Abstract:
An earth leakage breaker includes a main body housing having, in a single structure, a casing and a case cover, and an auxiliary cover for covering the case cover. The case cover has a recess for mounting an internal accessory device. Components including a main circuit contact, a contact switching mechanism, an operation handle, an overcurrent tripping device, an earth leakage detection circuit combined with a zero-phase current transformer, and an earth leakage tripping device, are retained in the main body housing. An earth leakage operation output switch is detachably mounted in the recess formed in the case cover of the main body housing. The earth leakage operation output switch is an internal accessory device that indicates earth leakage trip operation electrically and linking mechanically with the earth leakage trip device to operate the earth leakage operation output switch in the earth leakage trip operation.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
       [0001]    The present invention relates to an earth leakage breaker with overcurrent protection and ground fault protection functions in a low voltage distribution system. In particular, the invention relates to a structure for posterior mounting type earth leakage operation output switch, as an internal accessory device of an earth leakage breaker that electrically indicates an earth leakage trip operation of the earth leakage breaker. 
         [0002]    Known protection devices in a low voltage distribution system include a molded case circuit breaker and an earth leakage breaker. An earth leakage breaker produced in these days in Japan generally has an integrated structure assembling the parts for overcurrent protection function and the parts for ground fault protection function together in a single main body housing that has the same external dimensions as those of the molded case circuit breaker. 
         [0003]    Circuit breakers such as molded case circuit breakers and earth leakage breakers have various internal accessory devices including an auxiliary switch for electrical indication of ON, OFF states of a breaker, an alarm switch for indicating trip state, a voltage trip device and the like as optional devices in order to flexibly deal with a system change in the user side. The internal accessory devices can be installed to be taken out afterwards in a recess formed in a cover of a main body housing (for example, Patent Document 1). 
         [0004]    Conventional earth leakage breakers are normally equipped with an earth leakage indicating button of a pop-up type as a means for indicating the earth leakage trip operation (the indicator button projects from the cover of the main body housing in the earth leakage trip operation). Different from this means, an earth leakage operation output switch (a micro switch) for electrically indicating the earth leakage trip operation is installed in a known earth leakage trip device (for example, Patent Document 2).  FIGS. 16(   a ) and  16 ( b ) show an assembly structure of the prior art. 
         [0005]    Referring to  FIGS. 16(   a ) and  16 ( b ), the reference numeral  1  designates an earth leakage trip device mounted on a main body housing of the breaker. The earth leakage trip device has a structure wherein the essential components including a trip coil  3  (a plunger type electromagnet in combination of a retaining magnet and a driving spring), an earth leakage indicating button  4 , and an earth leakage operation output switch  5  responding to earth leakage trip operation are permanently installed in a unit case  2  (a molded resin casing). 
         [0006]    The earth leakage operation output switch  5  employs a micro switch with its actuator lever  5   a  arranged opposing a movable iron core  3   a  of the trip coil  3  in the unit case  2 . The movable iron core  3   a  of the trip coil  3  is driven in the direction of the arrow on receiving an earth leakage detection signal from an earth leakage detection circuit. Corresponding to the movement of the movable iron core  3   a , an actuating slider (not shown in the figures) strikes a trip crossbar of the breaker to trip a contact switching mechanism, and at the same time, the movable iron core  3   a  pushes an actuator lever  5   a  of the micro switch towards inside of the micro switch. As a result, a contact (a “make” contact) of the earth leakage operation output switch  5  turns ON to output an earth leakage operation signal. In  FIGS. 16(   a ) and  16 ( b ), the reference numeral  5   b  designates a plunger that transmits the movement of the actuator lever  5   a  to a movable contact of the micro switch. 
         [0007]    Patent Document 1: Japanese Unexamined Patent Application Publication No. H6-236726 (U.S. Pat. No. 5,581,219)(FIG. 1-3) 
         [0008]    Patent Document 2: Japanese Unexamined Patent Application Publication No. H9-63453 (FIGS. 1-3) 
         [0009]    Earth leakage breakers mounting the earth leakage trip device having the conventional structure as described above have following problems from a viewpoint of a user side. In the conventional structure shown in  FIGS. 16(   a ) and  16 ( b ), the earth leakage operation output switch  5  is fixedly installed in the casing of the earth leakage trip device  1  and engaged with the movable ion core  3   a  of the trip coil  3 , and the earth leakage breaker equipped with the earth leakage trip device  1  is shipped as a product incorporating the earth leakage operation output switch  5  at the time of shipment. 
         [0010]    For the users without using electrical indication of the earth leakage operation in the system employing an earth leakage breaker, the earth leakage operation output switch permanently incorporated in the earth leakage breaker deserves an excess specification. On the contrary, the users that purchased an earth leakage breaker with standard specification that is not equipped with an earth leakage operation output switch, cannot add an earth leakage operation output switch to the earth leakage breaker as it is. Consequently, these users can make a system including electrical indication of the earth leakage operation only by asking the manufacturer to exchange the earth leakage trip device for the one equipped with an earth leakage operation output switch, or by newly purchasing another earth leakage breaker with an earth leakage operation output switch. This is hardly dealt with by the users. 
         [0011]    In light of the above problems, it is an object of the present invention to provide an earth leakage breaker capable of indicating earth leakage operation by an electric signal, wherein a user can install later an earth leakage operation output switch as an optional internal accessory device similar to an auxiliary switch and an alarm switch, onto an earth leakage breaker of standard specification. The invention also provides a structure for mounting an earth leakage operation output switch afterwards. 
         [0012]    Further objects and advantages of the invention will be apparent from the following description of the invention. 
       SUMMARY OF THE INVENTION 
       [0013]    The foregoing object of the invention has been achieved by an earth leakage breaker that serves functions of over current protection and ground fault protection, and comprises a main body housing of a simplex structure composed of a casing and a case cover, the case cover being combined with an auxiliary cover that covers the case cover and having a recess with a pocket shape for mounting internal accessory devices. 
         [0014]    The circuit breaker contains components in the housing, the components including a main circuit contact, a contact switching mechanism, an operation handle, an overcurrent tripping device, an earth leakage detection circuit combined with a zero-phase current transformer, and an earth leakage tripping device. An earth leakage operation output switch is removable and allowed to be mounted in the recess formed in the case cover of the main body housing. The earth leakage operation output switch is an internal accessory device that indicates earth leakage trip operation electrically and links mechanically with the earth leakage trip device to operate the earth leakage operation output switch in the earth leakage trip operation (first aspect). More specifically, the earth leakage breaker of the invention is constituted by the following modes. 
         [0000]    (1) The earth leakage trip device mounted on the main body housing has a unit case including a switch housing for holding the earth leakage operation output switch, and the switch housing is disposed facing the recess of the case cover of the main body housing (second aspect).
 
(2) The earth leakage operation output switch is a micro switch, and an actuator of the micro switch is linked to an output end of the earth leakage trip device at a position of the micro switch inserted into the recess of the case cover of the main body housing (third aspect).
 
(3) The lead wires connected to the earth leakage operation output switch is placed to pass through a gap between the case cover of the main body housing and an auxiliary cover covering the case cover, and is lead out towards outer side or upper direction for wiring (forth aspect).
 
(4) The earth leakage operation output switch in the mode (3) above has a support member for the lead wires on a top of the switch, and the lead wires are entangled with the support member to be tightly bundled, lead out outwardly of the housing through the gap adjacent to the auxiliary cover for wiring (fifth aspect).
 
(5) The lead wires, in the mode (3) above, connected to the earth leakage operation output switch and leading out towards outwardly of the main body housing is pushed down and held by an edge of the auxiliary cover covering the case cover of the main body housing at an intermediate position of the lead wires running outwardly (sixth aspect).
 
         [0015]    In this structure, the earth leakage operation output switch (an optional device), similarly to the internal accessory device such as an auxiliary switch and an alarm switch installed later for usage in an earth leakage breaker, can be readily inserted and set in the form of a cassette into a recess formed in the case cover of the main body housing by a user. At this inserted position, the earth leakage operation output switch is linked with the earth leakage tripping device to electrically indicate the earth leakage operation. Posterior installation of the earth leakage operation output switch can be readily conducted to electrically indicate earth leakage trip operation, which has been hardly dealt with by the user side in the conventional products. Therefore, serviceability for the use is improved. 
         [0016]    The unit case of the earth leakage trip device installed in the earth leakage breaker has a monolithically formed switch housing with a pocket shape for engaging and holding the earth leakage operation output switch at a predetermined insertion position. In this constitution, the earth leakage operation output switch and the earth leakage trip device working together, ensure linkage between the two and switching operation. In addition, the earth leakage operation output switch can be inserted and held at the predetermined position without limitation of configuration of the recess formed on the case cover of the main body housing of the breaker. Therefore, the configuration and structure of the recess formed on the case cover of the housing can be simplified. 
         [0017]    Further by employing the wiring methods of the forth through sixth aspects for the lead wires of the post mounted earth leakage operation output switch, the lead wires connected to the earth leakage output switch can be lead out for wiring in a desired direction corresponding to the condition of the application site in the user side. In addition, when the lead wires are entangled with the support member for the lead wires formed on a top of the switch housing and tightly bundled, and further pushed down and held by an edge of the auxiliary cover covering the case cover of the main body housing at an intermediate position of the lead wires, the lead wires extending outwardly, even exerted by an external tensional force, do not accidentally come off from the earth leakage operation output switch or the switch does not slip out of the predetermined place. Therefore, high reliability is secured. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of an earth leakage breaker; 
           [0019]      FIG. 2  is a disassembled side view of a main body housing of the breaker of  FIG. 1 ; 
           [0020]      FIG. 3  is a perspective view showing the internal structure of the breaker with the main body housing disassembled; 
           [0021]      FIG. 4(   a ) through  FIG. 4(   d ) are supplementary illustrations showing arrangement of an earth leakage tripping device and an earth leakage operation output switch mounted on the earth leakage breaker, wherein  FIG. 4(   a ) is a plan view of the whole breaker with a top cover,  FIG. 4(   b ) is a plan view without a top cover,  FIG. 4(   c ) is an enlarged plan view of a region “P” in  FIG. 4(   b ), and  FIG. 4(   d ) is an enlarged plan view of the region “P” in which the earth leakage trip device and the earth leakage operation output switch are removed from the configuration in  FIG. 4(   c ) to empty the recess of the case cover; 
           [0022]      FIG. 5  is a perspective view in which an earth leakage operation output switch is inserted and held in the earth leakage trip device in  FIG. 1 ; 
           [0023]      FIG. 6  is a side view of  FIG. 5 ; 
           [0024]      FIG. 7  is a disassembled perspective view of a trip coil unit in  FIG. 5 ; 
           [0025]      FIG. 8  is a perspective view of the earth leakage trip device of  FIG. 5  before mounting an earth leakage operation output switch; 
           [0026]      FIG. 9  is a front view of the earth leakage operation output switch; 
           [0027]      FIG. 10(   a ) and  FIG. 10(   b ) are perspective views of  FIG. 9 , in which  FIG. 10(   a ) is seen from the front side and  FIG. 10(   b ) is seen from the rear side; 
           [0028]      FIG. 11(   a ) and  FIG. 11(   b ) are perspective views illustrating the earth leakage operation output switch with the lead wires entangled with the support member and lead out sidewardly, in which  FIG. 11(   a ) is seen from the front side, and  FIG. 11(   b ) is seen from the rear side; 
           [0029]      FIG. 12(   a ) and  FIG. 12(   b ) are perspective views illustrating the earth leakage operation output switch with the lead wires entangled with the support member and lead out forwardly, in which  FIG. 12(   a ) is seen from the front side, and  FIG. 12(   b ) is seen from the rear side; 
           [0030]      FIG. 13  is a perspective view illustrating the lead wires of the earth leakage operation output switch inserted and set in the case cover of the earth leakage breaker in the arrangement of the wires lead out sidewardly corresponding to  FIG. 11 ; 
           [0031]      FIG. 14  is a perspective view illustrating the lead wires of the earth leakage operation output switch inserted and set in the case cover of the earth leakage breaker in the arrangement of the wires lead out upwardly corresponding to  FIG. 12 ; 
           [0032]      FIG. 15  is a perspective view illustrating a configuration with the top cover (auxiliary cover) covering the case cover of the main body housing of  FIG. 13 ; and 
           [0033]      FIG. 16(   a ) and  FIG. 16(   b ) illustrate a conventional earth leakage tripping device having an earth leakage operation output switch installed in an earth leakage breaker, in which  FIG. 16(   a ) is a plan view of a partial cross section,  FIG. 16(   b ) is a plan view of a structure of an essential parts of  FIG. 16(   a ). 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0034]    Some preferred embodiments according to the invention will be described with reference to  FIGS. 1 through 15 .  FIG. 1  through  FIG. 4(   d ) show a structure of an earth leakage breaker mounting an earth leakage operation output switch;  FIG. 5  through  FIG. 8  show a structure of an earth leakage trip device mounted on an earth leakage breaker;  FIG. 9  to  FIG. 10(   b ) show a structure of an earth leakage operation output switch; and  FIG. 11(   a ) through  FIG. 15  show lead out and wiring structure of lead wires connected to the earth leakage operation output switch. 
         [0035]    Referring to  FIG. 1  through  FIG. 3 , a main body housing  6  of an earth leakage breaker has a structure divided into a case  6   a , a case cover  6   b , and a top cover (auxiliary cover)  6   c  made of molded resin. The case cover  6   b  in the figures is divided into a cover division  6   b - 1  covering a supply side area of the main body housing  6  and a cover division  6   b - 2  covering a load side area ( FIG. 2 ). The top cover  6   c  is attached for allowing opening and closing. One end of the top cover  6   c  is combined with the cover division  6   b - 2  by a hinged coupling, and the other end of the top cover  6   c  is combined with the upper surface of the cover division  6   b - 1  by a screw coupling. 
         [0036]    Installed in the case  6   a  are a switching operation handle  7 , a switching mechanism  15 , an arc extinguishing chamber  16 , a zero phase current transformer  17 , and an earth leakage trip device  1  in the side of the handle  7  ( FIG. 3 ). The case cover  6   b  covering the case  6   a  has a recess  6   b - 3  with a pocket configuration in the both sides of the operation handle  7  for accommodating various internal accessory devices including an earth leakage operation output switch  5  that is mounted on the earth leakage trip device  1  afterwards, an auxiliary switch, an alarm switch and the like. The case  6   a  and the accessories are covered by the top cover  6   c . In  FIG. 1 , the reference numeral  12  designates an earth leakage test button, and the numeral  13  designates knobs of switches for sensitivity current and operation time selection. These parts are installed in a unit case of the earth leakage trip device  1  as described below. 
         [0037]      FIGS. 4(   a ) through  4 ( d ) are supplementary illustrations of the earth leakage breaker with an earth leakage operation output switch  5  mounted afterwards in the main body housing  1 , in which  FIG. 4(   a ) shows a state with a top cover  6   c  shown in  FIG. 1 ,  FIG. 4(   b ) shows a state that the cover is removed,  FIG. 4(   c ) is an enlarged plan view of the region “P” in a state the cover division  6   b - 2  is removed, and  FIG. 4(   d ) is a drawing for reference showing a state in which the earth leakage trip device  1  and the earth leakage operation output switch  5  have been removed from the main body housing to empty the recess  6   b - 3  of the case cover  6   b . In  FIGS. 4(   c ) and  4 ( d ), the reference numeral  14  designates an earth leakage detection circuit (a printed circuit board) contained in a printed board accommodation portion  11   a  of the unit case  11  described later, and the numeral  15  designates a switching mechanism for a main circuit contact. A U-shaped groove  6   b - 4  is formed at the upper edge of a side wall of the case cover  6   b  for leading out lead wires  18  connected to the earth leakage operation output switch  5  outwardly. 
         [0038]    Descriptions will be made on an assembly structure of the earth leakage trip device  1  referring to  FIGS. 5 through 8 ; and on the structure of the earth leakage operation output switch  5  referring to  FIGS. 9 ,  10 ( a ) and  10 ( b ). 
         [0039]    The earth leakage trip device  1  shown in  FIG. 5  and  FIG. 6  comprises a unit case  11 ; components contained in the unit case  11  as a unit including an earth leakage detection circuit  14  ( FIG. 4(   c )), an earth leakage test switch  12 , switches  13  for sensitivity current and operation time selection, and an assembly of a trip coil unit  8  shown in  FIG. 7 ; and a switch housing  11   b  for accommodating and holding an earth leakage operation output switch  5  provided on a side surface of the unit case  11 . 
         [0040]    The trip coil unit  8  is, as shown in  FIG. 7 , an assembly comprising a case  10 ; and an earth leakage indication button  4  and a trip actuation slider  9  coupled with a trip coil  3  (a plunger type electromagnet) through a driver lever  3   b  inserted into the case  10 . This case  10  is fitted to the unit case  11  of the earth leakage trip device  1  by snap fitting ( FIG. 5 ). In this fitted state, the dog  9   a  for switching operation branched from the side of the actuation slider  9  is projecting to the bottom of the switch housing  11   b  formed on the unit case  11 . 
         [0041]    The earth leakage operation output switch  5  is a micro-switch including a contact mechanism (c-contact) provided with normally-open and a normally-close contact points. As shown in  FIG. 9  and  FIGS. 10(   a ) and  10 ( b ), a plunger  5   b , an actuator of the contact mechanism, is projecting from the bottom surface of a switch case (a molded resin case). On the left and right end surfaces, engage projections  5   d  and a hook  5   e  (snap fit) are formed in a monolithic construction. On the top of the micro switch, lead wire supports  5   c  (three pieces) are provided in a form of a bar with a rectangular cross section directing right-wards or left-wards and having an L-shaped bent at the tip. The lead wire supports are retaining members to entangle three lead wires  18  ( FIG. 8)  that are connected to the internal contacts and lead out to the top surface of the switch case. 
         [0042]    The unit case  11  (a molded resin case) of the earth leakage trip device  1  in  FIG. 8  includes a housing  11   a  for a printed circuit board  14  for the earth leakage detection circuit ( FIG. 4(   c )) and the switch housing  11   b  in a pocket shape for removably accommodating and holding the earth leakage operation output switch  5 . The housing  11   a  and the switch housing  11   b  are formed in a monolithic construction in the unit case  11 . The switch housing  11   b  has a fitting groove  11   b - 1  and snap fit part  11   b - 2  corresponding to the engage projections  5   d  and hook  5   e , respectively, of the earth leakage operation output switch  5 . The numeral  11   c  designates a snap fit member for engaging and holding the case  10  ( FIG. 7)  of the trip coil unit  8 . 
         [0043]    In the assembled state having the earth leakage trip device  1  mounted on the main body housing  6  ( FIG. 1 ), the switch housing  11   b  formed on the side surface of the unit case  11  ( FIG. 8 ) faces the recess  6   b - 3  formed in the case cover  6   b , and projecting from the top surface of the case cover  6   b  are the earth leakage indicating button  4 , a push button  12  of the earth leakage test switch, and the knobs  13  of the switches for rated sensitivity current and operation time selection. 
         [0044]    When an earth leakage operation output switch  5  is installed afterwards into the earth leakage breaker in the structure as described above, after opening the top cover  6   c  as shown in  FIG. 1 , the earth leakage operation output switch  5  is inserted from above towards the recess  6   b - 3  of the case cover  6   b  opening outside the earth leakage trip device  1  and pushed down into the switch housing  11   b  of the unit case  11  as shown in  FIG. 8 , and removably engaged and fixed at a predetermined position. In this held state of the switch, the tip of the dog  9   a  (which is cut tapered) branched from the actuation slider  9  of the trip coil unit  8  ( FIG. 7 ) is located opposing the side of the plunger (actuator)  5   b  of the earth leakage operation output switch (micro switch)  5  as shown in  FIG. 6 . 
         [0045]    In the above described structure, on the event of ground fault in the distribution system, the earth leakage detection circuit  14  detects earth leakage current in the main circuit. The output signal from the earth leakage detection circuit  14  operates the trip coil  3  of the earth leakage tripping device  1  driving the actuation slider  9  to trip the switching mechanism  15  and open the main circuit contacts. At the same time, the dog  9   a  branched from the actuation slider  9  moves to the direction of the arrow in  FIG. 6  and pushes the plunger (actuator)  5   b  of the earth leakage operation output switch  5  inwardly. The contact (a “make” contact) of the micro switch turns ON, and an electric signal indicating earth leakage operation is output through the lead wires  18 . When electric indication of earth leakage operation is not needed in the system, the earth leakage operation output switch  5  can be removed from the case cover  6   b  of the main body housing  6 , and the breaker can be used as a normal (standard specification) earth leakage breaker. In such a case, the earth leakage operation can be seen by pop-up action of the earth leakage indication button  4 . 
         [0046]    Next, a description will be made on a process, in the state of the earth leakage operation output switch  5  post-mounted on the earth leakage breaker, to arrange the lead wires  18  connected to the switch towards the side or above from the main body housing  6  of the breaker and lead out of the breaker referring to  FIG. 11(   a ) through  FIG. 15 . 
         [0047]    After the earth leakage operation output switch  5  is inserted and set on the main body housing  5  of the earth leakage breaker, in the case that the lead wires  18  connected to the earth leakage operation output switch  5  are lead out to the side of the main body housing  6  as shown in  FIG. 15  (the arrow “A” designates the lead out direction of the lead wires) and externally wired, the three lead wires  18  lead out above the switch are entangled with the lead wire support  5   c  and lined up tightly as shown in  FIGS. 11(   a ) and  11 ( b ). The lead wires are lead out through a groove  6   b - 4  ( FIG. 4(   d )) formed on the side edge of the cover  6   b  as shown in  FIG. 13 . When the top cover  6   c  of the main body housing  6  is closed in this state, the lead wires  18  are pressed between the side edge of the case cover  6   b  and the edge of the top cover  6   c  in the intermediate portion of the lead wires and fixedly held at this position. If an external tensional force is exerted on the lead out lead wires  18 , there is no risk that the lead wires come off accidentally from the micro switch or the switch itself slips off from the unit case  11  of the earth leakage trip device  1 . 
         [0048]    When the lead wires  18  cannot be lead out for wiring sideways as shown in  FIG. 15  due to restriction by the surroundings of the installed earth leakage breaker, and the lead wires  18  are to be lead out for wiring towards upward along the surface of the main body housing  6  as in  FIG. 14 , the three lead wires  18  are entangled with the lead wire support  5   c  and lined up tightly to draw out in the direction of the arrow “A” as shown in  FIGS. 12(   a ) and  12 ( b ). Then, the top cover  6   c  is put and bound in the same process as the above-described one. Thus, the lead wires  18  drawn out in the direction of the arrow “A” are pressed between the edge of the case cover  6   b  and the edge of the top cover  6   c  in the intermediate portion of the lead wires and fixedly held at this position. 
         [0049]    The lead wire supports  5   c  in a form of a bar with a rectangular cross section are provided on the top of the micro switch, and when the lead wires  18  are lead out for wiring from the earth leakage operation output switch  5  post-mounted on the main body housing  6  of the earth leakage breaker, the lead wires  18  can be lead out in a desired direction and held on the main body housing  6  by wiring in the above described process. 
         [0050]    The disclosure of Japanese Patent Applications No. 2006-282096 filed on Oct. 17, 2006 and No. 2006-105830 filed on Apr. 7, 2006 are incorporated as a reference. 
         [0051]    While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.