F O R M 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
PROVISIONAL SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. – “TRUE INDICATION OF CONTACT POSITION IN MINIATURE CIRCUIT BREAKERS”
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 describes the invention

FIELD OF INVENTION
The present invention relates to true indication of contact position in circuit breakers. More particularly, the invention relates to a circuit breaker mechanism comprising a link element being designed in a manner to establish true indication of miniature circuit breaker (MCB) contact position thereby minimizing paradox in the realization of the contact position maintaining safety of the end-user.
The present invention also relates to a method of true indication of contact position in circuit breakers.
BACKGROUND AND PRIOR ART
US4829147 relates to a circuit breaker having positive contact indication. Upon the circuit breaker tripping, the operating mechanism components unlatch,, moving the cradle, upper link and lower link upwards and opening the contacts. Upon the circuit breaker being manually opened, no operating mechanism components move except the. upper link and lower link which causes the contacts to open. Upon the occurrence of locked contacts and the operating mechanism receiving a trip signal, the operating mechanism components unlatch but move only slightly since the contacts cannot open. A shuttle, pivotally mounted on the cradle, moves upward slightly to catch its tail on a flipper spring. The shuttle rotates slightly to meet a tab positioned on the handle arm and to block and opening movement of the operating handle. But this relates to mostly air-circuit breakers, the same can't be implemented in a miniature circuit breaker.
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US 4165453 deals with a switch in which if the contacts of the
switch are lightly stuck together the switch control can still
separate them, but if the contacts are firmly stuck together then the switch control cannot be moved to the "off" position
which would give a dangerously erroneous indication of the
state of the circuit switched. A two arm locking lever is pivotally mounted and has a first stop constituted by a spring into which one of the arms penetrates, and a second stop constituted by a pivot axis of the device. But the same can't be implemented in a miniature circuit breaker.
Thus, the present invention which provides a means to give positive contact indication in case of circuit breakers such as MCBs, RCCBs and RCBOs and the like.
The present inventors have found that a link element designed in a unique manner establishes true indication of circuit breaker contact position thereby minimizing paradox in the
realization of the contact position.
OBJECTS OF INVENTION
Thus one object of the present invention is to provide a circuit breaker mechanism comprising a link element providing true indication of circuit breaker contact position.
Another object of the present invention is to provide zooming indication means.
Yet another objection of the present invention is to provide a method for true indication of contact position.
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SUMMARY OF INVENTION
Thus according to one aspect of the present invention there is provided a circuit breaker mechanism for providing true indication of contact position, said mechanism comprising :
housing;
transparent member of predetermined dimension being provided on front surface of the housing, said transparent member occupying partially or wholly the front surface; and
link element hinged with the contact and comprising component I and component II having; predetermined colour indications, said components being co-operatively located in the link element so as to provide true indication of contact position.
DETAILED DESCRIPTION OF INVENTION
The circuit breaker mechanism of the present invention comprises housing accommodating the circuit breaker components including contacts, link element hinged to pivot point of said contact and a transparent member located on the front facia (surface) of the housing.
In an embodiment of the present invention the link element comprises component I and , component II of predetermined dimensions wherein component II is bigger in size than component I and is fixed underneath component II. The component I is marked with green colour indication on the front surface of the circuit breaker below breaker knob if the
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circuit breaker is mounted vertically. Component II is marked with red and is square shaped of predetermined dimension.
Another embodiment of the present invention describes a transparent member located on top of the front surface covering partially or 'wholly the front surface. The transparent member comprises of convex polycarbonate projection so that it provides a zooming effect on the user's / operator's eyes to give a prominent green / red indication corresponding to OFF / ON condition of the circuit breaker.
BRIEF DESCRIPTION OF ACCOMPANYING FIGURES
Figure 1 illustrates the MCB in ON condition and the link element showing green in the indication window.
Figure 2 illustrates the MCB in OFF condition and the link element showing red in the indication window.
Figure 3 illustrates the link element of the present invention.
Figure 4 illustrates the zooming effect in the present invention.
DETAILED DESCRIPTION OF ACCOMPANYING FIGURES
Fig. 1 shows the MCB in OFF condition and the indication link 4 shows green color on the front facia of the MCB below the knob (1) if the MCB is mounted vertically. The square red component 3, which is bigger, in size is fixed underneath the green component {an extension of the said indication link) 3 attached with the link 4, which in turn is hinged at the
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mechanism pivot point 5. When the MCB is in off condition, the green component is situated on top of the said red component and the user views it as green if viewed from front perspective indicating off condition. Thus a true indication of the contact position is achieved. A transparent convex member is placed on top of, the indication window (6) to have a zooming effect on the user's eyes so that he sees a prominent GREEN when the MCB is OFF.,(Shown in the image Figure 03).
Fig. 2 shows the MCB in ON condition and the indication link showing red in the indication window (6) {shown in figure 4). The green flag 2, attached with the link 4 has moved upwards along with the mechanism pivot 5 as the MCB is turned ON from OFF. Hence the red flag 3 is depicted in the indication window (6). This ensures only the condition of the contacts are shown in the indication window (6) (shown in figure 4) . A transparent convex member (7) (shown in figure 4) (here referred to as zooming lens) is placed on top of the indication window (6) to have a zooming effect on the user's eyes so that he sees a prominent RED when the MCB is ON. (Shown in the image Figure 03).

Dated this 25th day of March 2006.

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