FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
Half Module Miniature Circuit Breaker
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. 0. 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.

Half Module Miniature Circuit Breaker Field of the invention
The present invention relates to a circuit breaker and more particularly, to a half module miniature circuit breaker for a low voltage switchgear device.
Background of the invention
Miniature circuit breaker is a protection device designed for domestic applications. Usually, the width of the circuit breaker is 17.5 mm which is called as one module size. The existing miniature circuit breakers (one module size) are too large due to use of more number of raw materials that occupy more space and hence not conducive to the installation in distribution boards and increases the cost of production in a small space.
Accordingly, there is a need to provide a miniature circuit breaker that is reduced in size to overcome the problems in the prior art.
Objects of the present invention
An object of the present invention is to provide a miniature circuit breaker that is cost effective and improved in performance.
Another object of the present invention is to facilitate easy installation of the miniature circuit breaker inside a distribution board with lesser space utilization due to fewer raw materials and reduced width size.

Summary of the invention
Accordingly, the present invention provides a half module miniature circuit breaker for switchgear devices/ distribution boards. The half module miniature circuit breaker comprises housing, an operating mechanism, an electromagnetic release mechanism, an arc chamber, a thermal release mechanism, a terminal with a box clamp and screw assembly and a cover.
The operating mechanism is secured to a top portion of the housing. The operating mechanism includes a moving contact, a U pin, a contact holder, a bimetal pin, a latch and a knob. The knob is positioned centrally on the top portion of the housing. The electromagnetic release mechanism is positioned on a middle portion of the housing. The electromagnetic release mechanism includes an electromagnet and a fixed contact. The electromagnet includes a C type fixed core and an I type moving core.
The arc chamber is positioned below the electromagnetic release mechanism in the housing. The arc chamber includes an arc chute assembly assembled thereto. The arc chute assembly includes a plurality of alternatively positioned de-ion plates. The arc chamber on a right side thereof includes the thermal release mechanism. The thermal release mechanism includes a bimetal and a double loop arc runner. The bimetal is coupled to the moving contact of the operating mechanism by a flexible copper braid.
The terminal with the box clamp and screw assembly is positioned on either sides of the housing for connecting to terminals of the thermal release mechanism and the electromagnetic release mechanism. The box clamp and screw assembly on either sides of the housing is adapted to move in opposite directions. The cover is adapted

to be secured onto the housing thereby forming the half module miniature circuit breaker. The half module circuit breaker utilizes lesser space inside the distribution boards resulting in an improved performance as compared to that of single module circuit breaker.
Brief description of the invention
The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,
Figure 1 shows a side view of a half module miniature circuit breaker for switchgear devices, in accordance with the present invention;
Figure 2 is an exploded view of the half module miniature circuit breaker of figure 1 showing a housing and a cover when kept open;
Figures 3-4 is a sectional view showing positions of components secured to the housing of figure 2;
Figure 5 shows a perspective view of an operating mechanism secured to the housing of figure 2;
Figure 6 shows a perspective view of a thermal mechanism and a terminal with a box clamp and screw assembly secured to the housing of figure 2;
Figure 7 is a perspective view showing connection of the operating mechanism and the thermal mechanism;

Figure 8 shows a perspective view of an electromagnetic release mechanism secured to the housing of figure 2; and
Figure 9 shows a perspective view of an arc chamber secured to the housing of figure 2.
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides a half module miniature circuit breaker for switchgear devices. The half module miniature circuit breaker is cost effective due to use of fewer raw materials and reduced width size. The half module miniature circuit breaker of the present invention is capable of being easily installed in distribution boards.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.
Referring now to figures 1-9, there is shown a half module miniature circuit breaker (100) (herein after 'the MCB (100)') for switchgear devices and distribution boards, in accordance with the present invention. Specifically, the switchgear device (not shown) is a low voltage switchgear device. The MCB (200) comprises a housing (20), an operating mechanism (40), an electromagnetic release mechanism (60), an arc chamber (80), a thermal release mechanism (100), a terminal with a box clamp

and screw assembly (110, 120) and a cover (140). Specifically, the operating mechanism (40), the electromagnetic release mechanism (60), the arc chamber/chute (80) and the thermal release mechanism (100) are secured to the housing (20). The position of the above mentioned components plays a vital role in the performance of the MCB (200).
The housing (20) (as shown in figures 2-4) includes the operating mechanism (40)
positioned on a top portion (not numbered) thereof. The operating mechanism (40)
includes a knob (30), a U pin (32), a contact holder (34), a bimetal pin (36), a latch
(38) and a moving contact (39) (refer to figure 5). The knob (30) is placed in a
centre of the housing (20) in such a way that the knob (30) is accessible for
operation of the moving contact (39) with required velocity and provide the
required contact pressure against a fixed contact (58) of the electromagnetic release
mechanism (60). The knob (30) has the U pin (32) extending from a bottom (not
numbered) thereof. The U pin (32) allows the contact holder (34) to hold the
moving contact (39). The one end of bimetal pin (36) is placed before a bimetal (90)
of the thermal release mechanism (100), transfers the bimetal (90) movement to the
thermal release mechanism (100) as trip signal.
The electromagnetic release mechanism (60) is positioned on a middle portion (not numbered) of the housing (20) to produce a thinner construction. The electromagnetic release mechanism (60) includes an electromagnet (50) and the fixed contact (58) (refer to figure 8). The electromagnet (50) is based on CI construction that means the electromagnet (50) consists of a C type fixed core (52) and an I type moving core (54) to give an angular torque and required tripping force with respect to a hinge point thereof. This required tripping force is directly applied to the operating mechanism (40) to make the MCB (200) into OFF state.

The arc chamber (80) is positioned in a portion of the housing (20) below the electromagnetic release mechanism (60). The arc chamber (80) includes an arc chute assembly (70) assembled thereto. The arc chute assembly (70) includes a plurality of alternatively positioned de-ion plates (75) (refer to figure 9). The plurality of alternatively positioned de-ion plates (75) enables lengthening of the arc thereby causing the arc chamber (80) to produce the let through energy at par with one module MCB.
The thermal release mechanism (100) is assembled on a right hand side (not numbered) of the arc chamber (80) in the housing (20). The thermal release mechanism (100) includes the bimetal (90) and an arc runner (95) as shown in figure 6. The bimetal (90) is coupled to the moving contact (39) of the operating mechanism (40). In an embodiment, the bimetal (90) is coupled to the moving contact (39) by means of a flexible copper braid (130) as shown in figure 7. In an embodiment, the arc runner (95) is a double loop arc runner which unlike the conventional arc runner used in the single module MCBs has one more permeable strip running parallel along the single strip, both carrying current in same direction during arcing.
The arc runner (95) (herein after 'the double loop arc runner (95)') plays an important role in arc quenching by reducing the running time. The double loop arc runner (95) is constructed in a way to produce more arc chamber volume, optimized length of current path, higher repulsion/ arc blowout force towards the arc chute assembly (70) and thereby improves the arc running.
The terminal with the box clamp and screw assembly (110, 120) is positioned on either sides of the housing (20) for connecting to terminals (not numbered) of the thermal release mechanism (100) and the electromagnetic release mechanism (60).

Unlike in conventional 1P+ IN, 1P+1P or half module MCB's where the terminal (120) position is offsetted on either sides, the terminal with the box clamp and screw assembly (110, 120) is maintained in the same position. In order to achieve this arrangement, the terminal with the box clamp (110) and screw arrangement (120) on either side of the housing (20) is made movable in opposite directions. In other words, the terminal with the box clamp and screw assembly (110, 120) on one side of the housing (20) moves upwards and moves downwards on another side of the housing (20). The terminal with the box clamp and screw assembly (110, 120) ensures the required clearance and creepage with the adjacent circuit breaker without any confusion. The cover (140) is configured with a plurality of slots (not numbered) for securing onto the housing (20) thereby forming the half module miniature circuit breaker (200) of the present invention.
Advantages of the present invention
1. The half module miniature circuit breaker (200) has advantage of raw material savings and space reduction when assembled in distribution board. This is possible by positioning the internal components at relevant and optimized location so as to improve the performance at this reduced volume of the MCB(lOO).
2. The dimension of the half module miniature circuit breaker (200) is reduced to half the size to provide space advantage in distribution boards.
3. The half module miniature circuit breaker (200) achieves the same/improved performance of one module product in half module width of at least 8.75mm.
4. The present invention accomplishes accommodating the double loop arc runner (74) in compact type half module miniature circuit breaker (200) which otherwise is a challenging task.

5. With present invention other one module products like 2 poles in one module, lpole + Neutral in one module and the like are derived without affecting the IP requirements.
6. The operating mechanism (40) provides all the required function similar to the operating mechanism of one module MCB and designed to fit into half module size.
7. The knob (30) is positioned at the center as in the case of full module MCB without compromising on compactness.
8. All electromagnets used in conventional MCBs use linear movement of moving core thereby giving linear force. The electromagnet (50) of the electromagnetic release mechanism (60) is based on CI construction thereby giving an angular deflection/torque with respect to the hinge point and enough trip force in the half module size thereby giving better performance in the half module miniature circuit breaker (200) of the present invention.
9. The double loop arc runner (95) gives high arc blow force.
10. The compact terminal with moving box clamp and screw assembly (110. 120) takes care of clearance and creepage between poles.
11. A proper arrangement and placing of the operating mechanism (40), the electromagnetic release mechanism (60). the arc chamber (80) and the thermal release mechanism (100) gives sufficient arc chamber volume and enough room to accommodate the double loop arc runner (95).
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the

claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.

We Claim:
1. A half module miniature circuit breaker (200) for switchgear devices/ distribution boards, the half module miniature circuit breaker (200) comprising:
• a housing (20);
• an operating mechanism (40) secured to a top portion of the housing (20), the operating mechanism (40) having a moving contact (39) and a knob (30) positioned centrally on the top portion of the housing (20);
• an electromagnetic release mechanism (60) positioned on a middle portion of the housing (20), the electromagnetic release mechanism (60) having an electromagnet (50) and a fixed contact (58), the electromagnet (50) having a C type fixed core (52) and an I type moving core (54);
• an arc chamber (80) positioned below the electromagnetic release mechanism (60) in the housing (20), the arc chamber (80) having an arc chute assembly (70) assembled thereto, the arc chute assembly (70) having a plurality of alternatively positioned de-ion plates (75);
• a thermal release mechanism (100) positioned on a right side of the arc chamber (80) in the housing (20), the thermal release mechanism (100) having a bimetal (90) and a double loop arc runner (95), the bimetal (90) coupled to the moving contact (39) of the operating mechanism (40);
• aterminal (120) with a box clamp and screw assembly (110)
positioned on either sides of the housing (20) for connecting to terminals of the
thermal release mechanism (100) and the electromagnetic release mechanism (60), the box clamp and screw assembly (110) on either sides of the housing (20) being adapted to move in opposite directions; and
• a cover (140) adapted to be secured onto the housing (20) thereby

forming the half module miniature circuit breaker (200) being capable of utilizing lesser space inside the distribution boards resulting in an improved performance as compared to that of single module circuit breaker.
2. The half module miniature circuit breaker (200) as claimed in claim 1, wherein the operating mechanism (40) further includes a U pin (32), a contact holder (34), a bimetal pin (36) and a latch (38).
3. The half module miniature circuit breaker (200) as claimed in claim 1, wherein the bimetal (90) of the thermal release mechanism (100) being coupled to the moving contact (39) of the operating mechanism (40) by a flexible copper braid (130).