Abstract:
The invention relates to a high-safety surge protective device which comprises a casing, at least one overvoltage protection component inside the casing, a release unit used to separate the overvoltage protection component from the AC or DC circuit or the equipment, an arc suppressing apparatus used to suppress electric arc generated while separating the overvoltage protection component from the AC or DC circuit or the equipment, and a box, Wherein: the release unit comprises a compression spring, a metal dome, a slide and a soft conductor; the arc suppressing apparatus comprises an arc chute assembly, a first arc striking sheet, a second arc striking sheet, a turning block and a torsional spring.

Description:
FIELD OF THE TECHNOLOGY 
       [0001]    The present invention relates to a protective device for electrical equipment, particularly relates to a surge protective device. 
       BACKGROUND 
       [0002]    With the development of electric power, communications and other industries, the surge protector is increasingly applied to a wider range and prone to more frequent failures during the application. However, fire and other accidents might occur if a deteriorated or overloaded surge protector is not separated from the AC or DC circuit and the equipment in a timely and safely manner, hence more and more concerns are given to the safety of such a deteriorated or overloaded surge protector. 
         [0003]    CN102132467A disclosed an overvoltage discharge device with at least one discharge component. In the event of short circuit or immediate vicinity of the the overvoltage discharge device, its mobile isolating part will intrude into the motion circuit of the conductor section or the conducting bridge to prevent or inhibit the electric arc between the conducting element and the isolating part from being re-ignited. However, a thermal stability test in accordance with IEC61643.1-2005 shows that, the current running through the overvoltage discharge device exceeds 0.5 mA if a maximum continuous running voltage is applied, which is not compliant with the requirements of IEC61643-1:2005. 
       SUMMARY 
       [0004]    The invention is intended to overcome shortcomings of the existing technology by providing a highly safe surge protector, so as to ensure the surge protector is separated from the circuit or the equipment when it is deteriorated or overloaded, thereby eliminating fire, electric leakage and other potential safety hazards. 
         [0005]    The high-safety surge protective device disclosed in the invention comprises a casing, at least one overvoltage protection component inside the casing, a release unit used to separate the overvoltage protection component from the AC or DC circuit or the equipment, an arc suppressing apparatus and a box used to suppress electric arc generated while separating the overvoltage protection component from the AC or DC circuit or the equipment, the overvoltage protection component is provided with a first pin connected with the first electrode and a second pin connected with or separated from the second electrode through the release unit, and is mounted on the box; the release unit comprises a compression spring, a metal dome, a slide and a soft conductor, wherein: the slide is mounted inside the slideway of the box, the compression spring is in contact with the slide at one end and fixed on the box at the other end; the metal dome is mounted on the slide, its one end is connected with the soft conductor, while the other end is welded with the second pin of the overvoltage protection component when it is in normal condition, but when the overvoltage protection component is in abnormal condition and causes this end to separate from the second pin of the overvoltage protection component, an elastic restoring force of the compression spring is applied on the slide which drives the metal dome to move to the first limit wall on the box, the soft conductor is connected with the second electrode; theThe arc suppressing apparatus comprises an arc chute assembly, a first arc striking sheet, a second arc striking sheet, a turning block and a torsional spring, wherein: the turning block is a bar-type block with an arc reflector plate provided at one end, a mounting hole at the other end and a spark chamber at the part close to the arc reflector plate, the turning block is attached to the pin roll on the box through the mounting hole at its end and is hinged with this pin roll whose position is such that: when the overvoltage protection component is in normal condition, the side at the end of the turning block with the arc reflector plate is in contact with the metal dome, but when the overvoltage protection component is in abnormal condition and causes the metal dome to separate from it, the turning block moves to the second limit wall on the box under the action of the torsional spring and the spark chamber on the turning block covers the second pin of the overvoltage protection component separated from the metal dome; the torsional spring is mounted on the turning block and is connected with the pin roll; the arc chute assembly is installed inside the arc extinguishing chamber surrounded by the box and the casing, the first arc striking sheet has one end connected with or close to the left end of the arc chute assembly and the other end positioned on the box and close to the first limit wall, the second arc striking sheet has one end connected with or close to the right end of the arc chute assembly and the other end positioned on the box and close to the second limit wall. 
         [0006]    The high-safety surge protective device disclosed in the invention also comprises an indicating device which further comprises a green display sheet and a red label, wherein the latter is attached on the upper end face of the slide and the former is hinged on the box; a transparent window is provided at the top of the housing of the casing from where the green display sheet or the red label is revealed. The green display sheet is revealed on the slide when the overvoltage protection component is in normal condition, but when the overvoltage protection component is in abnormal condition and causes the metal dome to separate from it, the green display sheet moves to the side of the box under the action of the slide and the red label attached on the upper end face is revealed. 
         [0007]    The metal dome within the release unit of the high-safety surge protective device disclosed in the invention successively comprises an arc guide end, a welding contact face, a connecting arm, and a fixed end. The metal dome can be made of elastic copper, silver or alloy of these two, wherein elastic copper is preferred. 
         [0008]    Braided annealed copper wire is preferred for the soft conductor within the release unit of the high-safety surge protective device disclosed in the invention. 
         [0009]    An air outlet of the arc extinguishing chamber is made on the box of the high-safety surge protective device disclosed in the invention, and an exhaust port is made at the part on the housing of the casing corresponding to the air outlet of the arc extinguishing chamber. 
         [0010]    The turning block within the arc suppressing apparatus of the high-safety surge protective device disclosed in the invention has a guide track groove between the spark chamber and the mounting hole, and a guide track matching the guide track groove is mounted at the corresponding part on the box. 
         [0011]    The second arc striking sheet within the arc suppressing apparatus of the high-safety surge protective device disclosed in the invention is V-bulged at the part close to the second pin of the overvoltage protection component, in order to accelerate the arc striking speed. 
         [0012]    The casing, box, slide and turning block of the high-safety surge protective device disclosed in the invention are made of gassing or non-gassing insulating material, wherein the former category is preferred as gas generated from such material can cool down the arc on the one hand and can, on the other hand, enhance the air-blowing function of the arc and accelerate the speed to move the arc to the arc chute assembly on the other hand. The gassing insulating material might be polyformaldehyde, nylon, or melamine. 
         [0013]    The box of the high-safety surge protective device disclosed in the invention has two concrete structures as follows: 
         [0014]    Firstly, on one facet of the box there is a chamber for the voltage protection component, while on the other facet there is an air outlet of the arc extinguishing chamber at the upper right top or on the side, a first limit wall at the upper left and a second limit wall at the lower right, wherein: a slideway for the slide is provided on the left of the first limit wall, a guide track for guiding the turning block to turn is provided on the left of the second limit wall together with a pin roll at its lower left. 
         [0015]    Secondly, on one facet of the box there is a chamber for the voltage protection component, while on the other facet there is an air outlet of the arc extinguishing chamber on the upper right side, a first limit wall at the upper left, a third limit wall at the lower left and a second limit wall at the lower right, wherein: a slideway for the slide is provided on the left of the first limit wall, a guide track for guiding the turning block to turn is provided on the left of the second limit wall together with a pin roll beneath the guide track. 
         [0016]    The high-safety surge protective device disclosed in the invention follows the operating principle as follows: 
         [0017]    After long-time service or repeated impact, the overvoltage protection component (piezoresistor) is gradually deteriorated and its temperature rises little by little, or its temperature rises quickly when a tremendous overload current runs through. When the temperature at the weld between the second pin of the overvoltage protection component and the metal dome within the release unit reaches the melting or fusion point of the welding flux, the metal dome is separated from the second pin of the overvoltage protection component, thereby reliving the acting force applied on the turning block within the arc suppressing apparatus and on the compression spring within the release unit. In this way, the turning block within the arc suppressing apparatus turns towards the direction of the second limit wall on the box under the action of the elastic restoring force of the compression spring, while the slide within the release unit carries the metal dome to move towards the direction of the first limit wall on the box under the action of the elastic restoring force of the compression spring. As the turning block turns, the metal dome and the second pin of the overvoltage protection component which have been separated from each other are hence electrically isolated. Meanwhile, the arc generated while separating the metal dome from the second pin of the overvoltage protection component is cooled down and the impact wave moving backwards generated by the arc is reflected. The arc is made able to access the arc chute assembly as quickly as possible since the reflected wave and the impact wave move in the same direction towards the arc chute assembly. The first and the second arc striking sheet also play a part to lead the arc into the arc chute assembly. When the turning block reaches the second limit wall on the box, the spark chamber on the turning block covers the second pin of the overvoltage protection component. The distance between the metal dome and the second pin of the overvoltage protection component is continuously enlarged as the slide moves upward, and electrical isolation between the metal dome and the second pin of the overvoltage protection is completed when the slide carrying the metal dome reaches the first limit wall on the box. 
         [0018]    The invention will render beneficial effects as follows: 
         [0019]    Firstly, the arc suppressing apparatus of the high-safety surge protective device disclosed in the invention is constructed such that it can extinguish hard arc. The release unit of the high-safety surge protective device disclosed in the invention, on the other hand, can quickly release the metal dome from the second pin of the overvoltage protection component so as to complete quick electrical isolation between them. Therefore, the combination of the release unit and the arc suppressing apparatus ensures secure separation of the surge protector from the circuit or the equipment in the event of a failure, thereby solving the technical problem of small-current thermally-stabilized isolation and large-current overloaded isolation of the surge protector when it is used in an AC/DC system. The secure level is very high particularly when it is used in AC/DC circuit or equipment of high system voltage and large short circuit current (e.g. wind or photovoltaic power generating installation). 
         [0020]    Secondly, the experiment shows that, when the slide carries the metal dome to reach the first limit wall on the box and completes separation of the metal dome from the second pin of the overvoltage protection component, the surge protector is completely isolated from the AC/DC circuit or the equipment and, when a maximum continuous running voltage is applied at its two ends, no current greater than 0.5 mA will run through, hence the high secure level. 
         [0021]    Thirdly, as the high-safety surge protective device disclosed in the invention is provided with an indicating device, the operator can easily monitor the state of the overvoltage protection component, timely identify any failure and replace, so as to ensure the safety of the protected circuit or equipment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is the first structural schematic view of the casing of the high-safety surge protective device disclosed in the invention; 
           [0023]      FIG. 2  is the second structural schematic view of the casing of the high-safety surge protective device disclosed in the invention; 
           [0024]      FIG. 3  is the third structural schematic view of the casing of the high-safety surge protective device disclosed in the invention; 
           [0025]      FIG. 4  is the first stereogram of functional devices and their combination within the high-safety surge protective device disclosed in the invention; 
           [0026]      FIG. 5  is the second stereogram of functional devices and their combination within the high-safety surge protective device disclosed in the invention; 
           [0027]      FIG. 6  is the third stereogram of functional devices and their combination within the high-safety surge protective device disclosed in the invention; 
           [0028]      FIG. 7  is a schematic view of the connection between pins of the overvoltage protection component and the first electrode within the high-safety surge protective device disclosed in the invention; 
           [0029]      FIG. 8  is a plane projection of  FIG. 4  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the second pin of the overvoltage protection component are connected; 
           [0030]      FIG. 9  is a plane projection of  FIG. 4  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the second pin of the overvoltage protection component are being separated; 
           [0031]      FIG. 10  is a plane projection of  FIG. 4  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the second pin of the overvoltage protection component are at the extreme position of separation; 
           [0032]      FIG. 11  is a plane projection of  FIG. 5  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the pin of the overvoltage protection component are connected; 
           [0033]      FIG. 12  is a plane projection of  FIG. 5  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the second pin of the overvoltage protection component are being separated; 
           [0034]      FIG. 13  is a plane projection of  FIG. 5  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the second pin of the overvoltage protection component are at the extreme position of separation; 
           [0035]      FIG. 14  is a plane projection of  FIG. 6  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the second pin of the overvoltage protection component are connected; 
           [0036]      FIG. 15  is a plane projection of  FIG. 6  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the second pin of the overvoltage protection component are being separated; 
           [0037]      FIG. 16  is a plane projection of  FIG. 5  showing the structure of the release unit, the arc suppressing apparatus and the indicating device, where: the metal dome within the release unit and the second pin of the overvoltage protection component are at the extreme position of separation; 
           [0038]      FIG. 17  is the first structural schematic view of the arc chute assembly; 
           [0039]      FIG. 18  is the front view of  FIG. 17 ; 
           [0040]      FIG. 19  is the top view of  FIG. 17 ; 
           [0041]      FIG. 20  is the A-A section view of  FIG. 18 ; 
           [0042]      FIG. 21  is the B-B section view of  FIG. 18 ; 
           [0043]      FIG. 22  is the C-C section view of  FIG. 18 ; 
           [0044]      FIG. 23  is the second structural schematic view of the arc chute assembly; 
           [0045]      FIG. 24  is the front view of  FIG. 23 ; 
           [0046]      FIG. 25  is the left view of  FIG. 23 ; 
           [0047]      FIG. 26  is the top view of  FIG. 23 ; 
           [0048]      FIG. 27  is a structural schematic view of the metal dome; 
           [0049]      FIG. 28  is a structural schematic view of the turning block. 
       
    
    
       [0050]    Where:  1 . casing;  11 . housing;  111 . exhaust port;  12 . transparent window;  2 . box;  201 . air outlet of arc-extinguishing chamber;  202 . first limit wall;  203 . second limit wall;  204 . pin roll;  205 . guide track;  206 . third limit wall;  3 . overvoltage protection component;  311 . first pin of overvoltage protection component;  312 . second pin of overvoltage protection component;  4 . release unit;  41 . compression spring;  42 . metal dome;  421 . arc guide end;  422 . welding contact face;  423 . connecting arm;  424 . fixed end;  43 . slide;  44 . soft conductor;  5 . arc suppressing apparatus;  51 . arc chute assembly;  511 . mounting plate;  512 . first arc chute;  513 . second arc chute;  52 . first arc striking sheet;  53 . second arc striking sheet;  54 . turning block;  541 . arc reflector plate;  542 . spark chamber;  543 . guide track groove;  544 . mounting hole;  55 . compression spring;  6 . indicating device;  61 . green display sheet;  62 . red label;  7 . second electrode;  8 . first electrode. 
       DETAILED DESCRIPTION 
       [0051]    The following text further specifies the construction of the high-safety surge protective device disclosed in the invention in detail in consideration of the embodiments and accompanying drawings. 
       Example 1 
       [0052]    In this embodiment, the high-safety surge protective device comprises a casing  1  (see  FIG. 1 ), an overvoltage protection component  3  within the casing, a release unit  4 , an arc suppressing apparatus  5 , an indicating device  6  and a box  2  (see  FIG. 5 ). The housing  11  of the casing is approximate to a rectangular solid in shape and is made of nylon, with a transparent window  12  and an exhaust port  111  (see  FIG. 1 ) provided at the top of the housing. The overvoltage protection component  3  is a piezoresistor with a first pin  311  and a second pin  312  (see  FIG. 7 ), wherein the former is connected with the first electrode  8  while the second is connected with or separated from the second electrode  7  through the release unit. The box  2  is made of nylon, where on one facet is a chamber for the voltage protection component  3 , while on the other facet is an air outlet of the arc extinguishing chamber  201  at the upper right top, a first limit wall  202  at the upper left and a second limit wall  203  at the lower right, wherein: a slideway for the slide is provided on the left of the first limit wall, a guide track  205  for guiding the turning block to turn is provided on the left of the second limit wall together with a pin roll  204  at its lower left (see  FIG. 5 ,  FIG. 11 ,  FIG. 12 ,  FIG. 13 ). The position of the pin roll  204  is required to be such that: when the overvoltage protection component is in normal condition, the side at the end of the turning block  54  within the arc suppressing apparatus where the arc reflector plate  541  is mounted contacts with the metal dome  42 , but when the overvoltage protection component is in abnormal condition and causes the metal dome  42  to separate from it, the turning block moves to the second limit wall  203  on the box along the guide track under the action of the torsional spring  55  and the spark chamber  542  on the turning block covers the second pin of the overvoltage protection component separated from the metal dome. The release unit  4  comprises a compression spring  41 , a metal dome  42 , a slide  43  and a soft conductor  44  (see  FIG. 11 ,  FIG. 12 ,  FIG. 13 ), wherein: the slide  43  is made of nylon and on its inside is a chamber for the compression spring; the metal dome  42  is made of elastic copper and comprises successively an arc guide end  421 , a welding contact face  422 , a connecting arm  423 , and a fixed end  424  (see  FIG. 27 ); the soft conductor  44  is a braided annealed copper wire; the slide  43  is mounted inside the slideway on the box; the compression spring  41  is mounted in the inner chamber of the slide, with its upper end contacted with the top of the inner chamber of the slide  43  and its lower end fixed on the box; the metal dome  42  is mounted on the slide, with its fixed end  424  connected with the soft conductor  44  and its welding contact face  422  brazed with the second pin  312  of the overvoltage protection component when it is in normal condition, but when the overvoltage protection component is in abnormal condition and causes the welding contact face  422  to separate from the second pin  312  of the overvoltage protection component, an elastic restoring force of the compression spring is applied on the slide which drives the metal dome to move upward to the first limit wall  202  at the upper left of the box; the soft conductor  44  is connected with the second electrode  7 . The arc suppressing apparatus  5  comprises an arc chute assembly  51 , a first arc striking sheet  52 , a second arc striking sheet  53 , a turning block  54  and a torsional spring  55  (see  FIG. 11 ,  FIG. 12 ,  FIG. 13 ), wherein: the turning block  54  is a bar-type block made of nylon with an arc reflector plate  541  provided at its upper end, a mounting hole  544  at its lower end, a spark chamber  542  at the part close to the arc reflector plate, and a guide track groove  543  (see  FIG. 28 ) between the spark chamber  542  and the mounting hole  544 ; the arc chute assembly  51  is of a monolithic construction as shown in  FIG. 17 ,  FIG. 18  and  FIG. 19  and is moulded with ceramic, where its inside is interwoven into a labyrinth arc extinguishing structure by the cross sections as shown in  FIG. 20  and  FIG. 21 ; the first arc striking sheet  52  and the second arc striking sheet  53  are made of copper plated iron sheets; the turning block is attached to the pin roll  204  on the box through the mounting hole  544  at its lower end and is hinged with this pin roll; the torsional spring  55  is mounted on the turning block and is connected with the pin roll  204 ; the arc chute assembly  51  is installed inside the arc extinguishing chamber surrounded by the box  2  and the housing  11  of the casing; the first arc striking sheet  52  has one end connected with the left end of the arc chute assembly  51  and the other end positioned on the box and close to the first limit wall  202 ; the second arc striking sheet  53  has one end connected with the right end of the arc chute assembly  51  and the other end positioned on the box and close to the second limit wall. The second arc striking sheet  53  is V-bulged at the part close to the second pin  312  of the overvoltage protection component, in order to accelerate the arc striking speed. The indicating device  6  comprises a green display sheet  61  and a red label  62 , wherein the former is attached on the upper end face of the slideway  43  and the latter is hinged on the box (see  FIG. 11 ,  FIG. 12 ,  FIG. 13 ). When the overvoltage protection component is in normal condition, the green display sheet  61  is on the slide  43  and is hence revealed, but when the overvoltage protection component is in abnormal condition and causes the metal dome to separate from it, the green display sheet  61  turns to the side of the box under the action of the slide and the red label attached on the upper end of the slide  43  is hence revealed; a transparent window  12  is provided at the top of the housing from where the operator can observe. 
       Example 2 
       [0053]    In this embodiment, the high-safety surge protective device comprises a casing  1 , an overvoltage protection component  3  within the casing, a release unit  4 , an arc suppressing apparatus  5 , an indicating device  6  and a box  2 . What is different from Embodiment  1  is that: the exhaust port  111  is arranged on the upper right side of the housing  11  of the casing (see  FIG. 2 ) and the air outlet of the arc extinguishing chamber  201  is arranged on the upper right side of the box  2  (see  FIG. 4 ,  FIG. 8 ,  FIG. 9  and  FIG. 10 ). 
       Example 3 
       [0054]    In this embodiment, the high-safety surge protective device comprises a casing  1 , an overvoltage protection component  3  within the casing, a release unit  4 , an arc suppressing apparatus  5 , an indicating device  6  and a box  2 . What is different from Embodiment 1 is that: the exhaust port  111  is arranged on the right side of the housing  11  of the casing (see  FIG. 3 ) and the air outlet of the arc extinguishing chamber  201  is arranged on the upper right side of the box  2  (see  FIG. 6 ,  FIG. 14 ,  FIG. 15  and  FIG. 16 ); on one facet of the box  2  is a chamber for the voltage protection component  3 , while on the other facet is an air outlet of the arc extinguishing chamber  201  at the upper right top, a first limit wall  202  at the upper left, a third limit wall  206  at the lower left a second limit wall  203  at the lower right, wherein: a slideway for the slide is provided on the left of the first limit wall, a guide track  205  for guiding the turning block to turn is provided on the left of the second limit wall together with a pin roll  204  beneath the guide track; when the voltage protection component  3  is in normal condition, the side at the end of the turning block  54  within the arc suppressing apparatus where the arc reflector plate  541  is mounted contacts with the metal dome  42  within the release unit and the left side o the turning block  54  is limited by the third limit wall  206  (see  FIG. 6 ,  FIG. 14 ,  FIG. 15 , and  FIG. 16 ); the arc chute assembly  51  is of a labyrinth arc extinguishing structure formed by metal chutes as shown in  FIG. 23 ,  FIG. 24 ,  FIG. 25  and  FIG. 26 ; the first arc striking sheet  52  and the second arc striking sheet  53  are made of copper plated iron sheets; the arc chute assembly  51  is installed inside the arc extinguishing chamber surrounded by the box  2  and the housing  11  of the casing; the first arc striking sheet  52  has one end close to the left end of the arc chute assembly  51  (with certain interstice between them) and the other end positioned on the box and close to the first limit wall  202 ; the second arc striking sheet  53  has one end close to the right end of the arc chute assembly  51  and the other end positioned on the box and close to the second limit wall; the second arc striking sheet  53  is V-bulged at the part close to the second pin  312  of the overvoltage protection component, in order to accelerate the arc striking speed.