JPH07245178A - Induction heating device - Google Patents

Abstract

PURPOSE:To judge coil block in which ground shortcircuit is generated on the basis of the memory of a ground shortcircuit sensing amperage when no ground shortcircuit is generated and the ground shortcircuit sensing current in the applicable coil block sensed by a current sensor. CONSTITUTION:A heating coil 30 consists of coil blocks 31-35, wherein arrangement is made in a straight line, and coils 31a-35a are connected parallel. An object to be heated 1 is conveyed inside the coil 30 continuously, and an electromagnetic induction current is generated in the object 1 by the high frequency current fed from a high frequency power supply and flowing through the coils 31a-35a, and heating to the specified temp. is made with Joule's heat generated at the time. Since the ground shortcircuit sensing current flows from AC mains 42 to the coils 31a-35a, the amperage is sensed using current transformers 51-55 and monitored always by a ground shortcircuit judging part 60, and the ground shortcircuit sensing current sensed when no ground shortcircuit exists in the blocks 31-35 is stored in memory. The judging part 60 compares the ground shortcircuit sensing current when a ground shortcircuit is generated in either of the blocks 31-35 with the stored value and judges in which block the ground shortcircuit is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating apparatus for generating an electromagnetic induction current in a material to be heated which is conveyed while moving inside a heating coil composed of a plurality of coil blocks and heating the material by Joule heat thereof, and more particularly, an earth heating apparatus. Relating to determining a tangled coil block.

[0002]

2. Description of the Related Art FIG. 5 shows, for example, Japanese Examined Patent Publication No. 61-35671.
6 is a circuit diagram of a conventional induction heating device disclosed in Japanese Patent Publication No.
FIG. 4 is a cross-sectional view showing the structure of a coil block that constitutes a heating coil. In FIG. 5 and FIG. 6, 1 is a rod-shaped material to be heated used for forging, 10 is a heating coil 11-11 for generating electromagnetic induction current in the material to be heated 1 and heating the material 1 by Joule heat.
Reference numeral 5 denotes a coil block that constitutes the heating coil 10 and has different inductances. Reference numerals 11a to 15a denote coils of the coil blocks 11 to 15, respectively, in which a copper pipe is wound in a spiral shape, and each turn is electrically insulated. 11
Reference numeral b is a cylindrical refractory tube made of a refractory material inserted inside the coil 11a, and the same ones are also inserted into the coils 12a to 15a. Reference numeral 19 is a skid rail on which the material to be heated 1 is conveyed, and 21 is a heating coil 1.
0 is a high frequency power source for supplying high frequency power, 22 is a direct current power source used for ground fault detection of the coil blocks 11-15, and 23 is a ground for detecting a ground fault detection current flowing from the direct current power source 22 due to a ground fault of the coil blocks 11-15. Contact detection relay, 24
Is a resistor for adjusting the ground fault detection current flowing from the DC power supply 22.

The conventional induction heating device is constructed as described above, and the heating coil 10 includes coil blocks 11 to 15.
Are arranged in a straight line, and the coils 11a to 15a are connected in series. The rod-shaped material to be heated 1 used for forging is placed on the skid rail 19, continuously conveyed and moved in the heating coil 10, and the high frequency power supply 21 causes the coils 11a to 15a.
An electromagnetic induction current is generated in the material to be heated 1 by the high-frequency current flowing in and the Joule heat heats the material to a predetermined temperature.

By the way, since the coils 11a to 15a are cooled by passing water through their copper tubes, they are grounded through water, but the resistance between the coils 11a to 15a and ground is relatively large, and the DC power source 22 Ground fault detection relay 2
3, the ground fault detection current flowing to the ground through the resistor 24, the coils 11a to 15a is small, and the ground fault detection relay 23 does not operate. However, if, for example, a crack occurs in the fireproof tube 11b of the coil block 11 due to thermal stress or deterioration and the oxide scale of the material 1 to be heated accumulated inside the fireproof tube 11b enters the crack, the fireproof tube is heated. 11b is further thermally destroyed to reach the coil 11a, and the heated material 1 and the coil 1
1a is short-circuited. Since the skid rail 19 is grounded and the material 1 to be heated placed on the skid rail 19 is also grounded, the coil 11a is grounded. At this time, the DC power source 22 is connected to the ground fault detection relay 2
3, a resistor 24, a ground-faulted coil 11a, a material to be heated 1, a skid rail 19, and a ground fault detection current flows to the ground and a ground fault detection relay 23 operates to issue an alarm. Do.

[0005]

The conventional induction heating apparatus is constructed as described above, and is a heating coil 10 in which the coil blocks 11 to 15 are linearly arranged and the coils 11a to 15a are all connected in series. There is a heating coil 10
When a ground fault occurs in, it is not possible to determine which coil block 11 has a ground fault, and it is necessary to sequentially disassemble and examine the coil blocks 11 to 15, which greatly increases the work of inspection and repair. There was a problem to be solved that it takes time and effort. Also, as the capacity of the heating coil increases, the number of coil blocks generally increases and each coil is connected in parallel, or a predetermined number of coils connected in series are connected in parallel. There was a problem that the block could not be determined.

The present invention has been made to solve the above problems, and is a coil block which is composed of a plurality of coil blocks and which is ground-faulted when a ground fault occurs in a heating coil in which each coil is connected in parallel. The first purpose is to obtain an induction heating device capable of making a judgment, and a coil block having a ground fault is judged even when a ground fault occurs in a heating coil composed of a plurality of coil blocks and each coil is connected in series. A second object is to obtain an induction heating device that can be used.

[0007]

In an induction heating apparatus according to the present invention, a plurality of coil blocks are arranged linearly, and heating coils formed by connecting the coil blocks in parallel are connected to a high frequency power source. A ground fault that is connected in parallel with a high frequency power source in a case where an electromagnetic induction current is generated by the high frequency current flowing through the heating coil in the material to be heated that is transported inside the heating coil by moving the terminal, and heating is performed by the Joule heat. Detection power supply, current detector that detects the ground fault detection current that flows from this ground fault detection power supply to each coil block, and stores the ground fault detection current detected by the current detector when no ground fault occurs in each coil block Then, the ground fault is detected based on the stored ground fault detection current and the ground fault detection current detected by the current detector when a ground fault occurs in one of the coil blocks. Determining the ground determining unit coil block without in which the provided.

Further, a plurality of coil blocks are arranged in a straight line, and a heating coil formed by connecting all the coil blocks in series is connected to a high frequency power source and one terminal thereof is grounded so that the heating coil is conveyed inside the heating coil. In the one that generates electromagnetic induction current by high frequency current flowing in the heating coil in the material to be heated and moves by the Joule heat,
Ground fault detection power supply connected in parallel with high frequency power supply, voltage detector that detects the ground fault detection voltage applied to each coil block by this ground fault detection power supply, voltage detector when no ground fault occurs in each coil block A ground fault is detected based on the stored ground fault detection voltage stored in the voltage detector and the ground fault detection voltage detected by the voltage detector when a ground fault occurs in one of the coil blocks. A ground fault determination unit that determines the coil block is provided.

The ground fault detection power source is an alternating current power source having a frequency different from that of the high frequency power source, and the current detector is a current transformer.

The ground fault detection power supply is a DC power supply, and the current detector is a DC current transformer.

The ground fault detection power source is an AC power source having a frequency different from that of the high frequency power source, and the voltage detector is a voltage transformer.

The ground fault detection power source is a DC power source, and the voltage detector is a resistor.

[0013]

According to the present invention, the current detector detects the ground fault detection current flowing in each coil block from the ground fault detection power source connected in parallel with the high frequency power source, and when the ground fault does not occur in each coil block. The ground fault detection current detected by the current detector is stored, and the ground fault detection current is stored and the ground fault detection current detected by the current detector when a ground fault occurs in any of the coil blocks The coil determining unit determines the coil block in which the ground fault has occurred.

Further, the voltage detector detects the ground fault detection voltage applied to each coil block by the ground fault detection power source connected in parallel with the high frequency power source, and the voltage detector when the ground fault does not occur in each coil block. The ground fault detection voltage stored in the ground fault detection unit is stored based on the stored ground fault detection voltage and the ground fault detection voltage detected by the voltage detector when a ground fault occurs in one of the coil blocks. Determine the coil block where the ground fault occurred.

A ground fault detected when an earth fault is generated in each coil block by detecting a ground fault detection current flowing in each coil block from an AC power source connected in parallel with a high frequency power source and having a different frequency. The detected current is stored, and the coil block in which the ground fault has occurred in the ground fault determination unit is based on the stored ground fault detection current and the ground fault detection current detected when a ground fault occurs in one of the coil blocks. judge.

A ground fault detection current flowing in each coil block from a DC power source connected in parallel with a high frequency power source is detected by a DC current transformer, and ground fault detection is performed when no ground fault occurs in each coil block. The current is stored, and the coil block in which the ground fault has occurred is determined by the ground fault determination section based on the stored ground fault detection current and the ground fault detection current detected when a ground fault occurs in one of the coil blocks. To do.

A ground fault detection voltage applied to each coil block is detected by an instrument transformer by an AC power source connected in parallel with a high frequency power source and having a different frequency, and is detected when no ground fault occurs in each coil block. A coil block in which a ground fault is generated in the ground fault determination unit based on the stored ground fault detection voltage and the stored ground fault detection voltage and the ground fault detection voltage detected when a ground fault occurs in one of the coil blocks. To judge.

A ground fault detection voltage applied to each coil block is detected by a resistor by a DC power source connected in parallel with a high frequency power source, and the ground fault detection voltage detected when no ground fault occurs in each coil block is stored. Then, based on the stored ground fault detection voltage and the ground fault detection voltage detected when a ground fault occurs in one of the coil blocks, the ground fault determination unit determines the coil block in which the ground fault has occurred.

[0019]

【Example】

Example 1. First Embodiment FIG. 1 is a circuit diagram showing a first embodiment of the present invention. In the figure, 30 is a heating coil 31 to generate an electromagnetic induction current in the material to be heated 1 and heat it by its Joule heat.
Reference numeral 35 is a coil block that constitutes the heating coil 10, and has different current capacity and inductance. 31a-3
Reference numeral 5a is a coil of coil blocks 31 to 35, and a copper tube is wound in a spiral shape to electrically insulate each turn. Reference numeral 41 is a high-frequency power supply that supplies high-frequency power to the heating coil 30, and reference numeral 42 is a ground fault detection power supply used for detecting the ground fault of the coil blocks 31 to 35, which is an AC power supply connected in parallel with the high-frequency power supply 41 and having a different frequency. 51-5
5 are coil blocks 31 from the ground fault detection power source 42, respectively.
Current transformers of current detectors that detect the ground fault detection currents flowing in to 35, 59 is a filter that blocks high-frequency current components on the secondary side of the current transformers 51 to 55, and 60 is a ground fault determination unit. The ground fault detection currents detected by the current transformers 51 to 55 are stored when the coil blocks 31 to 35 have no ground faults.
The stored ground fault detection current and the coil blocks 31 to 35
The coil blocks 31 to 35 in which the ground fault has occurred are determined based on the ground fault detection currents detected by the current transformers 51 to 55 when the ground fault occurs in any of the above.

The first embodiment is constructed as described above, and the heating coil 30 is composed of coil blocks 31 to 35, and the heating coils 30 are linearly arranged to connect the coils 31a to 35a in parallel. The material 1 to be heated is continuously conveyed and moved in the heating coil 30, and an electromagnetic induction current is generated in the material 1 to be heated by the high frequency current flowing from the high frequency power supply 41 to the coils 31a to 35a. Heat to temperature. Further, since a ground fault detection current flows from the AC power supply 42 to the coils 31a to 35a, this is detected by the current transformers 51 to 55 and constantly monitored by the ground fault determination unit 60, and the coil blocks 31 to 35 are ground faulted. The ground fault detection current detected when there is no occurrence is stored. High-frequency currents are also detected by the current transformers 51 to 55 at the same time, but they are blocked by the filter 59 and are not input to the ground fault determination unit 60. When a ground fault occurs in any of the coil blocks 31 to 35, the ground fault detection current flowing in the coil block increases, so this is detected by the current transformers 51 to 55, and the ground faults already stored are detected. The ground fault detection current when there is no occurrence is compared with the ground fault determination unit 60 to determine the occurrence of the ground fault and determine the coil blocks 31 to 35.

Example 2. 2 is a circuit diagram showing a second embodiment of the present invention, in which a DC power supply 44 is used as a ground fault detection power supply and the ground fault detection power supply flowing in each coil block 31 to 35 is a DC current transformer 71 of a current detector. Detect at ~ 75.
The ground fault detection unit 60 constantly monitors the detected ground fault current,
The ground fault detection current detected when no ground fault is generated in each coil block 31 to 35 is stored. Coil block 31
When a ground fault occurs in any one of the current transformers 35 to 35, the ground fault detection current flowing in the coil block increases.
˜55, the ground fault detection unit 60 compares the stored ground fault detection current when there is no occurrence of the ground fault with the ground fault determination unit 60 to determine the coil blocks 31 to 35 in which the ground fault has occurred. In the second embodiment, the same effect as the first embodiment can be obtained.

Example 3. FIG. 3 is a circuit diagram showing a third embodiment of the present invention, in which the heating coil 110 is a coil block 1.
11 to 113, and the coils 111a to 113a are connected in series. Each coil block 111 is provided by using the high frequency power source 43 and the AC power source 46 having a different frequency as the ground fault detection power source.
When the ground fault detection voltage applied to each of the coil blocks 111 to 113 is not detected, the ground fault detection voltage applied to each of the coil blocks 111 to 113 is detected by the voltage transformers 91 to 93 of the voltage detector. The detected ground fault detection voltage is stored. High-frequency current is detected at the same time by the instrument transformers 91 to 93,
It is blocked by the filter 99 and is not input to the ground fault determination unit 60. When a ground fault occurs in any of the coil blocks 111 to 113, the ground fault detection voltage applied to the coil block decreases, so that the occurrence of the ground fault detected by the instrument transformers 91 to 93 and already stored. The ground fault detection voltage when there is no ground fault is compared with the ground fault determination unit 60 to determine the coil blocks 111 to 113 in which the ground fault has occurred.

Although not shown in the figure, a coil block in which a ground fault similarly occurs even if a resistor is used to detect the ground fault detection voltage applied to each coil block 111 to 113 by using a DC power source as the ground fault detection power source. Can be determined.

Example 4. FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention, in which the coil blocks 131, 132 and the coil blocks 133 to 135 are connected in series, respectively, and these are connected in parallel with the coil block 136 to connect the heating coil 130. Constitute. A ground fault detection current flowing in each parallel branch path is detected by the current transformers 151 to 153 by using the high frequency power source 45 and the AC power source 48 having a different frequency as the ground fault detection power source, and the ground faults applied to the coil blocks 131 to 136 are detected. The detected voltages are respectively transformers 191 to 1 for measuring voltage detectors.
96, which is constantly monitored by the ground fault determination unit 160, and the ratio of the ground fault detection current and the ground fault detection voltage detected when there is no ground fault in each of the coil blocks 131 to 136, that is, the ground fault detection voltage / The ground fault detection current is stored. Current transformer 151-1
The high-frequency current is also detected by the voltage transformer 53 and the instrument transformers 191 to 196 at the same time. When a ground fault occurs in any of the coil blocks 131 to 136, for example, the coil block 134, the coil block 133
Although the ground fault detection current flowing in and the ground fault detection voltage applied thereto both increase, the ground fault detection voltage / ground fault detection current is the same as when no ground fault occurs, while the coil block 1
Since the ground fault detection voltage / ground fault detection current for 34 is smaller than that when no ground fault occurs, the ground fault determination unit 160 determines that a ground fault has occurred in the coil block 134. In addition,
In this case, the ground fault detection voltage / ground fault detection current for the coil block 135 is 0 or a value close to 0, but this is not judged to be the occurrence of a ground fault.

As described above, the present invention has the following effects.

[0026]

EFFECTS OF THE INVENTION A plurality of coil blocks are arranged in a straight line, and a heating coil formed by connecting the coil blocks in parallel is connected to a high frequency power source and one terminal thereof is grounded, and the coil is conveyed inside the heating coil. In the induction heating device that generates electromagnetic induction current by the high frequency current flowing through the heating coil in the material to be heated and moves by the Joule heat, a ground fault detection power source connected in parallel with the high frequency power source, A current detector that detects the ground fault detection current flowing in the coil block, and stores the ground fault detection current detected by the current detector when no ground fault occurs in each coil block and the stored ground fault detection current. When a ground fault occurs in one of the coil blocks, the ground fault is detected based on the ground fault detection current detected by the current detector. Since provision of the determination unit, if a ground fault occurs in the heating coil, it is possible to determine the ground fault the coil block.

A plurality of coil blocks are arranged in a straight line, and a heating coil formed by connecting all the coil blocks in series is connected to a high frequency power source, one terminal of which is grounded, and the inside of the heating coil is transported and moved. In an induction heating device that generates electromagnetic induction current by a high frequency current flowing through a heating coil in a material to be heated and heats it by its Joule heat, a ground fault detection power source connected in parallel with a high frequency power source, and each coil block by the ground fault detection power source. Voltage detector for detecting the ground fault detection voltage applied to the coil block, the ground fault detection voltage detected by the voltage detector when no ground fault occurs in each coil block, and the stored ground fault detection voltage and coil block When a ground fault occurs in any of the ground faults, the ground fault detection voltage detected by the voltage detector is used to determine the coil block in which the ground fault has occurred. Since providing a tough, if a ground fault occurs in the heating coil, it is possible to determine the ground fault the coil block.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram of a conventional induction heating device.

FIG. 6 is a cross-sectional view showing the structure of a coil block.

[Explanation of symbols]

 30 heating coil 31 coil block 31a coil 32 coil block 32a coil 33 coil block 33a coil 34 coil block 34a coil 35 coil block 35a coil 41 high frequency power supply 42 alternating current power supply 43 high frequency power supply 44 direct current power supply 45 high frequency power supply 46 alternating current power supply 48 alternating current power supply 71 DC current transformer 72 DC current transformer 73 DC current transformer 74 DC current transformer 75 DC current transformer 91 Meter transformer 92 Meter transformer 93 Meter transformer 110 Heating coil 111 Coil block 111a Coil 112 Coil block 112a Coil 113 Coil Block 113a Coil 130 Heating Coil 131 Coil Block 131a Coil 132 Coil Block 132a Coil 133 Coil Block 133a Coil 13 Coil block 134a Coil 135 Coil block 135a Coil 136 Coil block 136a Coil 151 Current transformer 152 Current transformer 153 Current transformer 160 Ground fault determination unit 191 Meter transformer 192 Meter transformer 193 Meter transformer 194 Meter transformer Transformer 195 transformer for instrument 196 transformer for instrument

Claims (6)

[Claims] 1. A plurality of coil blocks are arranged linearly, and a heating coil formed by connecting the coil blocks in parallel is connected to a high frequency power source and one terminal thereof is grounded, and the inside of the heating coil is In an induction heating device that generates electromagnetic induction current by a high frequency current flowing in the heating coil in a material to be conveyed and moves and heats it by its Joule heat, a ground fault detection power source connected in parallel with the high frequency power source, and this ground fault. A current detector that detects a ground fault detection current flowing from the detection power source to each coil block, and stores the ground fault detection current detected by the current detector when no ground fault occurs in each coil block. Based on the stored ground fault detection current and the ground fault detection current detected by the current detector when a ground fault occurs in any of the coil blocks, a ground fault is detected. An induction heating device comprising a ground fault determination unit that determines the coil block that has occurred. 2. A plurality of coil blocks are arranged linearly, and a heating coil formed by connecting all the coil blocks in series is connected to a high frequency power source and one terminal thereof is grounded, and the inside of the heating coil is In an induction heating device that generates electromagnetic induction current by a high frequency current flowing in the heating coil in a material to be conveyed and moves and heats it by its Joule heat, a ground fault detection power source connected in parallel with the high frequency power source, and this ground fault. A voltage detector that detects a ground fault detection voltage applied to each coil block by a detection power supply, and stores the ground fault detection voltage detected by the voltage detector when a ground fault does not occur in each coil block. A ground fault is detected based on the stored ground fault detection voltage and the ground fault detection voltage detected by the voltage detector when a ground fault occurs in any of the coil blocks. An induction heating device comprising a ground fault determination unit that determines the coil block that has occurred. 3. The heating device according to claim 1, wherein the ground fault detection power source is an AC power source having a frequency different from that of the high frequency power source, and the current detector is a current transformer. 4. The induction heating device according to claim 1, wherein the ground fault detection power source is a DC power source and the current detector is a DC current transformer. 5. The induction heating device according to claim 2, wherein the ground fault detection power source is an AC power source having a frequency different from that of the high frequency power source, and the voltage detector is a transformer for instrument. 6. The induction heating device according to claim 2, wherein the ground fault detection power source is a DC power source and the voltage detector is a resistor.