DESC:TECHNICAL FIELD

The present subject matter described herein, in general relates to a low voltage switchgear applications and more particularly, to a miniature circuit breaker and circuit breakers, using both alternating current and direct current source, and where current limiting principle is used.

BACKGROUND

In low voltage distribution system, circuit breakers provide rapid and reliable protection against both overload and short-circuit currents. The overload protection module consist of bimetallic element as an actuator and short-circuit protection module consist of coil and armature as an actuator. Signal from both these modules will be given to the mechanism for opening the contacts, thereby interrupting the circuit during abnormal condition.

When a circuit breaker is subjected to short circuit fault, the contacts start separating and an arc is struck across the contacts. Contact opening is facilitated by the repulsive forces acting on the contacts and the armature actuator force exerted by the short circuit protection module through the mechanism. The electromagnetic forces and gas dynamic forces developed by the arc pushes the arc towards the arcing chamber and will then finally quench it. The time taken by the contacts to sense the fault to the instant final quenching occurs is generally called as arcing time. The total arcing time can be divided in to four phases as initiation time, immobility time, running time and splitting time. Efficient contact system design and improved breaking can be achieved if total arcing time and energy let through is very less.

So there exists a need to provide a better and reliable protection by switchgear products with high breaking capacities. This calls for some improvements from the existing method of circuit breaking technique. This can be achieved by efficient blow out techniques using magnetically permeable materials or permanent magnets. Further, the use of permanent magnets makes the breaker polarity dependent. Hence there is also a need to deal with deals with the use of magnetic materials for achieving better breaking performance. Improving the breaking performance of alternating current power source will also have a positive impact on the direct current performance.

SUMMARY

This summary is provided to introduce concepts related to an improved circuit breaking technique for miniature circuit breaker. This summary is not intended to identify essential features of the subject matter nor is it intended for use in determining or limiting the scope of the subject matter.

In one implementation, a miniature circuit breaker and circuit breakers, using both alternating current and direct current source, and where current limiting principle is used is, disclosed.

In one implementation, a better and reliable protection by switchgear products with high breaking capacities is disclosed.

In one implementation, an improved circuit breaking technique is disclosed.

In one implementation, the use of magnetic materials for achieving better breaking performance is disclosed.

In one implementation, the breakers which operate on both alternating current (AC) and direct current source (DC) and where faster arc quenching is required are disclosed.

In one implementation, the purpose of the disclosed invention is to protect the appliances and equipments from damage using circuit breakers to sense the fault in an earlier stage and quench the arc at lower current with lesser time, which leads to lower energy let through. Improved breaking using present invention can help in this regards.

The Miniature circuit breakers are used for both AC and DC applications. For a same fault current, the breaking is comparatively easier for AC, as DC depends on the time constant. Higher time constants cause the fault current to build slowly, which indirectly decreases the electromagnetic forces acting on the arc and increases the breaking time. Many DC applications use permanent magnets to enhance the magnetic forces acting on the arc column, which will make the breaker polarity dependent.

Hence the disclosed invention includes a technique which will enhance the electromagnetic force acting on arc in spite of the current direction and helps in achieving lesser breaking time with lower energy let through.

In one implementation, an improved circuit breaker characterized in that having a fixed runner (19) held in position behind the fixed contact (15) comprising: a base rested on a common breaker housing (2), a flat surface (24) on a magnetic core (18), and slanting surface (23) aligned to said fixed contact (15).

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 a miniature circuit breaker (1) arrangement in ON condition is shown, in accordance with an embodiment of the present subject matter.

Figure 2 illustrates the single break contact system is shown, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates the detailed contact system region is shown, in accordance with an embodiment of the present subject matter.

Figure 4 illustrates the isometric views of fixed runner (19) is shown, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

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, the breakers which operate on both alternating current (AC) and direct current source (DC) and where faster arc quenching is required are disclosed.

In one implementation, the purpose of the disclosed invention is to protect the appliances and equipments from damage using circuit breakers to sense the fault in an earlier stage and quench the arc at lower current with lesser time, which leads to lower energy let through. Improved breaking using present invention can help in this regards.

The miniature circuit breakers are used for both AC and DC applications. For a same fault current, the breaking is comparatively easier for AC, as DC depends on the time constant. Higher time constants cause the fault current to build slowly, which indirectly decreases the electromagnetic forces acting on the arc and increases the breaking time. Many DC applications use permanent magnets to enhance the magnetic forces acting on the arc column, which will make the breaker polarity dependent.

Hence the disclosed invention includes a technique which will enhance the electromagnetic force acting on arc in spite of the current direction and helps in achieving lesser breaking time with lower energy let through.

While aspects of a an improved circuit breaking technique for miniature circuit breaker may be implemented in any number of different breakers, environments, and/or configurations, the embodiments are described in the context of the following exemplary system.

In one implementation, an improved circuit breaker characterized in that having a fixed runner (19) held in position behind the fixed contact (15) comprising: a base rested on a common breaker housing (2), a flat surface (24) on a magnetic core (18), and slanting surface (23) aligned to said fixed contact (15).

In one implementation, a magnetic trip unit (4) which issues a trip signal to mechanism (5), in case of short circuit fault condition, and a contact system (27) to operate when fault current exceeds a rated value of breaker thereby forming a force that will be developed which pulls the contacts apart leading to arc formation, are provided.

In one implementation, the arc being developed is quenched using a running material (8) for arc to shift its root; and an arc chamber (10, 22) is provided where arc will be de-ionized.

In one implementation, said fixed runner (19) offers the flux a lower reluctance path until arc reaches the arc chutes (10) and improves repulsion forces acting on the contacts (15, 16) which aids in faster contact opening.

In one implementation, said improved circuit breaker operates using current limiting principle in breaking higher fault currents.

In one implementation, the fixed runner (19) is designed in such a way that, at every plane the flat surface (24) and slanting surface (23) of fixed runner may be in parallel to the plane of fixed contact (15).The fixed runner (19) may be of 1 mm thickness but may not limited to it, and made of mild steel material but may not limited to it. Further, a nickel coating may be provided to the said fixed runner (19).

Referring now to figure 1, illustrates a miniature circuit breaker (1) arrangement in ON condition is shown, in accordance with an embodiment of the present subject matter.

In one embodiment, figure 1 shows a miniature circuit breaker (1) arrangement in ON condition, which has a mechanism (5), thermal release unit (6), magnetic release unit(4), terminals(7, 11),box clamp (12,17) arranged in a common housing (2). Din clips (13, 14) help to mount the breaker in din rail system. It has a moving contact (16) which makes contact with fixed contact (15) for current continuity. Arc chute (10) quenches the arc. Slot motor (9) and arc runner (8) gives magnetic force to pull the arc towards arc chute (10).

The components used in the figure 1 are as follows:
1. Miniature circuit breaker
2. Housing
3. Knob
4. Magnetic release
5. Mechanism
6. Thermal release
7. Right terminal
8. Arc runner
9. Slot motor
10. Arc chute
11. Left terminal
12. Left box clamp
13. Left din clip
14. Right din clip
15. Fixed contact
16. Moving contact
17. Right box clamp

In one example, the circuit breaker clears severe short circuit fault currents and protects the equipments and appliances connected to it. The performance of a circuit breaker depends on the magnitude of the fault current it allows and the time up to which it is flowing through the breaker. So an efficient breaker should limit the magnitude of fault current through it i.e. to clear the fault well before the actual current reaches its prospective peak (current limiting) and it should quench the arc very fast. Present invention relates to miniature circuit breaker (1) which operates using current limiting principle in breaking higher fault currents.

Miniature circuit breaker (1) consists of a magnetic trip unit (4) which gives away the trip signal to mechanism (5), in case of short circuit fault condition. A contact system (27) is designed in such a way that, when fault current exceeds the rated value of breaker Lorentz force will be developed which will pull the contacts apart leading to arc formation. This way the first two phases of arcing, initiation and immobility can be addressed. The arc being developed need to be quenched at the earliest, this is addressed in the next two phases of arcing, running and quenching. This is achieved by introducing suitable running material (8) for arc to shift its root and also a proper arc chamber (10, 22) where arc will be de-ionized fully. For achieving better arc running and quenching time, the force developed across the arc column should be high enough to pull the arc towards arc chute (10).

The present invention looks in to these four phases of arcing and comes up with a concept to improve the arcing time of all phases.

Accordingly a magnetic material is introduced, a fixed runner (19), and a other mechanism (21) where the former one helps in improving the arc initiation and immobility phases, and the latter one helps in improving the arc running and quenching phases. During the normal short circuit conditions the required electromagnet force for the arc is achieved by the rotating flux developed across magnetic core (18), slot motor (9), arc runner (8), and arc chute (10).The flux developed due to the current flow in fixed contact (15) will get reduced due to current reversal. Present invention includes a magnetic material, fixed runner (19) held behind fixed contact (15) which can contain the orthogonal flux developed due to current reversal. This can drastically improve the arc force during the initial arcing phases.

Referring now to figure 2, illustrates the single break contact system is shown, in accordance with an embodiment of the present subject matter.

In one embodiment, the figure 2 shows the single break contact system considered. It has fixed contact (15) being connected to magnetic core (18), with a fixed button (20) on which arc will be formed. Other mechanism (21) and fixed runner (19) are being introduced to improve the arcing performance in the arcing zone (22). This total arrangement improves the arcing time.

The components used in the figure 2 are as follows:
8. Arc runner
9. Slot motor
10. Arc chute
15. Fixed contact
16. Moving contact
18. Magnetic core
19. Fixed runner
20. Fixed button
21. Other mechanism
22. Arcing zone
27. Contact system

Referring now to figure 3, illustrates the detailed contact system region is shown, in accordance with an embodiment of the present subject matter.

In one embodiment, the figure 3 shows the detailed contact system region which helps in the arc initiation and immobility times. It include magnetic materials like magnetic core (18), fixed runner (19), slot motor (9) along with current carrying fixed contact (15), fixed button (20) and moving contact (16).

The components used in the figure 3 are as follows:
9. Slot motor
15. Fixed contact
16. Moving contact
18. Magnetic core
19. Fixed runner
20. Fixed button

Referring now to figure 4, illustrates the isometric views of fixed runner (19) is shown, in accordance with an embodiment of the present subject matter.

In one embodiment, figure 4 shows the isometric views of fixed runner (19), fixed contact (15) and magnetic core (18) according to an embodiment of this invention

The fixed runner (19) in figure 4 is held in position behind the fixed contact (15). The base is rested on the common breaker housing (2) and its flat surface (24) on the magnetic core (18) with slanting surface (23) aligned to the fixed contact (15). Fixed runner (19) developed will offer the flux a lower reluctance path until arc reaches the arc chutes (10) and also enhance the repulsion force acting on the contacts (15, 16) which aids in faster contact opening.

The components used in the figure 4 are as follows:
15. Fixed contact
18. Magnetic core
19. Fixed runner
23. Slanting surface
24. Flat surface

In one implementation, the basic functioning of miniature circuit breaker remains the same with the new fixed runner (19) component also. But in the event of short circuit fault the velocity with which the moving contact opens up is increased nearly 20%, with the new fixed runner (19). Also the arc pull force is increased to about 15-20%, this is tested (simulated and validated) using simulation soft tool ANSYS.

Further, the fixed runner (19) provided helps to improve the arc initiation and immobility time. Post short circuit testing the arcing time comparison shows that arc initiation time and immobility is reduced nearly 10%, leading to the reduction in overall arcing time.

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, the contact system disclosed in the invention is a single break contact system.

One feature of the invention is that, the fixed runner provided behind the fixed contact acts as slot motor concentrates the rotational magnetic flux produced.

One feature of the invention is that, the fixed runner provided behind the fixed contact increases the contact repulsion force, which leads to higher contact opening velocity.

One feature of the invention is that, the introduction of the fixed runner very well improves the arc initiation and immobility time.

Yet another feature of the invention is that, the additional magnetic flux generated acts orthogonally to arc, pushing the arc towards arc chamber.

Still another feature of the invention is that, the invention leads to improved breaking performance, polarity independent breaker.

Still another feature of the invention is that, instead of permanent magnet, a magnetic material behind the flanges is used. Along with said magnetic material on the third side and behind the fixed contact. Since no permanent magnet, breaker not polarity dependent (Also called no load - line bias).Magnetic material behind the fixed contact also doesn't demands any change in appliance, only insertion of component in its slot.

Although the improved circuit breaking technique for miniature circuit breaker 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 an improved circuit breaking technique for miniature circuit breaker.
,CLAIMS:1. An improved circuit breaker (1) CHARACTERIZED IN THAT having a fixed runner (19) held in position behind the fixed contact (15) comprising: a base rested on a common breaker housing (2), a flat surface (24) on a magnetic core (18),and slanting surface (23) aligned to said fixed contact (15), wherein said flat surface (24) and said slanting surface (23) are configured to be in parallel to the a plane of said fixed contact (15).

2. The improved circuit breaker (1)as claimed in claim 1 comprises:
a magnetic trip unit (4) which issues a trip signal to mechanism (5), in case of short circuit fault condition; and a contact system (27) to operate when fault current exceeds a rated value of breaker thereby forming a force that will be developed which pulls the contacts apart leading to arc formation.

3. The improved circuit breaker (1)as claimed in claims 1 and 2, wherein the arc being developed is quenched using a running material (8) for arc to shift its root; and an arc chamber (10, 22) where arc will be de-ionized.

4. The improved circuit breaker (1) as claimed in claims 1-3, wherein said fixed runner (19) offers the flux a lower reluctance path until arc reaches the arc chutes (10) and improves repulsion forces acting on the contacts (15, 16) which aids in faster contact opening.

5. The improved circuit breaker (1) as claimed in claims 1-4 operates using current limiting principle in breaking higher fault currents.

6. The improved circuit breaker (1) as claimed in claims 1-5, wherein said fixed runner (19) is, of thickness with range varying between 0.1 mm to 1.5 mm, preferably of 1 mm thickness.

7. The improved circuit breaker (1) as claimed in claims 1-5, wherein said fixed runner (19) is made, of a magnetically permeable material having permeability greater than 1.5 Tesla, preferably of mild steel material.

8. The improved circuit breaker (1) as claimed in claims 1-5, wherein said fixed runner (19) is nickel or Zinc coated