Surge arrester

Abstract

To accurately detect operation of a lightning arrestor while attaining structure simplification and cost reduction of the lightning arrestor.SOLUTION: A lightning arrestor 1 comprises: a surge current path 2 in which a surge current flows; an operation detection unit 3 for operating that the lightning arrestor 1 is operated by the surge current flowing in the surge current path 2; and a housing 4 in which the surge current path 2 and the operation detection unit 3 are stored. The operation detection unit 3 includes: a coil 31 in which a secondary voltage is generated by the surge current flowing in the surge current path 2; a comparator 33 which outputs a detection signal in a case where the secondary voltage exceeds a threshold; a flip-flop 34 which holds output of a lighting signal when the detection signal is inputted; and an operation lamp 35 which is lighted while the output of the lighting signal is held.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lightning arrester (SPD (Surge Protective Device)) used in power circuits and communication circuits such as in switchboards (cubicles) and distribution boards to protect electrical equipment from surge currents caused by direct lightning strikes or induced lightning strikes.

Background Art

[0002] A lightning arrester forms a bypass path to the ground when a surge current invades through a power system or the like to protect electrical equipment, and generally includes protection elements such as varistors and gaps (gas-filled discharge tubes or arresters).

[0003] However, even when these protection elements operate when a surge current invades, the traces often do not remain. That is, it is difficult to determine whether the lightning arrester has operated from the appearance of the protection element or the like.

[0004] Therefore, for example, Patent Document 1 discloses a lightning arrester including a phototransistor that detects light emission during discharge of a gas arrester due to a surge current, a microcomputer (CPU18) that controls a counter based on an output from the phototransistor, and a counter that displays the number of light emission times of the gas arrester based on an output from the microcomputer. This lightning arrester operates as follows. That is, when a surge current passes through the gas arrester, the gas arrester discharges and emits light, and the phototransistor receives the light. When the phototransistor detects the light emission of the gas arrester, it outputs an electrical signal to the microcomputer. The microcomputer programmatically processes the input electrical signal and electrically increases the count of the counter. Thereby, the number of operation times of the lightning arrester can be known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when using a microcomputer as in the lightning arrester disclosed in Patent Document 1, there is a problem that when a surge current flows through the lightning arrester, the microcomputer is likely to malfunction or be damaged. Therefore, a complex protection circuit such as an isolation transformer or a DC-DC converter is essential for the power supply circuit for the microcomputer. As a result, there is a problem that the structure of the lightning arrester becomes complicated and it is difficult to reduce the cost of the lightning arrester.

[0007] An object of the present invention is to accurately detect the operation of a lightning arrester while simplifying the structure and reducing the cost of the lightning arrester.

Means for Solving the Problems

[0008] (1) The present invention devised to solve the above problems is a lightning arrester comprising a surge current path through which a surge current flows, an operation detection unit that detects that the lightning arrester has operated due to the surge current flowing through the surge current path, and a housing that houses the surge current path and the operation detection unit, wherein the operation detection unit includes a coil that generates a secondary voltage by the surge current flowing through the surge current path, a first analog circuit that outputs a detection signal when the secondary voltage exceeds a threshold value, a second analog circuit that holds the output of a lighting signal when the detection signal is input, and an operation lamp that lights while the output of the lighting signal is held.

[0009] In this way, the presence or absence of the operation of the lightning arrester can be accurately determined by the presence or absence of the lighting of the operation lamp. That is, the operation of the lightning arrester can be accurately detected with a simple and inexpensive configuration of a coil, a first analog circuit, a second analog circuit, and an operation lamp without using a microcomputer.

[0010] (2) In the configuration of (1) above, it is preferable that the first analog circuit is a comparator and the second analog circuit is a flip-flop.

[0011] By doing so, it is possible to miniaturize the first analog circuit and the second analog circuit, which has the advantage of making it easier to accommodate these analog circuits in the housing. Also, power saving of the lightning arrester can be achieved.

[0012] (3) In the configuration of the above (1) or (2), it is preferable that the operation lamp is an LED.

[0013] By doing so, miniaturization and power saving of the lightning arrester can be achieved.

[0014] (4) In any of the configurations of the above (1) to (3), a plurality of sets including the first analog circuit, the second analog circuit, and the operation lamp are provided, the magnitude of the threshold value of the first analog circuit is different for each set, and a secondary voltage is input to the first analog circuit included in each set, and according to the magnitude of the surge current, the combination of the operation lamps that light up may be different.

[0015] By doing so, from the combination of the operation lamps that are lit, not only the presence or absence of the operation of the lightning arrester but also the magnitude of the surge current can be determined.

[0016] (5) In any of the configurations of the above (1) to (4), the surge current path includes a plurality of power supply terminals to be connected to a power system having a plurality of electric wires, a plurality of varistors each having one end connected to each of the power supply terminals and the other end connected to a common connection point, and a gap connected between the common connection point of the varistors and the ground terminal, and it is preferable that the coil is arranged between the common connection point of the varistors and the ground terminal.

[0017] By doing so, even when applying a lightning arrester to a power system having a plurality of electric wires such as an AC three-phase three-wire system, there is an advantage that only one coil is required to detect the operation of the lightning arrester.

Advantages of the Invention

[0018] According to the present invention, while simplifying and reducing the cost of the structure of the lightning arrester, the operation of the lightning arrester can be accurately detected.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each embodiment, the same reference numerals may be assigned to corresponding components, and redundant descriptions may be omitted. When only a part of the configuration is described in each embodiment, the configuration of other embodiments described previously can be applied to other parts of the configuration. Also, not only the combinations of configurations explicitly shown in the description of each embodiment, but also the configurations of multiple embodiments can be partially combined with each other without any problem in the combination, even if not explicitly shown.

[0021] (First Embodiment) As shown in FIGS. 1 and 2, as the lightning arrester 1 according to the first embodiment, an example is shown of one installed inside a distribution board connected to an AC three-phase three-wire power system (not shown). The lightning arrester 1 includes a surge current path 2 through which a surge current flows, an operation detection unit 3 that detects that the lightning arrester 1 has operated due to the surge current flowing through the surge current path 2, and a resin housing 4 (see FIG. 2) that houses the surge current path 2 and the operation detection unit 3 inside.

[0022] As shown in FIG. 1, the surge current path 2 includes three power supply terminals 5 to 7 to be connected to the lines of each phase of the power system (a total of three electric wires) and a ground terminal 8 to be connected to the ground. The surge current path 2 includes, between the power supply terminals 5 to 7 and the ground terminal 8, temperature fuses 9 to 11 made of low-temperature solder, varistors 12 to 15, and a gap (gas-filled discharge tube or arrester) 16 as the main circuit.

[0023] Specifically, a series circuit of the temperature fuses 9 to 11 and the varistors 12 to 14 is connected to each of the power supply terminals 5 to 7, and the varistor 12 to 14 sides of the respective series circuits are commonly connected at a common connection point 17. Also, a series circuit of the varistor 15 and the gap 16 is connected between the common connection point 17 and the ground terminal 8. The two varistors 12 to 14 between the power supply terminals 5 to 7 equally share and absorb the line-to-line surge, and the common varistor 15 between one of the varistors 12 to 14 between the power supply terminals 5 to 7, the common connection point 17, and the ground terminal 8 absorbs the line-to-ground surge.

[0024] Also, a series circuit of a deterioration display lamp (LED) 21, a resistor 22, and a diode 23 is connected between the connection point 18 of the temperature fuse 9 and the varistor 12 and the connection point 19 of the temperature fuse 10 and the varistor 13. The resistor 22 and the diode 23 are a protection circuit for the deterioration display lamp 21. Similarly, a series circuit of a deterioration display lamp (LED) 24, a resistor 25, and a diode 26 is connected between the connection point 19 of the temperature fuse 10 and the varistor 13 and the connection point 20 of the temperature fuse 11 and the varistor 14. The resistor 25 and the diode 26 are a protection circuit for the deterioration display lamp 24. When the lightning arrester 1 is sound, the deterioration display lamps 21 and 24 light up. On the other hand, when the temperature fuses 9 to 11 are blown due to abnormal heat generation (e.g., abnormal heat generation of the varistors 12 to 15) occurring during deterioration of the lightning arrester 1, the deterioration display lamps 21 and 24 go out.

[0025] As shown in FIG. 1, the operation detection unit 3 includes a coil 31, a bridge diode 32 as a rectifying unit, a comparator (comparator IC) 33 as a first analog circuit, a flip-flop (flip-flop IC) 34 as a second analog circuit, and an operation lamp 35 as a main circuit. The main circuit including the coil 31 is housed in the housing 4. The operation detection unit 3 does not include a counter for counting the number of operations of the lightning arrester 1.

[0026] The coil 31 generates a secondary voltage by the surge current flowing through the surge current path 2. The coil 31 is disposed near the gap 16, that is, between the common connection point 17 and the ground terminal 8. In the present embodiment, the coil 31 is disposed between the common connection point 17 and the ground terminal 8 and between the varistor 15 and the gap 16. In this way, the surge current passes through the coil 31 regardless of which power supply terminals 5 to 7 the surge current enters the surge current path 2, so that the operation of the lightning arrester 1 can be reliably detected.

[0027] The coil 31 is a toroidal coil using an annular ferromagnetic material as a core. A wire forming a part of the surge current path 2 is inserted through the central hole of the coil 31. In the present embodiment, the number of turns of the coil 31 is 7 to 15 turns (preferably about 10 turns). The reason for the small number of turns of the coil 31 is that in the present embodiment, the operating voltage of the operation detection unit 3 (comparator 33 and flip-flop 34) is not supplied from the secondary voltage of the coil 31. In other words, the number of turns of the coil 31 may be any number as long as it can ensure a secondary voltage (rectified voltage) capable of detecting the operation of the lightning arrester 1. The number of turns of the coil 31 is not particularly limited and can be changed as appropriate.

[0028] The bridge diode 32 rectifies the secondary voltage generated by the coil 31. Since the surge current has a positive polarity and a negative polarity, the secondary voltage generated by the coil 31 also becomes positive or negative according to the polarity of the surge current. Therefore, the bridge diode 32 converts the secondary voltage output by the coil 31 into a rectified voltage that is always positive. As a result, the internal circuits of the comparator 33 and the flip-flop 34 do not need to consider a negative voltage and only one circuit corresponding to a positive voltage is sufficient. That is, the internal circuits of the comparator 33 and the flip-flop 34 can be simplified.

[0029] The comparator 33 outputs a detection signal (analog signal) when the rectified voltage (secondary voltage) input from the bridge diode 32 exceeds the threshold value. This threshold value can be adjusted by changing the resistance value of the offset resistor 36. The offset resistor 36 is preferably a variable resistor so that the resistance value can be easily changed.

[0030] When a detection signal is input from the comparator 33, the flip-flop 34 outputs a lighting signal (analog signal) for lighting the operation lamp 35. The A-contact circuit of the flip-flop 34 is used for the output of the lighting signal. That is, the A-contact circuit of the flip-flop 34 is normally off (open state) and turns on (short state) when the rectified voltage caused by the surge current exceeds the threshold value. Therefore, when the rectified voltage exceeds the threshold value, the output of the lighting signal is held.

[0031] The operation lamp 35 lights while the output of the lighting signal from the flip-flop 34 is held, and is composed of an LED in this embodiment. That is, the operation lamp 35 is normally off and lights when the rectified voltage caused by the surge current exceeds the threshold value. In this way, the presence or absence of the operation of the lightning arrester 1 can be accurately determined by the presence or absence of the lighting of the operation lamp 35. Here, in this embodiment, the fact that the lightning arrester 1 has operated means that both the varistor 15 and the gap 16 have operated.

[0032] Note that, as shown in FIG. 2, the deterioration display lamps 21 and 24 and the operation lamp 35 can be visually confirmed from the outside of the housing 4 of the lightning arrester 1.

[0033] In the present embodiment, the operation detection unit 3 further includes the following configuration.

[0034] The operation detection unit 3 includes a reset switch 37 for releasing the lighting signal of the flip-flop 34. That is, even after the operation lamp 35 is lit, if the reset switch 37 is pressed, the lighting signal is released and the operation lamp 35 goes out. Thereby, the operation display of the lightning arrester 1 can be performed again. Note that, as shown in FIG. 2, the reset switch 37 can be pressed from the outside of the housing 4 of the lightning arrester 1.

[0035] The operation detection unit 3 includes a bidirectional VRD 38 on the output side of the coil 31. When an excessive surge current flows through the surge current path 2, the secondary voltage generated by the coil 31 becomes high, and there is a risk of malfunction or damage to the comparator 33. Therefore, the VRD 38 suppresses the magnitude of the excessive secondary voltage generated by the coil 31.

[0036] The operation detection unit 3 includes a resistor 39 on the output side of the coil 31. The resistor 39 is for adjusting the magnitude of the secondary voltage input to the bridge diode 32. The resistance value of the resistor 39 is, for example, about 1 Ω.

[0037] The operation detection unit 3 includes a voltage dividing resistor 42 composed of resistors 40 and 41 on the output side of the bridge diode 32. The magnitude of the rectified voltage input to the comparator 33 is adjusted by the voltage division by this voltage dividing resistor 42.

[0038] The operation detection unit 3 includes a capacitor 45 between the connection point 43 of the resistor 40 and the resistor 41 and the ground 44. Thereby, even when a steep surge current flows through the surge current path 2, the rectified voltage input to the comparator 33 can be smoothed and its rising speed can be slowed down. As a result, the operation of the comparator 33 becomes stable even against a steep surge current.

[0039] The operation detection unit 3 is configured to be supplied with power from the power supply terminals 5 and 6. A resistor (or capacitor) 46 is connected to the power supply circuit connected to these power supply terminals 5 and 6 in order to adjust the magnitude of the AC voltage constantly supplied from the power grid through the power supply terminals 5 and 6. Further, a varistor 47 and a bridge diode 48 are connected to this power supply circuit to protect the operation detection unit 3 from surge currents. The bridge diode 48 has a function of converting an AC voltage into a DC voltage. The DC voltage output from the bridge diode 48 is adjusted in magnitude by a resistor 49 and then converted into a constant DC voltage (for example, 5V) by a regulator 50. The comparator 33 and the flip-flop 34 operate using the constant DC voltage output from the regulator 50 as a startup power supply. Since the magnitudes of the voltages are adjusted by the resistors 46 and 49, the input rated voltage of the regulator 50 can be reduced within the range where the comparator 33 and the flip-flop 34 operate normally. Therefore, a small-sized regulator 50 can be used. Reference numerals 51 and 52 are capacitors for countermeasures against voltage ripple.

[0040] A capacitor 53 is connected in parallel to the reset switch 37. When a surge current invades again from the power supply terminal 5 or 6 when the operation lamp 35 is lit, and noise caused by the surge current may invade the flip-flop 34. In this case, the flip-flop 34 may misrecognize the short-term voltage drop due to the noise as a clear signal (reset signal by the reset switch 37) and turn off the operation lamp 35. Therefore, in order to prevent such malfunction of the flip-flop 34, the capacitor 53 prevents the short-term voltage drop due to the noise.

[0041] Next, the operation of the operation detection unit 3 of the lightning arrester 1 configured as described above will be described.

[0042] When a surge current flows through the surge current path 2, a secondary voltage is generated in the coil 31. The secondary voltage generated in the coil 31 is input to the bridge diode 32. At this time, regardless of whether the polarity of the secondary voltage is positive or negative, it is converted into a rectified voltage with a positive polarity by the bridge diode 32. The rectified voltage converted by the bridge diode 32 is input to the comparator 33.

[0043] When the rectified voltage is input, the comparator 33 determines whether the magnitude of the rectified voltage exceeds a threshold value. As a result, when the rectified voltage exceeds the threshold value, the comparator 33 outputs a detection signal to the flip-flop 34. The magnitude of the threshold value can be adjusted by the offset resistor 36.

[0044] When the detection signal is input, the flip-flop 34 outputs a lighting signal to the operation lamp 35. The lighting signal is held until the reset switch 37 is pressed.

[0045] The operation lamp 35 lights up when the lighting signal is input. That is, the operation lamp 35 lights up when the rectified voltage exceeds the threshold value of the comparator 33, and remains off when the rectified voltage is below the threshold value of the comparator 33.

[0046] Note that the lit operation lamp 35 turns off when the reset switch 37 is pressed. Thereby, the operation display of the lightning arrester 1 becomes possible again. Also, a situation where a surge current invades again when the operation lamp 35 is lit and the flip-flop 34 malfunctions and the operation lamp 35 turns off is prevented by the capacitor 53.

[0047] Here, the secondary voltage generated by the coil 31 changes according to the magnitude of the surge current. That is, depending on the magnitude of the surge current, the secondary voltage generated by the coil 31 can become excessive. Therefore, when an excessive secondary voltage is generated, in order to protect the comparator 33, the magnitude of the secondary voltage is suppressed by the VRD 38. Note that the magnitude of the secondary voltage input to the bridge diode 32 is adjusted by the resistor 39. Also, the magnitude of the secondary voltage (rectified voltage) input to the comparator 33 is adjusted by the voltage dividing resistors 42. Further, even when the secondary voltage generated by the coil 31 due to the surge current is steep, the rising speed of the secondary voltage (rectified voltage) is suppressed by the capacitor 45 so that the comparator 33 operates stably.

[0048] According to the above configuration, without using a microcomputer, the operation of the lightning arrester 1 can be accurately detected with an inexpensive and simple configuration including the coil 31, the comparator 33, the flip-flop 34, and the operation lamp 35. Also, since the operation detection unit 3 does not include a microcomputer, the protection circuit for protecting the operation detection unit 3 from the surge current can be simplified. Therefore, the operation detection unit 3 can be housed, for example, in a small housing 4 having a vertical dimension of 105 mm and a horizontal dimension of 75 mm.

[0049] (Second Embodiment) As shown in FIG. 3, the operation detection unit 3 of the lightning arrester 1 according to the second embodiment of the present invention includes two sets of a pair including comparators 33a and 33b, flip-flops 34a and 34b, and operation lamps 35a and 35b. And the magnitude of the threshold values of the comparators 33a and 33b is different for each set, and the rectified voltage (secondary voltage) is input to the comparators 33a and 33b included in each set, and according to the magnitude of the surge current flowing through the surge current path 2, the combination of the operation lamps 35a and 35b that light up is different. Note that in the present embodiment, the case where the operation detection unit 3 includes two sets of a pair including the comparators 33a and 33b, the flip-flops 34a and 34b, and the operation lamps 35a and 35b is illustrated, but the operation detection unit 3 may include three or more sets of a pair including a comparator, a flip-flop, and an operation lamp.

[0050] In this embodiment, the first comparator 33a, the first flip-flop 34a, and the first operation lamp 35a are grouped together, and the second comparator 33b, the second flip-flop 34b, and the second operation lamp 35b are grouped together. For example, the threshold value of the first comparator 33a is set to 2.5V, and the threshold value of the second comparator 33b is set to 3.5V. In this case, when both the first operation lamp 35a and the second operation lamp 35b are off, the surge current flowing through the surge current path 2 can be determined to be, for example, 200A or less. When only the first operation lamp 35a is lit, the surge current flowing through the surge current path 2 can be determined to be, for example, 200A to 1000A. When both the first operation lamp 35a and the second operation lamp 35b are lit, the surge current flowing through the surge current path 2 can be determined to be, for example, 1000A or more. Therefore, from the combination of the lit operation lamps 35a and 35b, not only the presence or absence of the operation of the lightning arrester 1 but also the magnitude of the surge current can be determined.

[0051] Note that in this embodiment, dedicated offset resistors 36a and 36b for adjusting the threshold value are connected to the comparators 33a and 33b, respectively. On the other hand, a common reset switch 37 is connected to each of the flip-flops 34a and 34b. By pressing this common reset switch 37, the output of the lighting signal of each of the flip-flops 34a and 34b is simultaneously released.

[0052] As described above, the lightning arrester according to the embodiment of the present invention has been described. However, the embodiments of the present invention are not limited to this, and various modifications can be made without departing from the gist of the present invention.

[0053] In the above-described embodiment, an example of the surge current path of the lightning arrester is one connected to an AC three-phase three-wire power system. However, the configuration of the surge current path is not limited to this. For example, the surge current path may be connected to other AC power systems such as an AC single-phase three-wire system or an AC single-phase two-wire system. Alternatively, the surge current path may be connected to a DC power system. That is, the number of power supply terminals (input terminals) and the circuit configuration of the surge current path can be changed according to the power system to which it is connected. When the power system is an AC single-phase two-wire system, if two electric wires of the power system are connected to the power supply terminal 5 and the power supply terminal 6 shown in FIGS. 1 and 3, the surge current path 2 in the figure can be used as it is.

[0054] In the above-described embodiment, the operation detection unit may output a contact when the lightning arrester operates. In this case, a signal may be output to the outside using a triac. Specifically, the A contact circuit of the flip-flop is used. The A contact circuit of the flip-flop is normally off (open state) and turns on (short state) when the rectified voltage caused by the surge current exceeds the threshold value. Therefore, if a triac is connected to the A contact circuit of the flip-flop, an external contact can be output when the lightning arrester operates.

[0055] In the above-described embodiment, the operation detection unit may send an email to an administrator or the like when the lightning arrester operates. In this case, a mail transmission unit or the like that operates when the A contact circuit turns on may be connected to the A contact circuit of the flip-flop.

[0056] In the above embodiment, the case where the first analog circuit is configured by a comparator has been described, but the first analog circuit is not limited to this. For example, the first analog circuit may be an operational amplifier or a combination of a plurality of operational amplifiers. Similarly, in the above embodiment, the case where the second analog circuit is configured by a flip-flop has been described, but the second analog circuit is not limited to this. For example, the second analog circuit may be a latch relay or the like. However, from the viewpoint of housing in a small casing (lightning arrester), it is preferable that the first analog circuit is a comparator and the second analog circuit is a flip-flop.

Explanation of Signs

[0057] 1 Lightning arrester 2 Surge current path 3 Operation detection unit 4 Casing 5 to 7 Power supply terminals 8 Ground terminal 9 to 11 Thermal fuses 12 to 15 Varistors 16 Gap 17 Common connection point 21, 24 Deterioration indication lamp 31 Coil 32 Bridge diode 33 Comparator (first analog circuit) 34 Flip-flop (second analog circuit) 35 Operation lamp 36 Offset resistor 37 Reset switch 38 VRD 39 Resistor 40 Resistor 41 Resistor 42 Voltage dividing resistor 44 Ground 45 Capacitor 46 Resistor 47 Varistor 48 Bridge diode 49 Resistor 50 Regulator 53 Capacitor

Claims

A lightning arrester comprising: a surge current path connected to a power system having an electric wire and through which a surge current flows; an operation detection unit that detects that the lightning arrester has operated due to the surge current flowing through the surge current path; and a housing that houses the surge current path and the operation detection unit, further comprising a power supply circuit connected to the power system and supplying power to the operation detection unit, wherein the power supply circuit includes a protection circuit that protects the operation detection unit from the surge current between the power system and the operation detection unit, wherein the operation detection unit includes: a coil that generates a secondary voltage due to the surge current flowing through the surge current path; a first analog circuit that outputs a detection signal when the secondary voltage exceeds a threshold value; a second analog circuit that holds the output of a lighting signal when the detection signal is input; and an operation lamp that lights while the output of the lighting signal is held. The lightning arrester is characterized by this.

2. The lightning arrester according to claim 1, wherein the first analog circuit is a comparator and the second analog circuit is a flip-flop.

3. The lightning arrester according to claim 1 or 2, wherein the operation lamp is an LED.

4. including a plurality of sets including the first analog circuit, the second analog circuit, and the operation lamp, wherein the magnitude of the threshold value of the first analog circuit is different for each set, and the secondary voltage is input to the first analog circuit included in each set, The lightning arrester according to any one of claims 1 to 3, wherein the combination of the operation lamps that light is different according to the magnitude of the surge current.

5. wherein the surge current path includes: a plurality of power supply terminals to be connected to a power system having a plurality of electric wires; a plurality of varistors each having one end connected to each of the power supply terminals and the other end connected to a common connection point; and a gap connected between the common connection point of the varistors and a ground terminal, The lightning arrester according to any one of claims 1 to 4, wherein the coil is disposed between the connection midpoint of the varistor and the ground terminal. A lightning arrester comprising: a surge current path through which a surge current flows; an operation detection unit that detects that the lightning arrester has operated due to the surge current flowing through the surge current path; and a housing that houses the surge current path and the operation detection unit, The operation detection unit includes a coil that generates a secondary voltage by the surge current flowing through the surge current path, a first analog circuit that outputs a detection signal when the secondary voltage exceeds a threshold value, a second analog circuit that holds the output of a lighting signal when the detection signal is input, and an operation lamp that lights while the output of the lighting signal is held. A plurality of sets including the first analog circuit, the second analog circuit, and the operation lamp are provided. The magnitude of the threshold value of the first analog circuit is different for each set, and the secondary voltage is input to the first analog circuit included in each set. A lightning arrester characterized in that the combination of the operation lamps that light is different according to the magnitude of the surge current.

Images