JPH0561858B2 - - Google Patents
Info
- Publication number
- JPH0561858B2 JPH0561858B2 JP59154901A JP15490184A JPH0561858B2 JP H0561858 B2 JPH0561858 B2 JP H0561858B2 JP 59154901 A JP59154901 A JP 59154901A JP 15490184 A JP15490184 A JP 15490184A JP H0561858 B2 JPH0561858 B2 JP H0561858B2
- Authority
- JP
- Japan
- Prior art keywords
- furnace
- reference value
- value
- current
- resistance value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000001514 detection method Methods 0.000 claims description 9
- 230000000052 comparative effect Effects 0.000 claims description 4
- 230000003213 activating effect Effects 0.000 claims 1
- 230000007423 decrease Effects 0.000 description 7
- 238000000034 method Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 239000012774 insulation material Substances 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 3
- 210000002268 wool Anatomy 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
Landscapes
- Emergency Protection Circuit Devices (AREA)
- Control Of Resistance Heating (AREA)
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、セラミツクなどの素材の焼成炉や
真空高温炉などに適用して好適な高温炉の漏電検
出装置に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a leakage detection device for a high-temperature furnace suitable for application to a firing furnace for materials such as ceramics, a vacuum high-temperature furnace, and the like.
炉内の温度が2000℃以上にもなる高温炉の断熱
材にはカーボンウールが使用される。この場合、
カーボンウールが良導体であると同時に、2000℃
以上で使用でできる絶縁物がないために、カーボ
ンウールとヒータとの間には絶縁空間を設けてい
る。そして、この空間は、低温域ではほぼ無限大
の抵抗値を示している。
Carbon wool is used as insulation material for high-temperature furnaces where the temperature inside the furnace reaches over 2000℃. in this case,
Carbon wool is a good conductor and at the same time
Since there is no insulating material that can be used in the above, an insulating space is provided between the carbon wool and the heater. This space exhibits an almost infinite resistance value at low temperatures.
ところで、上記絶縁空間の温度が上昇すると、
熱電子放射による電流や、熱電子との衝突によつ
て生じたイオン電流が増加し、1800℃を超える
と、これらの漏れ電流が急激に増大し、遂には放
電現象に至つてヒータや断熱材等を損傷してしま
うという問題があつた。
By the way, when the temperature of the insulation space rises,
Current due to thermionic radiation and ion current generated by collision with thermionic electrons increase, and when the temperature exceeds 1800°C, these leakage currents increase rapidly, eventually leading to a discharge phenomenon that causes damage to heaters and insulation materials. There was a problem that the product could be damaged.
この発明は、上記問題点を解決しようとするも
のである。 This invention attempts to solve the above problems.
上記問題点を解決するための、この発明は、ヒ
ータに電流を供給する変圧器の出力電圧を出力電
流で除することによつて、ヒータを含めた実際の
負荷抵抗値を求め、この負荷抵抗値を基準値と比
較することによつて漏れ電流の大きさを判断し、
警報を出力することを前提とし、前記負荷抵抗値
と比較される基準値を、炉内の真空度が低い場合
あるいは炉内に雰囲気ガスがある場合において一
定値の比較抵抗値として設定される第１基準値
と、炉内が高真空である場合において炉内温度の
上昇とともに一定の勾配で上昇する比較抵抗値と
して設定される第２基準値との２種類とすること
により、より適正な漏電検出を行う構成としたこ
とを特徴とする。
In order to solve the above problems, this invention calculates the actual load resistance value including the heater by dividing the output voltage of the transformer that supplies current to the heater by the output current, and calculates the actual load resistance value including the heater. Determine the magnitude of the leakage current by comparing the value with a reference value,
On the premise that an alarm is output, the reference value to be compared with the load resistance value is set as a constant comparison resistance value when the degree of vacuum in the furnace is low or when there is atmospheric gas in the furnace. By setting two types, the first reference value and the second reference value, which is set as a comparative resistance value that increases at a constant gradient as the temperature inside the furnace increases when the furnace is in high vacuum, more appropriate leakage can be achieved. It is characterized by having a configuration that performs detection.
上記構成において、変圧器の出力電圧をＶ、出
力電流をＩとし、ヒータの実際の抵抗値をＲ、漏
れ電流に相当する抵抗分（漏れ抵抗）の値をRa
とすれば、これらの抵抗値Ｒ，Raは並列に接続
された形となるから（第１図参照）、変圧器出力
端にはこれらの合成抵抗値ｒが接続されたことに
なり、
ｒ＝Ｖ／Ｉ＝Ｒ Ra／Ｒ＋Ra ……(1)
が成り立つ。そして、炉内の温度が余り高くない
ときには、Ra→∞としてよいから、
ｒ＝Ｒ ……(2)
となり、合成抵抗値ｒはヒータ抵抗値Ｒと一致す
る。ここで、高温抵抗加熱炉で広く使用されてい
るグラフアイトヒータの抵抗値Ｒは、第２図に示
すように、ある温度以上では略直線的に上昇する
から、合成抵抗値ｒも略直線的に上昇する。
In the above configuration, the output voltage of the transformer is V, the output current is I, the actual resistance value of the heater is R, and the value of the resistance corresponding to the leakage current (leakage resistance) is R a
Then, since these resistance values R and R a are connected in parallel (see Figure 1), the combined resistance value r is connected to the output terminal of the transformer, and r =V/I=R R a /R + R a ...(1) holds true. Then, when the temperature inside the furnace is not very high, R a →∞ may be set, so r=R (2), and the combined resistance value r matches the heater resistance value R. Here, as shown in Figure 2, the resistance value R of the graphite heater widely used in high-temperature resistance heating furnaces increases approximately linearly above a certain temperature, so the combined resistance value r also increases approximately linearly. rise to
ところで、炉内温度が上昇すると、熱電子流や
イオン流によつて漏れ抵抗値Raが次第に低下し、
放電直前に至ると急激に低下する。従つて、合成
抵抗値ｒも急激に低下し、この値が基準値Ｃより
も小さくなつたときには（ｒ＜Ｃのときには）警
報が出力され、放電によるヒータや断熱材の損傷
を未然に防止することができる。 By the way, as the temperature inside the furnace increases, the leakage resistance value R a gradually decreases due to thermionic current and ion current.
It drops rapidly just before discharge. Therefore, the combined resistance value r also rapidly decreases, and when this value becomes smaller than the reference value C (when r<C), an alarm is output to prevent damage to the heater and insulation material due to discharge. be able to.
この場合、上記基準値の設定方法としては、
(1) 予め定めた一定値ｃ１を基準値とする第１の
方法（第３図参照）と、
(2) 炉内温度によつて変化する値（たとえば、炉
内温度によつて直線的に上昇する値）ｃ２を基
準値とする第２の方法（第４図参照）と
がある。すなわち、炉内の真空度が低い場合、あ
るには、雰囲気ガスがある場合には、前記漏れ抵
抗値Ra、従つて合成抵抗値ｒの低下が急激であ
るため、上記第１の方法で十分に検出可能である
が、高真空の場合には、熱電子流は大きいものの
気体分子が少ないため、漏れ抵抗値Ra、合成抵
抗値ｒの低下が緩慢になり、第１の方法では検出
することができない。そこで、炉内温度に応じて
基準値を変化させる第２の方法によつて目的を達
成する。こうして、炉の使用態様によつて第１、
第２の方法を使い分けることによつて、十全な漏
電検出を行うことができる。 In this case, the methods for setting the above reference value are: (1) the first method in which a predetermined constant value c1 is used as the reference value (see Figure 3), and (2) a value that changes depending on the temperature inside the furnace. There is a second method (see FIG. 4) that uses c2 as a reference value (for example, a value that increases linearly depending on the temperature inside the furnace). That is, when the degree of vacuum in the furnace is low, or in some cases when there is atmospheric gas, the leakage resistance value R a , and therefore the combined resistance value r, decreases rapidly. However, in the case of high vacuum, although the thermionic current is large, there are few gas molecules, so the leakage resistance value R a and the combined resistance value r decrease slowly, and the first method cannot detect it. Can not do it. Therefore, the objective is achieved by a second method of changing the reference value according to the temperature inside the furnace. In this way, depending on how the furnace is used,
By properly using the second method, sufficient leakage detection can be performed.
以下、図面を参照して、本発明の実施例を説明
する。
Embodiments of the present invention will be described below with reference to the drawings.
第１図は、本発明の一実施例の構成を示すブロ
ツク図である。この図において、符号１は変圧器
であり、その出力側（２次側）にはヒータ２（抵
抗値Ｒ）が接続されている。このヒータ２には、
熱電子流やイオン流による漏れ電流Iaに対応する
漏れ抵抗３（抵抗値Ra）が並列に入つた形とな
り、ヒータ２に流れる電流をI1とすると、変圧器
１から流出する電流Ｉは、
Ｉ＝I1＋Ia ……(3)
となる。この出力電流Ｉは、変流器４によつて検
出された後、電流変換器５によつて後段の電子回
路に適合する値に変換される。そして、電圧変換
器６によつて適宜の値に変換された、変圧器１の
出力電圧Ｖとともに、除算器７に供給され、ここ
でＶ÷Ｉなる演算が行われ、(1)式に示す合成抵抗
値ｒが求められる。こうして、除算器７から出力
された合成抵抗値ｒは、比較器８，９へ供給さ
れ、基準値Ｃ１（第１基準値）、Ｃ２（第２基準
値）とそれぞれ比較される。ここで基準値Ｃ１は
一定値、基準値Ｃ２は温度とともに一定の勾配ａ
で上昇する値であり、基準値Ｃ２は、炉内温度信
号１０に基づいて関数発生器１１が形成し、比較
器９へ供給する。そして、合成抵抗値ｒが基準値
Ｃ１より小さくなつたときには比較器８が、Ｃ２
より小さくなつたときには比較器９が、オアゲー
ト１２を介して警報器１３を起動し、鳴動させ
る。 FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In this figure, reference numeral 1 is a transformer, and a heater 2 (resistance value R) is connected to its output side (secondary side). This heater 2 has
A leakage resistance 3 (resistance value R a ) corresponding to the leakage current I a due to thermionic current or ion flow is connected in parallel, and if the current flowing through the heater 2 is I 1 , the current I flowing out from the transformer 1 is I=I 1 +I a ...(3). This output current I is detected by a current transformer 4, and then converted by a current converter 5 to a value suitable for a subsequent electronic circuit. The output voltage V of the transformer 1, which has been converted into an appropriate value by the voltage converter 6, is then supplied to the divider 7, where the calculation V÷I is performed, as shown in equation (1). A combined resistance value r is determined. In this way, the combined resistance value r output from the divider 7 is supplied to comparators 8 and 9, and compared with reference values C1 (first reference value) and C2 (second reference value), respectively. Here, the reference value C1 is a constant value, and the reference value C2 is a constant slope a with temperature.
The reference value C2 is generated by the function generator 11 based on the furnace temperature signal 10 and is supplied to the comparator 9. Then, when the combined resistance value r becomes smaller than the reference value C1, the comparator 8
When it becomes smaller, the comparator 9 activates the alarm 13 via the OR gate 12 to make it sound.
このような構成において、炉内の温度が上昇
し、漏れ抵抗値Raが急激に低下すると、変圧器
１の出力電流Ｉが急増し、合成抵抗値ｒが急激に
低下する（第３図、第４図参照）。そして、すで
に述べたように、炉内の真空度が高いときには比
較器９がｒ＜Ｃ２を検出して警報器１３を起動す
る一方、炉内の真空度が低いか雰囲気ガスがある
場合は、比較器８がｒ＜Ｃ１を検出して警報器１
３を起動する。これによつて警報器１３から警報
が出力され、自動あるいは人手によつて変圧器１
の出力電圧Ｖを急激に低下させたり、出力電流Ｉ
を遮断する処置がとられ、放電によるヒータや断
熱材の損傷を未然に防止することができる。 In such a configuration, when the temperature inside the furnace rises and the leakage resistance value R a rapidly decreases, the output current I of the transformer 1 rapidly increases, and the combined resistance value r rapidly decreases (Fig. 3, (See Figure 4). As already mentioned, when the degree of vacuum in the furnace is high, the comparator 9 detects r<C2 and activates the alarm 13, while if the degree of vacuum in the furnace is low or there is atmospheric gas, Comparator 8 detects r<C1 and alarm 1
Start 3. As a result, an alarm is output from the alarm device 13, and the transformer 1 is automatically or manually activated.
If the output voltage V of
This prevents damage to the heater and insulation material due to electrical discharge.
以上説明したように、この発明は、炉のヒータ
に電流を供給する変圧器の出力電圧を、その出力
電流によつて除し、この値が基準値を逸脱したと
きに警報を出す構成とされているとともに、前記
基準値を、炉内の真空度が低い場合あるいは炉内
に雰囲気ガスがある場合において一定値の比較抵
抗値として設定された第１基準値と、炉内が高真
空である場合において炉内温度の上昇とともに一
定の勾配で上昇する比較抵抗値として設定された
第２基準値とするので、炉内の真空度の高低によ
り漏れ抵抗値の低下に緩急の差があつても、放電
によるヒータや断熱材の損傷を未然に防止するこ
とができ、十全な漏電検出を行うことが可能とな
る。
As explained above, the present invention has a structure in which the output voltage of a transformer that supplies current to a furnace heater is divided by its output current, and an alarm is issued when this value deviates from a reference value. At the same time, the reference value is a first reference value set as a comparative resistance value of a constant value when the degree of vacuum in the furnace is low or when there is atmospheric gas in the furnace, and when the inside of the furnace is under high vacuum. The second reference value is set as a comparative resistance value that increases at a constant gradient as the temperature inside the furnace increases, so even if there is a difference in the speed at which the leakage resistance value decreases depending on the degree of vacuum inside the furnace. , it is possible to prevent damage to the heater and the heat insulating material due to discharge, and it is possible to perform sufficient leakage detection.
第１図は、本発明の一実施例の構成を示すブロ
ツク図、第２図はグラフアイト製ヒータの温度と
抵抗値との関係を示すグラフ、第３図は炉内の真
空度が低いか雰囲気ガスがある場合の合成抵抗値
ｒと炉内温度との関係および基準値Ｃ１を示すグ
ラフ、第４図は炉内真空度が高い場合の合成抵抗
値ｒと路内温度との関係および基準値Ｃ２を示す
グラフである。
１…変圧器、２…ヒータ、３…漏れ抵抗、４…
変流器、５…電流変換器（以上４，５は電流検出
手段）、６…電圧変換器（電圧検出手段）、７…除
算器（演算手段）、８，９…比較器（比較手段）、
１１…関数発生器（基準値発生手段）、１３…警
報器、Ｃ１，Ｃ２…基準値。
Fig. 1 is a block diagram showing the configuration of an embodiment of the present invention, Fig. 2 is a graph showing the relationship between the temperature and resistance value of the graphite heater, and Fig. 3 is a graph showing whether the degree of vacuum in the furnace is low. A graph showing the relationship between the combined resistance value r and the temperature in the furnace when there is atmospheric gas and the reference value C1. Figure 4 shows the relationship between the combined resistance value r and the temperature in the passageway and the standard when the degree of vacuum in the furnace is high. It is a graph showing the value C2. 1...Transformer, 2...Heater, 3...Leakage resistance, 4...
Current transformer, 5... Current converter (4 and 5 above are current detection means), 6... Voltage converter (voltage detection means), 7... Divider (calculation means), 8, 9... Comparator (comparison means) ,
11...Function generator (reference value generation means), 13...Alarm device, C1, C2...Reference value.
Claims (1)
流を供給する変圧器とを具備してなる高温炉にお
いて、前記変圧器から流出する電流を検出する電
流検出手段と、前記変圧器の出力電圧を検出する
電圧検出手段と、前記出力電圧を前記電流で除算
する演算手段と、前記除算結果が基準値を逸脱し
たときに警報回路を起動する比較手段と、前記基
準値を前記比較手段に供給する基準値発生手段と
を具備し、 前記基準値を、炉内の真空度が低い場合あるい
は炉内に雰囲気ガスがある場合において一定値の
比較抵抗値として前記除算結果と比較される第１
基準値と、炉内が高真空である場合において炉内
温度の上昇とともに一定の勾配で上昇する比較抵
抗値として前記除算結果と比較される第２基準値
との２種類とすることを特徴とする高温炉の漏電
検出装置。[Scope of Claims] 1. In a high-temperature furnace comprising a heater installed in the furnace and a transformer that supplies current to the heater, current detection means for detecting the current flowing out from the transformer; Voltage detection means for detecting the output voltage of the transformer, calculation means for dividing the output voltage by the current, comparison means for activating an alarm circuit when the division result deviates from a reference value, and the reference value. and a reference value generating means for supplying the reference value to the comparison means, and converting the reference value to the division result as a comparative resistance value of a constant value when the degree of vacuum in the furnace is low or when there is atmospheric gas in the furnace. The first compared
It is characterized by having two types of values: a reference value and a second reference value, which is compared with the division result as a comparison resistance value that increases at a constant gradient as the temperature inside the furnace increases when the inside of the furnace is in high vacuum. Electrical leakage detection device for high temperature furnaces.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15490184A JPS6135113A (en) | 1984-07-25 | 1984-07-25 | Leakage detector of high temperature furnace |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15490184A JPS6135113A (en) | 1984-07-25 | 1984-07-25 | Leakage detector of high temperature furnace |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6135113A JPS6135113A (en) | 1986-02-19 |
| JPH0561858B2 true JPH0561858B2 (en) | 1993-09-07 |
Family
ID=15594435
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15490184A Granted JPS6135113A (en) | 1984-07-25 | 1984-07-25 | Leakage detector of high temperature furnace |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6135113A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62137595U (en) * | 1986-02-24 | 1987-08-29 | ||
| JPH0634375B2 (en) * | 1989-07-20 | 1994-05-02 | 株式会社フォレスト | Heater burnout alarm |
| JPH0353483A (en) * | 1989-07-20 | 1991-03-07 | Fuoresuto:Kk | Heater failure alarm |
| JPH0357180A (en) * | 1989-07-25 | 1991-03-12 | Fuoresuto:Kk | Temperature regulating device equipped with heater failure alarm |
-
1984
- 1984-07-25 JP JP15490184A patent/JPS6135113A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6135113A (en) | 1986-02-19 |
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