JP4877390B2 - PTC device - Google Patents

Description

  The present invention relates to a PTC device having a PTC element having a positive temperature characteristic.

  Conventionally, a thermistor (Positive Temperature Coefficient Thermistor) element (hereinafter referred to as “PTC element”) having a positive temperature characteristic in which a resistance value rapidly increases with temperature in a certain temperature range has been used as a heating element such as a heating appliance. Yes.

  In the region of positive temperature characteristics, when the temperature rises, the resistance value of the PTC element increases and the current is limited to restrict the heat generation. Conversely, when the temperature decreases, the resistance value decreases and a large amount of current flows to promote heat generation. By doing so, it is kept at a substantially constant temperature during heat generation, so that it can be easily used as a heating element.

  However, since it has a negative temperature characteristic in the high temperature region than in the positive temperature characteristic region, in the negative temperature characteristic region, as the temperature rises, the resistance value decreases and more current flows to promote heat generation, so-called thermal runaway It becomes a state.

Therefore, in a PTC device using a PTC element, a terminal area for supplying current to the PTC element is partially formed with a cross-sectional area reduction portion having a small cross-sectional area, and an abnormally large current (hereinafter referred to as “abnormal overcurrent”). ”), The cross-sectional area reducing portion selectively generates heat and melts and functions as a fuse (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 52-171738

  For example, in a warm air heater, as shown in the plan view of FIG. 1A, the front view of FIG. 1B, and the bottom view of FIG. A plurality of PTC elements 2 in which external electrodes 2b and 2c are formed are sandwiched on the surface of the body 2a on the side of the terminal plates 4 and 6, and on the outside thereof, as shown in the sectional view of FIG. The PTC device 1 in which the radiating fins 5 are arranged is incorporated, wind is applied to the radiating fins 5, and the heat generated in the PTC elements 2 is taken out from the radiating fins 5.

  As shown in FIG. 1, the terminal plates 4 and 6 have a width (cross section) between the main portions 4a and 6a sandwiching the PTC element 2 and the lead-out ends 4c and 6c connected to the power source. Narrow cross-sectional area decreasing portions 4b and 6b are formed. When an abnormal overcurrent flows between the drawing end portions 4c and 6c, the cross-sectional area reducing portions 4b and 6b are selectively heated because the resistance values of the cross-sectional area reducing portions 4b and 6b are larger than the other portions. Melts and eventually melts. Thereby, the abnormal overcurrent is interrupted.

  By the way, the PTC element has a temperature-resistance characteristic in which the resistance value temporarily decreases from normal temperature (for example, 25 ° C.) to a temperature at which heat generation is stabilized (for example, about 100 ° C.). Therefore, a larger current (inrush current) temporarily flows through the cross-sectional area reducing portions 4b and 6b than immediately when the heat generation is stable immediately after the start of operation. For example, in the case of a PTC device that is rated at 100 V and 1200 W, a maximum inrush current of 20 A flows. Since the cross-sectional area reduction part of the PTC device is required not to be melted by the inrush current, the allowable current of the cross-sectional area reduction part is set to 25 A, for example.

  As shown in FIG. 3, when the PTC device 94 with the allowable current of the cross-sectional area reduction portion of 25 A is incorporated in the hot air heater set 92 as described above, a 100 V system switchboard 90 to which the hot air heater set 92 is connected. Is provided with a 20A breaker, and a 20A glass tube fuse 96 is also provided in a set 92 of hot air heaters.

  Therefore, even if an abnormal overcurrent flows in the PTC device 94, the glass tube fuse 96 or the breaker of the switchboard 90 cuts off the current before the cross-sectional area reduction portion of the PTC device 94, and the PTC device 94 is disconnected. The area reduction part does not function. In other words, the hot air heater set 92 cannot detect and stop an abnormality until a large current of 20 A or more flows.

  Such a problem can be avoided by using a combination of a plurality of low-rated PTC devices, but this causes problems such as an increase in the number of parts and a complicated configuration.

  In view of such a situation, the present invention intends to provide a PTC device capable of reducing the allowable current of the cross-sectional area reduction portion that is melted by an abnormal overcurrent.

  In order to solve the above-mentioned problems, the present invention provides a PTC device configured as follows.

The PTC device is arranged in a row along the pair of terminal plates and the pair of terminal plates, sandwiched between the pair of terminal plates, and electrically connected in parallel between the pair of terminal plates. A plurality of PTC elements that are connected to a power source. Each of the pair of terminal plates includes two of the lead end of the terminal plate and the PTC element located closest to the lead end of the terminal plate and between the plurality of PTC elements. A cross-sectional area decreasing portion having a partially small cross-sectional area is formed in more than the portion. In each of the pair of terminal plates, the cross-sectional area decreases as the cross-sectional area decreasing portion exists at a position away from the drawer end.

  In the above configuration, the cross-sectional area reduction portion of the terminal plate is formed by, for example, forming a notch groove or a through hole in the terminal plate, cutting the width direction of the terminal plate, or cutting the width direction of the terminal plate. It is a part where the thickness is reduced. The plurality of PTC elements can be arranged in a line in an arbitrary shape such as a straight line, a curved line, or a zigzag.

  According to the said structure, a cross-sectional area reduction | decrease part will melt | fuse when an abnormal overcurrent flows, and functions as a fuse. Only the current flowing through the PTC element disposed on either side of the cross-sectional area reducing portion flows through the cross-sectional area reducing portion of the terminal plate provided between the adjacent PTC elements, and is one of the total currents flowing through the PTC device. Only the part flows. Therefore, the allowable current can be reduced as compared with the case where the total current flowing through the PTC device flows through the cross-sectional area reducing portion.

By several area reduction portion birefringence is formed in each of the pair of terminal plates, since it can withstand sufficiently inrush current even if an allowable current area reduction portion smaller, the area reduction portion The cross-sectional area can be designed to be smaller. For this reason, when an abnormal overcurrent occurs in any of the PTC elements, the cross-sectional area reduction portion can be blown with a smaller current.

  Preferably, each of the pair of terminal plates has a cross-sectional area reduction portion formed between the drawer end portion and the PTC element located closest to the drawer end portion and between all of the plurality of PTC elements. Yes. Further, the cross-sectional area decreasing portion has a smaller cross-sectional area as the cross-sectional area decreasing portion existing at a position away from the drawer end portion.

  In this case, when an abnormal overcurrent flows for each of the PTC elements, any one of the cross-sectional area decreasing portions adjacent to the PTC element can be melted. Compared with the case where a plurality of PTC elements are collectively provided with a reduced cross-sectional area, the reduced cross-sectional area can be blown with a small current, and the number of parts to be fused is increased, so that safety can be further improved.

  Preferably, a spacer that separates the PTC element from the reduced cross-sectional area of the terminal plate is disposed between at least one pair of adjacent PTC elements.

  In this case, it is possible to prevent the cross-sectional area reduction portion of the terminal plate from contacting the PTC element. Accordingly, it is possible to prevent the function of the cross-sectional area reducing portion of the terminal plate from being deteriorated due to contact between the cross-sectional area reducing portion of the terminal plate and the PTC element. Further, when the reduced cross-sectional area of the terminal plate is melted, the influence of the influence on the PTC element can be prevented by the spacer, and the damage can be minimized.

  Preferably, the allowable current of the cross-sectional area reducing portion of the terminal plate is smaller than the rated current of an overcurrent protection component connected between the lead-out end portion of the terminal plate and the power source.

  When the PTC device is connected to the power supply via an overcurrent protection component such as a fuse or breaker that suppresses overcurrent, the allowable current at the reduced cross-sectional area of the terminal plate is smaller than the rated current of the overcurrent protection component. By doing so, an abnormal overcurrent smaller than the rated current of the overcurrent protection component can be interrupted by the cross-sectional area reducing portion. Thereby, an abnormal overcurrent smaller than the rated current of the overcurrent protection component can be suppressed, and safety can be further improved.

  According to the present invention, it is possible to reduce the allowable current of the cross-sectional area reducing portion that is melted by an abnormal overcurrent.

It is the (a) top view, (b) front view, and (c) bottom view which show the state which pinched the PTC element between the terminal boards. It is sectional drawing of a PTC apparatus. It is a block diagram which shows the use condition of a PTC apparatus. It is sectional drawing of a PTC apparatus. Example 1 (A) The top view seen along line AA of FIG. 4, (b) The top view seen along line BB of FIG. Example 1 It is a principal part block diagram of a PTC apparatus. Example 1 It is sectional drawing seen along line CC of FIG. Example 1 It is a top view of a terminal board. (Example 2) It is a top view of a terminal board. (Example 3) It is a top view of a terminal board. (Experimental example)

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 PTC apparatus 11, 11A-11D, 11X, 11Y PTC element 20 Terminal board 20c, 20d Cross-sectional area reduction part 22 Terminal board 22c, 22d Cross-sectional area reduction part 40 Terminal board 40x Cross-sectional area reduction part 50 Terminal board 50c-50f Cross-sectional area Reduced portion 52 Terminal plate 52c to 52f Reduced cross-sectional area 80 Terminal plate 80x Reduced cross-sectional area 82 Terminal plate 82x Reduced cross-sectional area

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  Example 1 A PTC device of Example 1 will be described with reference to FIGS. 4 is a sectional view, FIG. 5 (a) is a plan view taken along line AA in FIG. 4, FIG. 5 (b) is a plan view seen along line BB in FIG. 4, and FIG. FIG. 7 is a cross-sectional view taken along line CC in FIG.

As shown in FIG. 4, the PTC device 10 includes a plurality of (four in the figure) PTC elements 11 sandwiched between a pair of terminal plates 20 and 22, and insulating plates 24 and 25 on the outside thereof. Case members 12 and 14 having radiating fins 30 are arranged. As shown in FIGS. 5 and 6, as the PTC element 11, a first external electrode 11b made of, for example, Ni is formed on the entire surface of the terminal plate side of the PTC element body 11a made of, for example, a BaTiO ₃ based semiconductor ceramic. A second external electrode 11 c made of, for example, Ag having a peripheral edge that is slightly smaller than the peripheral edge of the PTC element 11 is formed thereon.

  As shown in FIGS. 5 and 6, the PTC element 11 is disposed along the main portions 20 a and 22 a of the terminal plates 20 and 22, and the second external electrodes 11 c of the PTC element 11 are respectively connected to the terminal plates 20 and 22. The main parts 20a and 22a are in contact with each other and are electrically connected in parallel.

  The terminal plates 20 and 22 are formed using stainless steel, copper alloy, aluminum, or the like. Between the main portions 20a and 22a of the terminal plates 20 and 22 and the drawn end portions 20b and 22b, cross-sectional area reducing portions 20c and 22c having a partially small width (that is, a transverse cross section) are formed. Cross-sectional area decreasing portions 20d and 22d having a small width (that is, a cross section) are also formed at intermediate positions between the main portions 20a and 22a of the terminal plates 20 and 22. The cross-sectional area decreasing portions 20d and 22d at the intermediate positions of the main portions 20a and 22a are smaller in width (that is, cross-sectional area) than the cross-sectional area decreasing portions 20c and 20c on the drawer end portions 20b and 22b side.

  A spacer 28 is arranged in the center of the PTC elements 11 arranged in a line. The spacer 28 is opposed to the cross-sectional area decreasing portions 20d and 22d provided at the intermediate positions of the main portions 20a and 22a of the terminal plates 20 and 22, and the PTC element 11 is disposed so as to oppose the cross-sectional area decreasing portions 20d and 22d. To prevent it. A through hole 29 is formed in the spacer 28, and the cross-sectional area reducing portions 20 d and 22 d are exposed in the through hole 29. The spacer 28 is formed, for example, by punching mica, which is a heat-resistant and flame-retardant material.

  Since the cross-sectional area reduction portions 20d and 22d provided in the main portions 20a and 22a of the terminal plates 20 and 22 are exposed to the through holes 29 of the spacer 28 without contacting the PTC element 11, an abnormal overcurrent flows. When the heat is generated, the PTC element 11 is not deprived of heat, so that it is melted quickly and reliably. Further, the cross-sectional area reducing portions 20d and 22d are melted in the spacer 28, and the spacer 28 prevents the melted cross-sectional area reducing portions 20d and 22d from being scattered. Although it is possible to employ a configuration in which the spacer 28 is not provided, even in such a case, the PTC element 11 is prevented from contacting the cross-sectional area reducing portions 20d and 22d of the terminal plates 20 and 22. When the PTC element 11 comes into contact with the cross-sectional area reducing portions 20d and 22d of the terminal plates 20 and 22, the first external electrode 11b formed on the surface of the PTC element overlaps with the cross-sectional area reducing portions 20d and 22d. To the first external electrode 11b of the PTC element, the area of the cross-sectional area reducing portions 20d and 22d is reduced, and the effect is reduced.

  As shown in FIG. 4, the main portions 20 a and 22 a of the terminal plates 20 and 22 that sandwich the PTC element 11 are disposed between the case members 12 and 14 with the insulating plates 24 and 25 interposed therebetween. , 22 protrudes outward from the case members 12, 14 to the opposite sides. The insulating plates 24 and 25 are insulating plates that easily conduct heat, such as alumina plates.

  As indicated by a chain line, a terminal member 34 for supplying power is fixed to the drawn end portions 20b and 22b of the terminal plates 20 and 22. When the PTC device 10 is incorporated in a heater system, for example, as in FIG. 3, the terminal member 34 is connected to a power source via a fuse or breaker that is an overcurrent protection component. Further, between the terminal member 34 and the case members 12 and 14, a cap 32 that is fitted to the drawer end portions of the case members 12 and 14 is disposed. A protrusion (not shown) is provided on the inner side of the cap 32, and the protrusions (not shown) are pressed and positioned on both sides of the row of PTC elements 11 and spacers 28 arranged along the terminal plates 20 and 22. . The cap 32 is formed using an elastic insulating material such as resin or rubber.

  As shown in FIG. 7, the base members 12a and 14a provided with the heat radiation fins 30 are arranged to face each other, and the case members 12 and 14 are arranged between the base portions 12a and 14a from the base portions 12a and 14a, respectively. The pieces 12 b and 14 b and the second pieces 12 c and 14 c extend in an L-shaped cross section and are engaged via the spring member 16. That is, the second pieces 12c and 14c of the case members 12 and 14 face each other, and the spring member 16 is disposed between the second pieces 12c and 14c. The spring member 16 is a cylindrical elastic member in which a slit is formed in the axial direction. The spring member 16 presses the second pieces 12c and 14c of the case members 12 and 14 in a direction away from each other. The base portions 12a and 14a approach each other, and the state where the PTC element 11 and the spacer 28, the terminal plates 20 and 22 and the insulating plates 24 and 25 are sandwiched between the base portions 12a and 14a of the case members 12 and 14 is maintained. It is supposed to be.

  As shown in FIG. 7, the insulating plates 24 and 25 are wider than the terminal plates 20 and 22, and insulating members 26 and 27 are arranged on both sides of the terminal plates 20 and 22, the PTC element 11 and the spacer 28. Has been. The insulating members 26 and 27 are formed using mica, for example. The first pieces 12 b and 14 b of the case members 12 and 14 face the side surfaces of the insulating plates 24 and 25 and the insulating members 26 and 27. The insulating plates 24 and 25 and the insulating members 26 and 27 cover the periphery of the terminal plates 20 and 22, the PTC element 11 and the spacer 28, and insulate the terminal plates 20 and 22 from the case members 12 and 14.

  When assembling the PTC device 10, first, the second pieces 12c, 14c of the other case members 12, 14 are inserted between the second pieces 12c, 14c of the case members 12, 14 and the base portions 12a, 14a. The case members 12 and 14 are combined. Next, the PTC element 11, the spacer 28, and the terminal plate 20 are formed from the end portions of the case members 12 and 14 into a rectangular space formed by the base portions 12 a and 14 a and the first pieces 12 b and 14 b of the case members 12 and 14. , 22, insulating plates 24, 25, and insulating members 26, 27 are inserted in an appropriate order and arranged at predetermined positions, and then spring members between the second pieces 12 c, 14 c of the case members 12, 14. 16 is inserted, and the base members 12a and 14a of the case members 12 and 14 are biased by the spring member 16 so as to approach each other. Next, the cap 32 is put on the end portions of the case members 12 and 14, and the terminal member 34 is fixed to the drawing end portions 20b and 22b of the terminal plates 20 and 22 by spot welding or the like.

As indicated by a broken line in FIG. 6, a current flows from the drawing end 20 b of one terminal plate 20 to the drawing end 22 b of the other terminal plate 22 through the PTC element 11. Assuming that the currents flowing through the respective PTC elements 11 in order from the left are i ₁ , i ₂ , i ₃ , i ₄ , the cross-sectional area reducing portion 20 d of one terminal plate 20 is more illustrated than the cross-sectional area reducing portion 20 d. , Only the total current i ₃ + i _{4 of the} currents i ₃ and i ₄ flowing in the two right-hand PTC elements 11 flows. Only the total current i ₁ + i _{2 of the} currents i ₁ and i ₂ flowing through the two PTC elements 11 on the left side of the cross-sectional area reducing portion 22d flows in the cross-sectional area reducing portion 22d of the other terminal plate 22 in the drawing. . The total current i of currents i ₁ , i ₂ , i ₃ , i ₄ flowing in all the PTC elements 11 is provided in the cross-sectional area decreasing portions 20 c, 22 c provided on the lead end portions 20 b, 22 b side of the terminal plates 20, 22. ₁ + i ₂ + i ₃ + i ₄ flows.

  For example, in the PTC device 10 having a rated power of 1200 W (rated current of 12 A), four PTC elements 11 having a Curie temperature of 260 ° C. and a resistance value of 100Ω are arranged along the main portions 20 a and 22 a of the terminal plates 20 and 22. When the inrush current flows, the main portion 20a of the terminal plates 20 and 22 is set even if the allowable current of the cross-sectional area reducing portions 20c and 22c provided on the lead end portions 20b and 22b side of the terminal plates 20 and 22 is set to 30A. , 22a, the allowable current of the cross-sectional area reduction portions 20d, 22d can be set to 15A, which is half of the allowable current.

  When a device incorporating such a PTC device 10 is connected to a 100V system switchboard with a 20A breaker installed, the cross-sectional area provided on the lead-out end portions 20b and 22b side of the terminal plates 20 and 22 as in the prior art. With only the decreasing parts 20c and 22c (allowable current 30A), when an abnormal overcurrent flows through the PTC device 10, the 20A glass tube fuse provided in the 20A breaker or equipment cuts off the abnormal overcurrent first. By providing the cross-sectional area decreasing portions 20d and 22d in the main portions 20a and 22a of the plates 20 and 22 and setting the allowable current to half (15A), when an abnormal overcurrent flows through the PTC device 10, a breaker of 20A Further, before the 20A glass tube fuse provided in the device, the cross-sectional area reduction portions 20d and 22d interrupt the abnormal overcurrent. Thereby, since it can interrupt | block with a smaller electric current, abnormal overcurrent can be interrupt | blocked more safely.

  <Embodiment 2> The allowable current can be reduced no matter where the cross-sectional area reducing portion is provided between adjacent PTC elements. For example, as shown in FIG. 8, among the PTC elements 11 arranged along the terminal plate 40, when the cross-sectional area reducing portion 40x is formed between the adjacent PTC elements 11X and 11Y on the left side in the figure, the leftmost side in the figure The allowable current of the cross-sectional area reducing portion 40x can be determined only by the current flowing through the PTC element 11X. That is, in the first embodiment, abnormal overcurrent is detected and cut off for the total of the currents flowing through the two PTC elements, whereas in the second embodiment, the abnormal overcurrent is detected for the current flowing through one PTC element 11X. Can be detected and blocked. Therefore, safety can be further improved.

  <Embodiment 3> As shown in the plan view of FIG. 9, the pair of terminal plates 50 and 52 sandwiching the PTC elements 11A to 11D includes main portions 50a and 52a and drawer end portions 50b and 52b as in the conventional example. In addition to the cross-sectional area reduction portions 50c and 52c, cross-sectional area reduction portions 50d, 50e and 50f; 52d, 52e and 52f are provided between all adjacent PTC elements 11A, 11B, 11C and 11D. . The cross-sectional area decreasing portions 50c, 50d, 50e, 50f; 52c, 52d, 52e, 52f of the terminal plate 50; 52 have a smaller width (cross section) and a smaller allowable current as the distance from the drawing end 50b; 52b increases. Formed to be. For example, in order from the drawing end portions 50b and 52b, the allowable current of the cross-sectional area reducing portions 50c and 52c is 24A, the allowable current of the cross-sectional area reducing portions 50d and 52d is 18A, and the allowable current of the cross-sectional area reducing portions 50e and 52e is 12A. The allowable current of the cross-sectional area reducing portions 50f and 52f is 6A.

  As a result, when an abnormal overcurrent flows in the PTC element 11A, the cross-sectional area reducing portion 50f is blown, and when an abnormal overcurrent flows in the PTC element 11B, the cross-sectional area reducing portion 52d or 50e is blown, and the PTC element 11C is abnormal. When the overcurrent flows, the cross-sectional area reducing portion 52e or 50d is blown, and when the abnormal overcurrent flows for the PTC element 11D, the cross-sectional area reducing portion 50f is blown.

  Since the portion to be melted is increased and the cross-sectional area reduced portion can be melted with a smaller current, the safety can be further enhanced.

  <Experimental Example> As shown in the plan view of FIG. 10, stainless steel terminal plates 80 and 82 having main portions 80 a and 82 a and drawer end portions 80 b and 82 b are prepared. As shown in FIG. 10A, a terminal plate 80 provided with a cross-sectional area reducing portion 80x having a permissible current of 25 A on the drawing end portion 80b side is taken as a sample 1. As shown in FIG. 10B, a terminal plate 82 provided with a cross-sectional area reduction portion 82x having a permissible current of 12A at the center of the main portion 82a is referred to as sample 2.

表１から、サンプル２は、サンプル１よりも小さな電流で溶断することが分かる。For Samples 1 and 2, four PTC elements 11A to 11D are arranged side by side along the main portions 80a and 82a of the terminal plates 80 and 82, respectively, to constitute a 100 V PTC device with a rated current of 12A. With respect to Samples 1 and 2, one PTC element 11C hatched is short-circuited, and the magnitude of the current at which the cross-sectional area reduction portions 80x and 82x melt within 10 seconds was examined. The measurement results were as shown in Table 1 below.

From Table 1, it can be seen that Sample 2 is fused with a smaller current than Sample 1.

  That is, the sample 2 is provided with a cross-sectional area reduction portion at a position farther from the extraction electrode portion than the sample 1, and the current that flows substantially only needs to satisfy the allowable current of the PTC elements 11C and 11D. The cross-sectional area of the area reduction portion can be reduced. Thereby, the fusing current itself can be reduced.

  <Summary> As described above, by providing a cross-sectional area reduction portion between adjacent PTC elements for the terminal plate that sandwiches the PTC element, the allowable current of the cross-sectional area reduction portion that is blown by an abnormal overcurrent is reduced. can do.

  The present invention is not limited to the above-described embodiment, and can be implemented with various modifications. For example, although the case where the drawer end portions of the pair of terminal plates are arranged on the opposite sides is illustrated, it is also possible to adopt a configuration in which the drawer end portions of the pair of terminal plates are arranged on the same side. Further, the external electrode formed on the surface of the PTC element is not necessarily required to have two layers, and a single external electrode formed on the entire surface on the terminal plate side of the PTC element may be used.

Claims (4)

A pair of terminal plates facing each other;
A plurality of PTC elements arranged in a line along the pair of terminal plates, sandwiched between the pair of terminal plates, and electrically connected in parallel between the pair of terminal plates;
In the PTC device, wherein the drawer ends of the pair of terminal plates are each connected to a power source,
Each of the pair of terminal plates includes two of the lead end of the terminal plate and the PTC element located closest to the lead end of the terminal plate and between the plurality of PTC elements. The cross-sectional area reduction part where the cross-sectional area is partially small is formed above the place,
In each of the pair of terminal boards, the cross-sectional area decreasing portion present at a position away from the drawer end portion has a smaller cross-sectional area . Each of the pair of terminal boards has the cross-sectional area reduction portion formed between the drawer end portion and the PTC element located closest to the drawer end portion and between all of the plurality of PTC elements. And
2. The PTC device according to claim 1, wherein the cross-sectional area decreasing portion existing at a position away from the drawer end portion has a smaller cross-sectional area. The spacer which separates the said PTC element from the said cross-sectional area reduction | decrease part of the said terminal board is arrange | positioned between the at least 1 set of said PTC elements adjacent, The Claim 1 or 2 characterized by the above-mentioned. PTC device. The allowable current of the cross-sectional area decreasing portion of the terminal plate is smaller than a rated current of an overcurrent protection component connected between the lead-out end portion of the terminal plate and the power source. The PTC device according to any one of 1 to 3 .

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