FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Magnetic Fault Indication System for 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.

Magnetic Fault Indication System for Circuit Breaker
Field of the invention
The present invention relates to a circuit breaker and more particularly, to a magnetic fault indication system for the circuit breaker that provides protection from short circuit faults.
Background of the invention
Conventional types of fault in electrical switching devices results from an occurrence of a short circuit an over current. A circuit breaker is designed to trip and turn OFF power during short-circuit or fault condition and indicate short-circuit or fault to a user.
There are various systems available in the prior art to indicate short-circuit conditions. For example, European Patent No. EP1703533 describes an indicator system of magnetic fault having a lever flexibly connected to a movable core while the second side of the lever consists of an integral ring, which is concentrically placed with a drum. The ring is free to rotate irrespective of the drum. The relative position of the drum and the lever is such that said lever is in contact with the edge of the window. The projection of the drum is made in a way to interact with a knob cam for resetting.
During normal operation of the product, movable core remains in the left of the figure. The drum remains in the first stable position with elastic projection locked by edge. In this condition signaling arm is hidden indicating absence of the fault.
During short circuit, movable core moves in right of the Figure along with lever, which is flexibly connected to it. The movement of the lever causes the counterclockwise rotation of the drum through edge of the window. This moves

drum to second stable position. Meanwhile plunger which is attached to the movable core, trips the mechanism thus opening the contacts. This causes clockwise rotation of the control lever. During this rotation plane which is integral part of the control lever passes blade of drum by deflecting it in Z direction. Blade is designed to be flexible in Z direction.
In this position signaling arm becomes visible from window indicating short circuit. Meanwhile fault current stops flowing due to opening of contacts. This de-energizes the magnetic release system bringing movable core back to its original position, This causes the reverse rotation of lever. As window is present this rotation doesn't have any impact on drum retaining the indication.
Once fault is cleared breaker can be switched on manually. Control lever is moved in counter-clockwise direction. Cam of control lever carries drum through blade. Now breaker as well as indicator is reset for normal use.
The said solution comes with a possible malfunction of magnetic release, as knob is in direct contact with drum and in turn movable core, during the resetting phase of the indicator. Adding to it, this system uses two components which reduce the reliability and also it cannot be dropped in z direction during assembly to facilitate easy assembly.
US patent no. 4916420A describes an operating mechanism of miniature electrical breaker that consists of a mechanism with a provision of fault indication. In normal operation, latch and trip lever are always engaged, hence coloured mark is never seen from indicator window. In case of a fault, trip lever operates disengaging it from latch and latch is moved to such a position that coloured mark is visible from indicator window, showing device has tripped due to fault. The said solution though indicates that fault has occurred doesn't differentiate whether fault has happened due to the overload or the short circuit.

Accordingly, there exists a need to provide a magnetic fault indication system for a circuit breaker that provides indication of short circuit faults and overcomes the drawbacks of the prior art.
Objects of the invention
An object of the present invention is to provide a magnetic fault indication system having a single compliant component to reduce an assembly complexity and time.
Another object of the present invention is to reset the magnetic fault indication, system by a reset pin that works independent of a knob/input link which is operating means of mechanism that resets the invention component during fault condition thereby eliminating the malfunction of magnetic release.
Summary of the invention
Accordingly, the present invention provides a magnetic fault indication system for a circuit breaker. The circuit breaker comprises housing, an input link, a reset pin and a plunger having an annular collar. The housing houses a magnetic release system, a transparent window and a housing wall. The magnetic fault indication system comprises a slider, a first latch, a second latch, a lever, a flexible member,. an indication flag and a slot.
The slider includes a first end and a second end. The first end includes a cylindrical seat attached thereto. The cylindrical seat is detachably connected to the annular collar of the plunger. The second end is perpendicular to the slider. The first latch is configured on the second end of the slider. The lever is pivoted on a boss provided in the housing. The second latch is positioned on a first end of the lever facing the first latch. The flexible member is capable of deforming between the first end of the slider and the first end of the lever. The indication flag is integrated with the second end of the lever and includes a lower half coloured to

indicate a magnetic fault. The slot is used for resetting the magnetic fault indication system through the reset pin of the circuit breaker.
In case of magnetic fault, the magnetic release system operates the plunger in a rightward direction to give a trip signal causing the annular collar to enter into the cylindrical seat. The cylindrical seat that is integral to the slider translates in to the rightward direction thereby sliding against the housing wall and cause disengagement of the first latch and the second latch and regaining of a free state by the flexible member causing the lever to rotate in a counterclockwise direction with a pivot joint to facilitate visibility of the coloured portion of the indication flag through the transparent window to indicate the magnetic fault.
Brief description of the drawings
Figure 1 shows a side perspective view of a magnetic fault indication system for a circuit breaker, in accordance with the present invention;
Figures 2a-2c show different shapes of a flexible member of the magnetic fault indication system of figure 1;
Figure 3 shows an assembly of the magnetic fault indication system for the circuit breaker of figure 1;
Figure 4 shows a partial view of the circuit breaker with the magnetic fault indication system in normal operating condition/reset condition;
Figure 5 shows the partial view of the circuit breaker with the magnetic fault indication system in case of fault/short circuit; and
Figure 6 shows the partial view of the circuit breaker with the magnetic fault indication system in post short circuit condition.

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 embodiments.
The present invention provides a magnetic fault indication system for a circuit breaker. The magnetic fault indication system includes a single compliant component thereby reducing an assembly complexity and time. The magnetic fault indication system is reset by a reset pin that works independent of a knob/ input link. The knob is operating means of mechanism that resets the invention component during fault condition thereby eliminating the malfunction of magnetic release.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.
Referring to figure 1, a fault indication system (hereinafter "the system (100)") for a circuit breaker (200) in a free unloaded state in accordance with the present invention is shown. The system (100) comprises a slider (10), a flexible member (20), a first latch (30), a second latch (40), a lever (50), an indication flag (60) and a slot (70). However, it is, understood that the system additionally comprises several other components known in the art to achieve the complete functionality. The slider (10) includes a first end (4) and a second end (6). The first end (4) of the slider (10) includes a cylindrical seat (8) attached thereto. The second end (6) is perpendicular to the slider (10) and includes the first latch (30) positioned/configured thereon. The flexible member (20) is designed to elastically deform between the first end (4) of the slider (10) and a first end (44) of the lever

(50) such that the slider (10) and the lever (50) along with the first end (4) and the second end (6), the cylindrical seat (8), the first latch (30), the first end (44) of the lever (44), the second latch (40), the slot (70) and the indication flag (60) along with the flexible member (20) form a single component. Figures 2a, 2b and 2c. show different shapes of the flexible member (20).
The lever (50) is pivoted on a boss (not numbered) that is an integral part of the housing (120) of the circuit breaker (200) such that the second latch (40) positioned on the first end (44) of the lever (50) faces the first latch (30). The lever (50) integrates with the indication flag (60) on a second end (48) thereof. The slot (70) is provided to reset the system (100). In an embodiment, the slot (70) is an oblong slot and a lower half of the indication flag (60) is coloured to indicate a magnetic fault.
Referring to figures 2-3, the circuit breaker (200) comprises the housing (120), an. input link (140), a reset pin (160) and a plunger (180). The housing (120) includes a magnetic release system (not shown), a transparent window (102) and a housing wall (104). The housing (120) includes the boss as an integral part thereof. The magnetic release system is required for an operation of the circuit breaker (200). The transparent window is used for visible indication of the magnetic fault. The reset pin (160) is part of a kinematic system that operates and trips the circuit breaker (200). The reset pin (160) resets the system (100) through the slot (70), The input link (140) is responsible for manually switching on/off the circuit breaker (200).
The cylindrical seat (8) of the system (100) is detachably attached to an annular, collar (175) of the plunger (180). In an operating condition of the circuit breaker (200), the plunger (180) disengages from the cylindrical seat (8) of the system (100). The system (100) is assembled by latching the first latch (30) with the second latch (40). In a latched condition, the flexible member (20) undergoes compression. The system (100) is then dropped in the circuit breaker (200) such

that a feature (106) of the housing (120) and a cylindrical hole (not numbered) of the system (100) forms a pin/pivot joint (108).
Now referring to figure 3, the circuit breaker (200) is shown in a normal working condition. In the normal working condition, the input link (340) is in an ON condition of the circuit breaker (200) which means a circuit is closed and the-plunger (180) is in a retracted position. The first latch (30) and the second latch (40) are engaged. The indication flag (60) remains in a first stable state and the reset pin (160) is held in a rightmost position of the slot (70).
As shown in figure 4, in case of magnetic fault, the magnetic release system operates the plunger (180) in a rightward direction. The plunger (180) gives a trip signal to the magnetic release system to open the circuit. Subsequently annular collar (175) of the plunger (180) enters into the cylindrical seat (8) of the system (100). The cylindrical seat (8) firmly connects to the slider (10) and translates in to the rightward direction thereby sliding against the housing wall (104). This translation disengages the latches (30, 40) and the flexible member (20) tries to regain a free state causing the lever (50) to rotate in a counterclockwise direction with the pivot joint (108). In this state, coloured portion of the indication flag (60) becomes visible through the transparent window (102) showing/indicating occurrence of the magnetic fault condition.
When the circuit breaker (200) opens, the input link (140) is brought to OFF position. In this state as contacts are open, current stops flowing, de-energizing the magnetic release system. The plunger (180) is retracted to an initial position along with the annular collar (175) by a spring (not shown) present in the magnetic release system. Retraction of the plunger (180) allows the flexible member (20) to regain the free state by pushing the slider (10) to a leftward end.-In this state, surface of the first latch (30) and the second latch (40) comes in contact to obtain a second stable state. In this state, the latches (30, 40) are not latched but rest on non latching surfaces. In such a state coloured portion of the

indication flag (60) still remains visible through the transparent window (102) to indicate the magnetic fault. This state remains till the magnetic fault is cleared and the circuit breaker (200) is switched on manually.
As shown in figure 5, once the magnetic fault is cleared, the circuit breaker (200) is switched on by rotating the input link (140) in the counter-clockwise direction. As the circuit breaker (200) is switched on, the reset pin (160) of the kinematic system moves in the clockwise direction inside the slot (70) carrying the lever (50) along. This causes engagement of the latches (30, 40) thereby bringing the system (100) in the first stable position where coloured portion of the indication flag (60) is hidden.
Advantages of the invention
1. Resetting of the system (100) is done by the reset pin (140) which is part of the kinematic system instead of a knob. This kinematic system works independent of knob during fault condition thereby eliminating the malfunction of magnetic release system.
2. The system (100) consists of a single compliant component instead of three required to do the same overall function. This adds more reliability, reduces cost and assembly time during production.
3. The system (100) is designed to be dropped in the assembly reducing the assembly time. This is also referred as single z direction assembly
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above, teaching. The embodiments were chosen and described in order to best explain the

principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.

We Claim:
1. A magnetic fault indication system (100) for a circuit breaker (200), the circuit breaker having a housing (120), an input link (140), a reset pin (160) and a plunger (180) having an annular collar (175), the housing (120) having a magnetic release system, a transparent window (102) and a housing wall (104), the magnetic fault indication system (100) comprising:
a slider (10) and a having a first end (4) and a second end (6), the first end (4) having a cylindrical seat (8) attached thereto, the cylindrical seat (8) detachably attached to the annular collar (175) of the plunger (180), the second end (6) being substantially perpendicular to the slider (10);
a first latch (30) configured on the second end (6) of the slider
(10);
a lever (50) pivoted on boss (106) which is integral in housing;
a second latch (40) positioned on a first end (44) of the lever (50) facing the first latch (30);
a flexible member (20) being capable of deforming between the first end (4) of the slider (10) and the first end (44) of the lever (50);
an indication flag (60) integrated with a second end (48) of the lever (50), the indication flag (60) having a lower half coloured to indicate a magnetic fault; and
a slot (70) for resetting the magnetic fault indication system (100) through the reset pin (160) of the circuit breaker (200),
wherein in case of magnetic fault, the magnetic release system operates the plunger (180) in arightward direction to give a trip signal causing the annular collar (175) to enter into the cylindrical seat (8), the cylindrical seat (8) then connects to the slider (10) and translates in to the rightward direction thereby sliding against the housing wall (104) causing disengagement of the first latch (30) and the second latch (40) and regaining of a free state by the flexible member (20) causing the lever (50) to rotate in a counterclockwise direction with a pivot

joint (108) thereby facilitating visibility of the coloured portion of the indication flag (60) through the transparent window (102) to indicate the magnetic fault.
2. The magnetic fault indication system as claimed in claim 1, wherein the slider (10) and the lever (50) along with the first end (4) and the second end (6), the cylindrical seat (8), the first latch (30), the first end (44) of the lever (44), the second latch (40), the slot (70) and the indication flag (60) along with the flexible member (20) form a single component.