Claims:1. A molded case circuit breaker comprising:
a contact system (1) comprising current carrying elements and arc quenching elements (116), enclosed together inside molded cassettes (111, 112, 122, 123) to form pole assemblies (11, 12) which includes central pole assembly (11) and at least two outer pole assemblies (12), wherein said pole assemblies (11, 12) comprises at least two fixed contacts (113, 114) and a moving contact contained in a shaft assembly (115), wherein said shaft assembly is a compression spring based flip lockable arrangement, wherein said cassette (111, 112) comprises means (1121, 1151) to provide a bearing area for shaft means for pivoting said shaft assembly to minimize friction;
an operating mechanism (2) directly coupled with said pole assemblies (11, 12) simultaneously by means of mounting screw means (121) having a shank diameter equal to thread diameter to restrict vibrations of said operating mechanism during operation, wherein said operating mechanism includes a mechanism knob (23) with an extended knob (231) assembled with a double cover arrangement (24, 25) for ingress protection;
a release assembly (3) consists of sub-assemblies for detecting abnormal condition in the power system and issuing desired trip command to said operating mechanism; and
a chassis (4, 42) assembled with arrangement of said operating mechanism (2) with said contact system (1) forming an outermost structure to cover internal parts of said breaker for operator safety and/or to house internal accessories.
2. The molded case circuit breaker as claimed in claim 1, wherein said operating mechanism (2) includes at least two lower link means (21) to transfer operating mechanism force to said central pole assembly (11).

3. The molded case circuit breaker as claimed in claim 2, wherein said operating mechanism (2) assembled with said central pole assembly (11) by passing through at least two drive shaft pins (22) through said lower link means.
4. The molded case circuit breaker as claimed in claim 1, wherein said two outer pole assemblies are coupled together by means of at least two through pin means (125) adapted to pass through said shaft assembly (115) of central pole assembly (11).
5. The molded case circuit breaker as claimed in claim 4, wherein said through pins (125) couple with said operating mechanism by means of insulating coupler (124) to provide electrical insulation of said mechanism.
6. The molded case circuit breaker as claimed in claim 1, wherein said shaft (115) upon rotation enables said moving contact to touch said fixed contacts simultaneously, and with rotation in reverse direction said moving contact loses contact with said fixed contacts.
7. The molded case circuit breaker as claimed in claim 6, wherein said central pole assembly comprises:
arc chute means (116) to cover the trajectory of said moving contact rotation;
a magnetic shield means (117) placed between a curve profile of said fixed contacts, to reduce effect of forces between a lower link means of said fixed contact and said moving contact;
a nut plate means (118) trapped inside said cassettes (111, 112) and forms means for electrical connection along with release electrical connection screw means (119), wherein said nut plate sandwich said fixed contact and a conductor from said release assembly (3) and ensures required contact pressure.
8. The molded case circuit breaker as claimed in claim 7, wherein said release electrical connection screw means (119) is covered by chassis (42) for operator safety.
9. The molded case circuit breaker as claimed in claims 1-8, wherein said pole assembly (11, 12) comprises an arrow markings on shaft coupler (130) and a scale marking (1211) on said cassettes (111, 112, 122, 123), for visual indication of said shaft (115) position with respect to said cassettes.
10. A pole assembly in a molded case circuit breaker (MCCB) as claimed in claims 1-9, comprising:
at least two cassettes (111, 112) adapted to house internal components of said MCCB, wherein at least two fixed contacts assembled in respective cavities of said cassettes (111, 112), wherein said cassettes (111, 112) riveted together to restrict movements of said internal components;
a shaft assembly (115) including a moving contact and hinged in said cassettes (111, 112) allowing said shaft assembly to rotate along its axis, wherein said shaft assembly (115) is a compression spring based flip lockable arrangement, wherein said cassettes (111, 112) comprises means (1121, 1151) for pivoting said shaft assembly to minimize friction;
at least one arc chute assembly (116) to cover the trajectory of said moving contact rotation;
at least one magnetic shield means (117) placed between a curve profile of said fixed contacts, to reduce effect of forces between a lower link means of said fixed contact and said moving contact;
a nut plate (118) trapped inside said cassettes (111, 112) and forms means for electrical connection along with one or more release electrical connection screw means (119), wherein said nut plate sandwich said fixed contact and a conductor from said release assembly (3) and ensures required contact pressure.
, Description:TECHNICAL FIELD OF THE INVENTION

[001] The present subject matter described herein, in general, relates to circuit breakers, and more particularly relates to the arrangement of a molded case circuit breaker with electric pole assembly of contact system.

BACKGROUND OF THE INVENTION

[002] Molded case circuit breakers (MCCB) are circuit breakers whose current carrying parts, mechanism and trip devices are all completely contained within a molded case of insulating material. The molded case circuit breakers are designed to provide circuit protection for low voltage distribution systems which protects connected devices against both overload and short circuit conditions.

[003] The MCCB comprise one or more electric poles, which constitute the interruption section of the circuit breaker. Each pole comprises at least one arc chute and two electric contacts: a fixed contact and a moving contact, which can be mutually coupled/uncoupled; in turn, the contacts are connected electrically to the phase or neutral conductor associated with said pole by virtue of appropriate connection terminals.

[004] These molded case circuit breakers can be divided into four main structural sub-assemblies:
1. contact system assembly: which consists of different poles for each phase coupled together,
2. Operating mechanism assembly: which drives the breaker. It is the user interface which allows user to toggle between states of the breaker (i.e., between ON, OFF & TRIP are states of the breaker);
3. Release assembly: which trips the breaker under abnormal operating conditions.
4. Other parts forming outer body: which comprises of the outer periphery of the breaker and also to protect the user from internal parts of the breaker.
[005] For some existing arrangement of molded case circuit breakers, reference is made to US7116194 B2 which relates to an electric pole for a low voltage power circuit breaker which consists of an insulating enclosure that has a lower wall, an upper wall , two sides , a rear wall and a front wall .It consists of one fixed contact and at least one moving contact that can be mutually coupled/uncoupled and insulating enclosures , a first half shell and a second half shell are mutually coupled along corresponding coupling surfaces that form a self-supporting structure.

[006] Reference is also made to US 5298874A which discloses a modular low voltage multipole circuit breaker, including a plurality of identical single-pole breaking units each including a parallelipipedic insulating box having two opposite parallel large side faces and two opposite parallel small side faces, a stationary contact electrically connected to one of the terminals , a moveable contact co-operable between a first position contacting the stationary contact and a second position separated from the stationary contact and a molded case for housing the single-pole breaking units.

[007] Further, reference is also made to US6377144, which discloses a molded case circuit breaker housing which employs a tri-furcated design that imparts structural stability and manufacturing efficiency. The design provides a separate top cover, mid cover and base wherein the mid-cover wall height to base wall height ratio is such that the stresses imparted upon the base sidewalls when the pressures are exerted.

[008] However, the inventors of the present invention felt a need to provide an improved arrangement of molded case circuit breaker arrangement over the designs of the prior art, that can reduce operating mechanism vibration, electrical insulation, ingress protection, operator safety etc.

SUMMARY OF THE INVENTION

[009] 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.

[0010] An object of the present invention is to provide an arrangement of a molded case circuit breaker which consists of different cassette assembly for central pole and outer pole which are stacked using special type of screws to restrict operating mechanism vibrations.

[0011] Another object of the present invention is to provide a cassette arrangement which consist of shafts which are compression spring based flip lockable arrangement.

[0012] Yet another object of the present invention is to provide an operating mechanism which is directly coupled with minimum three poles avoiding the transmission of rotation loss from one pole to another

[0013] Another object of the present invention is to provide a double cover arrangement in the circuit breaker to provide ingress protection.

[0014] Yet another object of the present invention is to provide an arrangement of molded case circuit breaker wherein the release electrical connection screw is covered by chassis for operator safety.

[0015] Still another object of the present invention is to provide an arrangement of molded case circuit breaker wherein the extended knob forms safety feature for removal of front cover.

[0016] Accordingly to one aspect, the present invention provides a molded case circuit breaker comprising:
a contact system comprising current carrying elements and arc quenching elements, enclosed together inside molded cassettes to form pole assemblies which includes central pole assembly and at least two outer pole assemblies, wherein said pole assemblies comprises at least two fixed contacts and a moving contact contained in a shaft assembly, wherein said shaft assembly is a compression spring based flip lockable arrangement, wherein said cassette comprises means for pivoting said shaft assembly to minimize friction;
an operating mechanism directly coupled with said pole assemblies simultaneously by means of mounting screw means having a shank diameter equal to thread diameter to restrict vibrations of said operating mechanism during operation, wherein said operating mechanism includes a mechanism knob with an extended knob assembled with a double cover arrangement for ingress protection;
a release assembly consists of sub-assemblies for detecting abnormal condition in the power system and issuing desired trip command to said operating mechanism; and
a chassis assembled with arrangement of said operating mechanism with said contact system forming an outermost structure to cover internal parts of said breaker for operator safety and/or to house internal accessories.

[0017] In another aspect of the present invention, there is provided an pole assembly in a molded case circuit breaker (MCCB) as mentioned above, comprising:
at least two cassettes adapted to house internal components of said MCCB, wherein at least two fixed contacts assembled in respective cavities of said cassettes, wherein said cassettes riveted together to restrict movements of said internal components;
a shaft assembly including a moving contact and hinged in said cassettes allowing said shaft assembly to rotate along its axis, wherein said shaft assembly is a compression spring based flip lockable arrangement, wherein said cassettes comprises means for pivoting said shaft assembly to minimize friction;
at least one arc chute assembly to cover the trajectory of said moving contact rotation;
at least one magnetic shield means placed between a curve profile of said fixed contacts, to reduce effect of forces between a lower link means of said fixed contact and said moving contact;
a nut plate trapped inside said cassettes and forms means for electrical connection along with one or more release electrical connection screw means, wherein said nut plate sandwich said fixed contact and a conductor from said release assembly and ensures required contact pressure.

[0018] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[001] 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:

[002] Figure 1 illustrates module wise exploded view of complete breaker assembly, according to one embodiment of the present invention.

[003] Figure 2 illustrates the exploded view of single pole assembly according to one embodiment of the present invention.

[004] Figure 3 illustrates a central pole assembly according to one embodiment of the present invention.

[005] Figure 4 illustrates an outer pole assembly according to one embodiment of the present invention.

[006] Figure 5 illustrates a single pole assembly showing shaft position marking, according to one embodiment of the present invention.

[007] Figure6 illustrates an exploded view of pole and operating mechanism assembly according to one embodiment of the present invention.

[008] Figure 7 illustrates pole and operating mechanism assembly, according to one embodiment of the present invention.

[009] Figure 8 illustrates a contact system and mechanism assembly, according to one embodiment of the present invention.

[0010] Figure 9 illustrates a housing and mechanism contact assembly (mech-contact assembly) according to one embodiment of the present invention.

[0011] Figure 10 illustrates the complete arrangement of the mech-contact assembly with housing according to one embodiment of the present invention.

[0012] Figure 11 illustrates Chassis Assembly with mech-contact assembly, according to one embodiment of the present invention.

[0013] Figure 12 illustrates Release assembly with mech-contact assembly and outer components according to one embodiment of the present invention.

[0014] Figure 13 illustrates the Release and Front Cover assembly according to one embodiment of the present invention.

[0015] Figure 14 illustrates the Accessory Layout according to one embodiment of the present invention.

[0016] Figure 15 illustrates the Accessories Insertion in chassis according to one embodiment of the present invention.

[0017] Figure 16 illustrates Skin and Extended Knob assembly according to one embodiment of the present invention.

[0018] 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

[0019] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0020] 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 of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0021] 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.

[0022] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] In one implementation, as shown in figure 1, the molded case circuit breakers (referred herein as MCCB or breaker) can be divided into four main structural sub-assemblies such as:
1. Contact system (1) consists of current carrying elements of the breaker .current carrying elements are along with arc quenching elements are enclosed together inside molded cassettes to form a pole assembly, wherein the contact system can include two stable states:
? Contacts open (not touching each other) referred as OFF condition of breaker; and
? Contacts close (touching each other) referred to as ON condition of breaker.
2. Operating mechanism (2) which is coupled with shaft assembly of contact system and is used for transition between states and keep contact system stable in one state .It consist of user interface parts that allows the user to toggle between the breaker states with the help of mechanical input.
3. Release assembly (3) which consist of sub-assemblies used for detecting abnormal condition in the power system and issuing desired trip command to the operating mechanism.
4. Outer body parts (4) that form the outermost structure of the breaker and are used to cover internal parts for operator safety and some of which are used to house internal accessories.

[0027] In one implementation, referring to figure 2, a pole assembly of the contact system has been described which forms the most basic assembly of the breaker. The single pole assembly consist of two cassettes 111, 112 to house all other components having fixed contacts 113,114 which are assembled in respective cavities in the cassettes. The cassettes 111, 112 are riveted together, which then restricts the movements of the internal components. The moving contact can be part of the shaft assembly 115 which also includes compression spring based flip locking mechanism, wherein said shaft assembly is hinged in the cassette 111, 112 allowing it to rotate along its axis.

[0028] In one implementation, as shown in figure 3, the cassette is having features 1121, 1151which provides the bearing area for shaft. The bearing area provided the location of the shaft with the cassette for pivoting to minimize the friction of the shaft assembly with cassettes .The spring mechanism opposes the repulsion force in normal condition and assists the repulsion force during short circuit. The shaft assembly include features to compensate for loss (erosion) of material from contact buttons due to operations or short circuits .The moving contact contained in the shaft 115 upon rotation touches both the fixed contacts simultaneously and with rotation in the reverse direction it loses contact with the fixed contacts.

[0029] In one implementation, as shown in figure 2, arc chutes 116 are placed such that they cover the trajectory of the moving contact rotation. Magnetic shied 117 are placed between the curve profile of fixed contacts, in order to reduce the effect of forces between the lower link of the fixed contact and the moving contact .Nut plate 118 is trapped inside the cassettes and it forms means of electrical connection along with screw 119, wherein said nut plate 118 and the release electrical connection screw means 119 sandwich one fixed contact and conductor coming from release assembly 3 and ensures required contact pressure. After assembling all these components the two cassettes 111, 112 can be riveted together with the help of at least three rivets and after riveting complete pole assembly is formed.

[0030] In general, all the poles of the breaker are identical. However, in the present invention, the pole on which mechanism is mounted is different when compared with rest of the poles, which are identical. Pole assembly on which mechanism is mounted is referred as central pole assembly (11) (as shown in figure 3) and other identical pole assemblies are referred as outer pole assembly (12) (as shown in figure 4). Major difference between central pole assembly (11) and outer pole assembly (12) is their respective cassettes. Internal components of outer pole assembly are exactly similar to that of central pole, except that an additional nut plate is entrapped between cassettes.

[0031] In implementation, referring to figure 5, a single pole assembly (11, 12) having unique feature for visual indication of shaft 115 position with respect to cassettes 111, 112 ,122, 123 has been described. An arrow marking on the shaft coupler is indicated by 130 and scale markings on cassettes 111, 112, 122 and 123 are indicated by 1211. In normal condition when the breaker is in a stable condition, the shaft 115 will rotate by certain fixed angle and attain its fixed position , which can be visually marked on the breaker in case of any defects.

[0032] In one implementation, referring to figures 6 and 7, which illustrates the arrangement of operating mechanism assembly 2 with central pole assembly 11. There are at least two drive shaft pins 22 which are passed through the two lower links 21 of the operating mechanism 2.These two lower links 21 as shown in figure 6, facilitate means to transfer the operating mechanism 2 forcing it towards pole 11. The mechanism is then rigidly fixed on the pole 11 with two mounting screws 121 as shown in figure 9 explained in the below paragraphs. The mounting screws means 121 are special type of screws having their shank diameter equal to thread diameter which helps in reducing the clearance between mounting screws 121 and pole 11 and operating mechanism 2 restricting vibrations of the operating mechanism 2 during operations, which may result in tripping of mechanism 2. These screws 121 can be same as those used for connecting all poles together and needed to be removed further for assembling more poles with this assembly. Features 1112 are provided in the cassettes of the central pole as shown in figure 7.

[0033] In one implementation, as shown in figure 8, for coupling outer poles 12 with this assembly, two through pins 125 are assembled which pass through the shaft 115 of the central pole 11 and protrude out on both end allowing coupling of outer poles 12 from both the ends. Two components 124 made of insulating material are assembled on the through pins 125 and positioned in between the central pole 11 and outer pole 12 acting as through pin sleeve. The central pole assembly 11 along with the outer pole assembly 12 forms the contact system 1 of the present invention.

[0034] The outer poles 12 can be joined from both ends and their shafts 115 can be coupled together by means of through pins 125 thereby providing alignment to the shaft 115 of all the poles. The drive shaft pins 22 as shown in figure 7 are also coupled with the remaining two outer poles 12. As the operating mechanism 2 is directly coupled with all the three poles simultaneously, any loss of rotation in any of the poles is not transferred to other pole.

[0035] In one implementation, two spacers 126 can be assembled between the central pole 11 and outer pole 12 as shown in figure 8. Thermal magnetic release resetter 128 can be assembled between the central pole and outer pole as shown in figure 9. One of the inter poles screw 121 passes through the outer pole 12, mechanism assembly 2, resetter 128 and outer pole 12. All the poles are then rigidly fixed with the help of four screws 121 and nuts 1212, two of these screws form means for fixing operating mechanism 2 with the contact system 1. An actuator 127 is hinged on operating mechanism 2 as shown in figure 9. Knob 23 can be fitted with the operating mechanism 2 and acts as a user interface for operating the breaker. The operating mechanism assembly 2 along with the contact assembly 1 forms a mech-contact assembly. Bottom cover 41 can be assembled to the mech-contact assembly from the bottom and fixed with the help of screws 411 (shown in figure 10) and nuts 129.

[0036] In one implementation, referring to figure 11, wherein a chassis 42 contains cavities designed to house accessories. The L shaped nuts 421, as shown in figure 10, can be fixed on the outer pole 12 cavities .These L shaped nuts help to fix the chassis 4 with the mech-contact assembly. The actuators which are required to actuate and reset the accessories are assembled in the chassis 42. The chassis 42 when assembled with the mech-contact assembly as shown in figure 11, the portion 422 gets engaged with poles 11, 12 in forming venturi type construction in the channel for disposal of gases. This type of construction helps in channelizing the gases at a faster pace and also prevents any gases from going to the termination region which may result in flash over during short circuit conditions. After the chassis gets fixed, it is tightened with the help of four screws 423 as shown in figure 11.

[0037] In one implementation, the release electrical connections screws 119 (as shown in figures 2, 3) join fixed contact 114 with release conductor of each pole separately. Chassis 42 includes features to cover these screws 119 so as to provide operator with protection against electrical shocks.

[0038] In one implementation, as shown in figure 12, the release assembly can be fixed to contact system with the help of at least two screw means 31 .The nuts 311, as shown in figure 8, are trapped between the central pole 11 and outer pole 12 during mechanism contact assembly. The release assembly is further fixed to the chassis 42 with the help of screws 423 and two nuts 425, as shown in figure 14, which are located on the chassis 42. The release assembly can be either thermal magnetic type or microprocessor based type and both can be used interchangeably.

[0039] In one implementation, a mechanism knob 23, as shown in figure 16, will be assembled with a cover 24 for ingress protection. The front cover 43, as shown in figure 13, is assembled with a cover 25 for ingress protection (IP). The IP cover 25 can be assembled in the slot of the front cover and the front cover 43 can be assembled with the help of four self-tapping screw means 431 which gets locked in the chassis 42 after tightening.

[0040] In another implementation, referring to figure 14 , wherein an accessory layout showing different cavities in chassis 42 which is designed for mounting accessories .The cavity 422 is for under voltage /shunt release. The cavity 423 is used as a tripping medium for flux shifting device along with microprocessor based release .The flux shifting device is fixed in the cavity 423 with the help of self-tapping screws .Two cavities are provided for auxiliary contacts and transportation accessories.

[0041] In one implementation, referring to figure 15, which illustrates an UV or shunt release 45 is fixed with the help of a screw and auxiliary contacts 46 are assembled in the chassis with the help of a screw means.

[0042] In one implementation, referring to figure 16, wherein the mechanical assembly of the skin 432 and extended knob with the whole breaker is shown .The skin 432 is attached with the front cover 43 with the help of snap fits .The extended knob has been provided for the ease of operation for the customer .The extended knob 231 is fixed with the knob 23 with the help of screw. Nut 321 is trapped into the nut retainer 32 (as shown in figure 13) which can be assembled in the termination region of release assembly 3 as well as contact system 1, which helps in direct termination of bus bars and cable lugs .The nut retainer 32 can be click fitted with the assembly and for different termination type requirement the nut retainer 32 can be replaced with other ones that are suitable for the termination types used.

[0043] Some of the noteworthy features of the present invention, are as follows:
? Shaft assembly is compression spring based flip lockable arrangement.
? Cassette has special features for pivoting the shaft to minimize friction.
? Visual indication of shaft position with respect to cassette.
? Operating mechanism is directly coupled with minimum three Poles avoiding transmission of rotation loss from one pole to another.
? Shafts coupled together by means of two through pins which are coupled with operating mechanism by an insulating coupler which also ensures electrical insulation of mechanism.
? Use of special type of screws to restrict operating mechanism vibrations
? Different cassette assembly for central pole & outer pole.
? Double cover arrangement for ingress protection.
? Release electrical connection screw is covered by chassis for operator safety.
? Extended Knob forms Safety feature for removal of Front Cover.

[0044] Some of the non-limiting advantages of the present invention, are as follows:
• The assembly of the present invention provides extended knob that forms safety features for the removal of front cover
• The other attractive characteristics of the arrangement of molded case circuit breaker includes the operating mechanism which is directly coupled with minimum three poles to avoid transmission of rotation loss from one pole to another.
• In the present invention, the upper wall is enclosed with the help of double cover arrangement (i.e., front cover and skin) and the rear and the side of the circuit breaker is covered by an insulating cover called as housing for ingress protection.
• The present invention consists of different cassette assembly for central pole and outer pole and are stacked using special type of screws to restrict operating mechanism vibrations.
• The cassette arrangement consists of shafts which are compression spring based flip lockable arrangement.
• The ingress protection is provided by the double cover arrangement.
• The release electrical connection screw is covered by chassis for operator safety.
• Extended knob forms safety feature for removal of front cover.

[0045] Although an arrangement of molded case 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 of the arrangement of molded case circuit breakers.