JP6183863B2 - SPD with deterioration warning function - Google Patents

Description

  The present invention relates to an SPD (Surge Protective Device) configured with a varistor that protects electrical equipment by limiting a surge voltage caused by a lightning strike, and relates to an SPD with a degradation alarm function that detects degradation of the varistor by a thermal fuse.

  In power lines drawn from single-phase or three-phase AC circuits to factories and general households, for example, to prevent lightning damage caused by direct lightning strikes or induced lightning, surge currents that are transient overvoltages caused by lightning strikes are limited. As a device for protecting electrical equipment by shunting, an SPD is installed on the power line. As this SPD, there is a structure in which a zinc oxide type varistor (hereinafter simply referred to as a varistor) is incorporated.

  When a lightning surge is repeatedly applied, the varistor deteriorates with time depending on the current level of the lightning surge. When the varistor deteriorates, the leakage current increases and heat is generated, causing smoke and ignition due to thermal runaway. For this reason, the present applicant has previously proposed an SPD with a degradation alarm function that detects the degradation of the varistor with a thermal fuse in order to prevent smoke and ignition due to thermal runaway caused by the degradation of the varistor (for example, patents). Reference 1).

  In the SPD with a deterioration alarm function disclosed in Patent Document 1, a series circuit including a disconnecting temperature fuse and a varistor is connected to a power supply terminal to which a distribution line is connected, and the varistor side of the series circuit is connected in common. And a circuit having a gas arrester connected between the common connection point and the ground terminal.

  In an SPD equipped with the above-described configuration circuit, the thermal fuse arranged at a position close to the varistor is blown when abnormal heat generation due to significant deterioration of the varistor is detected. Due to the melting of the thermal fuse, the deteriorated varistor is disconnected from the power supply terminal. This prevents smoke and ignition due to thermal runaway of the varistor. On the other hand, when the surge current flows from the power supply terminal to the ground terminal until the thermal fuse is blown due to the significant deterioration of the varistor, the gas arrester discharges and emits light.

  In the aforementioned SPD, a control circuit for a deterioration alarm function is provided separately from the basic configuration circuit of the SPD. This control circuit is arranged close to the gas arrester, detects a light emission at the time of discharge of the gas arrester due to a surge current, a CPU that controls a counter based on an output from the phototransistor, and an output of the CPU And a contact output terminal for sending out the deterioration information of the varistor to the outside.

  In the control circuit having the above-described configuration, light emission at the time of discharging of the gas arrester is detected by a phototransistor. The CPU determines the deterioration state of the varistor based on the light emission time of the gas arrester based on the output from the phototransistor. That is, the CPU determines whether or not the threshold value set based on the light emission time of the gas arrester is exceeded, and notifies the deterioration information of the varistor from the contact output terminal to the outside based on the determination result.

JP 2012-104598 A

  By the way, in the SPD with the deterioration alarm function disclosed in the above-mentioned Patent Document 1, it is necessary to provide a control circuit having a varistor deterioration information sending contact output terminal for operating the deterioration alarm function, in addition to the SPD constituent circuit. There is.

  For this reason, the circuit configuration of the entire SPD in which a control circuit is added to the basic configuration circuit of the SPD becomes complicated, and the SPD tends to increase. For this reason, there has been a demand for the simplification of the circuit configuration in the SPD with a deterioration warning function and the compactness of the SPD with a deterioration warning function.

  Accordingly, the present invention has been proposed to improve the above-described improvements, and an object of the present invention is to provide an SPD with a degradation alarm function that can easily realize simplification and compactness of the circuit configuration. .

  As technical means for achieving the above-mentioned object, the present invention includes a plurality of varistors connected between a power supply terminal connected to a distribution line and a ground terminal, and connected between the power supply terminal and the varistor. SPD with a degradation alarm function equipped with a thermal fuse for disconnection, having a contact output terminal for outputting varistor degradation information to the outside, and between a common connection point where the varistors are commonly connected and the contact output terminal A contact output temperature fuse is provided, and the fusing temperature and the lightning surge resistance of the contact output temperature fuse are separated and set to be smaller than the fusing temperature and the lightning surge resistance of the temperature fuse for contact.

  In the present invention, a contact output terminal for enabling deterioration information to be transmitted is provided, a contact output temperature fuse is provided between the contact output terminal and a common connection point of the varistor, and the contact output temperature fuse By setting the fusing temperature and lightning surge resistance to be smaller than the temperature fuse for disconnection, the temperature fuse for contact output is blown before the temperature fuse for disconnection reacts due to abnormal heat generation due to significant deterioration of the varistor or a large surge current.

  By blowing the contact output temperature fuse, it is possible to output varistor deterioration information from the contact output terminal to the outside. This eliminates the need for a conventional control circuit having a deterioration alarm function separately from the basic configuration circuit of the SPD. As a result, the SPD circuit configuration can be easily simplified and made compact.

  In the present invention, the contact output terminal is composed of first and second contact output terminals, the contact output thermal fuse is composed of first and second contact output thermal fuses, the common connection point and the first A first contact output temperature fuse is connected between the first contact output terminal and the second contact output temperature fuse between the common connection point, the second contact output terminal and the ground terminal, It is desirable that the fusing temperature and lightning surge resistance of the first contact output temperature fuse be set smaller than the fusing temperature and lightning surge tolerance of the second contact output temperature fuse.

  As described above, if the fusing temperature and the lightning surge withstand capability of the first contact output temperature fuse are set smaller than those of the second contact output temperature fuse, the second heat is generated due to abnormal heat generation or a large surge current due to significant deterioration of the varistor. Before the contact output temperature fuse reacts, the first contact output temperature fuse is blown. Thereby, since it can avoid that a big surge current flows out from a 1st contact output terminal, damage to the electric equipment connected to the 1st contact output terminal can be prevented.

  According to the present invention, the contact output temperature fuse is blown before the disconnection temperature fuse reacts due to abnormal heat generation due to significant deterioration of the varistor or a large surge current. By blowing the contact output temperature fuse, it is possible to output varistor deterioration information from the contact output terminal to the outside. This eliminates the need for a conventional control circuit having a deterioration alarm function separately from the basic configuration circuit of the SPD. As a result, the SPD circuit configuration can be easily simplified and made compact, and a small SPD with a deterioration alarm function can be provided.

In embodiment of this invention, it is a circuit diagram which shows the structure of SPD with a degradation warning function for three phases. It is a circuit diagram which shows the structure of SPD with a deterioration alarm function for single phases in other embodiment of this invention. It is a top view which shows the state which mounted the circuit component of SPD of FIG. 1 on the wiring board. FIG. 4 is a front view of FIG. 3. FIG. 4 is a left side view of FIG. 3.

  An embodiment of an SPD with a deterioration warning function according to the present invention will be described in detail below. The embodiment shown in FIG. 1 illustrates an SPD installed in an AC three-phase three-wire distribution line, and the embodiment shown in FIG. 2 illustrates an SPD installed in an AC single-phase three-wire distribution line. To do. Hereinafter, the SPD (see FIG. 1) installed in the AC three-phase three-wire distribution line will be described. In FIG. 2, the same parts as those in FIG.

  The SPD of this embodiment has a circuit configuration as shown in FIG. That is, a plurality (three in the figure) of varistors 5 to 7 connected between the power supply terminals 1 to 3 and the ground terminal 4 to which the distribution lines of each phase are connected, and the power supply terminals 1 and 3 and the varistors 5 and 5. 7 is a basic circuit comprising a disconnecting thermal fuse 8, 9 connected to 7, a common connection point 10 commonly connecting varistors 5 to 7, and a gas arrester 11 connected between the ground terminal 4. It is configured.

  In this basic circuit, the varistors 5 to 7 are mainly composed of ZnO, for example, and the gas arrester 11 has a discharge gap. At least two of the varistors 5 to 7 operate in series with respect to the lightning surge between the lines, and with respect to the lightning surge between the ground, any of the varistors 5 to 7 and the gas arrester 11 are connected in series. Connected body works. In this way, the electrical devices are protected from lightning surges by the operation of the varistors 5 to 7 and the gas arrester 11.

  In addition to the basic circuit described above, the SPD includes first and second contact output terminals 12 and 13 that send out deterioration information of the varistors 5 to 7 to the outside. First and second contact output temperature fuses 14 and 15 are provided between a common connection point 10 where the varistors 5 to 7 are connected in common and the first and second contact output terminals 12 and 13.

  That is, the first contact output temperature fuse 14 is connected at the connection midpoint 16 between the common connection point 10 of the varistors 5 to 7 and the first contact output terminal 12. A second contact output temperature fuse 15 is connected between the common connection point 10 and the second contact output terminal 13. The second contact output temperature fuse 15 is connected to the ground terminal 4 via the gas arrester 11 at a connection midpoint 17.

  As shown in FIGS. 3 to 5, the SPD having the above-described configuration circuit includes a varistor 5 to 7, a gas arrester 11, disconnection temperature fuses 8 and 9, and first and second contact output temperature fuses 14. , 15 are mounted on a wiring board 18 and housed in a resin case 19.

  In the mounting structure of the component parts on the wiring board 18, the thermal fuses 8 and 9 for separation are brought close to the main body surface of the varistors 5 and 7 on both outer sides of the two varistors 5 and 7 connected to the power supply terminals 1 and 3. It is arranged in the state.

  By adopting such an arrangement structure, the heat generated by the deterioration of the varistors 5 and 7 can be easily conducted to the disconnecting temperature fuses 8 and 9, and the disconnecting temperature fuses 8 and 9 react quickly due to the generated heat. I try to blow.

  Further, the first contact output temperature fuse 14 is arranged so as to be sandwiched between the two varistors 5 and 6 connected to the power supply terminals 1 and 2 in the state of being close to the surface of the main body of both varistors 5 and 6. ing. Further, the second contact output temperature fuse 15 is arranged so as to be sandwiched between the two varistors 6 and 7 connected to the power supply terminals 2 and 3 in the state of being close to the surface of the main body of both varistors 6 and 7. ing.

  By adopting such an arrangement structure, if any one of the varistors 5 to 7 deteriorates and generates heat, the heat is easily conducted to the first and second contact output temperature fuses 14 and 15. The heat generation causes the first and second contact output temperature fuses 14 and 15 to react and blow.

  In the SPD configured as described above, the disconnecting temperature fuses 8 and 9 disposed in proximity to the varistors 5 and 7 are blown when abnormal heat generation due to significant deterioration of the varistors 5 to 7 is detected. The fusing varistors 5 to 7 are disconnected from the power supply terminals 1 and 3 by the melting of the disconnecting temperature fuses 8 and 9. As a result, smoke and fire due to thermal runaway due to deterioration of the varistors 5 to 7 is prevented in advance.

  On the other hand, surge current flows from the power supply terminals 1 to 3 through the gas arrester 11 to the ground terminal 4 in a state until the thermal fuses 8 and 9 for disconnection due to significant deterioration of the varistors 5 to 7 are reached. Surge current is released to ground.

  In this SPD, the fusing temperature and the lightning surge resistance of the first and second contact output temperature fuses 14 and 15 are set smaller than the fusing temperature and the lightning surge resistance of the disconnecting temperature fuses 8 and 9.

  For example, if the fusing temperature of the disconnecting temperature fuses 8 and 9 is 131 ° C. and the lightning surge resistance is 12 kA, the fusing temperature of the first contact output temperature fuse 14 is 100 ° C., the lightning surge resistance is 6 kA, and the second The fusing temperature of the contact output temperature fuse 15 is 111 ° C., and the lightning surge resistance is 10 kA.

  Note that the values of the fusing temperature and the lightning surge withstand described above are examples, and the optimum values can be set and changed according to conditions such as the type of varistor. The fusing temperature and lightning surge resistance of the disconnecting temperature fuses 8 and 9 and the first and second contact output temperature fuses 14 and 15 are the materials and cross-sectional areas of the temperature fuses 8, 9, 14, and 15 and the like. It can be set by selecting the optimum one.

  This SPD has first and second contact output terminals 12 and 13, and the first and second contact output between the first and second contact output terminals 12 and 13 and the common connection point 10. The thermal fuses 14 and 15 are provided, and the fusing temperature and the lightning surge resistance of the first and second contact output thermal fuses 14 and 15 are set smaller than those of the disconnecting thermal fuses 8 and 9, so that the varistor 5 First, the first and second contact output temperature fuses 14 and 15 are blown before the disconnection temperature fuses 8 and 9 react due to abnormal heat generation due to significant deterioration of 7 or a large surge current.

  By fusing the first and second contact output temperature fuses 14 and 15, deterioration information of the varistors 5 to 7 can be sent to the outside from the first and second contact output terminals 12 and 13. This eliminates the need for a conventional control circuit having a deterioration alarm function separately from the basic configuration circuit of the SPD. As a result, the SPD circuit configuration can be easily simplified and made compact.

  Here, the first contact output temperature fuse 14 connected at the connection middle point 16 between the common connection point 10 of the varistors 5 to 7 and the first contact output terminal 12 and the common connection of the varistors 5 to 7. For the second contact output temperature fuse 15 connected at the connection middle point 17 between the point 10 and the second contact output terminal 13, the fusing temperature and the lightning surge resistance of the first contact output temperature fuse 14 are set. The second contact output temperature fuse 15 is set to be smaller than the fusing temperature and the lightning surge resistance.

  For example, as described above, the fusing temperature of the first contact output temperature fuse 14 is 100 ° C., the lightning surge resistance is 6 kA, the fusing temperature of the second contact output temperature fuse 15 is 111 ° C., and the lightning surge resistance is 10 kA. And

  As described above, by setting the fusing temperature and the lightning surge resistance of the first contact output temperature fuse 14 to be smaller than those of the second contact output temperature fuse 15, abnormal heat generation due to significant deterioration of the varistors 5 to 7 or large Before the second contact output temperature fuse 15 reacts with the surge current, the first contact output temperature fuse 14 is blown.

  Thereby, since it can avoid that a big surge current flows out from the 1st contact output terminal 12, damage to the electric equipment connected to the 1st contact output terminal 12 can be prevented.

  Here, when the fusing temperature and the lightning surge resistance of the second contact output temperature fuse 15 are set to be smaller than those of the first contact output temperature fuse 14, before the first contact output temperature fuse 14 reacts. The second contact output temperature fuse 15 is blown. Then, a large surge current flows from the first contact output terminal 12 to the second contact output terminal 13, the gas arrester 11 and the ground terminal 4 through the electric device, and the electric device is damaged by the surge current. become.

  For this reason, it is inappropriate to set the fusing temperature and lightning surge resistance of the second contact output temperature fuse 15 to be smaller than that of the first contact output temperature fuse 14, and conversely, for the first contact output. Setting the fusing temperature and lightning surge resistance of the thermal fuse 14 to be smaller than that of the second contact output thermal fuse 15 is effective in preventing damage to the electrical equipment due to the surge current.

  Even when the fusing temperature of the first contact output temperature fuse 14 is set to 111 ° C. and the fusing temperature (111 ° C.) of the second contact output temperature fuse 15 is made the same, the second contact output temperature fuse 14 is used. By disposing the first contact output temperature fuse 14 closer to the varistors 5 to 7 than the temperature fuse 15, the first contact output temperature fuse 14 before the second contact output temperature fuse 15 reacts. Can be melted.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

1 to 3 Power supply terminal 4 Grounding terminal 5 to 7 Varistor 8 and 9 Decoupling temperature fuse 10 Common connection point 12 First contact output terminal 13 Second contact output terminal 14 First contact output temperature fuse 15 Second Thermal fuse for contact output

Claims (2)

An SPD with a deterioration alarm function comprising a plurality of varistors connected between a power supply terminal connected to a distribution line and a ground terminal, and a disconnecting temperature fuse connected between the power supply terminal and the varistor. There,
A contact output terminal for transmitting deterioration information of the varistor to the outside, and a contact output temperature fuse is provided between a common connection point where the varistors are commonly connected and the contact output terminal; An SPD with a deterioration alarm function is characterized in that the fusing temperature and lightning surge withstand are set smaller than the fusing temperature and lightning surge withstand of the disconnecting temperature fuse.   The contact output terminal includes a first contact output terminal and a second contact output terminal, and the contact output temperature fuse includes a first contact output temperature fuse and a second contact output temperature fuse. The first contact output temperature fuse is connected between the common connection point and the first contact output terminal, and between the common connection point and the second contact output terminal and the ground terminal. The second contact output temperature fuse is connected to the first contact output temperature fuse, and the fusing temperature and the lightning surge resistance of the first contact output temperature fuse are set smaller than the fusing temperature and the lightning surge resistance of the second contact output temperature fuse. The SPD with a deterioration alarm function according to claim 1.

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