DESC:DOOR MOUNTED ROTARY OPERATING MECHANISM

Field of the invention

The present invention relates to an operating mechanism of circuit breakers/switching devices, and more particularly to a door mounted rotary operating mechanism for circuit breakers/switching devices.

Background of the invention

Generally, low voltage current limiting circuit breakers are commonly used to receive, supply, protect and isolate the current supply in an electrical circuit. The circuit breakers typically serves two basic purposes, i.e. as a switching device for switching ON/OFF during normal operating conditions for the purposes of operation and maintenance, and as a protecting device for tripping or isolating by breaking the contacts interrupting the fault current during abnormal conditions such as short-circuit, overload and under voltage.

The circuit breakers/ switching devices are designed for use in switchboards, control panels and combination starters in separate enclosures for effective single location distribution and control. Also, the circuit breakers are housed inside the enclosure to provide safety to users operating the same.

In the most common type of installation, an operating handle is mounted on a control panel door while the circuit breaker is mounted inside the panel door. The circuit breaker device has a shaft coming out that has to be rotated to switch the circuit breaker ON and OFF.

When door of the control panel is closed, the shaft of the circuit breaker device engages with the handle mounted on the panel door and the circuit breaker can be operated by using the handle. When the door of the control panel is open, the handle is decoupled from the shaft of the circuit breaker and no engagement is left with the shaft and the handle. Accordingly, under standard design conditions, while the door of the control panel is open, due to decoupling of the shaft and the operating handle, switching ON and switching OFF operations of the circuit breaker are not possible. This is also required from safety perspective since operating the handle under these conditions is unsafe because of live power inside the enclosure/control panel.

However, for UL listed assemblies, requirement in NFPA 79 (Electrical Standard for Industrial Machinery) states that in case the devices such as circuit breakers are used for emergency like fire, safety alarms and the like, provisioning of operations of the circuit breakers should be made even in conditions where the door of the control panel is open. Additionally, the requirement in NFPA 79 states that an intent to close a disconnect switch when the 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 the door mounted rotary handles have a peculiar design aspect that, with an open control panel door, there no longer is a mechanical linkage established between the circuit breaker and the door.

For switches requiring emergency, the North American standard stipulates that the operating handle must always be permanently connected to the switching device/ circuit breaker. This applies even when the control panel door is open. In conventional control panels, the operating means are not coupled to the switching device/circuit breaker irrespective of the door conditions. Further, when the circuit breaker/switching device is in ON condition, there is no interlock to the door.

Specifically, a US Patents 5494083 discloses a door interlocking arrangement in a similar switching device configuration. The design is however too complex and does not clearly address issues of door interlock defeat and its restoration.
Another US Patents 6518536 and 6969813 also cite an example of rotary add-on mechanism connected to a switching device, but the operational safety aspects of the door interlock, its defeat is not disclosed anywhere.

The patent applications of prior art show that though they provide rotary operating mechanism in door mounted type, the mounting of the mechanism on the panel door is difficult and requires use of tools. Owing to the constraints of huge panel doors, it’s highly impossible to mount the rotary operating mechanism on the control panel with single person involvement. Further, a shaft misalignment due to over hanging from the large depth panels is also of a major concern.

Accordingly, there exists a need to provide a door mounted rotary operating mechanism for switching devices / circuit breakers, that overcomes above mentioned drawbacks of the prior art.

Objects of the invention

An object of the present invention is to provide an easy alignment of a rotary handle on a door of a control panel with an overhanging shaft from a circuit breaker /switching device and to have added safety feature.

Another object of the present invention is to provide a correct indication of the circuit breaker/switching device state outside the control panel.

Yet another object of the present invention is to have a working torque within the operational ergonomic limits for the end user.

Still another object of the present invention is to have an interlock to the rotating handle once the door of the control panel is in open condition to prevent accidental switching.

Further object of the present invention is to provide an auto restoration system for closing the door, when the door of the control panel is defeated during emergency ON.

Furthermore object of the present invention is to provide interlocking of the door of the control panel in locked condition within the system and with less number of components.

One more object of the present invention is to provide defeatable interlock for the door of the control panel by trained operators by intentional action thus providing the requisite safety.

Another object of the present invention is to have the door interlock for the control panel while the switching device/circuit breaker is in ON condition which prevents the door from opening.

Yet another objective is to have a defeat which enables trained technicians with right kind of tool to defeat the interlock for cases of emergency.

Summary of the invention

Accordingly, the present invention provides a door mounted rotary operating mechanism for a circuit breaker. The circuit breaker is enclosed in a control panel. The circuit breaker includes a shaft. The shaft is coupled to the door mounted rotary operating mechanism for operating the circuit breaker to any one of ON and OFF conditions. The door mounted rotary operating mechanism comprises a base plate, an interlocking slider, an excusion plate and a rotary handle.

The base plate is mounted on a door of the control panel through a ring member. The ring member is a gasket fitted on the base plate. The base plate includes at least four projections, at least two bosses and a curved member configured thereon. The at least four projections is configured on the base plate typically on a rear side thereof in all four directions at 90 degree rotation. The at least four projections is adapted for axi-symmetrical snap fitting on the door. The at least two bosses is configured on the base plate to avoid self rotation thereof on the door. Typically, the at least two bosses is configured diagonally at 180 degree on the base plate. The curved member is configured on the base plate typically on the rear side thereof for fitting and aligning the shaft thereon.

The interlocking slider is fitted on the base plate. The interlocking slider includes a centre portion, a projection, a spring and a wedge configured thereon. The centre portion is positioned over the curved member for removably engaging with the shaft in the ON condition of the circuit breaker to lock the door of the control panel. The projection is configured at one side of the interlocking slider. The projection is capable of being pushed by a defeat tool for moving up the interlocking slider to release the shaft thereby allowing opening of the door of the control panel in an emergency situation. The spring is configured at another side of the interlocking slider for restoring back the interlocking slider upon completion of the defeat operation.

The excusion plate is fitted on the base plate thereby enclosing the interlocking slider there between. The excusion plate includes a central opening, an opening and a lock plate configured thereon. The central opening is adapted for allowing the rotary handle to pass there through for locking with the shaft. The opening is configured at a bottom side of the excusion plate for being accessed with the defeat tool for pushing the projection on the interlocking slider. The lock plate is fitted in a centre portion of the excusion plate.

The rotary handle is locked on the excusion plate through the lock plate. The rotary handle is adapted for rotating the shaft therewith. The rotary handle includes a padlock button configured thereon. The padlock button includes a padlock pin that pushes the wedge of the interlocking slider in the ON condition of the circuit breaker.

Brief description of the drawings

Other features as well as the advantages of the invention will be clear from the following description.
In the appended drawings:

Figure 1 show a rotary operating mechanism mounted on a control panel door of the circuit breaker, in accordance with the present invention;

Figure 2 shows the door mounted rotary operating mechanism, in accordance with the present invention;

Figure 3 shows a perspective view of a back plate of the door mounted rotary operating mechanism of figure 2; and

Figures 4a - 4d show an assembly for interlocking and defeat of the door of the control panel, in accordance with the present invention.

Detailed description of the invention

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 embodiment.

The present invention provides a door mounted rotary operating mechanism for a switching device/circuit breaker. The door mounted rotary operating mechanism includes self locking snap fits that are placed axi-symmetrically and they align themselves on a cutout and get fitted in without any hindrance. The door mounted rotary operating mechanism enhances ease and experience of the user. Further, the door mounted rotary operating mechanism provides ease of alignment with an overhanging shaft from the circuit breaker and to have added safety feature.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.

Referring to figures 1, there is shown a circuit breaker (100) in accordance with the present invention. The circuit breaker (100) is enclosed in a control panel (not shown). The circuit breaker (100) for example a molded case circuit breaker (MCCB) includes a truncated rack mechanism (70), a coupler (80), an outwardly extending shaft (90) (herein after ‘the shaft (90)’) and a door mounted rotary operating mechanism (60). The truncated rack mechanism (70) uses a rack (not shown) driven by multiple pinions (not shown) to convert a toggle MCCB to a rotary operable MCCB. The coupler (80) connects the shaft (90) to the door mounted rotary operating mechanism (60). The shaft (90) is coupled to the door mounted rotary operating mechanism (60) for operating the circuit breaker (100) to any one of ON and OFF conditions.

Referring to figures 2-4d, there is shown the door mounted rotary operating mechanism (60) (hereinafter “the mechanism (60)”) for the circuit breaker (100), in accordance with the present invention. Specifically, the mechanism (60) is mounted on a door (150) of the control panel. The mechanism (60) comprises a base plate (50), an interlocking slider (40), an excusion plate (30) and a rotary handle (20).

The base plate (50) is mounted on the door (150) of the control panel through a ring member (45). In an embodiment, the ring member (45) is a gasket fitted on the base plate (50). The base plate (50) includes at least four projections (46A, 46B, 46C, 46D), at least two bosses (44A, 44B) and a curved member (42) configured thereon as shown in figure 3.

The at least four projections (46A, 46B, 46C, 46D) is configured on the base plate (50) for axi-symmetrical snap fitting on the door (150) and to restrict translational motion of the base plate (50) on the door (150). Specifically, the at least four projections (46A, 46B, 46C, 46D) is configured on a rear side (not numbered) of the base plate (50) in all four directions at 90 degree rotation. The at least four projections (46A, 46B, 46C, 46D) is designed in consideration to a hole dimension of the door (150) and the flexing is also provided based on the same calculation. Further, leg of the at least four projections (46A, 46B, 46C, 46D) designed to accommodate the ring member (45) within an available length thereof is decided based on a minimum and a maximum thickness of the door (150).

The at least four projections (46A, 46B, 46C, 46D) is configured on the base plate (50) in all directions to ensure that the locking of the base plate (50) to the door (150) of the control panel happens perfectly without a need of a screw. The at least four projections (46A, 46B, 46C, 46D) is configured at 90 degree rotation so as to achieve uniform flexing/compression and locking thereof in a particular position thereby ensuring a uniform load distribution of the at least four projections (46A, 46B, 46C, 46D) along an axis while assembly on the door (150) as well as during opening and closing of the door (150).

The at least two bosses (44A, 44B) is configured on the base plate (50) to avoid self rotation thereof on the door (150). Specifically, the at least two bosses (44A, 44B) is configured diagonally at 180 degree on the base plate (50). In order to achieve the assembly of the mechanism (100) in a right way and in a proper angle, first, the at least two bosses (44A, 44B) are made to enter into the door (150) of the control panel followed by snap fitting of the at least four projections (46A, 46B, 46C, 46D) on the door (150).

The curved member (42) is configured on the base plate (50) for fitting and aligning the shaft (90) thereon. Specifically, the curved member (42) is a typical curve configured on the rear side of the base plate (50).

The interlocking slider (40) is fitted on the base plate (50). The interlocking slider (40) includes a centre portion (38), a projection (36), a spring (34) and a wedge section arrangement (32) (herein after ‘the wedge (32)’) configured thereon. The centre portion (38) is positioned over the curved member (42) for removably engaging with the shaft (90) in the ON condition of the circuit breaker (100) to lock the door (150) of the control panel.

The projection (36) is configured at one side (not numbered) of the interlocking slider (40). The projection (36) is capable of being pushed by a defeat tool (not shown) for moving up the interlocking slider (40) to release the shaft (90) thereby allowing opening of the door (150) of the control panel in an emergency situation. The spring (34) is configured at another side (not numbered) of the interlocking slider (40) for restoring the interlocking slider (40) once the defeat operation is completed. The assembly of the interlocking slider (40) on the excusion plate (30) takes care of the door interlocking and defeat which is achieved with a single component.

The excusion plate (30) is fitted on the base plate (50) thereby enclosing the interlocking slider (40) there between. The excusion plate (30) includes a central opening (22), an opening (24) and a lock plate (26) configured thereon. The central opening (22) is adapted for allowing the rotary handle (20) to pass there through for locking with the shaft (90). The opening (24) is configured at a bottom side (not numbered) of the excusion plate (30) for being accessed with the defeat tool for pushing the projection (36) on the interlocking slider (40). The lock plate (26) is fitted in a centre portion (not numbered) of the excusion plate (30).

The rotary handle (20) is locked on the excusion plate (30) through the lock plate (26). The lock plate (26) is adapted for fixing the rotary handle (20) with the excusion plate (30) and restricts the rotary handle (20) from coming out of the excusion plate (30). The rotary handle (20) passes through the central opening (22) for locking with the shaft (90). The rotary handle (20) is adapted for rotating the shaft (90) therewith. The rotary handle (20) includes a padlock button (10) configured thereon. The padlock button (10) includes a padlock pin (not shown) configured thereon.

The padlock button (10) is capable of being pushed up and down in the rotary handle (20). In an embodiment, the padlock button (10) is pushed up and down manually. Specifically, the padlock button (10) is pushed down in a locked condition of the door (150) when padlocking is required. Once pushed down, the padlock pin of the padlock button (10) pushes the wedge (32) on the interlocking slider (40) in the ON condition of the circuit breaker (100) thereby pushing the interlocking slider (40) through a wedge action. Further pushing of the padlock button (10) causes the interlocking slider (40) to move and lock the shaft (90) in its position thereby locking the door (150) and thus preventing opening of the door (150) without permission (Refer figure 4d).

Referring again to figure 1-4d, an operation of the mechanism (100) in ON condition, OFF condition and emergency situation is illustrated in accordance with the present invention.

During ON condition of the circuit breaker (60) inside the control panel and the locked condition of the door (150) (figure 4d), the padlock button (10) of the rotary handle (20) is pushed down such that the padlock pin thereof pushes the wedge (32) on the interlocking slider (40) thereby pushing the interlocking slider (40) through the wedge action. Further pushing of the padlock button (10) causes the interlocking slider (40) to move and lock the shaft (90) in the centre portion (38) thereof such that a shaft head (90A) of the shaft (90) is locked in a vertical position therein thereby locking the door (150) and thus preventing opening of the door (150) without permission.

During OFF condition of the circuit breaker (100), the shaft head (90A) rotates to 220 degrees due to the rotation of the rotary handle (20). The shaft head (90A) rotates to move to a position for pushing the projection (36) on the interlocking slider (40) to release the shaft (90) from the centre portion (38) thereby resulting in opening of the door (150).

Further, during emergency situation, the opening (24) at the bottom of the excusion plate (30) is accessed with the defeat tool thereby pushing the projection (36) on the interlocking slider (40) to move up and release the shaft (90) thereby resulting in opening of the door (150) of the control panel. The spring (34) restore the interlocking slider (40) once the defeat operation is completed.

Advantages of the invention

1. The mechanism (60) is assembled on the panel door (150) with great ease and without any hardware and still able to arrest all degrees of motion and thus enhances the user experience.
2. The mechanism (60) provides a self locking assembly of handle with mechanism which can be assembled with single person intervention.
3. The at least four projections (46A, 46B, 46C, 46D) enables one hand assembly of the mechanism (60) and reduces time involved for fixing the base plate (50) to the door (150).
4. The mechanism (60) addresses the issue of shaft misalignment in the same component.
5. The mechanism (60) achieves door interlocking and defeat with a single component.
6. The mechanism (60) is always coupled to the circuit breaker (100) irrespective of the door open/closed conditions.
7. The mechanism (60) provides a door interlock in ON condition of the circuit breaker (100) and the door interlock is also defeatable in case of emergency requirement by means of the defeat tool.
8. The mechanism (60) provides restoration of door interlock back to initial conditions once the door (150) is defeated.
9. The mechanism (60) provides operating torques in the ergonomic limits for the end user.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.
,CLAIMS:We claim

1. A door mounted rotary operating mechanism (60) for a circuit breaker (100), the circuit breaker (100) enclosed in a control panel, the circuit breaker (100) having a shaft (90) being coupled to the door mounted rotary operating mechanism (60) for operating the circuit breaker (100) to any one of ON and OFF conditions, the door mounted rotary operating mechanism (60) comprising:
• a base plate (50) mounted on a door (150) of the control panel through a ring member (45), the base plate (50) having,
at least four projections (46A, 46B, 46C, 46D) configured thereon for axi-symmetrical snap fitting on the door (150),
at least two bosses (44A, 44B) configured thereon to avoid self rotation thereof on the door (150), and
a curved member (42) configured thereon for fitting and aligning the shaft (90) thereon;
• an interlocking slider (40) fitted on the base plate (50), the interlocking slider (40) having,
a centre portion (38) positioned over the curved member (42) for removably engaging with the shaft (90) in the ON condition of the circuit breaker (100) to lock the door (150) of the control panel,
a projection (36) at one side thereof for being pushed by a defeat tool for moving up the interlocking slider (40) to release the shaft (90) thereby allowing opening of the door (150) of the control panel in an emergency situation,
a spring (34) at another side thereof for restoring the interlocking slider (40) upon completion of the defeat operation, and
a wedge (32) configured thereon;
• an excusion plate (30) fitted on the base plate (50) thereby enclosing the interlocking slider (40) there between, the excusion plate (30) having,
a central opening (22) configured thereon,
an opening (24) at a bottom side thereof for being accessed with the defeat tool for pushing the projection (36) on the interlocking slider (40) there through, and
a lock plate (26) fitted in a centre portion thereof; and
• a rotary handle (20) locked on the excusion plate (30) through the lock plate (26), the rotary handle (20) passes through the central opening (22) for locking with the shaft (90), the rotary handle (20) adapted for rotating the shaft (90) therewith, the rotary handle (20) includes a padlock button (10) configured thereon, the padlock button (10) includes a padlock pin that pushes the wedge (32) of the interlocking slider (40) in the ON condition of the circuit breaker (100).

2. The door mounted rotary operating mechanism (60) as claimed in claim1, wherein the ring member (45) is a gasket fitted on the base plate (50).

3. The door mounted rotary operating mechanism (60) as claimed in claim1, wherein the at least four projections (46A, 46B, 46C, 46D) is configured on a rear side of the base plate (50) in all four directions at 90 degree rotation.

4. The door mounted rotary operating mechanism (60) as claimed in claim1, wherein the at least two bosses (44A, 44B) is configured diagonally at 180 degree on the base plate (50).

5. The door mounted rotary operating mechanism (60) as claimed in claim1, wherein the curved member (42) is configured on the rear side of the base plate (50).