Patent Publication Number: US-8995107-B2

Title: Modular lightning surge protection apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates generally to a lightning surge protection apparatus, and more particularly to a modular lightning surge protection apparatus. 
     2. Description of Related Art 
     With science and technology progress, the electric appliance products or the electronic products are increasingly precise. Hence, the surge protection and avoidance have become important topics. There are two main reasons of generating surge: switch surge and lightning surge. The circuit internally generates surge which is mostly associated with the actuation of the circuit components, it is called the switch surge. In addition, the circuit externally generates surge which is indirectly or directly caused by lightning strikes, it is called the lightning surge. Whether the switch surge or lightning surge, the light impact is to cause circuit malfunction and shorten the life of electronic components and the heavy impact is to cause circuit instantly overload and even burned. Therefore, a surge protection mechanism is essential besides the avoidance of generating surge. 
     Most of the industry commonly use surge prevention components to absorb or release the received surge energy. The more common components are metal oxide varistor (MOV) and gas discharge tube (GDT). The MOV is usually sintered by metal oxides such as zinc oxide and bismuth oxide. The MOV is also referred to as the surge absorber. The surge absorber has the nonlinear characteristics of high resistance value in low voltage and low resistance value in high voltage. In addition, the surge absorbers have different valve resistances according to their different proportion and composition of materials. The resistance of the surge absorber drastically reduces when a voltage difference is greater than the valve resistance, thus causing the massive current flow to inrush. Accordingly, the surge energy can be rapidly brought into the surge absorber so as to protect other electronic components from the surge. The gas discharge tube is internally filled with inert gas for discharging. Also, the surge energy in the GDT is released by the inert gas and converted into the thermal energy. Accordingly, the surge energy can be rapidly brought into the GDT so as to protect other electronic components from the surge. 
     Reference is made to  FIG. 1  which is a perspective schematic view of prior art surge protection element with a coating layer. As mentioned above, the metal oxide varistor is usually used to provide the lightning surge protection. It is assumed that a first metal oxide varistor  101 A, a second metal oxide varistor  102 A, and a third metal oxide varistor  103 A are applied to a single-phase three-wire power system with a line, a neutral, and a ground. Also, the amount of the metal oxide varistor is determined depending on different protection operations of the circuit, but not limited. Especially, each of the metal oxide varistors  101 A˜ 103 A is coated with a coating layer  111 A˜ 113 A of epoxy resin material. Also, each of the metal oxide varistors  101 A˜ 103 A is individually inserted on a printed circuit board (PCB)  30 A. Accordingly, the metal oxide varistors  101 A˜ 103 A and other circuit elements form the lightning surge protection structure. However, the whole printed circuit board  30 A (including components mounted thereon) must be discarded and replaced once any one metal oxide varistor is damaged. Hence, the prior art surge protection circuit has the disadvantages of larger occupied space, more complicated manufacturing process, and higher costs. 
     Accordingly, it is desirable to provide a modular lightning surge protection apparatus to integrate surge protection elements, temperature fuses, and jumper elements to form a small-scale modular circuit integration structure to provide the lightning surge protection. 
     SUMMARY 
     An object of the present disclosure is to provide a modular lightning surge protection apparatus to solve the above-mentioned problems. Accordingly, the modular lightning surge protection apparatus is applied to a single-phase three-wire power system with a line, a neutral, and a ground. The modular lightning surge protection apparatus includes a substrate, a surge protection unit, a first temperature fuse, and a second temperature fuse. The surge protection unit has a first surge protection element having a first pin and a second pin, a second surge protection element having a first pin and a second pin, and a third surge protection element having a first pin and a second pin. The second pin of the first surge protection element is connected to the first pin of the second surge protection element and the first pin of the third surge protection element to form a wye connection. The second pin of the third surge protection element is connected to the ground. The first temperature fuse has a first pin and a second pin. The second pin of the first temperature fuse is connected to the first pin of the first surge protection element. The first pin of the first temperature fuse is connected to the line. The second temperature fuse has a first pin and a second pin. The second pin of the second temperature fuse connected to the second pin of the second surge protection element. The first pin of the second temperature fuse is connected to the neutral. The surge protection unit, the first temperature fuse, and the second temperature fuse are electrically connected on the substrate to form a small-scale modular circuit integration structure. 
     Another object of the present disclosure is to provide a modular lightning surge protection apparatus to solve the above-mentioned problems. Accordingly, the modular lightning surge protection apparatus is applied to a single-phase three-wire power system with a line, a neutral, and a ground. The modular lightning surge protection apparatus includes a substrate, a surge protection unit, a first temperature fuse, and a second temperature fuse. The surge protection unit has a first surge protection element having a first pin and a second pin, a second surge protection element having a first pin and a second pin, and a third surge protection element having a first pin and a second pin. The second pin of the first surge protection element is connected to the first pin of the second surge protection element, the first pin of the first surge protection element is connected to the first pin of the third surge protection element, and the second pin of the second surge protection element is connected to the second pin of the third surge protection element to form a delta connection. The second pin of the first surge protection element is connected to the ground. The first temperature fuse has a first pin and a second pin. The second pin of the first temperature fuse is connected to the first pin of the first surge protection element. The first pin of the first temperature fuse is connected to the line. The second temperature fuse has a first pin and a second pin. The second pin of the second temperature fuse is connected to the second pin of the second surge protection element. The first pin of the second temperature fuse is connected to the neutral. The surge protection unit, the first temperature fuse, and the second temperature fuse are electrically connected on the substrate to form a small-scale modular circuit integration structure. 
     Further another object of the present disclosure is to provide a modular lightning surge protection apparatus to solve the above-mentioned problems. Accordingly, the modular lightning surge protection apparatus is applied to a single-phase three-wire power system with a line, a neutral, and a ground. The modular lightning surge protection apparatus includes a substrate, a surge protection unit, a first temperature fuse, and a second temperature fuse. The surge protection unit has a first surge protection element, a second surge protection element, and a third surge protection element. The first surge protection element, the second surge protection element, the third surge protection element, the first temperature fuse, and the second temperature fuse are inserted on the substrate to form a small-scale modular circuit integration structure. The first surge protection element, the second surge protection element, and the third surge protection element are electrically connected to each other and the corresponding line, neutral, and ground to form a wye connection or a delta connection. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the present disclosure as claimed. Other advantages and features of the present disclosure will be apparent from the following description, drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The features of the present disclosure believed to be novel are set forth with particularity in the appended claims. The present disclosure itself, however, may be best understood by reference to the following detailed description of the present disclosure, which describes an exemplary embodiment of the present disclosure, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective schematic view of prior art surge protection element with a coating layer; 
         FIG. 2A  is a circuit diagram of a modular lightning surge protection apparatus according to a first embodiment of the present disclosure; 
         FIG. 2B  is a circuit diagram of the modular lightning surge protection apparatus according to a second embodiment of the present disclosure; 
         FIG. 2C  is a circuit diagram of the modular lightning surge protection apparatus according to a third embodiment of the present disclosure; 
         FIG. 3A  is a circuit diagram of the modular lightning surge protection apparatus according to a fourth embodiment of the present disclosure; 
         FIG. 3B  is a circuit diagram of the modular lightning surge protection apparatus according to a fifth embodiment of the present disclosure; 
         FIG. 3C  is a circuit diagram of the modular lightning surge protection apparatus according to a sixth embodiment of the present disclosure; 
         FIG. 4A  is a circuit diagram of the modular lightning surge protection apparatus according to a seventh embodiment of the present disclosure; 
         FIG. 4B  is a circuit diagram of the modular lightning surge protection apparatus according to an eighth embodiment of the present disclosure; 
         FIG. 4C  is a circuit diagram of the modular lightning surge protection apparatus according to a ninth embodiment of the present disclosure; 
         FIG. 5  is an assembled schematic view of a surge protection unit of the modular lightning surge protection apparatus according to the present disclosure; 
         FIG. 6  is a perspective schematic view of the modular lightning surge protection apparatus according to an embodiment of the present disclosure; and 
         FIG. 7  is a perspective schematic view of the modular lightning surge protection apparatus according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the drawing figures to describe the present invention in detail. 
     Reference is made to  FIG. 2A  which is a circuit diagram of a modular lightning surge protection apparatus according to a first embodiment of the present disclosure. The modular lightning surge protection apparatus  100  is applied to a single-phase three-wire power system with a line L, a neutral N, and a ground G. The modular lightning surge protection apparatus  100  includes a substrate  30  (as shown in  FIG. 6  or  FIG. 7 ), a surge protection unit  10 , a first temperature fuse  11 , and a second temperature fuse  12 . In particular, the substrate  30  can be a printed circuit board (PCB). However, the embodiment is only exemplified but not intended to limit the scope of the disclosure. The surge protection unit  10  has a first surge protection element  101  having a first pin  1011  and a second pin  1012 , a second surge protection element  102  having a first pin  1021  and a second pin  1022 , and a third surge protection element  103  having a first pin  1031  and a second pin  1032 . In particular, the second pin  1012  of the first surge protection element  101  is connected to the first pin  1021  of the second surge protection element  102  and the first pin  1031  of the third surge protection element  103  to form a wye connection. The second pin  1032  of the third surge protection element  103  is connected to the ground G. 
     The first temperature fuse  11  has a first pin  111  and a second pin  112 . The second pin  112  of the first temperature fuse  11  is connected to the first pin  1011  of the first surge protection element  101 . The first pin  111  of the first temperature fuse  11  is connected to the line L. The second temperature fuse  12  has a first pin  121  and a second pin  122 . The second pin  122  of the second temperature fuse  12  is connected to the second pin  1022  of the second surge protection element  102 . The first pin  121  of the second temperature fuse  12  is connected to the neutral N. Especially, the surge protection unit  10 , the first temperature fuse  11 , and the second temperature fuse  12  are electrically connected on the substrate  30  to form a small-scale modular circuit integration structure. 
     Reference is made to  FIG. 2B  which is a circuit diagram of the modular lightning surge protection apparatus according to a second embodiment of the present disclosure. Comparing with the above-mentioned first embodiment, the modular lightning surge protection apparatus  100  in the second embodiment further includes a first jumper element  21  and a second jumper element  22 . The first jumper element  21  is electrically connected between the first surge protection element  101  and the first temperature fuse  11  on the substrate  30 , and the second jumper element  22  is electrically connected between the second surge protection element  102  and the second temperature fuse  12  on the substrate  30 . In particular, the first jumper element  21  and the second jumper element  22  can be conducting wires or zero-ohm resistors to provide layout connections on the substrate  30 . 
     The detailed operation of the modular lightning surge protection apparatus  100  will be described hereinafter as follows. For convenient explanation, the second embodiment in the  FIG. 2B  is exemplified for further demonstration. The first surge protection element  101 , the second surge protection element  102 , and the third surge protection element  103  of the surge protection unit  10  are metal oxide varistors (MOVs), which are also called surge absorbers. That is, the first surge protection element  101  is a first metal oxide varistor, the second surge protection element  102  is a second metal oxide varistor, and the third surge protection element  103  is a third metal oxide varistor, respectively. When a lightning surge occurs between the line L and the neutral N, the first metal oxide varistor  101  or the second metal oxide varistor  102  is in a short-circuit condition to absorb a lightning surge energy, and then the first temperature fuse  11  or the second temperature fuse  12  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. In addition, when the lightning surge occurs between the line L and the ground G, the first metal oxide varistor  101  or the third metal oxide varistor  103  is in a short-circuit condition to absorb a lightning surge energy, and then the first temperature fuse  11  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. Furthermore, when the lightning surge occurs between the neutral N and the ground G, the second metal oxide varistor  102  or the third metal oxide varistor  103  is in a short-circuit condition to absorb a lightning surge energy, and then the second temperature fuse  12  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. 
     Reference is made to  FIG. 3A  and  FIG. 3B  which are circuit diagrams of the modular lightning surge protection apparatus according to a fourth embodiment and fifth embodiment of the present disclosure, respectively. In particular, the major difference between the fourth embodiment and the above-mentioned first embodiment is that the third surge protection element  103 —the metal oxide varistor is replaced by a gas discharge tube (GDT). Similarly, the major difference between the fifth embodiment and the above-mentioned second embodiment is that the third surge protection element  103 —the metal oxide varistor is replaced by a gas discharge tube (GDT). For convenient explanation, the fifth embodiment in the  FIG. 3B  is exemplified for further demonstration. The first surge protection element  101  and the second surge protection element  102  are metal oxide varistors (MOVs) and the third surge protection element  103  is a gas discharge tube (GDT). That is, the first surge protection element  101  is a first metal oxide varistor, the second surge protection element  102  is a second metal oxide varistor, and the third surge protection element  103  is a first gas discharge tube, respectively. When a lightning surge occurs between the line L and the neutral N, the first metal oxide varistor  101  or the second metal oxide varistor  102  is in a short-circuit condition to absorb a lightning surge energy, and then the first temperature fuse  11  or the second temperature fuse  12  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 102  and the first gas discharge tube  103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. In addition, when the lightning surge occurs between the line L and the ground G, the first metal oxide varistor  101  or the first gas discharge tube  103  is in a short-circuit condition to absorb a lightning surge energy, and then the first temperature fuse  11  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 102  and the first gas discharge tube  103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. Furthermore, when the lightning surge occurs between the neutral N and the ground G, the second metal oxide varistor  102  or the first gas discharge tube  103  is in a short-circuit condition to absorb a lightning surge energy, and then the second temperature fuse  12  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 102  and the first gas discharge tube  103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. 
     Reference is made to  FIG. 2C  which is a circuit diagram of the modular lightning surge protection apparatus according to a third embodiment of the present disclosure. Comparing with the above-mentioned second embodiment, the modular lightning surge protection apparatus  100  in the third embodiment further includes a signal output main line S0, a first signal output branch line S1, a second signal output branch line S2, a first indicating unit  41 , and a second indicating unit  42 . The signal output main line S0 is connected to the first pin  111  of the first temperature fuse  11 . The first signal output branch line S1 is connected between the first pin  1011  of the first surge protection element  101  and the first jumper element  21 . The second signal output branch line S2 is connected between the second pin  1022  of the second surge protection element  102  and the second jumper element  22 . The first indicating unit  41  has a first light-emitting diode D1 and a first current-limiting resistor R1 connected in series to the first light-emitting diode D1. The first indicating unit  41  is connected between the signal output main line S0 and the second signal output branch line S2 to indicate that an external power source is normal or abnormal for supplying the modular lightning surge protection apparatus  100 . The second indicating unit  42  has a second light-emitting diode D2 and a second current-limiting resistor R2 connected in series to the second light-emitting diode D2. The second indicating unit  42  is connected between the first signal output branch line S1 and the second signal output branch line S2 to indicate that the modular lightning surge protection apparatus  100  is available or unavailable for providing the lightning surge protection. When the external power source can normally supply the modular lightning surge protection apparatus  100 , the first light-emitting diode D1 of the first indicating unit  41  provides illumination. On the other hand, the first light-emitting diode D1 of the first indicating unit  41  does not illuminate when the external power source cannot normally supply the modular lightning surge protection apparatus  100 . Accordingly, the first indicating unit  41  can indicate that the external power source is normal or abnormal for supplying the modular lightning surge protection apparatus  100 . In addition, the second light-emitting diode D2 of the second indicating unit  42  does not illuminate when one of the first temperature fuse  11 , the second temperature fuse  12 , the first jumper element  21 , and the second jumper element  22  is in an open-circuit condition due to cutting off the power supply during the surge protection operation of the modular lightning surge protection apparatus  100 . On the other hand, the second light-emitting diode D2 of the second indicating unit  42  provides illumination when all of the first temperature fuse  11 , the second temperature fuse  12 , the first jumper element  21 , and the second jumper element  22  are conductive. Accordingly, the second indicating unit  42  can indicate that the modular lightning surge protection apparatus  100  is available or unavailable for providing the lightning surge protection. However, the embodiments are only exemplified but not intended to limit the scope of the disclosure. 
     Reference is made to  FIG. 3C  which is a circuit diagram of the modular lightning surge protection apparatus according to a sixth embodiment of the present disclosure. Comparing with the above-mentioned third embodiment, the major difference between the sixth embodiment and the above-mentioned third embodiment is that the third surge protection element  103 —the metal oxide varistor is replaced by a gas discharge tube (GDT). Similarly, the first indicating unit  41  and the second indicating unit  42  are provided to indicate that the external power source is normal or abnormal for supplying the modular lightning surge protection apparatus  100  and indicate that the modular lightning surge protection apparatus  100  is available or unavailable for providing the lightning surge protection, respectively. 
     Reference is made to  FIG. 4A  which is a circuit diagram of the modular lightning surge protection apparatus according to a seventh embodiment of the present disclosure. The modular lightning surge protection apparatus  100  is applied to a single-phase three-wire power system with a line L, a neutral N, and a ground G. The modular lightning surge protection apparatus  100  includes a substrate  30  (as shown in  FIG. 6  or  FIG. 7 ), a surge protection unit  10 , a first temperature fuse  11 , and a second temperature fuse  12 . In particular, the substrate  30  can be a printed circuit board (PCB). However, the embodiment is only exemplified but not intended to limit the scope of the disclosure. The surge protection unit  10  has a first surge protection element  101  having a first pin  1011  and a second pin  1012 , a second surge protection element  102  having a first pin  1021  and a second pin  1022 , and a third surge protection element  103  having a first pin  1031  and a second pin  1032 . In particular, the second pin  1012  of the first surge protection element  101  is connected to the first pin  1021  of the second surge protection element  102 , the first pin  1011  of the first surge protection element  101  is connected to the first pin  1031  of the third surge protection element  103 , and the second pin  1022  of the second surge protection element  102  is connected to the second pin  1032  of the third surge protection element  103  to form a delta connection. The second pin  1012  of the first surge protection element  101  is connected to the ground G. 
     The first temperature fuse  11  has a first pin  111  and a second pin  112 . The second pin  112  of the first temperature fuse  11  is connected to the first pin  1011  of the first surge protection element  101 . The first pin  111  of the first temperature fuse  11  is connected to the line L. The second temperature fuse  12  has a first pin  121  and a second pin  122 . The second pin  122  of the second temperature fuse  12  is connected to the second pin  1022  of the second surge protection element  102 . The first pin  121  of the second temperature fuse  12  is connected to the neutral N. Especially, the surge protection unit  10 , the first temperature fuse  11 , and the second temperature fuse  12  are electrically connected on the substrate  30  to form a small-scale modular circuit integration structure. 
     Reference is made to  FIG. 4B  which is a circuit diagram of the modular lightning surge protection apparatus according to an eighth embodiment of the present disclosure. Comparing with the above-mentioned seventh embodiment, the modular lightning surge protection apparatus  100  in the seventh embodiment further includes a first jumper element  21  and a second jumper element  22 . The first jumper element  21  is electrically connected between the first surge protection element  101  and the first temperature fuse  11  on the substrate  30 , and the second jumper element  22  is electrically connected between the second surge protection element  102  and the second temperature fuse  12  on the substrate  30 . In particular, the first jumper element  21  and the second jumper element  22  can be conducting wires or zero-ohm resistors to provide layout connections on the substrate  30 . 
     The detailed operation of the modular lightning surge protection apparatus  100  will be described hereinafter as follows. For convenient explanation, the eighth embodiment in the  FIG. 4B  is exemplified for further demonstration. The first surge protection element  101 , the second surge protection element  102 , and the third surge protection element  103  of the surge protection unit  10  are metal oxide varistors (MOVs), which are also called surge absorbers. That is, the first surge protection element  101  is a first metal oxide varistor, the second surge protection element  102  is a second metal oxide varistor, and the third surge protection element  103  is a third metal oxide varistor, respectively. When a lightning surge occurs between the line L and the neutral N, the third metal oxide varistor  103  is in a short-circuit condition to absorb a lightning surge energy, and then the first temperature fuse  11  or the second temperature fuse  12  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. In addition, when the lightning surge occurs between the line L and the ground G, the first metal oxide varistor  101  is in a short-circuit condition to absorb a lightning surge energy, and then the first temperature fuse  11  or the second temperature fuse  12  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. Furthermore, when the lightning surge occurs between the neutral N and the ground G, the second metal oxide varistor  102  is in a short-circuit condition to absorb a lightning surge energy, and then the first temperature fuse  11  or the second temperature fuse  12  is in an open-circuit condition to provide a lightning surge protection via cutting off power supply and preventing combustion of the metal oxide varistors  101 ˜ 103  when the lightning surge energy is converted into a thermal energy to achieve a particular high temperature. 
     Reference is made to  FIG. 4C  which is a circuit diagram of the modular lightning surge protection apparatus according to a ninth embodiment of the present disclosure. Comparing with the above-mentioned eighth embodiment, the modular lightning surge protection apparatus  100  in the ninth embodiment further includes a signal output main line S0, a first signal output branch line S1, a second signal output branch line S2, a first indicating unit  41 , and a second indicating unit  42 . The signal output main line S0 is connected to the first pin  111  of the first temperature fuse  11 . The first signal output branch line S1 is connected between the first pin  1011  of the first surge protection element  101  and the first jumper element  21 . The second signal output branch line S2 is connected between the second pin  1022  of the second surge protection element  102  and the second jumper element  22 . The first indicating unit  41  has a first light-emitting diode D1 and a first current-limiting resistor R1 connected in series to the first light-emitting diode D1. The first indicating unit  41  is connected between the signal output main line S0 and the second signal output branch line S2 to indicate that an external power source is normal or abnormal for supplying the modular lightning surge protection apparatus  100 . The second indicating unit  42  has a second light-emitting diode D2 and a second current-limiting resistor R2 connected in series to the second light-emitting diode D2. The second indicating unit  42  is connected between the first signal output branch line S1 and the second signal output branch line S2 to indicate that the modular lightning surge protection apparatus  100  is available or unavailable for providing the lightning surge protection. When the external power source can normally supply the modular lightning surge protection apparatus  100 , the first light-emitting diode D1 of the first indicating unit  41  provides illumination. On the other hand, the first light-emitting diode D1 of the first indicating unit  41  does not illuminate when the external power source cannot normally supply the modular lightning surge protection apparatus  100 . Accordingly, the first indicating unit  41  can indicate that the external power source is normal or abnormal for supplying the modular lightning surge protection apparatus  100 . In addition, the second light-emitting diode D2 of the second indicating unit  42  does not illuminate when one of the first temperature fuse  11 , the second temperature fuse  12 , the first jumper element  21 , and the second jumper element  22  is in an open-circuit condition due to cutting off the power supply during the surge protection operation of the modular lightning surge protection apparatus  100 . On the other hand, the second light-emitting diode D2 of the second indicating unit  42  provides illumination when all of the first temperature fuse  11 , the second temperature fuse  12 , the first jumper element  21 , and the second jumper element  22  are conductive. Accordingly, the second indicating unit  42  can indicate that the modular lightning surge protection apparatus  100  is available or unavailable for providing the lightning surge protection. However, the embodiments are only exemplified but not intended to limit the scope of the disclosure. 
     Reference is made to  FIG. 5  which is an assembled schematic view of a surge protection unit of the modular lightning surge protection apparatus according to the present disclosure. For convenient explanation, the first surge protection element  101 , the second surge protection element  102 , and the third surge protection element  103  of the surge protection unit  10  are metal oxide varistors (MOVs) for further demonstration. Especially, the first surge protection element  101 , the second surge protection element  102 , and the third surge protection element  103  are adjacently disposed to each other and are insulated by a dispensing process so as to significantly save occupied space, simplify the complexity of the process, and reduce costs. 
     Reference is made to  FIG. 6  which is a perspective schematic view of the modular lightning surge protection apparatus according to an embodiment of the present disclosure. The modular lightning surge protection apparatus  100  is applied to a single-phase three-wire power system with a line L, a neutral N, and a ground G. The modular lightning surge protection apparatus  100  includes a substrate  30 , a surge protection unit  10 , a first temperature fuse  11 , and a second temperature fuse  12 . In particular, the substrate  30  can be a printed circuit board (PCB). However, the embodiment is only exemplified but not intended to limit the scope of the disclosure. The surge protection unit  10  has a first surge protection element  101 , a second surge protection element  102 , and a third surge protection element  103 . The first surge protection element  101 , the second surge protection element  102 , the third surge protection element  103 , the first temperature fuse  11 , and the second temperature fuse  12  are inserted on the substrate  30 . In this embodiment, the first surge protection element  101 , the second surge protection element  102 , and the third surge protection element  103  are adjacently inserted on the substrate  30  to each other. Also, the first temperature fuse  11  is adjacently disposed to the first surge protection element  101  and the second temperature fuse  12  is adjacently disposed to the third surge protection element  103  to form a small-scale modular circuit integration structure. In particular, the surge protection elements  101 ˜ 103  are insulated by a dispensing process. In other words, the first surge protection element  101 , the second surge protection element  102 , and the third surge protection element  103  are disposed between the first temperature fuse  11  and the second temperature fuse  12 . The first surge protection element  101 , the second surge protection element  102 , and the third surge protection element  103  are electrically connected to each other and the corresponding line, neutral, and ground to form a wye connection or a delta connection. 
     In addition, the modular lightning surge protection apparatus  100  further includes a first jumper element  21  and a second jumper element  22 . The first jumper element  21  is inserted on the substrate  30  and electrically connected between the first surge protection element  101  and the first temperature fuse  11 . The second jumper element  22  is inserted on the substrate  30  and electrically connected between the second surge protection element  102  and the second temperature fuse  12 . 
     In addition, the first surge protection element  101 , the second surge protection element  102 , and the third surge protection element  103  of the surge protection unit  10  are metal oxide varistors (MOVs). Also, the first surge protection element  101  and the second surge protection element  102  of the surge protection unit  10  are metal oxide varistors (MOVs) and the third surge protection element  103  of the surge protection unit  10  is a gas discharge tube (GDT). 
     Furthermore, the modular lightning surge protection apparatus  100  further includes a signal output main line, a first signal output branch line, a second signal output branch line, a first indicating unit, and a second indicating unit. The signal output main line is connected to the first temperature fuse  11 . The first signal output branch line is connected between the first surge protection element  101  and the first jumper element  21 . The second signal output branch line is connected between the second surge protection element  102  and the second jumper element  22 . The first indicating unit has a first light-emitting diode and a first current-limiting resistor connected in series to the first light-emitting diode. The first indicating unit is connected between the signal output main line and the second signal output branch line to indicate that an external power source is normal or abnormal for supplying the modular lightning surge protection apparatus  100 . The second indicating unit has a second light-emitting diode and a second current-limiting resistor connected in series to the second light-emitting diode. The second indicating unit is connected between the first signal output branch line and the second signal output branch line to indicate that the modular lightning surge protection apparatus  100  is available or unavailable for providing the lightning surge protection. 
     Reference is made to  FIG. 7  which is a perspective schematic view of the modular lightning surge protection apparatus according to another embodiment of the present disclosure. Comparing with the above-mentioned embodiment, the major difference is that the first temperature fuse  11  is adjacently disposed between the first surge protection element  101  and the second surge protection element  102  and the second temperature fuse  12  is adjacently disposed between the second surge protection element  102  and the third surge protection element  103  to form a small-scale modular circuit integration structure. However, the difference between the two embodiments is previously described, but the rest is the same. Hence, the detail description is omitted here for conciseness. 
     In conclusion, the present invention has following advantages: 
     1. The surge protection unit  10 , the temperature fuses  11 , 12 , and the jumper elements  21 , 22  are integrated into a small-scale modular lightning surge protection apparatus  100  which can be simply installed in an electric outlet for providing the lightning surge protection. In addition, when the modular lightning surge protection apparatus  100  is damaged, another new one can be directly installed to provide normally operations after the damaged one is removed; 
     2. The surge protection elements  101 ˜ 103  without a coating layer are insulated by a dispensing process so as to significantly save occupied space of the components, simplify the complexity of the process, and reduce costs; 
     3. The surge protection elements  101 ˜ 103  are integrated and modularized to reduce resistances between the surge protection elements  101 ˜ 103  so as to reduce residual voltage across the discharge gap of the surge protection elements  101 ˜ 103 ; 
     4. The modular lightning surge protection apparatus  100  can be directly certificated to reduce the safety certification application fee and application time, thus raising visibility of products and competitiveness of companies; 
     5. The wye-connected modular lightning surge protection apparatus  100  can use the surge protection elements with withstand voltage reducing by half to reduce thickness of the elements, thus minimizing the modular lightning surge protection apparatus  100 ; 
     6. The metal oxide varistor (MOV) in the wye-connected modular lightning surge protection apparatus  100  can be replaced by a gas discharge tube (GDT); and 
     7. The first indicating unit  41  and the second indicating unit  42  are used to indicate that the external power source is normal or abnormal for supplying the modular lightning surge protection apparatus  100  and indicate that the modular lightning surge protection apparatus  100  is available or unavailable for providing the lightning surge protection, respectively, thus correctly and effectively operating the modular lightning surge protection apparatus  100  for users. 
     Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the present disclosure is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the present disclosure as defined in the appended claims.