DESC:TECHNICAL FIELD

The present subject matter described herein, in general relates to circuit breakers and more particularly, to an arc quenching system with improved venting system for expelling arc products generated in circuit breakers during fault clearance.

BACKGROUND

Electrical switching apparatus, such as circuit breakers, are employed in power distribution systems, to provide protection for electrical equipment from electrical fault conditions. The faulty conditions may include but not limited to the current overloads, the short circuits, the abnormal level voltage conditions, and the like. The breaking capacity of any circuit breaker is totally governed by the performance of the arc quenching chamber available in the circuit breakers.

During short circuit, due to arcing ionized gases are generated with pressure. The pressure build up inside the arc chamber depends upon the intensity of short circuit current being cleared and other parameters inside the arc chamber like the arc chamber material or presence or gassing material inside the arc chamber. For effective arc quenching, it is necessary to flush out the ionized gases from the arc chute.

The vent of the arc chamber of the circuit breaker allows the arc products generated during fault clearance, to escape out from the circuit breaker. However the vent should not allow the outside solid material to get inside the circuit breaker.

The prior art circuit breakers consist of an arc chamber assembly which when subjected to a short circuit current of few kilo amperes quench the arc with certain arcing times. The long arcing times lead to severe stresses on the downstream equipments due to large amount of let through energy. The energy dissipated during arcing and hence the stress developed during arcing depends on the total arcing time. Higher arcing times leads to severe stresses on the downstream equipments due to large amount of let through energy. The prior art circuit breakers consist of conventional venting systems using plastic or metal perforations.

Further, the prior art circuit breakers consist of venting system made up of solid material that can be either insulating material or metals. The conventional venting system is generally are either porous or having holes to allow the arc products to escape from the circuit breaker.

One of the major drawback of the venting systems available in the prior art is, during short circuit, the ionized gases escaping from the circuit breaker passes through the perforated or porous vents. Some part of the gas will hit directly on the solid part of the vent. This gas will be scattered in all the directions which will hinder the escaping ionized gas. Thereby the arc quenching time increases.

The prior-art U. S. Document US 8648274 also disclosed a flap that opens from a fault pressure in the pressure relief chamber to direct the internal pressure or flames toward a next access flap leading to the next adjacent pressure relief chamber. However, the invention employs traditional vents made up of layers of insulating material along with flap in single direction. The flap in single direction guides. The limitation of the cited patent application is that it uses a rigid perforated vent that creates hindrances to the ionized gases escaping through the circuit breaker during short circuit. Moreover the single sided opening on the flappers will have tendency to guide the escaping ionized gases in one direction only. This may create the trouble of earth fault if there is an earthed part near the vents.

Due to above mentioned limitations; there exists a need to provide an arc quenching chamber with an improved venting system for circuit breakers, which enhances the circuit breakers breaking capacity by faster movement of arc towards arc chute. Further, there is also need for avoiding the losses due to scattering effect in order to provide an effective venting so the arcing time is reduced.

SUMMARY

This summary is provided to introduce concepts related to improved venting system for expelling arc products generated in circuit breakers during fault clearance. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

In one implementation, an arc quenching system with improved venting system is provided which avoids the losses due to scattering effect in order to provide an effective venting so the arcing time is reduced.

In one implementation, the improved venting system enhances the circuit breakers breaking capacity by faster movement of arc towards arc chute because of higher venting area.

In one implementation, the proposed venting system does not allow any external particles get inside the circuit breaker during normal operating conditions.

In one implementation, the proposed venting system provides a venting area proportional to the force generated by the arcing products. Higher the arc intensity, higher the gases generated, so the vent flappers will open to their fullest extent. Thereby provide higher venting area. Once the short circuit has been cleared and the ionized gases have been escaped from the arc chamber, the flappers of the vent will come back to its original position due to flexibility of the component.

Accordingly, in one implementation, an improved venting system in an arch quenching system (5) of an electrical circuit breaker (1) of the type having vents (2) in said electrical circuit breaker for expelling arc products generated during fault clearance. The improved venting system comprises of at least one vent (2) having two ribs (7) on one side and an attaching means on the other side, wherein said two ribs (7) are fixed to said at least one vent (7) at one end and movable at the other end, and said two ribs (7) are operative in two positions comprising an open position and a close position.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1 illustrates an isometric view of moulded case circuit breaker (MCCB) showing vents placed on the MCCB is shown, in accordance with an embodiment of the present subject matter.

Figure 2 illustrates a sectional view of MCCB with contacts in closed position is shown, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates a sectional view of contact system of MCCB showing position of various components is shown, in accordance with an embodiment of the present subject matter.

Figure 4 illustrates a sectional view of MCCB showing contacts opened under fault and the arc is initiated is shown, in accordance with an embodiment of the present subject matter.

Figure 5 illustrates a Sectional view of MCCB showing arc has elongated and the vents (7) opened up are shown, in accordance with an embodiment of the present subject matter.

Figure 6 illustrates an isometric view of the vents is shown, in accordance with an embodiment of the present subject matter.

Figure 7 illustrates a cross sectional view of vents (2) in normal condition is shown, in accordance with an embodiment of the present subject matter.

Figure 8 illustrates a cross sectional view of vents (2) under short circuit condition, wherein the vents flapper opened up is shown, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION

Preferred embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

The terms and words used in the following description 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.

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.

In one implementation, an improved venting system that enhances the circuit breakers breaking capacity by faster movement of arc towards arc chute because of higher venting area is proposed. The proposed venting system provides a venting area proportional to the force generated by the arcing products. Hence, higher the arc intensity, higher the gases generated, so the vent flappers will open to their fullest extent. Thereby provide higher venting area. Once the short circuit has been cleared and the ionized gases have been escaped from the arc chamber, the flappers of the vent will come back to its original position due to flexibility of the component.

Construction of the assembly mechanism of the present invention is explained with reference to the accompanying figures.

List of components:
1. MCCB
2. Vent
3. Moving contact
4. Fixed contact
5. Arc chute
6. Arc stuck between fixed and moving contact
7. At least one rib/ Ribs of vent/ Vent flaps

The present invention relates to improved venting system that enhances the circuit breakers breaking capacity by faster movement of arc towards arc chute because of higher venting area.

When the contacts separate in any electrical switching device, say a circuit breaker, arc is struck between fixed and moving contact. An arc basically is a discharge of electric current, which produce plasma between the contacts. Because of arc, there are rapid temperatures changes which develop a very high pressure inside the arcing chamber. Also the splitter plates of the arc chute in the circuit breaker exert a magnetic pull on the arc. The arc is blown towards the arc chute due to force exerted on it which is a balance of magnetic forces and the gas dynamics due to high pressure generated inside the arcing chamber. As the arc enters the arc chute, it is split & cooled and thereby effectively quenched.

The arc velocity during its movement towards the arc chute is dependent on balance of magnetic forces and gas dynamics. The gas flow towards the arc chute is because of the pressure difference between arc front and behind it. It is desirable to have high pressure behind the arc and lower pressure in front of it. Due to this, the gas dynamics aids the magnetic forces on the arc and helps the arc to move towards the arc chute. To achieve this, vents are provided behind the arc chute.

During short circuit, the pressure build up inside the arc chamber depends upon the intensity of short circuit current being cleared and other parameters inside the arc chamber like the arc chamber material or presence or gassing material inside the arc chamber. For effective arc quenching, it is necessary to flush out the ionized gases from the arc chute. The present invention provides venting area proportional to the force generated by the arcing products. Higher the arc intensity, higher the gases generated, so the vent flappers will open to their fullest extent. Thereby provide higher venting area. Once the short circuit has been cleared and the ionized gases have been escaped from the arc chamber, the flappers of the vent will come back to its original position due to flexibility of the component. Thus the vents will not allow any external particles get inside the circuit breaker.

In one implementation, an improved venting system in an arch quenching system (5) of an electrical circuit breaker (1) of the type having vents (2) in said electrical circuit breaker for expelling arc products generated during fault clearance is disclosed. The improved venting system comprises of at least one vent (2) having two ribs (7) on one side and an attaching means on the other side, wherein said two ribs (7) are fixed to said at least one vent (7) at one end and rotatable at the other end, and said two ribs (7) are operative in two positions comprising an open position and a close position.

In one implementation said vent(s) (2) are made of a flexible material selected from a group comprising of a flexible plastic or elastomers or combination thereof. The flexible material may be a polymer that may exhibit an elasticity property (i.e., having elasticity).

In one implementation the vent (2) is made up of the flexible material like elastomers. The vent (2) in normal condition does not allow any external material to enter the circuit breaker. During the short circuit the pressure is created inside the arc chamber that pushes the flexible flappers of the vent (2). The flapper of the vent (2) deflects and opens up. Thus the vent (2) allows maximum amount of venting depending on the internal pressure generation. This allows the arc products to escape the circuit breaker. Moreover the two flaps of the vent (2) facilitate guiding the material in straight direction.

In one implementation, during short circuit when the ionized gases escape the circuit breaker, the vent will have tendency to open up due to internal pressure. So the open vent will provide complete exist to the ionized gases. So the losses due to scattering effect are minimal. This results into effective venting so the arcing time is reduced.

In one implementation, said attaching means is coupled to electrical circuit breaker (1) to fix said at least one vent (2) firmly with said electrical circuit breaker (1).

In one implementation, said close position of said two ribs (7) prohibits external material to enter in said electrical circuit breaker (1).

In one implementation, said close position is a normal position of said two ribs (7), wherein said rotatable end of two ribs (7) are in contact with each other.

In one implementation, said two ribs (7) are rotatable about a longitudinal axis at an angle between 0 degrees and 90 degrees relative to said fixed end of said ribs (7), wherein said two ribs are co-axially positioned along said longitudinal axis defined by said at least one vent (2).

In one implementation, movement / opening of said two ribs (7) is limited to 0° to more than 90°, depending on the pressure generated by arc products during short circuit.

In one implementation, in said open position said rotating end of said two ribs (7) are pushed out to expel said arc products generated during fault clearance in said electrical circuit breaker (1).

Referring now to figure 1, the MCCB (1) in which the placement of vents is shown, in accordance with an embodiment of the present subject matter.

Referring now to figure 2 and figure 3, the MCCB contact are in closed condition and the arrangement of various components like fixed contacts (4), moving contacts (3), arc chutes (5) and vents (2) in the MCCB is shown, in accordance with an embodiment of the present subject matter.

Referring now to figure 4, the moving contact (3) has started separating from fixed contact (4) under fault condition. The arc (6) has been initiated between fixed and moving contact is shown, in accordance with an embodiment of the present subject matter.

Referring now to figure 5, the arc (6) has moved from fixed (4) and moving contact (3) towards the arc chute (5), due to magnetic forces on the arc. The ionized gases are produced in the arc chute, the gases strike on the vent flappers (7). The vent flappers open up depending on the intensity of gas pressure. The direction of arrow shows the direction of ionized gas exit is shown, in accordance with an embodiment of the present subject matter.

Referring now to figure 6 and figure 7, the vent (2) and vent flaps (7) in normal condition is shown, in accordance with an embodiment of the present subject matter.

Referring now to figure 8, the vent (2) and vent flaps (7) getting opened up due to pressure generated inside the MCCB arc chute is shown, in accordance with an embodiment of the present subject matter.

Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features:

One feature of the invention is that, a flexible material for vents of circuit breaker is used.

Another feature of the invention is that, the vent is designed and manufactured in such a way that the vent has two ribs on side and a structural part that allows the vent to be fixed firmly on the circuit breaker.

Yet another feature of the invention is that, the vent in normal condition does not allow any external material to enter the circuit breaker. During the short circuit, the vent allows maximum amount of venting.

Yet another feature of the invention is that, during the short circuit the pressure is created inside the arc chamber that pushes the flexible flappers of the vent. The flapper of the vent deflects and opens up. This allows the arc products to escape the circuit breaker.

Yet another feature of the invention is that, the effective venting leads to less arcing time thus reducing let through energy to the downstream equipments.

Still another feature of the invention is that, the proposed venting system leads to increase in the breaking capacity of the arc quenching chamber.

Although the improved venting system that enhances the circuit breakers breaking capacity by faster movement of arc towards arc chute because of higher venting area has been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations for the improved venting system that enhances the circuit breakers breaking capacity by faster movement of arc towards arc chute because of higher venting area. ,CLAIMS:1. An improved venting system in an arch quenching system (5) of an electrical circuit breaker (1) of the type having vents (2) in said electrical circuit breaker for expelling arc products generated during fault clearance, said improved venting system comprising:
at least one vent (2) having two ribs (7) on one side and an attaching means on the other side, wherein said two ribs (7) are fixed to said at least one vent (7) at one end and rotatable at the other end, and said two ribs (7) are operative in two positions comprising an open position and a close position.

2. The improved venting system as claimed in claim 1, wherein said vent(s) (2) are made of a flexible material selected from a group of material comprising a flexible plastic, like elastomers and combination thereof.

3. The improved venting system as claimed in claim 1 and 2, wherein said attaching means is coupled to said electrical circuit breaker (1) to fix said at least one vent (2) firmly with said electrical circuit breaker (1).

4. The improved venting system as claimed in claim 1 and 2, wherein said close position of said two ribs (7) prohibits external material to enter in said electrical circuit breaker (1).

5. The improved venting system as claimed in claim 1, 2 and 4, wherein said close position is a normal position of said two ribs (7), wherein said rotatable end of two ribs (7) are in contact with each other.

6. The improved venting system as claimed in claim 1, 2, 4 and 5, wherein said two ribs (7) are rotatable about a longitudinal axis at an angle between 0 degrees and more than 90 degrees relative to said fixed end of said ribs (7), wherein said two ribs are co-axially positioned along said longitudinal axis defined by said at least one vent (2).

7. The improved venting system as claimed in claim 1, 2, 4, 5, and 6, wherein rotation of said two ribs (7) is limited to 0° to more than 90°.

8. The improved venting system as claimed in claim 1, wherein in said open position said rotating end of said two ribs (7) are pushed out to expel said arc products generated during fault clearance in said electrical circuit breaker (1).