F0RM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. - MODULAR MCCB (MOULDED CASE CIRCUIT
BREAKER)
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:

FIELD OF THE INVENTION
The present invention relates to current limiting moulded case circuit breaker (MCCB). More
particularly, the invention relates to two pole MCCB or three po}e MCCB or n pole
MCCB derivable from two or three or n single-poles (where n is an integer 2,
3, ,n) such that the construction requires low inventory and is cost effective.
BACKGROUND OF THE INVENTION
A circuit breaker should typically have an arrangement to generate enough contact pressure so that under normal operating conditions (i.e. breaker operated at rated current or the permissible level of overload values), the temperature rise of the current carrying components of the breaker should not exceed the allowable limit set by the relevant product standards whilst simultaneously satisfying the requirements necessitated by the current limiting feature of the circuit breaker.
The circuit breaker is called upon to protect the equipment in an installation in case of over currents arising out of abnormal circuit conditions. A circuit breaker typically comprises a spring loaded contact system to carry, make & break the current under normal and abnormal conditions involving very high over-currents. The circuit breaker is expected to operate to interrupt the fault current rapidly so as to minimize damage to the installations (downstream equipments) resulting from thermal and mechanical stresses.
In case of multiple MCCB having drive-shaft interlocking the drive-shafts assembly (Fig.5) which causes the angular movement of whole switching components are connected together and the tripping mechanisms are independent of each other. If an abnormal condition such as overload is sensed by one MCCB in this modular design then the release system will give the tripping command to one pole of modular MCCB thus causing the switching OFF operation. The mechanical movement of drive-shaft in one MCCB leads to the subsequent movement of drive-shaft of other MCCB. Drive-shaft interlocking is inherently slow in performance because of mechanical inertia of one drive-shaft assembly over the other one. However, in the prior art as described hereinabove no high speed operation during normal and abnormal switching conditions.
Therefore, to avoid the problems in the prior art, the present invention provides a modular MCCB having minimum number of components and also economic. The present invention

provides a tripping mechanism interlocking to avoid the problem of slowness in performance of drive-shaft assembly.
OBJECTS OF THE INVENTION
Basic object of the present invention is to overcome the problems in the prior art.
Another object of the present invention is to provide multi-pole MCCBs deriving from single pole MCCBs with minimum number of components and low capital investment.
Another object of the present invention is to provide a design of multi-pole MCCBs having no riveting.
Another object of the present invention is to provide trip-plate mechanism for interlocking between individual MCCBs as against drive-shaft interlocking.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a two or multiple pole modular MCCB assembly derivable from at least two single poles such that the said assembly rivetless requiring less number of components, said assembly comprising: a housing; a cover means; a trip plate assembly of each single pole MCCB comprising a trip plate means adapted to interlock plurality of the single pole MCCBs and being interconnected to the trip plate means of the adjacent single pole MCCB by means of first connector elements; plural second connectors means interlocking the MCCB housing and the cover; a first knob means providing simultaneous switching ON of all the poles of the modular MCCBs; a second knob means providing simultaneous switching OFF of all the poles of the modular MCCBs: and a phase barrier providing an increased electrical clearance between adjacent phases; wherein said first connector elements operatively connecting the trip plate means of plurality of the single pole MCCBs such that in the event of any electrical faults in any one of the poles, all the poles of MCCB trip simultaneously; and wherein said cover means being such that it facilitates the mechanical interlocking of plurality of the trip-plates means with the first connector elements.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 illustrates MCCB assembly & trip-plate connector Fig. 2 illustrates placement of bottom side nut-plate connectors. Fig. 3 illustrates placement of top nut-plate connector-Fig. 4 illustrates placement of common knob. Fig. 5 illustrates drive shaft assembly.
DETAILED DESCRIPTION OF THE INVENTION
In the present invention multi-pole MCCBs can be derived by single pole MCCBs with minimum number of additional components and in very low assembly time.
The working principle of the moulded case circuit breaker of the present invention is generally based on the conventional current limiting principle where in the over current flowing through the circuit breaker contacts results in electro-dynamic repulsive forces between the stationary and moving contacts. The stationary contact being secured to the base of the moulded case, repulsive forces exerted cause the moving contact to trace a curvilinear locus as the contacts separate. Consequent to this motion of moving contact, incremental resistance is introduced between the stationary and moving contacts and this resistance irt turn creates an increasing arc voltage that acts opposite to the system voltage and limits the fault current to quench the arc.
In the present invention MCCBs are placed beside each other such that cover groove (8) are aligned. In the present invention to make modular MCCBs (in this case a 2-pole MCCB), trip-plate (4) of two single pole MCCB are mechanically connected together by a non conducting first connector element, which is a trip-plate connector (5), which ensures that in case of any electrical fault (short-circuit/overload) in one pole both the poles of a modular MCCB will get tripped simultaneously. This way a 1-pole MCCBs can be made to function as a 2-pole or 3-pole MCCB.

In the present invention, Cover (2) of MCCB has been designed such that the moulding of cover near trip plate (4) resting area can be easily chipped-off to facilitate the mechanical interlocking of two trip-plates (4) with a trip-plate connector (5).
in order to provide the simultaneous switching of MCCBs in a multi-pole MCCB the operating handles (3) of individual MCCBs are connected together by a first knob means, which is a non conducting common knob (12).
In the present invention the riveting of MCCB housings (1) &. covers (2) are avoided for the ease of assembly and to reduce the assembly time. In the present invention plural second connectors means are nut-plate connectors wherein two nut-plate connectors (10 & 11) are provided at the release (6) end of MCCB; one nut-plate connector (9) is provided at the arc-interrupting chamber (7) end of MCCB. When screws (13) are tightened through these nut-plate connectors (9, 10 and 11, these nut-plate connectors hold the individual breaker assembly rigidly, thus making a multi-pole MCCB. In present design the use of simple nut-plate connectors avoids the use of riveting in housing and cover assemblies.
In present invention the interlocking between individual MCCB is achieved by mechanical interlocking of trip-plate assemblies as against the drive-shaft interlocking. In the present invention the trip-plate interlocking ensures the high speed of operation during both normal and abnormal switching conditions as the inertia of trip-plate assembly is very low as compared to drive-shaft assembly.
in present invention when manual tripping command is given by a second knob means which is a push trip button (14), the interlocking ensures the simultaneous switching OFF of all poles of modular MCCB. Similarly for simultaneous switching ON of all poles of modular MCCB a common knob (12) has been provided.
1-pole MCCB has been designed in such that when used in for modular MCCB the electrical clearance between adjacent phases can be increased by use of phase barrier (17) in phase-barrier groove (15). In modular design of MCCB, in spite of the use of single pole MCCBs technically desired features such as flexibility of mounting (DIN-rail (18) and panel mounting (16) of MCCB has been achieved. Modular construction has been achieved such that electrical clearance between adjacent phases can be increased by use of phase-barrier (17).

WE CLAIM
1. A two or multiple pole modular MCCB assembly derivable from at least two single
poles such that the said assembly rivetless requiring less number of components, said
assembly comprising:
a housing;
a cover means;
a trip plate assembly of each single pole MCCB comprising a trip plate means adapted to interlock plurality of the single pole MCCBs and being interconnected to the trip plate means of the adjacent single pole MCCB by means of first connector elements;
plural second connectors means interlocking the MCCB housing and the cover;
a first knob means providing simultaneous switching ON of all the poles of the modular MCCBs;
a second knob means providing simultaneous switching OFF of all the poles of the modular MCCBs; and
a phase barrier providing an increased electrical clearance between adjacent phases;
wherein said first connector elements operatively connecting the trip plate means of plurality of the single pole MCCBs such that in the event of any electrical faults in any one of the poles, all the poles of MCCB trip simultaneously; and
wherein said cover means being such that it facilitates the mechanical interlocking of plurality of the trip-plates means with the first connector elements.
2. The assembly as claimed in claim 1, wherein the first connector element is a non conductor.
3. The assembly as claimed in claim 1, wherein said second connector means comprises two nut-plate connectors located at release end of the MCCB.
4. The assembly as claimed in claim 1, wherein said second connector means comprises a further nut-plate connector located at an arc-interrupting chamber end of the MCCB.

5. The assembly as claimed in claim 1, wherein the first knob means is a non conducting common knob adapted to connect plurality of operating handles of the single pole MCCBs.
6. The assembly as claimed in claim 1, wherein said second knob means is a trip push button.
7. The assembly as herein substantially described and illustrated with the accompanying drawings.