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 USING CLUTCH CABLE
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 interlock 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 effect 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 interlock 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) having mounting plates (PI
& P2) installed on it;
at least two actuator cable means (CI & C2) connected to plural actuator means (Al, A2, A3 &
A4), said actuator means being operatively connected to the ends of the said cable means (CI &
C2);
at least two push to trip means (13 & 14) located in the said MCCBs

wherein when said MCCB Ml is switched on keeping MCCB M2 in off position, actuator Al moves along with the knob Kl actuating push to trip means (13) of MCCB M2 by means of said actuator A2 on other side of cable CI whereby the MCCB M2 trips and the knob K2 of MCCB M2 moves to trip position.
According to another aspect there is provided an interlocking arrangement as described above wherein when said MCCB M2 is switched on keeping MCCB Ml in off position, actuator A3 moves along with the knob K2 actuating push to trip means (14) of MCCB Ml by means of said actuator A4 on other side of cable C2 whereby the MCCB Ml trips and the knob Kl of MCCB Ml moves to trip position.
According to another aspect there is provided an interlocking arrangement as described above wherein when both the MCCBs i.e Ml (1) & M2 (2) are attempted to be switched on simultaneously from off position, actuator means Al and A3 are actuated simultaneously thereby in operation actuating actuators A2 and A4 so as to actuate push to trip means (13 & 14) thereby tripping the MCCBs Ml & M2 simultaneously.
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 M2 is switched ON while MCCB Ml is still in switched OFF stage
Figure 5 shows the MCCB M2 is switched ON while MCCB Ml is tried to be switched ON
Figure 6 shows both the knobs return to tip position after the knobs are released (immediately after condition of Fig-5),

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.
Figure-1 shows the plan view of mechanically interlocked MCCBs placed adjacent to each other. The MCCBs Ml (1) & M2 (2) are connected by mounting plates PI (3) & P2 (4) the mounting plate is connected to the cover of the MCCBs by screws of suitable size. On the mounting plate we have two actuators cables CI (5) & cable C2 (6) which are mounted on the suitable threads mounting plates PI (3) & P2 (4) respectively. There exists actuators Al (7) & A2 (8) on both ends of cable CI (5) and actuators A3 (9) & A4 (10) on both ends of cable C2 (6). The actuator A3 (9) is actuated by knob Kl (11) of MCCB Ml (1) while the actuator A4 (10) actuates push to trip (hence forth represented as PTT (13) of MCCB M2 (2). While the actuator Al (7) is actuated by knob K2 (12) of MCCB M2 (2) while the actuator A2 (8) actuates PTT (14) of MCCB Ml (1) 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 Kl (11) of MCCB Ml (1) moves from off position to on position as shown in fig-3. The actuator Al (7) moves along with the knob Kl (11) thereby the actuator A2 (8) on other side of cable CI (5) actuates the PTT (13) of MCCB M2 (2). Since the PTT (13) of MCCB M2 (2) is pressed by actuator A2 (8), the MCCB M2 (2) trips and the knob (12) of MCCB M2 (2) moves to trip position as shown in fig-3 below.
As long as the MCCB Ml (1) is in ON condition, the PTT (13) of MCCB M2 (2) will remain pressed so MCCB M2 (2) cannot be reset and hence it cannot be turned ON.

Similarly when the MCCB M2 (2) is switched on keeping MCCB Ml (1) in off position, the knob K2 (12) of MCCB M2 (2) moves from off position to on position as shown in fig-4. The actuator A3 (9) moves along with the knob K2 (12) thereby the actuator A4 (10) on other side of cable C2 (6) actuates the PTT (14) of MCCB Ml (1). Since the PTT (14) of MCCB Ml (1) is pressed by actuator A4 (10), the MCCB Ml (1) trips and the knob (11) of MCCB Ml (1) moves to trip position as shown in fig-4 below.
As long as the MCCB M2 (2) is in ON condition, the PTT (14) of MCCB Ml (1) will remain pressed so MCCB Ml (1) cannot be reset and hence it cannot be turned ON.
As shown in fig-5, when both the MCCBs i.e Ml (1) & M2 (2) are tried to be switched on simultaneously from off position. The knobs Kl (11) & K2 (12) actuate actuators Al (7) & A3 (9) simultaneously. The simultaneous movement of actuators Al (7) & A3 (9) causes actuators A2 (8) & actuators A4 (10) to actuate PTT (14) of MCCB Ml (1) & PTT (13) of MCCB M2 (2) thereby tripping both the MCCB i.e. MCCB Ml (1) & MCCB M2 (2) simultaneously before the dead centre of MCCB Ml (1) & MCCB M2 (2) is reached, therefore the MCCB mechanism de-latches before the contacts close. Thus the contacts will not close and the MCCBs will be tripped. When both the knobs are released, both the knobs will return to tripped condition. This condition is shown in fig-6 below.
Thus the interlocking is explained in detail by figures-1 till figure-6. 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, the mounting plates PI (3) & P2 (4) are selected to fit to the MCCBs Ml & M2 properly.
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 MCCBs, said arrangement comprising:
at least two MCCBs (Ml & M2) having operating knobs (Kl & K2) having mounting plates (PI & P2) installed on it;
at least two actuator cable means (CI & C2) connected to plural actuator means (Al, A2, A3 & A4), said actuator means being operatively connected to the ends of the said cable means (CI & C2);
at least two push to trip means (13 & 14) located in the said MCCBs wherein when said MCCB Ml is switched on keeping MCCB M2 in off position, actuator Al moves along with the knob Kl actuating push to trip means (13) of MCCB M2 by means of said actuator A2 on other side of cable CI whereby the MCCB M2 trips and the knob K2 of MCCB M2 moves to trip position.
2. An interlocking arrangement for interlocking plural MCCBs, said arrangement comprising:
at least two MCCBs (Ml & M2) having operating knobs (Kl & K2) having mounting plates (PI & P2) installed on it;
at least two actuator cable means (CI & C2) connected to plural actuator means (Al, A2, A3 & A4), said actuator means being operatively connected to the ends of the said cable means (CI &C2);
at least two push to trip means (13 & 14) located in the said MCCBs wherein when said MCCB M2 is switched on keeping MCCB Ml in off position, actuator A3 moves along with the knob K2 actuating push to trip means (14) of MCCB Ml by means of said actuator A4 on other side of cable C2 whereby the MCCB Ml trips and the knob Kl of MCCB Ml moves to trip position.

3. Arrangement as claimed in claim 1, wherein said push to trip (13) of MCCB M2 remains pressed not allowing resetting and/or turning ON of MCCB M2 as long as the MCCB Ml is in ON condition.
4. Arrangement as claimed in claim 2, wherein said push to trip (14) of MCCB Ml remains pressed not allowing resetting and/or turning ON of MCCB Ml as long as the MCCB M2 is in ON condition.
5. Arrangement as claimed in claims 1 and 2 wherein said cables are clutch cables.
6. An interlocking arrangement for interlocking plural MCCBs, said arrangement comprising:
at least two MCCBs (Ml & M2) having operating knobs (Kl & K2) having mounting
plates (PI & P2) installed on it);
at least two actuator cable means (CI & C2) connected to plural actuator means (Al, A2,
A3 & A4), said actuator means being operatively connected to the ends of the said cable
means (CI & C2);
at least two push to trip means (13 & 14) located in the said MCCBs
wherein when both the MCCBs i.e Ml (1) & M2 (2) are attempted to be switched on
simultaneously from off position, actuator means Al and A3 are actuated simultaneously
thereby in operation actuating actuators A2 and A4 so as to actuate push to trip means (13
& 14) thereby tripping the MCCBs Ml & M2 simultaneously.
7. Arrangement as claimed in claim 6 wherein said MCCBs trip before the dead centre of MCCB Ml (1) & MCCB M2 (2) is reached.
8. Arrangement as claimed in claim 6 wherein said cables are clutch cables.
9. The MCCBs Ml & M2 as described in this invention can be similar or dissimilar.

10. An interlocking arrangement for interlocking plural MCCBs as herein described and illustrated with reference to accompanying drawings.