FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13)
"Residual Current Circuit Breaker with Overcurrent Protection (RCBO) with an Improved Neutral Pole Kinematic Chain"
LARSEN & TOUBRO LIMITED
L & T House, Ballard Estate, P. O. Box No. 278,
MUMBA1400 001
The following specification particularly describes the invention and the manner
in which it is to be performed.

Field of the Invention
[0001] The present invention relates to circuit breakers. More particularly, relates to residual circuit breakers with overload protection with an improved neutral pole kinematic chain.
Background of the Invention
[0002] A conventional residual current circuit breaker with overcurrent protection ("RCBO") includes single housing configured to provide a miniature circuit breaker (MCB) portion and a residual current (for example, a ground fault) device (RCD) portion for providing combined protection from the risk of electrocution and protection against the risk of an electrical fire and overcurrent protection of equipment and cables. A typical conventional RCBO is of a size of approximately 125 mm in height, 18 mm in width and 70 mm deep.
[0003] The conventional residual current circuit breaker with overcurrent protection includes a single housing configured to enclose together the kinematic chain of neutral pole and one of the residual current devices. In a RCBO the kinematic chain of the neutral pole and one of the residual current devices interweave each other.
[0004] The housing is multi-sectional and includes an interior wall dividing the space within the housing to provide equal or unequal distribution of the space within the RCBO. The space constraints in the conventional housing may affect the functionality of the devices provided within the housing. The RCBO's currently in use are complex and difficult to be realized since the kinematic chains of the neutral pole and the residual current device lie in the same enclosure in the same housing. The proximity of the two kinematic chains leads to a condition where braking of one of the components of one kinematic chain causes an obstacle for the other.

[0005] Accordingly, there exist a need to provide separate sections for the neutral pole kinematic chain and the residual current device having optimized space allocation within the circuit breaker is desired.
Objects of the invention
[0006] An object of the present invention is to provide a residual circuit breakers with overload protection with an improved neutral pole kinematic chain to avoid interweaving of a kinematic chain of the neutral pole and one of the residual current devices into each other.
[0007] Another object of the present invention is to provide a residual circuit breakers with overload protection with an improved neutral pole kinematic chain which overcomes the constraint of space having with conventional RCBO.
Summary of the Invention
[0008] Accordingly, the present invention provides a residual current breaker with overcurrent protection (RCBO), comprising a first housing enclosing a miniature circuit breaker (MCB) and a second housing separated from the first housing by a main frame. The second housing includes a first enclosure for a neutral kinematic chain and a second enclosure for a residual current device. The first enclosure and the second enclosure is separated by a secondary frame thereby physically separating neutral pole kinematic chain from a residual current kinematic chain of the residual current device. A pin of the MCB protrudes inside the first enclosure of the second housing having the neutral kinematic chain.
Brief description of the drawings

[0009] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings:
[0010] Figure 1 shows a perspective view of a residual current breaker with overcurrent protection (RCBO) with improved neutral pole kinematic chain, having a stable starting position of the working phase of the RCBO;
[0011] Figure 2 shows a side view the residual current breaker with overcurrent protection (RCBO) of figure 1;
[0012] Figure 3 shows a schematic diagram of the a residual current breaker with overcurrent protection (RCBO) illustrating an intermediate position of the working phase of the RCBO;
[0013] Figure 4 shows a schematic diagram of the residual current breaker with overcurrent protection (RCBO) illustrating the stable ending position of the working phase of the RCBO;
[0014] Figure 5 shows a right side view of the residual current breaker with overcurrent protection RCBO, illustrating the separate enclosures in the second housing provided for the neutral pole and the residual current device and the secondary frame, in accordance with an embodiment of the invention;
[0015] Figure 6 shows a front view of the residual current breaker with overcurrent protection RCBO illustrating a secondary frame, in accordance with an embodiment of the invention; and

[0016] Figure 7 shows the secondary frame of the residual current breaker with overcurrent protection (RCBO), used to separate the neutral pole and residual current device in the second housing of the RCBO.
Detailed description of the Invention
[0017] The foregoing objects of the 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.
[0018] Accordingly, the present invention provides provide a residual circuit breakers with overload protection (RCBO) with an improved neutral pole kinematic chain. The RCBO of the present invention avoids interweaving of a kinematic chain of the neutral pole and one of the residual current devices into each other. Further, the RCBO overcomes the constraint of space having with conventional RCBO.
[0019] 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.
[0020] Referring now to figure 1-7, there is shown a residual circuit breakers with overload protection (herein after 'RCBO') with improved neutral pole kinematic chain, in accordance with an embodiment of the invention. Specifically, the figure 1 shows a perspective view of RCBO (100). The RCBO (100) includes a first housing (1A) and a second housing (IB).
[0021] The first housing (1A) encloses a MCB portion and components thereof. The second housing (IB) includes a first enclosure (1C) for neutral

kinematic chain and a second enclosure (ID) for a residual current device. The first housing (1A) and second housings (IB) are separated from each other by means of a main frame (4). Further, the first enclosure (1C) and the second enclosure (ID) are separated by a secondary frame (5) as shown in figure 5. The separation ensures that the two kinematic chains i.e. one for the neutral pole and the one for residual current are physically separated, hence overcoming the drawbacks present in the current RCBOs. The two kinematic chains of the neutral pole and residual current device act on common components in order to allow the operation of the RCBOs.
[0022] A pin (6) of the MCB in the first housing (1 A) protrudes inside the first enclosure (1C) of the second housing (IB) having the neutral kinematic chain. Specifically, a first lever (10) mounted in the first enclosure (1C) and is engaged by the pin (6) of the MCB mounted in the first housing (1 A). The first lever (10) is rotatable around the axis (11). The axis (11) hinges on the main frames (4) and 5. The first lever (10) comprises of an elongated slot (13). Specifically, a neutral pole having a neutral contact (18) and a fixed neutral contact (20) in the RCBO must close its contact before the contact closure of the MCB and open its contact after the opening of the contact of the MCB , to avoid any danger. The slot (13) provides for a prolonged delay in opening of the neutral phase.
[0023] The first lever (10) is rotatably coupled with an arm (15) which is in turn rotatably coupled with a second lever (16). The second lever (16) is rotatable around its axis (17). The other end of the second lever (16) is joined to a neutral contact (18). The neutral contact (18) is connected to a neutral terminal and faces the fixed neutral contact (20). The neutral circuit consisting of neutral contact (18) and the fixed neutral contact (20) may be closed or opened using the second lever (16). The second lever (16) is provided with an elongated slot, such that the axis (17) may be housed in the same. This axis (17) extends between the mainframe (4) and the secondary frame (5).

[0024] Further, the RCBO (100) includes a compression spring (25) which acts between the second lever (16) and an external casing of the RCOB (100) so as to force the second lever (16) to move in counter clockwise direction. The window W in figure shows a movable contact (21) and a fixed contact (90) of the MCB mounted in the first housing (1 A).
[0025] Referring now to figure 1, 3 and 4, the three distinct phases of a closure operation of the RCOB are described.
[0026] As shown in figure 1, the window W shows the fixed contact (90) and mobile contact (21) of the MCB mounted in the first housing (1A) are not in contact. In this position the neutral contact (18) and the fixed neutral contact (20) is also not established. Specifically, the compression spring (25) push the second lever (16) thus maintaining the disengaged condition between (18) and (20).
[0027] The intermediate non-stable position of the RCBO closure operation is shown in figure 3. Specifically, the pin (6) is moved in a counter clockwise direction along an arched trajectory, as a furtherance of the operator action on the handle of the MCB. The pin (6) is moved to the left thereby rotating the first lever (10) in counter clockwise direction, which in turn moves the arm (15). The arm (15) pushes the second lever (16) in a clockwise direction around the axis (17) so as to close the neutral contact (18) and the neutral fixed contact (20).
[0028] Further, the figure 4 shows ending of the stable position of the RCBO closure operation. Specifically, the pin (6) is moved further to the left, which in turn moves the arm (15) further. This movement pushes the second lever (16) but the movement of second lever (16) along the axis (17) is prevented as the second lever (16) is already engaged to neutral fixed contact (20) through the neutral contact (18). Accordingly, due to the force exerted on the second lever (16), the second lever (16) is forced to slide with respect to its axis (17) owing to the elongated slot (19) through which the axis (17) can move. The rotational

point between first lever (10) and the arm (15) and the rotational point between arm (15) and the second lever (16) align on the same line. This alignment and the spring action of the compression spring (25) keeps the second lever (16) in a stable position. The force exerted by the compression spring (25) improves the stability of the neutral pole established by the closure of the neutral contact (180 and the neutral fixed contact (20).
[0029] The release operation of the RCBO (100) is driven by two conditions for example ,manual release and the automatic release.
[0030] In the manual release, the operator acts on the MCB handle causing the pin (6) to move in a rear-ward direction, therefore performing the reverse action as described in the previous paragraphs and not described herein again for the sake of brevity of the invention. During this release operation, the elongated slot (13) provides for a certain delay in the opening of the neutral pole (consisting of neutral contact (18) and neutral fixed contact (20)) ensuring that the phase pole (consisting of the fixed contact (90) and the movable contact (20) of the MCB) disengages before the neutral pole.
[0031] The automatic release is driven by the residual current portion of
the RCBO (100) or by the MCB, which causes the pin (6) to move in a rearward direction as in the manual release.
Advantages of the invention
[0032] The RCBO (100) of the present invention avoids interweaving of a kinematic chain of the neutral pole and one of the residual current devices into each other.
[0033] The RCBO (100) overcomes the constraint of space having with conventional RCBO.

[0034] 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, 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 omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We Claim:
\, A residual current circuit breaker with overcurrent protection (RCBO) with an improved neutral pole kinematic chain, the RCBO comprising:
a first housing enclosing a miniature circuit breaker (MCB) with a phase pole, the phase pole comprising a fixed contact and a movable contact;
a second housing separated from the first housing by a main frame, the second housing having first enclosure for a neutral kinematic chain and a second enclosure for a residual current device, the first enclosure and the second enclosure separated by a secondary frame thereby physically separating neutral pole kinematic chain from a residual current kinematic chain of the residual current device, wherein a pin of the MCB protrudes inside the first enclosure of the second housing having the neutral kinematic chain;
a first lever mounted in the first enclosure and engaged by the pin, the first lever is rotatable around an axis hinged on the main frame and the secondary frame, the first lever having an first elongated slot;
an first arm rotatably coupled to the first lever, the first arm in turn rotatably coupled with a second lever rotatable around the axis thereof, the other end of the second lever coupled to a second arm which in turn is joined to a neutral contact;
a fixed neutral contact capable of being coupled to the neutral contact, wherein when the second lever is rotated, a neutral pole formed by the neutral contact with the fixed neutral contact is opened or closed.
an elongated slot provided in the second lever having axis extending between the main frame and the secondary frame;
a compression spring for forcing the second lever to rotate in a counter clockwise direction,
wherein, when the phase pole of the MCB is open, then the neutral pole is also open, thereafter upon pressing handle of the MCB moves the pin in counter clockwise direction thereby pushing the second lever in a clockwise motion so as to close the neutral pole and simultaneously the phase pole is closed, and a further movement of the pin in counter clockwise direction

prevents rotational movement of the second lever around its axis after which the second lever slides in the second elongated slot to keep the second lever in a stable position.
2. A residual current circuit breaker with overcurrent protection (RCBO) as claimed in claim 1, wherein the release operation is driven by manual release and automatic release so that the phase pole of the MCB become disengaged before than the neutral pole.