circuit breaker and through all the frame sizes. So, it will in turn minimize the tooling cost which could have been incurred separately for earth leakage module for a three pole as well as four pole circuit breaker and for different frame sizes. The inventory management will be easier in the assembly line.
• The modular construction of L-shaped module configuration gives advantage over conventional L-shaped module, with respect to the fact that the same modules can be configured differently to form earth leakage modules for a three pole circuit breaker as well as four pole circuit breaker. Connecting modules in the sequence as explained in the description & images, earth leakage modules for three & four pole can be assembled.
• The assembly being modular, it is easy to replace the defective module on line, instead of entire module.
• Minimal tooling cost required for development of earth leakage modules for three pole as well as four pole circuit breaker.
• Easy inventory management on the assembly line.

[00101] Although a isolation mechanism module for earth leakage module for moulded case circuit breaker of different frame sizes, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific methods or devices described herein. Rather, the specific features are disclosed as examples of implementations of the isolation mechanism module for earth leakage module for moulded case circuit breaker of different frame sizes.