FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Mechanism For Operating Moulded Case Circuit Breaker (MCCB"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: Larsen & Toubro Limited
Electrical & Automation North Wing, Gate 7, Level 0, Powai Campus, Saki Vihar Road, Mumbai 400 072, INDIA
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification
particularly describes the invention and
the manner in which it is to be
performed.

Mechanism For Operating Moulded Case Circuit Breaker (MCCB)
Field of the invention
The present invention relates to an operating mechanism for a moulded case circuit breaker (MCCB), and more particularly, to the operating mechanism for a moulded case circuit breaker (MCCB) without use of an upper link.
Background of the invention
The circuit switching devices and circuit interrupters such as circuit breakers, motor starters, motor controllers and other load controllers are used to protect electrical circuitry and equipment from damage due to abnormal conditions, such as an overload condition or a relatively high level short circuit or fault condition.
One such switching device is a moulded case circuit breaker (hereinafter 'the MCCB') which is generally used to provide over current and short circuit protection for various types of electrical equipment.
The MCCB have three stable positions i.e. ON, OFF and TRIP. Specifically, the MCCB comprises three systems, for example, a contact system, a mechanism and a release system. The above mentioned operations such as ON, OFF and TRIP are performed by these systems. The release system senses any abnormal condition (over current or short circuit) and executes tripping signal to mechanism system. After receiving the trip command from the release system, the mechanism system separates the moving and fixed contact in the MCCB. To perform all the above mentioned operations, the MCCB follows toggling mechanism i.e. a spring of the MCCB stores energy up to dead centre and releases it once the spring crosses the dead centre and takes the contacts to their respective position.

However, the conventional mechanism of the MCCB uses various mechanism for operation thereof which increases assembly time thereby reducing productivity. Also, more number of components used in the conventional MCCB leads to friction and thus the overall performance of the -MCCB is reduced as the wear and tear increases.
Accordingly, there exists a need to provide a mechanism for operating the MCCB which overcomes the drawbacks of the prior art.
Objects of the invention
An object of the present invention is to provide a mechanism for MCCB which uses reduced number of components therein thereby reducing cost thereof.
Another object of the present invention is to provide a mechanism for MCCB which provides ease of assembly thereby increasing productivity.
Yet another object of the present invention is to provide a mechanism for MCCB which may be used in existing MCCB.
Still another object of the present invention is to provide a mechanism for MCCB having lesser friction thereby enhancing performance of the MCCB.
Summary of the invention
Accordingly, the present invention provides a mechanism for operating a modular case circuit breaker (MCCB) without use of an upper link, the mechanism comprising
a fork profile;
a latch profile having an arcuate base, the latch profile mounted on a mechanism plate;

a toggle pin capable of being rolled over the latch profile to follow a circular path;
a knob for operating the MCCB;
a spring coupled to the fork at one end and to the toggle pin at another end;
a lower link coupled operatively to the toggle pin;
'a drive shaft coupled to the lower link; and
an upper contact having a contact button and the said upper contact coupled to the drive shaft, wherein the said upper contact button detachably attaches to a lower contact button,
wherein upon applying force on the knob, the fork moves, the spring extends and the toggle pin starts to roll over the main latch profile which in turn rotates the drive shaft to attach/detach the upper contact button with the lower contact button thereby allowing the MCCB to attains any one of ON position, OFF and toggling position.
Brief description of drawings
Figure 1 shows a side view of a moulded case circuit breaker (MCCB) of the prior art with toggling mechanism;
Figure 2 shows a side view of the MCCB mechanism of the prior art with ON condition;
Figure 3 shows a side view of the MCCB mechanism of the prior art with OFF condition;
Figure 4 shows a perspective view of a latch profile of the prior art.
Figure 5 shows a side view of the MCCB mechanism with OFF condition, in accordance with the present invention;

Figure 6 shows a side view of the MCCB mechanism with ON condition, in accordance with the present invention;
Figure 7 shows a side view of a moulded case circuit breaker (MCCB) with toggling mechanism, in accordance with the present invention; and
Figure 8 shows a perspective view of a modified latch profile, in accordance with the present invention.
Detailed description of the present invention
The foregoing objects of the 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.
Accordingly, the present invention provides a mechanism for modular case circuit breaker (MCCB) which uses reduced number of components therein thereby reducing cost thereof. Further, the mechanism for MCCB provides ease of assembly thereby increasing productivity. Furthermore, the mechanism for MCCB may be used in existing MCCB with very few changes. Also, the mechanism for MCCB provides lesser friction thereby enhancing performance of the MCCB.
Referring now to figure 1, 2 and 3, there is shown a mechanism for operating the modular case circuit breaker (100) (hereinafter 'the MCCB (100)') of the prior art.
The MCCB (100) includes a knob (10), a fork (20), a mechanism spring (30), a toggle pin (40), a lower link (50), a main latch (60), a drive shaft (70), and an

upper link (80) to form four bar link mechanism, an upper contact (90) and a lower contact (92), as shown in Fig 3.
The spring (30) with one end at the fork (20) and the other end at toggle pin (40) pulls the toggle pin (40) in positive X direction which makes the MCCB (100) in equilibrium with a stopper (not numbered) in the driveshaft (70). To switch ON the MCCB (100), the spring's (30) axis crosses the upper link (80) which is the toggling position as shown in figure 1. Once the spring's (30) axis crosses the upper link (80), direction of force on the toggle pin (40) changes from positive X direction to negative X direction and through the lower link (50), the drive shaft (70) rotates and make the contacts as shown in figure 2.
Referring now to figure 4 to 6, there is shown an improved mechanism for operating the modular case circuit breaker (200) (hereinafter 'the MCCB (200)), without use of an upper link, in accordance with the present invention. The mechanism (200) includes a fork profile (110), a latch profile (120), a toggle pin (130), a knob (140), a spring (150), a lower link (160), a drive shaft (170), an upper contact button (180) and a lower contact button (190).
In a preferred embodiment, the latch profile (120) have an arcuate base (122) as shown in figure 8. The latch profile (120) is mounted on a mechanism plate
(not shown).
The toggle pin (130) is capable of being rolled over the latch profile (120) to follow a circular path. In conventional mechanism of the MCCB (100) of the prior art, the toggle pin (40) follows a circular path having radius equal to the length of the upper link (80). The centre of the circular path is at the main latch (60) and upper link's (80) hinge point. According to the present invention, the latch profile (120) is modified in such a manner that the toggle pin (130) rolls over the latch profile (120) and follows the same circular path as it was following in the conventional method of the prior art.

The knob (140) operates the MCCB (200). The knob (140) is coupled to the spring (150). The spring (150) couples the fork (140) at one end and to the toggle pin (130) at another end.
Further, the lower link (160) is coupled operatively to the toggle pin (130) and the drive shaft (170).
Furthermore, the upper contact (180) having a contact button is coupled to the drive shaft (170) and upper contact button coupled to the upper contact, wherein the upper contact button detachably attaches to a lower contact button.
Referring to figure 5, which shows the MCCB (200) in OFF condition. To switch ON the MCCB (200), the force is applied on the knob (140). The knob (140) moves the fork profile (110). As the fork profile (110) moves, the spring (150) extends and the force required to move the spring (150) further increases as the toggle pin (130) is stationary. The toggle pin (130) remain stationary because of the direction of the spring (150) force.
As the direction of the spring (150) force changes from positive x-direction to negative X-direction, the toggle pin (130) starts to roll over the latch profile (120) which in turn rotates the drive shaft (170) and the mechanism attains ON position, as shown in figure 6.
As in case of the prior art, the dead centre is visible. The spring (30) of the prior art stores energy up to dead centre and releases the energy once the spring crosses the dead centre and takes the contacts to their respective position .
However, dead centre is not visible in the toggle pin (130) of the mechanism (200) of the present invention. As the motion of the toggle pin (130) remains in a fixed circular path, the dead centre remains in the same fixed line. As the

spring' (150) axis crosses the dead centre, the force direction changes. Specifically, figure 7 shows the MCCB in toggle position and once the spring (150) crosses the dead centre, the driveshaft (170) moves and the MCCB attains the ON condition as shown in figure 6.
The mechanism (200) operated similarly as described above when the MCCB operates from ON to OFF condition.
According to the mechanism for operating the MCCB (200), the present invention eliminates the use of upper link, as compared to the prior art which reduces the assembly cost. Also the lesser number of components result in lesser friction. This increases the overall performance of the breaker.
Advantages of the invention
1. The MCCB (200) provides reduction of the number of components in the mechanism for operation thereof.
2. Reduction in the number of components in the MCCB (200) reduction in total cost.
3. The MCCB (200) provides ease of assembly hence increased productivity.
4. The modification in the existing MCCB can be done in with a very few
changes.
5. The MCCB (200) uses less number of components which results in lesser
friction and thus enhance the overall performance of the MCCB (200).
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,

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 omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We Claim:
1. A mechanism for operating a modular case circuit breaker (MCCB) without use of an upper link, the mechanism comprising
a fork profile;
a latch profile having an arcuate base, the latch profile mounted on a mechanism plate;
a toggle pin capable of being rolled over the latch profile to follow a circular path;
a knob for operating the MCCB;
a spring coupled to the fork at one end and to the toggle pin at another end;
a lower link coupled operatively to the toggle pin;
a drive shaft coupled to the lower link; and
an upper contact having a contact button and the said upper contact coupled to the drive shaft, wherein the said upper contact button detachably attaches to a lower contact button,
wherein upon applying force on the knob, the fork moves, the spring extends and the toggle pin starts to roll over the main latch profile which in turn rotates the drive shaft to attach/detach the upper contact button with the lower contact button thereby allowing the MCCB to attains any one of ON position, OFF and toggling position.
2. The mechanism of claim 1, wherein the drive shaft includes a stopper to attain equilibrium with the MCCB when the spring pulls the toggle pin.