JP4852398B2 - Electric heater - Google Patents

Description

  The present invention relates to an electric heater, and more particularly to an electric heater provided with a leakage detection device that detects a leakage of the electric heater with high sensitivity when a liquid enters a quartz tube heater having a heater wire, for example, in a quartz tube. It relates to the heater.

  Many electric heaters are used to heat liquids such as chemical solutions in plating apparatuses and other equipment. Among these electric heaters, a quartz tube heater in which an insulator such as a quartz tube is used for an external housing is often used because of its chemical resistance and insulation.

  In particular, in a plating apparatus such as an electrolytic plating apparatus, it is important to configure the inside of the plating tank with an insulator in order to prevent and eliminate stray currents that adversely affect product quality. It is also an important reason why many electric heaters used for the body are used.

  On the other hand, a conventional electric heater that uses an insulator such as a quartz tube for an outer casing, a so-called quartz heater, is a ground wire electrode for detecting leakage as compared with an electric heater that uses a metal and a conductive outer casing. It was very difficult to configure, and it was difficult to detect leakage with high sensitivity.

  This leakage detection is for the purpose of preventing electric shock accidents and fire accidents, and is a very important quality requirement for electrical equipment including electric heaters.

  Referring to FIG. 6, in a quartz tube heater 101 as a conventional electric heater, for example, a winding core 105 (or bobbin) made of ceramic having a spiral groove on the outer periphery inside a quartz tube housing 103, and A heater wire 107 (nichrome wire) wound around the winding core 105, a power supply wire 109 for supplying power to the heater wire 107, and a connecting portion 111 ("" that connects the power supply wire 109 to the heater wire 107 (Also referred to as “conductor exposed portion”), a ground line electrode 113 for detecting leakage, and a ground line 115 connected to the ground line electrode 113 are airtightly provided.

  For example, in FIG. 6, the quartz tube housing 103 has an L shape, and the winding core 105, the heater wire 107, the connecting portion 111, the power supply wire 109, the ground wire electrode 113, and the ground wire 115 are included in the quartz tube housing. The power supply wire 109 and the ground wire 115 are each protected by an insulation coating portion and inserted into an extension insulation coating tube 117 and protected from the outside. An insulating sheath tube 117 is hermetically sealed at the top of the quartz tube housing 103.

  When the heater wire 107 is composed of, for example, three-phase U, V, and W wires, three heater grooves (not shown) are spirally formed on the outer periphery of the winding core 105. A three-phase heater wire 107 is wound around each of the heater grooves. In addition, flange portions 119 are provided at both ends of the winding core 105. Further, each of the heater wires 107 is illustrated by a dotted line as shown in FIG. 6, but is actually an exposed conductor wire wound in a spiral shape. The heater wire 107 is exposed to the power supply wire 109. The conductor is connected by a connecting portion 111 (so-called exposed conductor portion). The heater wire 107 may be a single phase.

  In addition, the tip of the ground wire 115 inserted into the quartz tube casing 103 from the above-described insulating insulation tube 117 extends only to the vicinity of the L-shaped upper portion of the quartz tube casing 103. The ground wire electrode 113 is connected to the tip of the wire 115. That is, the ground line electrode 113 is located near the upper portion of the L-shape of the quartz tube housing 103.

  As shown in FIG. 7, the quartz tube heater 101 is usually charged into a tank 121 (liquid container) containing a chemical solution or other liquid to heat the liquid. In the case of a plating apparatus, the tank 121 (liquid container) is made of, for example, a resin insulator.

  At this time, when a conductive liquid is immersed in the quartz tube casing 103 due to damage or pinholes in the quartz tube casing 103 of the quartz tube heater 101 as indicated by arrows in FIG. Then, electric leakage occurs from the heater wire 107. In order to detect this electric leakage, the quartz tube heater 101 is provided with the electric leakage detection device 123 including the ground wire electrode 113 and the ground wire 115 described above.

  For example, as the electric leakage detection device 123, as shown in the electric circuit diagram of FIG. 8, the power supply wire 109 supplying power to the three-phase heater wire 107 is connected to the ground wire 115 from the ground wire electrode 113. An earth leakage circuit breaker 127 having a ZCT 125 (zero phase current detection transformer) for detecting the earth leakage flowing in is provided.

  Therefore, when the liquid enters the inside of the quartz tube casing 103 and diffuses or fills, the heater wire 107 and the ground wire electrode 113 where the charging unit is exposed are short-circuited (electrically conductive) by the liquid, and grounded. A leakage current flows from the line electrode 113 to the ground via the ground line 115. The zero-phase current generated by this leakage current is detected by the ZCT 125 (zero-phase current detection transformer) of the above-mentioned leakage breaker 127, and at the same time, the leakage breaker 127 stops supplying power to the quartz tube heater 101.

  As a conventional electric heater, for example, Patent Document 1 discloses a ceramic heater. A heater wiring is arranged between two ceramic layers, and a crack detection wiring and another ceramic layer are formed on the upper surface of the ceramic layer. Is disposed. Here, when the other ceramic layer is cracked and the heater wiring is exposed, the crack detection wiring is disconnected. When the disconnection of the crack detection wiring is detected by the detection circuit, the power supply to the heater wiring is stopped.

Patent Document 2 discloses a heater device for liquid heating as an electric heater, and a heat-resistant inner member obtained by winding a Kanthal wire through an intermediate member with respect to a heat-resistant outer member that covers the entire heater. Is attached, and the interval between the two is spaced so that the Kanthal wire does not contact the outer member. Further, a water leakage detection lead is disposed in the outer member, and the erosion state can be grasped by detecting a water leak state in a short state of the lead.
JP-A-9-266060 Japanese Utility Model Publication No. 5-75995

  By the way, in the conventional electric heater, there existed a problem that a leak detection was impossible with respect to minute liquid immersion.

  In the quartz tube heater 101 as the electric heater shown in FIGS. 6 and 8, since the conductor is exposed in the charging exposed portion such as the conductor exposed portion of the heater wire 107 and the connecting portion 111, the leakage current is detected in these charging exposed portions. If the ground wire electrode 113 for detection is disposed close to the ground wire electrode 113, there is a risk that the voltage applied to the charge exposed portion such as the heater wire 107 and the connecting portion 111 may cause a ground fault. It was. For this reason, the ground wire electrode 113 is set back to a position away from the charging exposed portion such as the heater wire 107 and the connecting portion 111 so as not to cause the ground fault.

  Therefore, for example, as shown in FIGS. 9 and 10, in a state where the liquid has entered the quartz tube casing 103 from minute damage or pinholes generated in the quartz tube casing 103, the liquid is heated by the heater wire 107. So that it does not reach the above-mentioned ground wire electrode 113. For this reason, as shown in FIG. 10, the leakage current path is not formed, so that the leakage breaker 127 does not operate and the leakage detection cannot be performed.

  Note that the liquid that has entered the inside of the quartz tube housing 103 and has reached the charging exposed portion of the heater wire 107 or the connecting portion 111 has the same potential as the charging exposing portion. Therefore, when the earth leakage breaker 127 does not operate as shown in FIG. 10, there is a risk that the potential of the liquid rises up to the potential applied to the heater wire 107 at the maximum.

  Therefore, in a situation where minute liquid immersion occurs, as shown in FIG. 11, when a human touches the liquid in the tank 121 of the plating apparatus, for example, a leakage current flows through the human body, Risk of electric shock. Furthermore, when the above leakage current flows through a high resistance path for a long time, there is a problem that there is a risk of fire.

  Further, in Patent Document 1, the heater wiring is laminated between two ceramic layers, and the crack detection wiring is disposed and insulated on the upper surface of the ceramic layer. Since the ceramic layer is a complicated structure, the manufacturing process is complicated, so that there is a problem that the manufacturing cost is increased due to a decrease in manufacturing efficiency and the cost is increased because three ceramic layers are required.

  Further, in Patent Document 2, since this is a system that detects a short state (short circuit) between two water leakage detection conductive wires, when the voltage used for measurement of this continuity (short circuit) is low, a Kanthal wire ( There is a problem in that a minute leakage current from the heater wire 107 to the outside cannot be measured. Therefore, if a voltage corresponding to the ground voltage of the Kanthal line is applied, it is possible to detect a minute leakage current. Even in this case, two leakage detection conductive lines are connected between the detection devices. In addition, there is a problem in that it is expensive because it requires a separate voltage generator for measurement.

In order to achieve the problem to be solved by the above invention, an electric heater according to the present invention includes a heater wire winding portion made of an insulator and an heater wire winding portion inside an insulator casing made of an insulator. A heater wire wound around, a power supply wire for supplying power to the heater wire, a connecting portion for connecting the power supply wire to the heater wire, a ground wire electrode for detecting a leakage, and a ground wire electrode and a ground line for connecting together airtightly provided, in an electric heater provided with the earth leakage breaker for cutting off the power supply by detecting a leakage flow to the ground line from the grounding line electrode to the power supply wire, said electric heater when you put in a bath containing the liquid, the ground wire electrode, disposed at a position lower than the charging exposure unit including the heater wire and the connecting portion, the ground line electrode, said insulator housing Gold placed on the bottom of the inner surface Or in which composed of a heat-resistant conductive material, and between the heater line and the ground line electrode characterized by being insulated with braided tape insulative fibers.

In the electric heater according to the present invention, in the electric heater, the insulator casing is formed in a cylindrical shape, and the ground wire electrode is convexly curved toward the bottom surface side of the inner surface of the insulator casing. It is preferable that it is formed.

In the electric heater of the present invention, it is preferable that the ground wire electrode is provided over the entire length of the bottom surface of the insulator casing.

An electric heater according to the present invention includes an insulator casing made of an insulator, a heater wire winding portion made of an insulator, a heater wire wound around the heater wire winding portion, and a power supply to the heater wire. A power supply wire to be supplied, a connecting portion for connecting the power supply wire to the heater wire, a grounding wire electrode for detecting a leakage, and a grounding wire connected to the grounding wire electrode are provided in an airtight manner, and the grounding is performed. In an electric heater provided with a leakage breaker that detects a leakage current flowing from the wire electrode to the ground wire and interrupts the power supply to the power supply wire, the ground wire electrode is connected to the heater wire winding portion via an insulator. It is a wound structure, wherein the insulator is formed of a braid or woven fabric of insulating fibers, and the ground wire electrode is covered with the braid or woven fabric .

  Moreover, the electric heater of this invention WHEREIN: It is preferable in the said electric heater that the material of the said insulator is quartz glass or ceramics which has heat resistance.

  As can be understood from the means for solving the above problems, according to the electric heater of the present invention, the ground wire electrode is disposed at a position lower than the exposed charging portion such as the heater wire and the connecting portion, and the heater wire. Because it is insulated from the charged exposed parts such as and connection parts with an insulator, it is inexpensive because it has a simple structure. It becomes possible to detect electric leakage, electric shock, and fire.

  In addition, since the leakage current is measured with the ground voltage of the heater wire between one ground wire and the heater wire, a minute leakage current can be detected. Moreover, since leakage detection is possible with only one ground wire, there is an effect in terms of securing a space in the electric heater.

  In addition, since the ground wire electrode is connected to the ground wire in a state insulated from the charging exposed portion such as the heater wire and the connection portion with an insulator, the ground wire electrode is grounded in the state where no liquid enters from the outside of the insulator housing. No fault accident occurs, and the power can be shut off by the earth leakage breaker before the one-line ground fault when liquid enters.

  According to another electric heater of the present invention, the same effect as that of the electric heater described above can be obtained, except that the ground wire electrode is twisted in a state where the heater wire winding portion is insulated from the heater wire. Therefore, when liquid enters the inside of the insulator housing, if the liquid accumulates to a level at which conduction is established between the heater wire and the ground wire electrode, the heater wire and the ground wire electrode are reliably short-circuited by the liquid, Leakage current is detected by the earth leakage breaker via the wire, and the power supply to the heater wire can be stopped reliably.

  In this case, since the ground wire electrode can be wired in parallel with the heater wire with a simpler structure as compared with the conventional structure in which insulation is performed with several ceramic layer insulators, the cost is low.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1A, for example, a quartz tube heater 1 as an electric heater according to the first embodiment is an example of a quartz tube housing 3 as an insulator housing made of a quartz tube as an insulator. Inside, for example, a winding core 5 (or bobbin) as a heater wire winding portion made of, for example, ceramic as an insulator having a spiral groove on the outer periphery, and for example, a nichrome wire wound around the winding core 5 A heater wire 7, a power supply wire 9 for supplying power to the heater wire 7, a connecting portion 11 (also referred to as “conductor exposed portion”) for connecting the power supply wire 9 to the heater wire 7, and detecting a leakage The ground line electrode 13 to be connected and the ground line 15 connected to the ground line electrode 13 are airtightly provided.

  For example, in FIG. 1A, the quartz tube housing 3 has an L shape, and the winding core 5, the heater wire 7, the connection portion 11, the power supply wire 9, the ground wire electrode 13, and the ground wire 15 are included. The power supply wire 9 and the grounding wire 15 are each protected by an insulation coating portion and inserted into the extension insulation coating tube 17 to be protected from the outside. The extension insulating coating tube 17 is hermetically sealed at the upper part of the quartz tube housing 3.

  When the heater wire 7 is composed of, for example, three-phase U, V, and W wires, the outer periphery of the winding core 5 is for three heaters as shown in FIG. The groove portions 19 are formed in a spiral shape, and the three-phase heater wires 7 are wound around the respective heater groove portions 19. Further, left and right flange portions 21 and 23 having a diameter larger than the diameter of the winding core 5 are provided at both ends of the winding core 5. Further, each of the heater wires 7 is shown by a dotted line as shown in FIG. 1A, but is actually an exposed conductor wire wound in a spiral shape. The heater wire 7 is a power supply wire. 9 is a configuration in which a conductor connection portion 11 (so-called conductor exposed portion) is exposed. The heater wire 7 may be a single phase.

  The left and right flange portions 21 and 23 on both sides are made of the same material as the winding core 5 and are so-called insulator structures. On the outer periphery of the right flange portion 23 on one side of the left and right flange portions 21 and 23 on both sides (in this embodiment, the right flange portion close to the side where the ground wire 15 is disposed) Such a ground wire electrode 13 is wound around the entire circumference. Connected to the ground wire electrode 13 is a ground wire 15 inserted from the above-mentioned insulating covering tube 17 for extension into the quartz tube housing 3.

  In addition, since the ground line electrode 13 is a necessary component that is disposed at a position lower than a charge exposed portion such as the heater wire 7 or the connection portion 11 (conductor exposed portion), the ground line electrode 13 is Even if the entire circumference of the right flange portion 23 is not wound, the lower portion of the right flange portion 23 is partially at a position lower than the horizontal height of the charging exposed portion such as the heater wire 7 and the connection portion 11. It may be fixed. Alternatively, the insulator structure provided with the ground wire electrode 13 may be a spacer made of an insulator fixed to the winding core 5 or other insulator structure, instead of the right flange portion 23 described above. .

  The quartz tube heater 1 is usually charged in a tank (liquid container) containing a chemical solution or other liquid to heat the liquid. In the case of a plating apparatus, the tank (liquid container) is made of a resin insulator.

  At this time, as indicated by an arrow in FIG. 1C, a conductive liquid is introduced into the quartz tube housing 3 due to damage or pinholes in the quartz tube housing 3 of the quartz tube heater 1. When soaked, electric leakage occurs from the heater wire 7. In order to detect this electric leakage, the quartz tube heater 1 is provided with the electric leakage detection device 25 including the ground wire electrode 13 and the ground wire 15 described above.

  For example, as the leakage detection device 25, as shown in the electric circuit diagram of FIG. 1C, the power supply wire 9 supplying power to the three-phase heater wire 7 is connected to the ground wire electrode 13. An earth leakage breaker 29 having a ZCT 27 (zero phase current detection transformer) for detecting an earth leakage flowing in the grounding wire 15 is provided.

  With the above configuration, when the liquid enters the inside of the quartz tube housing 3 due to damage or pinholes in the quartz tube housing 3, charging of the heater wire 7 and the connecting portion 11 where the charging unit is exposed is performed. When the liquid accumulates to a level at which electrical conduction is established between the exposed portion and the ground line electrode 13, the charge exposed portion and the ground line electrode 13 are short-circuited by the liquid, and a leakage current flows from the ground line electrode 13 through the ground line 15. It will flow to the ground. The zero-phase current generated by this leakage current is detected by the ZCT 27 (zero-phase current detection transformer) of the above-mentioned leakage breaker 29, and at the same time, the leakage breaker 29 stops supplying power to the quartz tube heater 1.

  In the case of the first embodiment, the lower side portion of the L-shape of the quartz tube housing 3 is inclined from the horizontal by an inclination angle θ of about 5 °, for example, so that the right flange 23 side is downward. Alternatively, if the L-shaped portion is bent at a right angle of, for example, about 5 ° so that the liquid tends to accumulate on the right flange 23 side, the leakage detection is accelerated.

  From the above, the ground line electrode 13 is provided on the right flange portion 23, which is an insulator structure, at a position lower than the horizontal height of the charge exposed portions such as the heater wire 7 and the connection portion 11, so that it is simple. Because of its structure, it is inexpensive and can detect leakage current even for minute liquid immersion, and can prevent leakage accidents, electric shock accidents, and fire accidents.

  Moreover, even if there is only one ground wire 15, the leakage current is measured by the voltage between the heater wire 7 and the ground wire 15 (the ground voltage of the heater wire 7), so that a minute leakage current can be detected. In addition, since leakage detection is possible with only one ground wire 15, it is advantageous in securing a space inside the quartz tube heater 1.

  Further, since the ground wire electrode 13 is connected to the ground wire 15 while being insulated from the charging exposed portion such as the heater wire 7 and the connecting portion 11 by the right flange portion 23 which is an insulator structure, the quartz tube housing When no liquid enters from the outside of the body 3, a ground fault does not occur. When the liquid enters, the power supply can be shut off by increasing the zero-phase current of the earth leakage breaker 29 before the one-line ground fault.

  Next, for example, a quartz tube heater 31 as an electric heater according to a second embodiment of the present invention will be described. The same members as those of the quartz tube heater 1 of the first embodiment described above are denoted by the same reference numerals, detailed description thereof is omitted, and only different portions will be mainly described.

  Referring to FIG. 2, the quartz tube heater 31 is a ground wire electrode such as a copper tape on the outer periphery of the left and right flange portions 21 and 23 on both sides of the winding core 5 of the quartz tube heater 1 of the first embodiment. 13A and 13B are wound around the entire circumference, and a ground wire 15 inserted into the inside of the quartz tube housing 3 from the above-described insulating covering tube 17 is connected to the ground wire electrodes 13A and 13B. Yes.

  That is, the grounding wire 15 is directly connected to the grounding wire electrode 13B of the right flange portion 23 as in the first embodiment, but the central portion of the winding core 5 is connected to the grounding wire electrode 13A of the left flange portion 21. 2 is connected to the left end of the metal bar 33 in FIG. 2 and is branched from the ground wire 15 to the right end of the metal bar 33.

  The other configurations of the ground line electrodes 13A and 13B of the left and right flange portions 21 and 23 are the same as those of the ground line electrode 13 of the right flange portion 23 of the first embodiment described above. Further, as in the left and right flange portions 21 and 23, two or more insulator structures reaching a position lower than the horizontal height of the charging exposed portion such as the heater wire 7 and the connecting portion 11 are provided. The insulator structure can be provided with ground line electrodes such as ground line electrodes 13A and 13B.

  With the above configuration, since the ground wire electrodes 13A and 13B are provided on the left and right flange portions 21 and 23 on both sides of the winding core 5, for example, breakage or pinholes on the tip side of the L-shaped horizontal portion of the quartz tube housing 3 For this reason, when the liquid enters the inside of the quartz tube housing 3, the leakage detection can be performed earlier than in the first embodiment. In addition, even when the heater wire 7 of the winding core 5 is not horizontally disposed, it is possible to reliably detect a leakage with one of the ground wire electrodes 13A and 13B of the left and right flange portions 21 and 23. Other effects are almost the same as those of the first embodiment described above.

  Next, for example, a quartz tube heater 35 as an electric heater according to a third embodiment of the present invention will be described. The same members as those of the quartz tube heater 1 of the first embodiment described above are denoted by the same reference numerals, detailed description thereof is omitted, and only different portions will be mainly described.

  Referring to FIGS. 3A and 3B, the quartz tube heater 35 is a curved flat plate instead of the ground wire electrode 13 of the right flange portion 23 of the quartz tube heater 1 of the first embodiment. A ground line electrode 37 made of a metal or a heat-resistant conductive material is disposed on the bottom surface of the inner surface of the quartz tube housing 3 similar to the quartz tube heater 1 of the first embodiment. Further, the ground wire electrode 37 and the heater wire 7 are insulated by a braided tape 39 of insulating fiber such as glass fiber as an insulator. The braided tape 39 made of insulating fibers is not limited to glass fibers, but may be fibers of other materials. The reason for using the braided tape 39 is that when water simply enters, the water is transmitted to the gap between the braided tape 39, and the leakage can be detected quickly.

  The ground wire electrode 37 is connected to the ground wire 15 inserted into the quartz tube housing 3 from the above-described extension insulation coating tube 17. The curved flat ground line electrode 37 is preferably provided over substantially the entire length of the bottom surface of the quartz tube housing 3.

  With the above configuration, since the ground wire electrode 37 is disposed on the bottom surface of the inner surface of the quartz tube housing 3, when a liquid enters the inside of the quartz tube housing 3, earlier leakage detection can be performed. In addition, if the ground wire electrode 37 is provided over almost the entire length of the bottom surface of the quartz tube housing 3, it is possible to reliably detect leakage even when the heater wire 7 of the winding core 5 is not disposed horizontally. It becomes. Other effects are almost the same as those of the first embodiment described above.

  Next, for example, a quartz tube heater 41 as an electric heater according to a fourth embodiment of the invention will be described. The same members as those of the quartz tube heater 1 of the first embodiment described above are denoted by the same reference numerals, detailed description thereof is omitted, and only different portions will be mainly described.

  Referring to FIG. 4, the quartz tube heater 41 is replaced with the ground wire electrode 13 of the right flange portion 23 of the quartz tube heater 1 of the first embodiment, for example, a ground wire electrode wire 43 as a ground wire electrode. However, it is twisted together with, for example, a three-phase U, V, W wire as the heater wire 7 in a state where it is insulated from a winding core 5 as a heater wire winding portion.

  In this case, four heater grooves 19 as shown in FIG. 1B are formed in a spiral shape on the outer periphery of the core 5, and the three-phase heater wire 7 and the ground wire electrode wire are formed. Since 43 is wound around each heater groove 19 of the winding core 5 which is an insulator, the three-phase heater wire 7 and the ground wire electrode wire 43 are insulated from each other.

  Further, the ground wire 15 inserted from the above-described insulating covering tube for extension 17 into the quartz tube housing 3 is connected to the above-mentioned ground wire electrode wire 43.

  With the above configuration, for example, a ground wire electrode wire 43 as a ground wire electrode is wound around the winding core 5 in a state of being insulated from the three-phase U, V, and W wires of the heater wire 7. When the liquid has accumulated up to a level at which electrical conduction is established between the heater wire 7 where the charging unit is exposed and the ground wire electrode wire 43 when entering the inside of the housing 3, the heater wire 7 and the ground wire electrode wire 43. Is reliably short-circuited by the liquid, and the leakage current flows from the ground wire electrode wire 43 to the ground via the ground wire 15 and is detected by the ZCT 27 (zero phase current detection transformer) of the leakage breaker 29. 29 can reliably stop the power supply to the quartz tube heater 1.

  In this case, the ground wire electrode wire 43 can be wired in parallel with the heater wire 7 with a simpler structure as compared with the conventional structure in which the insulating material of the ceramic layers is insulated as in Patent Document 1. It is cheap because it can. Other effects are almost the same as those of the first embodiment described above.

  Note that the three-phase U, V, W wires of the ground wire electrode wire 43 and the heater wire 7 are wound around the winding core 5 at the same pitch. The heater wire 7 and the grounding wire electrode wire 43 can be short-circuited to detect leakage even if the liquid enters, but it is not necessarily required to be wound at the same pitch.

  As another embodiment for the quartz tube heater 41 of the fourth embodiment, as shown in FIG. 5, the ground wire electrode wire 43 is an insulator, for example, a plurality of short lengths. It can also be wound around the core 5 in a state of being inserted through the hollow cylindrical body 45. By making the hollow cylinder 45 short, the ground wire electrode electric wire 43 insulated by the hollow cylinder 45 can be bent and wound around the core 5. In this case, it is desirable in that the ground wire electrode electric wire 43 is reliably insulated from the three-phase U, V, and W wires of the heater wire 7 by a plurality of short hollow cylindrical bodies 45.

  In addition, the insulator can be constituted by a braid or a woven fabric of insulating fibers (not shown) instead of the plurality of short hollow cylindrical bodies 45. That is, the ground wire electrode wire 43 is wound around the winding core 5 in a state of being covered with a braid or fabric of an insulating fiber. In this case as well, as in the case of the plurality of short hollow cylinders 45 described above, the ground wire electrode wire 43 is reliably insulated from the three-phase U, V, and W wires of the heater wire 7 by a braid or fabric of insulating fiber. It is desirable in that it is. In addition, the ground wire electrode wire 43 is covered with an insulating fiber braid or fabric because the water is transmitted from the gap between the braid or fabric when water is simply infiltrated, so that the electric leakage can be detected quickly. It is.

  The material of the hollow cylindrical body 45 or the insulating fiber as the insulator is preferably quartz glass or ceramics having heat resistance in that heat resistance is provided in addition to insulation.

(A) is a schematic perspective view which shows the inside of the electric heater of 1st Embodiment of this invention, (B) is a partial perspective view of a winding core, (C) is a schematic of the electric heater. FIG. It is a schematic perspective view which shows the inside of the electric heater of 2nd Embodiment of this invention. (A) is a schematic perspective view which shows the inside of the electric heater of the 3rd Embodiment of this invention, (B) is principal part sectional drawing of the bottom face vicinity of a quartz tube housing | casing. It is a schematic perspective view which shows the inside of the electric heater of 4th Embodiment of this invention. It is a partial perspective view of the winding core by which the electric wire for heater wires and a grounding wire electrode was wound. It is a schematic perspective view which shows the inside of the conventional electric heater. It is a schematic explanatory drawing of the state which has supplied the electric heater in the liquid in a tank. It is a schematic electric circuit diagram of a conventional electric heater. It is a schematic perspective view which shows a state when micro liquid immersion has arisen inside the conventional electric heater. FIG. 10 is a schematic electric circuit diagram of FIG. 9. It is a schematic explanatory drawing which shows the risk of an electric shock accident.

Explanation of symbols

1 Quartz tube heater (electric heater of the first embodiment)
3 Quartz tube housing (insulator housing)
5 Winding core (heater wire winding part)
7 Heater wire 9 Power supply wire 11 Connection part (conductor exposed part)
13 Grounding wire electrode 15 Grounding wire 17 Insulating sheath tube 19 Extension groove 21 Heater flange portion 21 Left flange portion 23 Right flange portion 25 Leakage detector 27 ZCT (Zero-phase current detection transformer)
29 Earth Leakage Breaker 31 Quartz Tube Heater (Electric Heater of Second Embodiment)
33 Metal bar 35 Quartz tube heater (electric heater of the third embodiment)
37 Grounding wire electrode 39 Braided tape 41 Quartz tube heater (electric heater of the fourth embodiment)
43 Grounding wire electrode wire (grounding wire electrode)
45 Hollow cylinder

Claims (5)

Inside an insulator housing made of an insulator, a heater wire winding portion made of an insulator, a heater wire wound around the heater wire winding portion, a power supply electric wire for supplying power to the heater wire, A connecting portion for connecting the power supply wire to the heater wire, a grounding wire electrode for detecting leakage, and a grounding wire connected to the grounding wire electrode are hermetically provided, and flows from the grounding wire electrode to the grounding wire. In an electric heater provided with a leakage breaker that detects leakage and cuts off the power supply to the power supply wire,
The electric heater when put in a bath containing the liquid, the ground wire electrode, disposed at a position lower than the charging exposure unit including the heater wire and the connecting portion,
The ground wire electrode is made of a metal or a heat-resistant conductive material disposed on the bottom surface of the inner surface of the insulator housing, and the ground wire electrode and the heater wire are insulated with a braided tape of insulating fiber. electric heater, characterized in that to become to. The insulator housing is formed in a cylindrical shape,
2. The electric heater according to claim 1, wherein the ground line electrode is formed so as to be convexly curved toward the bottom surface of the inner surface of the insulator casing. 3. The electric heater according to claim 1, wherein the ground line electrode is provided over the entire length of the bottom surface of the insulator casing. Inside an insulator housing made of an insulator, a heater wire winding portion made of an insulator, a heater wire wound around the heater wire winding portion, a power supply electric wire for supplying power to the heater wire, A connecting portion for connecting the power supply wire to the heater wire, a grounding wire electrode for detecting leakage, and a grounding wire connected to the grounding wire electrode are hermetically provided, and flows from the grounding wire electrode to the grounding wire. In an electric heater provided with a leakage breaker that detects leakage and cuts off the power supply to the power supply wire,
The ground wire electrode is wound around the heater wire winding portion via an insulator,
An electric heater, wherein the insulator is formed of a braid or woven fabric of insulating fibers, and the ground wire electrode is covered with the braid or woven fabric . 5. The electric heater according to claim 4, wherein the insulator is made of quartz glass or ceramics having heat resistance.

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