Claims:1. An indication mechanism for earth leakage fault indication in residual current circuit breakers (RCCB) 101, the said mechanism comprising:
a slot on the cover for RCCB to indicate earth fault;
an indication means comprising a lever link and a flag area with color codes; and
a plunger assembled to a PMR assembly with permanent magnetic relay;
WHEREIN
during leakage fault, the core balanced current transformer (CBCT) of RCCB actuates the permanent magnet relay adapted to continuously compare the input leakage current received from the CBCT with a predetermined threshold and consequently move the plunger linearly resulting in de-latching of PMR assembly to trip the RCCB and also to provide an impact force to actuate the said indication means to display the corresponding color code for earth leakage fault in the said slot of the cover of RCCB.

2. The mechanism as claimed in claim 1, wherein the indication means is a link consisting of indication flag with different color codes corresponding to the detection of earth leakage fault.

3. The mechanism as claimed in claim 1, wherein the said core balanced current transformer is adapted to provide signal proportional to the amount of leakage current.

4. The mechanism as claimed in claim 1, wherein the said lever link rotates to turn the indication flag area.

5. The mechanism as claimed in claim 1, wherein the said flag area is color coded in White and Yellow.

6. The mechanism as claimed in claim 1, wherein the color code is changed when the tripping mechanism is reset.
, Description:TECHNICAL FIELD OF THE INVENTION

The present subject matter described herein, in general, relates to circuit breaker and more specifically, to an indication mechanism for earth fault indication in residual current circuit breakers

BACKGROUND OF THE INVENTION

Circuit breakers are conventionally used to protect electric power distribution circuits against arcing faults, ground faults, short circuit faults, and/or overloads. RCCBs are used to interrupt the circuit in case of an earth leakage fault. An RCCB in particular is used to detect the presence of a leakage current in the circuit and trip in case the value of the leakage current goes beyond a threshold value. A residual current circuit breaker (RCCB) is expected to trip when an earth leakage fault occurs. The operating knob of the RCCB can switch to OFF position either due to presence of an earth leakage fault or due to manual tripping.

When a RCCB trips, it is advantageous to know whether the breaker has tripped on an earth fault or not. This helps in taking rapid corrective action to eliminate the source of fault. The operating knob of the circuit breaker switches to OFF state when the RCCB clears an earth leakage fault. However, the knob can be manually switched OFF too. Thus mere position of operating knob doesn’t provide clear indication about whether the circuit breaker has experienced an earth leakage fault or it has been manually switched OFF. Thus, it is required to have an indication means that clearly indicate that circuit breaker has cleared an earth leakage fault.

In prior art documents, CN 201868358 U patent discloses a dual indication of leakage circuit breakers, comprising a handle, trip, leakage indicator and contact base, the handle and contact base linkage with the tripping device and the drain indication linkage, wherein the contact seat is fixed movable contact, characterized in that: said contact holder is fixed part off indicator. It solves the problem that the present residual current circuit breaker has poor safety and a single function. It provides the function of indication by linking indication device with the contacts.

In prior art documents, CN 203434103 U patent discloses an earth leakage circuit breaker tripping indication means, consisting of a trip arm, return spring, drive block, trip rod, push plate, L-type baffle and contact plate. This provides a solution to the existing complex structure of trip mechanism, slow tripping, poor stability, and the assembly difficulty.

However, various indication means of leakage circuit breakers are available, but none provide a means to distinguish between an earth fault tripping and manual tripping. Thus, there is a need to provide an indication mechanism for specific earth fault indication in residual current circuit breakers, which is reliable.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

Accordingly, the object of the present invention is to overcome the drawbacks of prior art.

It is another object of the present invention is to provide an indicator means for earth fault indication in residual current circuit breakers.

It is another object of the present invention is to provide an indicator means for distinguishing tripping of RCCB on earth fault from manual tripping.

It is yet another object of the present invention to provide a means to provide indication of earth fault based on permanent magnet relay.

It is still another object of the present invention is to provide true and reliable indication mechanism for earth fault indication in residual current circuit breakers.

According to the present invention, the foregoing and other objects and advantages are attained by providing an indication mechanism for earth leakage fault indication in residual current circuit breakers (RCCB), the said mechanism comprising:
a slot on the cover for RCCB to indicate earth fault;
an indication means comprising a lever link and a flag area with color codes; and
a plunger assembled to a PMR assembly with permanent magnetic relay;
WHEREIN, during leakage fault, the core balanced current transformer (CBCT) of RCCB actuates the permanent magnet relay adapted to continuously compare the input leakage current received from the CBCT with a predetermined threshold and consequently move the plunger linearly resulting in de-latching of PMR assembly to trip the RCCB and also to provide an impact force to actuate the said indication means to display the corresponding color code for earth leakage fault in the said slot of the cover of RCCB.

Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

Figure 1 illustrates the Front view, side view and Isometric view of a RCCB.

Figure 2 illustrates the Front and Isometric view of a PMR, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates the Front view, side view and Isometric view of an Indicator link, in accordance with an embodiment of the present subject matter.

Figure 4 illustrates the Front side and isometric view of open RCCB assembly with indication link, in accordance with an embodiment of the present subject matter.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

The terms and words used in the following description and claims 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 as defined by the appended claims and their equivalents.

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.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

The present invention relates to an indication mechanism for earth leakage fault indication in circuit breakers. More specifically to an indication mechanism which may distinguish between tripping of an RCCB on earth fault from manual tripping.

It provides an indication means or link consisting of indication flag with different color codes corresponding to the detection of earth leakage fault and adapted to directly actuate on receiving signals form permanent magnet relay.

An RCCB in particular is used to detect the presence of a leakage current in the circuit and trip in case the value of the leakage current goes beyond a threshold value. A core balanced current transformer is used to detect the presence of the leakage current. In case of a leakage, the core balanced current transformer generates an output that is proportional to the amount of leakage that is produced in the system. The output of the core balanced current transformer is fed to a permanent magnet relay. When the leakage current exceeds a predetermined threshold, the permanent magnet relay triggers the mechanism and it interrupts the circuit. The present invention uses this trigger to indicate the tripping on occurrence of an earth leakage fault.

In one embodiment, the present invention provides an indication mechanism for earth leakage fault indication in residual current circuit breakers (RCCB). The said mechanism comprising: a slot on the cover for RCCB to indicate earth fault; an indication means comprising a lever link and a flag area with color codes; and a plunger assembled to a PMR assembly with permanent magnetic relay.

Referring now to Figure 1 which illustrates front view, side view and the isometric view of an RCCB (101). The RCCB assembly consists of Housing (102) and Cover (103). The cover is visible from the front of the RCCB. The operating knob (104) is used to switch ON and switch OFF the RCCB. A test button (105) is used to test the RCCB periodically. The cover also consists of a rectangular transparent slot (106) from which the Earth Fault indication will be visible from outside.

In an embodiment, when the RCCB detects the earth fault / leakage current in the system, the CBCT (Core balanced current transformer) gives an output signal to the permanent magnet relay (201). The permanent magnet relay has a mechanical construction such that it constantly compares the amount of input received from CBCT. Once this value reaches a predetermined threshold, a plunger (202) which is assembled in the Permanent Magnet Relay (PMR) assembly translates linearly and strikes the indicator link (301). This linear translation of the plunger is also used to de-latch the mechanism assembly and ultimately trip the tripping mechanism of the RCCB. On receiving impact from the plunger, the indication link rotates along the rotation axis (302). The indication link consists of an indication flag (303). When the indication link rotates, the indication flag correspondingly rotates. The flag area of the indication link is color coded in White (303(a)) and Yellow (303(b)). When the indication link rotates due to a strike from the PMR plunger, the flag correspondingly rotates to Yellow. As soon as the tripping mechanism is reset, the flag area changes back to White. These colored indication flags are visible from the rectangular transparent slot present in the cover.

Referring now to figure 2 which illustrates the PMR assembly. The PMR assembly consists of a plunger coupled to a magnet relay. The plunger is adapted to de-latch the mechanism assembly, thus trip the tripping mechanism of the RCCB. The plunger is also adapted to provide rotational motion to the indication means.

In an embodiment, the indication means is adapted to provide a link between the permanent magnet relay and the indication flag with different color codes corresponding to the detection of earth leakage fault. These color codes may be changed when the tripping mechanism is reset.

Referring now to figure 3 which illustrates the indication means. The indication means comprises of a link, a flag means and an attachment means capable of rotational motion.

In an embodiment, the actuation of the indication link is only dependent upon the strike from the Plunger. The indication link is actuated only when there is an earth leakage fault. Normal Switch ON and Switch OFF process of the mechanism do not rotate the indication link.

Apart from the advantages and benefits mentioned above, other advantages and benefits are mentioned below:
• The present invention is reliable;
• The present invention provides true indication of the earth fault as it is a result of direct actuation from permanent magnet relay;
• The present invention provides indication of earth fault from outside on the unit.

The illustrations of arrangements described herein are intended to provide a general understanding of the structure of various embodiments, and they are not intended to serve as a complete description of all the elements and features of apparatus and systems that might make use of the structures described herein. Many other arrangements will be apparent to those of skill in the art upon reviewing the above description. Other arrangements may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Figures are also merely representational and may not be drawn to scale. Certain proportions thereof may be exaggerated, while others may be minimized. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

Thus, although specific arrangements have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific arrangement shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments and arrangements of the invention. Combinations of the above arrangements, and other arrangements not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.