FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION Secondary handle of an electrical switching device for emergency usage.
2. APPLICANT(S)
(a) NAME : Larsen 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
4. DESCRIPTION (Description shall start from next page)
5. CLAIMS (not applicable for provisional specification. Claims should start with the preamble -
"I/We claim" on separate page)
6. DATE AND SIGNATURE (to be given on the last page of specification)
7. ABSTRACT OF THE INVENTION (to be given along with complete specification on the
separate page)
Note:
* Repeat boxes in case of more than one entry
*To be signed by the applicant(s)or the authorized registered patent agent
*Name of the applicant should be given in full, family name in the beginning
*Complete address of the applicant should be given stating with postal index no. / code, state and
country
*Strike out the column which is/are not applicable

Secondary handle of an electrical switching device for emergency usage Field of the invention
The present invention relates to Low Voltage current limiting circuit breaker and the likes, which are commonly used to receive, supply, protect and isolate the current supply in an electrical circuit. More particularly the invention relates to operating handle for electrical device to operate it in emergency conditions.
Background 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 the current supply in an electrical circuit.
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.
2. As a protecting device: Tripping or Isolating by breaking the contacts interrupting the fault current during abnormal conditions such as short-circuit, overload and under voltage.
Circuit breaker consists of one or more electric poles, whose number is determined by the application as single pole circuit breaker, two pole circuit breaker, three pole circuit breaker, four pole circuit breaker and so on.
They are designed for use in Switchboards, Control Panels, and Combination Starters in separate enclosures for effective single location distribution and control. Also these are housed inside an enclosure to provide safety to users operating the same.
In the most common type of installation, an operating handle is mounted on the panel door while the switching device is mounted inside the panel door. The mounting device has a shaft coming out that has to be rotated to switch the circuit breaker ON and OFF.
When panel door is closed the shaft engage with the handle mounted on the panel door and breaker can be operate by using the handle. When panel door is open the handle is decouple with

the shaft and no engagement is left with the shaft and handle. Under standard design conditions while a door is open, due to the decoupling of the shaft and operating handle operations under this condition is not possible. This is also required from safety perspective since operating a handle under these conditions is unsafe because of live power inside the enclosure.
NFPA 79 is the widely recognized official standard in the US for electrical and electronic a apparatus and systems for industrial machinery. The standard is analogous in its scope with the European Machinery Directive standard IEC / EN 60 204-1 [5]. The standard now more clearly reinforces, for UL listed assemblies, the requirement in NFPA 79 that states that in case of devices used for emergency like fire, safety alarms etc, provisioning of operations of the switching devices should be made even in conditions where the door is open. Additionally it states that an intent to close a disconnect switch when a control panel is open must first be prevented through an interlocking provision, which can then only be bypassed through deliberate action. Main disconnect switches equipped with door mounted rotary handles have the peculiar design aspect that, with an open control panel door, there no longer is a mechanical linkage established between switch and door. For switches requiring emergency The North American standard stipulates that the operating handle must always be permanently connected to the switch. This applies even when the control panel door is open.
What is required is a secondary operating handle that permits operations of a circuit breaker even if the door is open but with a deliberate and definite action by the user, thus being in line with NFPA 79 standards. This particular design should also establish permanent connection with the breaker even when the control panel door is open. It necessary to incorporate the deliberate action feature into the supplementary handle mounted inside the panel, in order to fully meet the intent of the standard. The handle remains permanently connected with the circuit breaker in line with the intent of the standard.
The handle design should be adaptable for mounting on almost all types of makes of shaft that connects to its corresponding operating handle of a circuit breaker / switching device that are provided by the competition.

Object of the invention:
Object of the present invention is to provide a secondary safety handle which remains connected with the circuit breaker even when the panel door is open and allows deliberate operation of the breaker in emergency.
Another object of the present invention is to have a handle permanently coupled to the switching device / circuit breaker irrespective of the door position.
Yet another objective is to provide a secondary handle to operate the breaker when panel door is in open condition by using deliberate action. It is operable only if there is deliberate action and not by accident.
Further objective of this handle is to avoid the misuse/ accidental use of shaft for switching ON and OFF the breaker by help of additional adaptable tools since the matting portion gets covered up, while the door is opened. When panel door is open the shaft pin is not accessible.
Another object of the invention is to keep the design simple with usage of a 4 components in the design assembly. The design can be used in addition to existing operating handle that gets mounted on the panel door and switching device on inside the panel that makes the entire design compliant to NFPA 79 , UL and north American standards. Design offers modularity by replacing a couple of components to adapt any shaft and handle designs that are presently in the market. So this forms a universal concept of add on module to existing design for conversion to the above standard.
Summary of the invention:
The emergency operating handle consists of a handle portion having cut slots for better grip and extended tubular structure for connecting the grip to internal mechanism. The tubular portion of the handle has teeth at its end. The handle has a marking pointer on its outer surface. A shaft from the circuit breaker is connected to the breaker on one end and other end of the shaft has pin connected to it. A circular fixed base having a cavity at its centre is fixed on the shaft by passing the shaft through the cavity. The circular base has slots on its inner surface for engaging it with teeth of the shaft and a marking pointer on its outer surface for indicating the. engagement of the circular base with the handle. When teeth engage marking pointer on the circular base coincides

with the marking pointer on the operating handle. A compression spring is wound around the shaft with its one end connected to the fixed base and another end connected to the operating handle. The shaft rotates only if the teeth on operating handle engage with the slots on the circular base which is indicated by coinciding of the marking pointers on the said outer surface of the operating handle and fixed base and in all other positions shaft will not rotate thus avoiding accidental access to the ON-OFF mechanism of the electrical device.
Detail Description of the Drawings:
Figure 1, represents the assembly of MCCB (3), in an enclosure(l), with the extended operating shaft (4), mounted along with the secondary handle (5), and enclosed with a door (2) with primary operating handle (6) mounted on it. Primary operating Handle (6) is used to operate the mechanism through extended handle (4) in normal cases. But in case of emergency, when the door is opened, the condition is to enable the operation of MCCB, with the Help of secondary handle (5), which is the customer requirement.
Figure 2, represents the side view of the assembly, Represents the assembly of MCCB (3), in an enclosure(l), with the extended operating shaft (4), mounted along with the secondary handle (5), and enclosed with a door (2) with primary operating handle (6) mounted on it.
Figure 3, represents the Door in the opened condition, which gives a clear view of the secondary operating handle(5), assembled on the extended shaft (4), to operate the MCCB in case of emergency.
Figure 4 represents the Secondary handle (5) in normal mode, assembled along with extended shaft (4), which is the basic, invention mentioned. During normal mode, the handle is disengaged from the operation of MCCB. Secondary Handle (5), can only be used to operate the MCCB, through intended means and through deliberate action. Initially the handle (5) is free to rotate without engaging with the extended shaft (4). The means of engagement and free rotation will be far clear from the descriptions below.
Figure 5 represents the exploded view of the Handle assembly (5). Handle assembly (5) consists of Operating Handle (7), Compression Spring (8), Fixed Base (9), Holder pin (10), and Stopper pin (11). Fixed base (9), along with the spring (8) is assembled from the direction shown and the

extended shaft (4) is also assembled in the same direction. Once the extended shaft (4) is assembled, A Holder pin (10) and the likes are used to arrest the longitudinal motion of the Fixed base (9). Two more stopper pins (11) and the likes are used in the axis perpendicular to the shaft assembly to arrest the longitudinal movement of the operating handle (7).
Figure 6 represents the Operating handle (7), which consists of unique slot (7a), and Plurality of female slots (7b), (7c), (7d) which is used for engaging the handle during deliberate action with the fixed base (9). The surface (7e) is used for the resting of compression Spring (8), which keeps the handle in normal condition always, unless and until required for intended pushing and rotation. Compression Spring force is Sufficient enough and maintained in the level, so as to give ease of operation during pushing and rotation of the handle, when intended.
Figure 7 represents the fixed base (9), which consists of a unique projection (9a), and Plurality of male projections (9b), (9c), (9d) which is used for engaging the handle during deliberate action with the operating handle (7).
Figure 8 represents the detailed view of the fixed base (9) and Operating Handle (7), which Represents the Operating handle (7), which consists of unique slot (7a), and Plurality of female slots (7b), (7c), (7d). Which is used for engaging the handle during deliberate action with the fixed base (9) and Represents the Fixed base (9), which consists of a unique projection (9a), and Plurality of male projections (9b), (9c), (9d) which is used for engaging the handle during deliberate action with the operating handle (7)
Figure 9 represents the Handle (7), in pushed mode, where the handle is now engaged with the Fixed Base (9), and ready to operate the MCCB (3) and the likes. Handle will be enabled to be pushed inside only when the arrow (12) and the likes, provided on the operating handle (7), and the arrow (13) and the likes, provided on the fixed base (9), matches with each other. The markings are provided so as to enable the plurality of slots provided on the operating handle (7) to match with the plurality of fixed base (9), and the operation is enabled in only one mode by provision of poka-yoke through unique projection (9a), and along with unique slot (7a).
Figure 10, represents the way of engagement during operation mode, where the markings of operating handle (7) and fixed base (9) are matched and the various plurality of slots provided on the operating handle (7) to match with the plurality of fixed base (9), and the engagement of

provision of poka-yoke through unique projection(9a), and along with unique slot (7a),9b with 7b.9c with 7c and 9d with 7d.The detailed description, gives a clear view of the functioning of the Operating Handle. Operating Handle (7), gives a unique way of engaging the fixed base during emergency condition, and through intended operation. Operating Handle (7).
Figure 11, represents the Handle (7), in Pushed condition, when the door is closed and operating handle (7) is not engaged with the Fixed Base (9), and handle is not able to operate the MCCB, because the arrow and likes are not matched .In every orientation when panel door will be closed the operating handle will be push at some extent and shaft head pin will be come outside and engage with the rotary operated handle (ROH) mounted on the panel door.
Figure 12 represents the condition when arrow and the likes are not matched and operating handle (7) is pushed. In this condition operating handle will be pushed at some extent but the plurality of slot which is provided on operating handle(7),will not match with the unique projection provided on the fixed handle base(9).
Detailed Description:
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
List of components:
1. Operating handle
2. Fixed base
3. Shaft
4. Spring
5. Pin
Elements and Construction:
1: Operating Handle: It is operating handle which will align with the fixed handle base. The external diameter has a few undercuts that form means to hold and rotate. The undercuts are designed for better grip which eases the switching efforts. It also has a circular cut through

which the shaft with the pin pops out. The back portion of the operating handle has unique Slots for meshing of to the corresponding profiled protrusion available on the fixed base.
2: Fixed base: It is the component which will be fixed on the shaft with the help of holder pin. On this component there are profiled protrusions made to suitable adapt the unique slots made on the operating handle.
The fixed base gets mounted to the shaft assembly by means of a holder pin.
3. Shaft: This is a shaft having rectangular cross sectional area coming out from the switching device / circuit breaker. A few of the circuit breakers have a inherent rotary operations while a few have add-on mechanisms to convert any other type of motions to a rotary motion. The shaft assembly generally has a pin on its head with a cross pin that primarily gets adapted to the handle.
4. Compression Spring: It is a compression spring which will be mounted on fixed part. This makes the operating handle pop out in case the door is opened thus preventing the access of the head of the shaft. For usage, the operating handle needs to be pressed.
5. Support pin: This supporter pin will stop the operating handle to come outside from the fixed base
6. Holder pin: The fixed base will be fixed on the shaft with the help of a holder pin.

We claim,
1) Secondary handle arrangement for an electrical switching device for emergency usage comprising;
a central shaft, one end of the shaft connected to the ON-OFF mechanism of the electrical device and another end has a hodling pin fixed at its tip,
a circular base, the circular base having plurality of slots on its inner surface and the base is fixed on the said central shaft and the circular base has marking pointer on its outer surface,
an operating handle, the handle having plurality of cuts for manual grip and tubular extension mounted inside the inner surface of the said circular base and the tubular structure has teeth to engage the operating handle with slots on the said circular base and the handle has marking pointer for indicating engagement of teeth with the said circular base.
an external button housing engaged with the said pin on the shaft and mounted around the manual grip of the said operating handle,
a connecting spring, one end of the connecting spring fixed to the said circular base and another end connected to the operating handle, the spring is wound around the said central shaft,
wherein, the shaft rotates only if the teeth on operating handle engage with the slots on the circular base which is indicated by coinciding of the marking pointers on the said outer surface of the operating handle and fixed base and in all other positions shaft will not rotate thus avoiding accidental access to the ON-OFF mechanism of the electrical device.

2) Secondary handle arrangement for an electrical switching device for emergency usage of the claim 1, wherein, the shaft will not rotate when the handle is rotated if teeth on the circular base do not engage with the slots on the fixed base.
3) Secondary handle arrangement for an electrical switching device for emergency usage of the claim 1. wherein, the fixed base is fixed on the handle using support pin.
4) Secondary handle arrangement for an electrical switching device for emergency usage of the claim 1, wherein, the operating handle is prevented from coming out by holder pin.