FORM 2
THE PATENTS ACT, 1970 (39 Of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
"An Operating Handle with an Interlock Float"
2. APPLICANT(S)
(a) NAME: Lars en and Toubro Ltd.
(b) NATIONALITY: Indian
(c) ADDRESS: L&T House, Ballard Estate, Mumbai-400 001, India
3. PREAMBLE TO THE DESCRITION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Title
An operating handle with an interlock float
Field of the invention
The present invention is related to Low Voltage current limiting circuit breaker and the likes, which are commonly used to receive, supply, protect and isolate current supply in an electrical circuit. More particularly it relates to an operating handle for a panel door for remotely accessing a circuit breaker assembly.
Background of the invention
An electrical circuit breaker typically serves two basic purposes:
1. as a switching device: Switching On/Off during normal operating conditions for the purpose of operation and maintenance; and
2. as a protecting device: "Tripping" or "isolating", i.e. breaking electrical contacts, and thereby interrupting fault current during abnormal conditions such as short-circuit, overload and under voltage.
A circuit breaker may have one or more electric poles, and be known as single pole circuit breaker, or two pole circuit breaker, or three pole circuit breaker, or four pole circuit breaker, and so on, depending upon the number of poles as required by respective application.
Circuit breakers are designed for use in Switchboards, Control Panels, and Combination Starters in separate enclosures for effective single location distribution and control. In order to provide safety to operator these devices are housed inside an enclosure.
Typically these devices get mounted inside a board or panel for added safety to the operator. Most often these devices are required to be operated from outside the panel with means of an operating handle that is coupled to the circuit breaker (functioning as a switching device or as a protecting device).
In the most common type of installation, an operating handle is mounted on the panel door while the circuit breaker/switching device is mounted inside the panel door. The mounting arrangement typically has a shaft coming out, which has to be rotated in order to switch the circuit breaker ON and OFF.
For safety sake, only when the panel door is closed the shaft can engage itself with the operating handle mounted on the panel door, and the circuit breaker can be operated by using the operating handle. When panel door is open the operating handle is

decoupled from the shaft and no engagement is left with the shaft and handle, and thus the circuit breaker can no more be operated while the panel door is open.
For proper functioning of the operating handle the shaft has to properly get aligned and adapted to the operating handle. One common issue for loss of functionality is misalignment and sagging of the shaft due to manufacturing error and/or assembly error.
Misalignment takes place because the circuit breaker is first fixed inside the panel; then the shaft is fastened to a coupler rotating on a mechanism mounted on the circuit breaker; and thereafter the panel door cut-outs are made. In this construction, the panel door cut-outs do not get aligned with the shaft coming from the circuit breaker. Sagging is due to self-weight of the shaft, as the shaft is fixed rigidly at one of its ends and is free at the other end. It is therefore necessary to incorporate a feature within the operating handle assembly that can compensate for/nullify any variation in mounting caused due to the aforesaid manufacturing/human errors and limitations.
Further, as mentioned above, standard requirements of an operating handle assembly call for a door interlock ensuring that the panel door remains closed when the switching device is in ON condition.
However, in addition to the aforesaid requirement there is yet another requirement of the operating handle assembly, which is to have a provision for defeating the panel door interlock by usage of a tool (so that in exceptional situations the circuit breaker can be accessed even when it is switched ON) and further a feature of auto-restoration to initial state of door interlock.
The above requirements, due to their different natures, pose a challenge to integrate all the different functionalities into a single operating handle assembly and yet to provide required flexibility for respective different purposes/operations as per the need of the respective situation.
Objects of the invention
Accordingly, one of the objects of the invention is to have an operating handle assembly that can take care of misalignment coming due to assembly / installation error or sagging of the shaft.
Another object is to provide a door interlock in ON condition of the switching device.
Yet another object of the invention is to have a tool-operated interlock defeat so that by a trained person in cases of emergency the door could be opened for inspection/repair while the switching device is ON.
A further object of the invention is to provide a feature of auto-restoration to normal state (i.e. negating the door defeat), once the door is opened in ON condition.

Yet another object of the invention is to integrate the stated features by means of minimum number of components and make the assembly compact yet efficient.
Summary of the invention
In accordance with the above objects, there is provided an operating handle assembly for a panel door for remotely accessing and operating a circuit breaker assembly, by means of a shaft, the assembly comprising:
an actuation plate;
a slider defeat operatively connected with the actuation plate;
a knob assembly comprising a knob, the knob assembly being capable of rotating over the actuation plate;
a bottom disc fixed with the knob assembly, the bottom disc having one or more protrusions;
a middle plate having a set of one or more slots for accommodating the protrusions of the bottom disc and having another set of slots;
a top plate being capable of moving over the middle plate and having one or more protrusions engaging in the other set of slots of the middle plate, the top plate having a shaft-adapting profile for accommodating an end of the shaft;
a flexible shaft-guiding plate placed over the top plate and connected with the actuation plate by flexible means, the flexible shaft-guiding plate having a shaft-guiding profile for facilitating movement of the shaft inside the top plate, and having two pairs of cuts on the shaft-guiding profile in different orientations; and
a back plate connected with the flexible shaft-guiding plate,
wherein in normal conditions the flexible shaft-guiding plate holds the knob assembly, the actuation plate and the middle plate in line with centre axis of the knob; and wherein when the circuit breaker is in OFF condition, the shaft-guiding profile and the differently-oriented pairs of cuts on the flexible shaft-guiding plate allow the shaft to get coupled with a rotary switching device of the circuit breaker so that required torque can be transmitted to the circuit breaker ensuring that the panel door remains closed; and wherein the panel door can be opened while the circuit breaker is ON, by moving the slider defeat, which in turn rotates the flexible shaft-guiding plate at

required angle, bringing the shaft-adapting profile 6b over a shaft pin (not shown) and thereby removing the shaft; and wherein while closing the panel door again i.e. during auto-restoration the shaft gets positioned at the required place traversing the shaft-guiding profile of the flexible shaft-guiding plate, and the flexible shaft-guiding plate reorients itself according to the shaft position, using the flexible means of its connection with the actuation plate.
Brief Description of Drawings
Fig. 1 shows arrangement and relative placement of the circuit breaker, the shaft, the operating handle, the door, and the panel, in accordance with the present invention.
Fig. 2-a shows the front view and Fig. 2-b shows the back view of the operating handle in accordance with the present invention, used for operating circuit breaker inside the panel with extended handle fixed on the panel door.
Fig. 3 shows exploded view of the operating handle in accordance with the present invention.
Fig. 4-a shows knob assembly and its components, which is part of the operating handle in accordance with the present invention; Fig. 4-b shows bottom disc and its components; Fig. 4-c shows middle plate and its components; Fig. 4-d shows top plate and its components; and Figs. 4-d, 4-e and 4-f show flexible shaft-guiding plate and its components.
Fig. 5 shows complete operating handle assembly.
Fig. 6 shows a flexible plate providing a guiding profile to the shaft.
List of Components

Component No. Name of the Component
1 Knob assembly
la Knob assembly part connected to bottom disc
2 Slider defeat
3 Actuation plate
4 Bottom disc
4a Bottom disc connected with knob assembly

4b
Protrusions on bottom disc sliding in slots of top plate
5 Middle plate
5a Slots in middle plate for accommodating protrusions over bottom disc
5b Slots in middle plate for accommodating protrusions over top plate
6 Top plate
6a Protrusions on top plate sliding in slots of middle plate
6b Shaft-adapting-profile on top plate
7 Flexible shaft-guiding plate
7a Shaft-guiding profile over flexible shaft-guiding plate
7b, 7c Cut over shaft-guiding profile
8 Back plate
9 Circuit breaker
10 Shaft
11 Operating handle
12 Panel door
13 Panel
Detailed Description
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.
By the term "substantially" it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
Accordingly, there is provided an operating handle assembly with an interlock float, for a panel door for remotely accessing and operating a circuit breaker assembly, by means of a shaft. The assembly comprises three discs sliding over each other. Firstly a knob assembly rotates over an actuation plate and is fixed with a bottom disc at la by means of a screw. The area 4a of the bottom disc is fixed at area la of the knob. Further, there is provided a middle plate two pairs of slots 5a and 5b that are substantially at right angle to each other. A top plate moves over the middle plate and has a shaft adapting profile 6b. 4b and 6a move in 5a & 5b made on the middle plate. The complete assembly is mounted on the panel door.
Further, there is provided a flexible shaft-guiding plate which is placed the over top plate. The flexible shaft-guiding plate is connected with the actuation plate by a means of four springs. The flexible shaft-guiding plate has a shaft guiding profile 7a which helps the shaft to easily move inside the top plate.
In normal condition the flexible shaft-guiding plate will hold all the other plates/discs at the centre in line with the knob axis. The flexible shaft-guiding plate it is held tightly between a back plate and the actuation plate. There are two pairs of cuts 7b & 7c in different orientations on the shaft guiding profile of flexible shaft-guiding plate.
The shaft is fastened with a screw on a coupler rotating on the mechanism mounted on the circuit breaker. The mechanism (scotch yoke) has some clearances for smooth operation. These clearances create a play in the fixing of coupler over mechanism which gets transferred to shaft in the form of misalignment. Moreover, the shaft due to its own weight sags from the coupler side where it is fixed. This sagging magnifies itself at the front due to cantilever effect. This creates problem while closing the panel

door. As a result, the panel door cannot be closed properly and hence breaker cannot be operated. This problem arises because the circuit breaker is placed inside the panel, the shaft is fixed on it with mechanism, and then door cut-outs are made separately. The present invention provides a solution that compensates for both, the sagging and the misalignment. Sagging can be taken care of by the flexible shaft-guiding plate as it is spring-loaded. When the shaft is sagging due to its self-weight, the flexible shaft-guiding plate comes down and reorients itself according to the position of the shaft. The insertion/entry of the shaft in the flexible shaft-guiding plate is ensured by the shaft-guiding profile on the flexible shaft-guiding plate.
When the circuit breaker is in OFF condition, one of the pairs of cuts on the flexible shaft-guiding plate allows the shaft to get coupled with the circuit breaker/switching device so that required torque can be transmitted to the breaker. The requirement that the panel door should not open when the circuit breaker is in ON condition is met, as the other pair of cuts on the flexible shaft-guiding plate is at a particular angle (i.e. at an orientation) to the first pair of cuts.
According to the standards and considering safety, panel door cannot be opened in ON condition without any deliberate action. So if the panel door has to be opened a slider defeat connected with the actuation plate has to be moved which rotates the flexible shaft-guiding plate at required angle, which brings the cut 6b over a shaft pin {not shown) and thereby the shaft can be removed easily from the knob mounted on the panel door. In this way, the whole assembly on the panel door which is necessary for operating the circuit breaker can be disengaged from it.
Once the door is opened in ON state of the circuit breaker using the slider defeat arrangement, as per standard, an auto-restoration feature should be available, i.e. the panel door should get closed. The flexible shaft-guiding plate has required profile for achieving this feature, which guides the shaft to get coupled with the circuit breaker. Auto-restoration is accomplished by the shaft-guiding profile of the flexible shaft-guiding plate. The shaft-guiding profile is formed out of a guiding surface at an angle which allows the shaft to get positioned at the required place. Since the flexible shaft-guiding plate is spring-loaded, it reorients itself according to the shaft position and so the door can be closed again.

We Claim:
1. An operating handle assembly for a panel door for remotely accessing and operating a circuit breaker assembly, by means of a shaft, the assembly comprising:
an actuation plate;
a slider defeat operatively connected with the actuation plate;
a knob assembly comprising a knob, the knob assembly being capable of rotating over the actuation plate;
a bottom disc fixed with the knob assembly, the bottom disc having one or more protrusions;
a middle plate having a set of one or more slots for accommodating the protrusions of the bottom disc and having another set of slots;
a top plate being capable of moving over the middle plate and having one or more protrusions engaging in the other set of slots of the middle plate, the top plate having a shaft-adapting profile for accommodating an end of the shaft;
a flexible shaft-guiding plate placed over the top plate and connected with the actuation plate by flexible means, the flexible shaft-guiding plate having a shaft-guiding profile for facilitating movement of the shaft inside the top plate, and having two pairs of cuts on the shaft-guiding profile in different orientations; and
a back plate connected with the flexible shaft-guiding plate,
wherein in normal conditions the flexible shaft-guiding plate holds the knob assembly, the actuation plate and the middle plate in line with centre axis of the knob; and wherein when the circuit breaker is in OFF condition, the shaft-guiding profile and the differently-oriented pairs of cuts on the flexible shaft-guiding plate allow the shaft to get coupled with a rotary switching device of the circuit breaker so that required torque can be transmitted to the circuit breaker ensuring that the panel door remains closed; and wherein the panel door can be opened while the circuit breaker is ON, by moving the slider defeat, which in turn rotates the flexible shaft-guiding plate at required angle, bringing the shaft-adapting profile 6b over a

shaft pin (not shown) and thereby removing the shaft; and wherein while closing the panel door again i.e. during auto-restoration the shaft gets positioned at the required place traversing the shaft-guiding profile of the flexible shaft-guiding plate, and the flexible shaft-guiding plate reorients itself according to the shaft position, using the flexible means of its connection with the actuation plate.
2. The assembly of Claim 1 which is mounted on the panel door.
3. The assembly of Claim 1 wherein the flexible means connecting the flexible shaft-guiding plate with the actuation plate are springs.