FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: MECHANICAL INTERLOCKING ARRANGEMENT OF MCCB
2. Applicant(s):

(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to mechanical interlocking and more particularly, to an interlocking arrangement between two MCCBs mounted adjacent to each other and connected to each other in such a way that operation of one MCCB will affect or control the operation of other MCCB. In such arrangements only one of the two switches can be closed at any given instant, and the other remains open. The mechanical interlocking is used for preventing actuation of apparatus when other apparatus are actuated.
BACKGROUND AND THE PRIOR ART
In electrical installation where alternative source of power supply are available to given electrical load. It is often desired that the load should be connected to any one source while the other source should be kept isolated.
If by any means both the sources of power supplies are connected to each other, it may lead to excessive circulating currents that may damage the source. Therefore it is imperative not to connect both sources at a time. This can be accomplished by interlocking the circuit breakers controlling each source of supply so that at any given moment any one MCCB can be switched on, whenever the second MCCB is tried to be switched on either the MCCB cannot be switched on or the first MCCB which is already switched on should be switched off before this second MCCB is switched on.
In past Interlocking mechanisms of MCCBs have been developed, they are bulky, complex & have more number of parts. Some mechanical interlocks are located from behind and thus difficult to install and service.

The inventors have found that there still remain a scope of improvement of interlocking arrangement of MCCBs which would be able to address the problems faced in the prior art.
OBJECTS OF THE INVENTION
An object of the present invention is to overcome the disadvantages/drawbacks of the known art.
A primary object of the present invention is to provide an improved interlock mechanism for the use with a pair of circuit breakers each of which has an operating member movable from one to other position whereby the operating members of both the breakers may be simultaneously disposed in one of the said positions but upon movement of either operating member to its other position the other operating member cannot be moved to other position until first operating member is returned to inoperative position.
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying
drawings.
SUMMARY OF THE INVENTION
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.

There is provided an improved mechanical interlocking arrangement.
According to one aspect of the present invention there is provided an interlocking arrangement for interlocking plural MCCBs., said arrangement comprising: at least two MCCBs (Ml & M2) having operating knobs (Kl & K2), said MCCBs being operatively connected to each other by means of a mounting plate (3);
at least two actuator means (A1 and A2), said actuator means being pivotally mounted on said mounting plate and in proximity to respective knobs K1 and K2 such that in operation said knobs comes in engagement with said actuator means A1
and A2;
wherein when the MCCB Ml is switched on keeping MCCB M2 in off position, the knob Kl moves from OFF position to ON whereby said actuator A1 comes in engagement with said knob Kl and attains its final position such that movement of said actuator A2 is restricted when MCCB M2 is attempted to be switched ON.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
So that those having ordinary skill in the art will more readily understand how to construct an improved mechanical interlocking arrangement for MCCBs in accordance with the present disclosure, exemplary embodiments are described in details herein below with reference the accompanying drawings wherein:
Figure 1 shows the front view of the interlocking arrangement
Figure 2 shows the exploded view of interlocking arrangement showing all the components
Figure 3 shows the MCCB Ml is switched ON while MCCB M2 is still in switched OFF stage

Figure 4 shows the MCCB Ml is switched ON while MCCB M2 is tried to be switched ON
Figure 5 shows the MCCB M2 is switched ON while MCCB Ml is still in switched OFF stage
Figure 6 shows the MCCB M2 is switched ON while MCCB Ml is tried to be switched ON
Figure 7 shows both the MCCBs i.e. Ml & M2 are tried to be switched on
simultaneously,
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
The figure-1 below shows the plan view of mechanically interlocked MCCBs placed adjacent to each other. The MCCBs Ml & M2 are connected by a mounting plate (3) which is connected to the cover of the MCCBs by screws of suitable size. On the mounting plate two actuators A1 (6) & Actuator A2 (7) are mounted on the mounting plate using pins P1 (8) & P2 (9). There exists a spring S (15) in such a way that the spring ensures that both the actuators A1 (6) & A2 (7) always rest against pins P3 (12) & P4 (13) respectively when the knobs K1 (4) & K2 (5) of the MCCBs (1) & (2) respectively are in off position. The spring S (15) is mounted on the pin P5 (14) on the mounting plate (3). There exists a protrusion L1 (10) on actuator Al (6) and protrusion L2 (11) on actuator A2 (7) as shown in figure-1 below. Fig-2 shows the exploded view of the assembly showing all the parts.

When the MCCB Ml (1) is switched on keeping MCCB M2 (2) in off position, the knob K1 (4) of MCCB Ml (1) moves from off position to on position as shown in fig-3. The actuator A1 (6) is placed in such a way that the actuatorAl (6) moves along with the knob Kl (4) of MCCB Ml (1). The actuator Al (6) moves and attains final position as shown in figure-3 below.
When the MCCB M2 (2) is tried to be switched on while the MCCB Ml (1) is already switched on and the actuator A1 (6) is in its final position as shown in figure 3&4. The Actuator A2 (7) moves along with the knob K2 (5) of MCCB M2 (2). The protrusion L2 (11) being the integral part of the actuator A2 (7) moves, the motion the actuator A2 (7) gets restricted due to interference between protrusion LI (10) & protrusion L2 (11) as shown in fig-4 below. The interference of protrusion LI (10) & protrusion L2 (11) occurs well before knob K2 (5) of MCCB M2 (2) reaches its dead centre. Therefore the MCCB M2 cannot be switched on.
Similarly when the MCCB Ml (1) is tried to be switched on while the MCCB M2 (2) is already switched on and the actuator A2 (7) is in its final position as shown in figure 5&6. The Actuator Al (6) moves along with the knob Kl (4) of MCCB Ml (1). The protrusion L1 (10) being the integral part of the actuator Al (6) moves, the motion the actuator Al (6) gets restricted due to interference between protrusion L2 (11) & protrusion L1 (10) as shown in fig-6 below. The interference of protrusion L2 (11) & protrusion L1 (10) occurs well before knob Kl (4) of MCCB Ml (1) reaches its dead centre. Therefore the MCCB Ml cannot be switched on.
When both the MCCBs i.e Ml (1) & M2 (2) are tried to be switched on simultaneously from off position. The knobs Kl (4) & K2 (5) actuate actuators Al
(6) & A2 (7) simultaneously. The simultaneous movement of actuators Al (6) & A2
(7) causes the movement and hence interference of protrusion LI (10) & protrusion L2 (11) as shown in fig-7. This happens before both the MCCBs Ml (1) & M2 (2)

reach their dead centre. Thus knobs K1 (4) & knob K2 (5) both the MCCBs Ml (1) & M2 (2) return back to off position.
Thus the interlocking is explained in detail by figures-3 till figure-8.The figures show both the MCCBs Ml & M2 are of similar frame however this invention can be applied on MCCBs of different frames. For interlocking the MCCBs of different frames, either the sizes of actuators Al (6) & A2 (7) has to be varied according to the size of the MCCBs Ml (1) & M2 (2) or the location of pins PI (8) & P2 (9) has to be varied. By doing either of the above two methods the present invention (interlocking) can be extended to MCCBs of different shape and sizes provided MCCBs are mounted in such a way that the mounting plate (3) is parallel to the mounting surface.
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM:
1. An interlocking arrangement for interlocking plural similar or dissimilar
MCCBs, said arrangement comprising:
at least two MCCBs (Ml & M2) having operating knobs (Kl & K2), said MCCBs being operatively connected to each other by means of a mounting plate (3);
at least two actuator means (A1 and A2), said actuator means being pivotally mounted on said mounting plate and in proximity to respective knobs Kl and K2 such that in operation said knobs comes in engagement with said actuator
means Al and A2;
wherein when the MCCB Ml is switched on keeping MCCB M2 in off position, the knob Kl moves from OFF position to ON whereby said actuator Al comes in engagement with said knob Kl and attains its final position such that movement of said actuator A2 is restricted when MCCB M2 is attempted to be switched ON.
2. An interlocking arrangement for interlocking plural MCCBs, said
arrangement comprising:
at least two MCCBs (Ml & M2) having operating knobs (Kl & K2), said MCCBs being operatively connected to each other by means of a mounting
plate (3);
at least two actuator means (Al and A2), said actuator means being pivotally mounted on said mounting plate and in proximity to respective knobs Kl and K2 such that in operation said knobs comes in engagement with said actuator means A1 and A2;

wherein when the MCCB M2 is switched on keeping MCCB Ml in off position, the knob K2 moves from OFF position to ON whereby said actuator A2 comes in engagement with said knob K2 and attains its final position such that movement of said actuator A1 is restricted when MCCB Ml is attempted to be switched ON.
3. Interlocking arrangement as claimed in claims 1 and 2 wherein said actuator means (A1 and A2) comprising integral protrusion profiles (L1 and L2).
4. Interlocking arrangement as claimed in claims 1 and 3 wherein during attempting to switch ON the MCCB M2 said integral protrusion profile L2 of actuator A2 is restricted from its motion due to interference with protrusion profile L1 well before knob K2 reaches its dead centre.
5. Interlocking arrangement as claimed in claims 2 and 3 wherein during attempting to switch ON the MCCB Ml said integral protrusion profile L1 of actuator A1 is restricted from its motion due to interference with protrusion profile L2 well before knob K1 reaches its dead centre.
6. An interlocking arrangement for interlocking plural MCCBs, said arrangement comprising:
at least two MCCBs (Ml & M2) having operating knobs (Kl & K2), said MCCBs being operatively connected to each other by means of a mounting plate (3);
at least two actuator means (A1 and A2), said actuator means being pivotally mounted on said mounting plate and in proximity to respective knobs K1 and K2 such that in operation said knobs comes in engagement with said actuator
means A1 and A2;

wherein when both MCCBs Ml & M2 are tried to be switched on simultaneously, movement of said actuators A1 and A2 are restricted when actuated by the knobs K1 and K2 simultaneously.
7. Interlocking arrangement as claimed in claim 6 wherein said actuator means (Al and A2) comprising integral protrusion profiles (L1 and L2).
8. Interlocking arrangement as claimed in claims 6 and 7 wherein during attempting to switch ON the MCCBs Ml and M2 said integral protrusion profiles L1 and L2 of actuators A1 and A2 provide mutual restriction from motion due to interference caused by the protrusion profiles L1 and L2 well before knobs Kl and K2 reach their dead centers.
9. Interlocking arrangement as claimed in any preceding claim further comprising at least one pin means.
10. Interlocking arrangement as claimed in any preceding claim further comprising spring means.
11. An interlocking arrangement for interlocking plural MCCBs as herein described and illustrated with reference to accompanying drawings.