JPS625024Y2 - - Google Patents
Info
- Publication number
- JPS625024Y2 JPS625024Y2 JP16760383U JP16760383U JPS625024Y2 JP S625024 Y2 JPS625024 Y2 JP S625024Y2 JP 16760383 U JP16760383 U JP 16760383U JP 16760383 U JP16760383 U JP 16760383U JP S625024 Y2 JPS625024 Y2 JP S625024Y2
- Authority
- JP
- Japan
- Prior art keywords
- heating
- coil
- high frequency
- conductor
- voltage
- 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
Links
- 238000010438 heat treatment Methods 0.000 claims description 56
- 239000004020 conductor Substances 0.000 claims description 52
- 238000012544 monitoring process Methods 0.000 claims description 14
- 230000005856 abnormality Effects 0.000 claims description 7
- 230000006698 induction Effects 0.000 claims description 7
- 230000004907 flux Effects 0.000 description 11
- 239000000463 material Substances 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 230000007257 malfunction Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Description
【考案の詳細な説明】
本考案は誘導加熱コイルのコイル電流監視回路
に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coil current monitoring circuit for an induction heating coil.
誘導加熱装置では複数の被加熱材または単数の
被加熱材の複数箇処を同時に加熱するため、単数
の電源に並列接続される複数の加熱導体を具えて
いる場合がある。 Induction heating devices may include a plurality of heating conductors connected in parallel to a single power source in order to simultaneously heat a plurality of materials to be heated or a plurality of locations on a single material to be heated.
例えばクランクシヤフトの複数のジヤーナル部
またはピン部を焼入れするため、ジヤーナル部の
加熱に適合する複数の加熱導体とピン部の加熱に
適合する複数の加熱導体とをそれぞれ具えるが如
く構成した装置がこれに該当する。 For example, in order to harden a plurality of journal parts or pin parts of a crankshaft, an apparatus configured to include a plurality of heating conductors suitable for heating the journal parts and a plurality of heating conductors suitable for heating the pin parts, respectively, is provided. This applies.
上記この種の誘導加熱装置では、従来加熱電源
がインバータの場合には当該インバータの高周波
出力電圧および電流を、また加熱電源が真空管発
振器の場合には入力直流電圧および電流を監視し
て加熱状態の常または異常を判断していた。 Conventionally, in this type of induction heating device described above, when the heating power source is an inverter, the high frequency output voltage and current of the inverter is monitored, and when the heating power source is a vacuum tube oscillator, the input DC voltage and current are monitored to determine the heating state. It was judged as normal or abnormal.
ところが、上記監視方法は複数の加熱導体が単
一の電源に並列接続となつているため、複数の加
熱導体の出力としての電圧・電流が検知されるの
で、例えば前述クランクシヤフトの焼入れライン
の場合を例にとれば、監視装置が正常値を示して
いるにも拘らず、同時加熱・焼入れされた筈の複
数のジヤーナル部の１箇処は全く加熱・焼入れが
施されておらず、これに反して他の箇処は過負荷
がもたらす焼入れ過剰となつているような現象が
時に発生し、その原因が、割型タイプの加熱導体
の１つが接触不良であり、他の加熱導体には上記
接触不良加熱導体へ流れる筈の高周波電流が加重
して流れたためであることが究明された。 However, in the above monitoring method, since multiple heating conductors are connected in parallel to a single power supply, the voltage and current as outputs of multiple heating conductors are detected. For example, although the monitoring device shows a normal value, one of the multiple journal parts that should have been heated and hardened at the same time was not heated or hardened at all, and this caused the problem. On the other hand, over-hardening caused by overload sometimes occurs in other parts, and the reason for this is a poor contact in one of the split-type heating conductors, and the other heating conductors are It was determined that this was due to the high-frequency current that was supposed to flow to the poor contact heating conductor flowing in a weighted manner.
本考案は上述単一電源に並列接続される複数の
加熱導体それぞれの加熱について従来方法では検
知し得なかつた監視方法を改善する目的でなされ
たものであつて、従来装置に本考案にかかる監視
回路を付加するだけで、通称片焼きと云われるよ
うな上述の如きトラブルの絶無を可能として自動
化焼入れラインの信頼性と品質の保証を確保せし
めるものである。 The present invention was made for the purpose of improving a monitoring method that could not be detected by conventional methods regarding the heating of each of a plurality of heating conductors connected in parallel to the single power source. By simply adding a circuit, it is possible to eliminate the above-mentioned trouble commonly known as single quenching, thereby ensuring the reliability and quality of the automated quenching line.
本考案にかかる誘導加熱コイルのコイル電流監
視回路の要旨は、高周波電源に並列接続された複
数の加熱導体それぞれに貼着したサーチコイル、
各サーチコイルに誘起する高周波電圧を直流に変
換するHF／DCコンバータ、当該HF／DCコンバ
ータの出力が入力するメータリレーとからなり、
当該メータリレーは入力直流がプリセツトされて
いる所定上下限電圧値を超えた場合に動作となる
ように設定することによつて、複数の加熱導体そ
れぞれの状態を検知し、かつ異常に対処するよう
にした誘導加熱コイルのコイル電流監視回路にあ
る。 The gist of the coil current monitoring circuit for an induction heating coil according to the present invention is that a search coil attached to each of a plurality of heating conductors connected in parallel to a high frequency power source,
It consists of an HF/DC converter that converts the high frequency voltage induced in each search coil into direct current, and a meter relay to which the output of the HF/DC converter is input.
By setting the meter relay to operate when the input DC exceeds preset upper and lower voltage limits, it is possible to detect the status of each of the multiple heating conductors and to deal with abnormalities. It is in the coil current monitoring circuit of the induction heating coil.
本考案を図に示す実施例に従つてさらに詳述す
る。 The present invention will be described in further detail with reference to embodiments shown in the drawings.
図において、１Ａおよび１Ｂはそれぞれ高周波
電源Ｅに並列接続された加熱導体である。当該加
熱導体１Ａ・１Ｂそれぞれは例えば１本のクラン
クシヤフトの複数の被焼入れ部を加熱する割型タ
イプであつて、図視上方の導体部１１Ａおよび１
１Ｂそれぞれは絶縁材Ｓを介して２分された導体
が電源Ｅの異る極と接続されて不動であり、図視
下方の導体部１２Ａおよび１２Ｂそれぞれは単体
からなり矢印ａ−ｂ方向へ可動に構成されてい
る。従つてクランクシヤフトＷの加熱定位置えの
装着および当該位置からの搬出には下方導体部１
２Ａ・１２Ｂそれぞれをｂ方向へ変位とし、加熱
時には下方導体部１２Ａ・１２Ｂそれぞれをａ方
向へ変位させ、下方導体部１２Ａの上方端面接点
１２１Ａと上方導体部１１Ａの下方端面接点１１
１Ａとを、また下方導体部１２Ｂの上方端面接点
１２１Ｂと上方導体部１１Ｂの下方端面接点１１
１Ｂとをそれぞれ接触せしめて電気的回路を閉成
可能である。 In the figure, 1A and 1B are heating conductors connected in parallel to a high frequency power source E, respectively. Each of the heating conductors 1A and 1B is of a split type that heats a plurality of hardened parts of one crankshaft, for example, and the conductor parts 11A and 1 in the upper part of the figure are
Each of the conductors 1B is divided into two parts via an insulating material S and is connected to different poles of the power source E, and is immovable, and each of the conductor parts 12A and 12B shown in the lower part of the figure is a single body and is movable in the direction of the arrow a-b. It is composed of Therefore, the lower conductor part 1 is used to attach the crankshaft W to a heated position and to carry it out from that position.
2A and 12B are each displaced in the b direction, and during heating, the lower conductor parts 12A and 12B are each displaced in the a direction, and the upper end contact 121A of the lower conductor part 12A and the lower end contact 11 of the upper conductor part 11A are
1A, and the upper end contact 121B of the lower conductor portion 12B and the lower end contact 11 of the upper conductor portion 11B.
1B can be brought into contact with each other to close an electrical circuit.
上記の如き高周波電源Ｅに並列接続された複数
の加熱導体１Ａおよび１Ｂそれぞれに本考案に
かゝるコイル電流監視回路が付加される。加熱導
体１Ａのコイル電流監視回路は、絶縁導線を複数
回巻回してコイル状に形成し、例えば上方導体部
１１Ａの表面に貼着したサーチコイル２Ａ、高周
波電圧を直流に変換するHF／DCコンバータ３Ａ
およびメータリーレからなる。加熱導体１Ａが
閉成され高周波電源Ｅが投入されると、加熱導体
１Ａにはコイル磁束が発生し、当該コイル磁束の
一部によつてサーチコイル２Ａにはコイル磁束に
比例した高周波電流が誘起される。 A coil current monitoring circuit according to the present invention is added to each of the plurality of heating conductors 1A and 1B connected in parallel to the high frequency power source E as described above. The coil current monitoring circuit of the heating conductor 1A is formed by winding an insulated conductor wire multiple times to form a coil, and includes, for example, a search coil 2A attached to the surface of the upper conductor portion 11A, and an HF/DC converter that converts high frequency voltage into direct current. 3A
and meter relay. When the heating conductor 1A is closed and the high-frequency power source E is turned on, a coil magnetic flux is generated in the heating conductor 1A, and a high-frequency current proportional to the coil magnetic flux is induced in the search coil 2A by a part of the coil magnetic flux. be done.
誘記した高周波電流は端子間に介挿された抵抗
R1によつて抵抗R1によつて高周波電圧HFとされ
たうえでHF／DCコンバータ３によつて直流に変
換される。当該HF／DCコンバータは例えばブリ
ツヂ接続された４ケのダイオードＤ、当該ダイオ
ードＤと直列接続された交流カツト用チヨークコ
イルCh1・Ch2、当該チヨークコイルCh1・Ch2を
介して上記ダイオードＤにそれぞれ並列接続され
たコンデンサC1・C2および直流電流−直流電圧
変換用抵抗R3、上記コンデンサC2の入力側に介
挿された抵抗R2からなる。当該HF／DCコンバー
タ３Ａによつて高周波電圧から変換された直流は
直列接続された固定抵抗R4および可変抵抗Ｒを
介してメータリレーに入力される。上記メータ
リレーは入力直流電圧が予め設定されている上
下限電圧値を超えると動作となり、例えば高周波
電源ＥをOFFとする信号を出力するように構成
する。 The induced high-frequency current is caused by a resistor inserted between the terminals.
The high frequency voltage HF is converted by the resistor R 1 into a high frequency voltage HF by the resistor R 1 , and then converted into direct current by the HF/DC converter 3 . The HF/DC converter includes, for example, four bridge-connected diodes D, AC cutting coils Ch 1 and Ch 2 connected in series with the diodes D, and the respective diodes D via the respective diodes D. It consists of capacitors C 1 and C 2 connected in parallel, a DC current-DC voltage conversion resistor R 3 , and a resistor R 2 inserted on the input side of the capacitor C 2 . The direct current converted from the high frequency voltage by the HF/DC converter 3A is input to the meter relay via a fixed resistor R4 and a variable resistor R connected in series. The meter relay is configured to operate when the input DC voltage exceeds preset upper and lower voltage limits, and outputs a signal to turn off the high frequency power source E, for example.
加熱導体１Ｂにも上記加熱導体１Ａに付加され
たコイル電流監視回路と全く同一の構成、即ちサ
ーチコイル２Ｂ・抵抗R1・HF／DCコンバータ・
固定抵抗R4・可変抵抗Ｒおよび同一上下限電圧
値に設定されたメータリレーからなるコイル電
流監視回路が付加される。 The heating conductor 1B has exactly the same configuration as the coil current monitoring circuit added to the heating conductor 1A, that is, search coil 2B, resistor R 1 , HF/DC converter,
A coil current monitoring circuit consisting of a fixed resistor R4 , a variable resistor R, and a meter relay set to the same upper and lower voltage limits is added.
上記の構成からなるコイル電流監視回路が付加
された同一形状の加熱導体１Ａ・１Ｂで同一径・
同一巾からなる例えばジヤーナル部２ケ処を加熱
する場合について説明する。 Heating conductors 1A and 1B of the same shape with the coil current monitoring circuit configured as described above have the same diameter and
A case will be described in which, for example, two journal parts having the same width are heated.
加熱導体１Ａおよび１Ｂそれぞれが、図視加熱
導体１Ｂの如く上方導体部１１Ｂと下方導体部１
２Ｂの接触が十分に維持された状態であれば電気
回路が閉成されているので、高周波電源ＥをON
とすることによつて両加熱導体１Ａ・１Ｂからコ
イル磁束が発生し、当該コイル磁束はそれぞれの
加熱導体１Ａ・１Ｂに貼着されたサーチコイル２
Ａ・２Ｂにコイル磁束に比例した高周波電流を誘
起せしめ、当該高周波電流は直流電圧に変換さ
れ、それぞれのメータリレーに入するが、当該
入力直流は上記プリセツトされている上下限電圧
値以内にあるので、両メータリレーそれぞれは
動作しない。 The heating conductors 1A and 1B each have an upper conductor portion 11B and a lower conductor portion 1, as shown in the heating conductor 1B in the drawing.
If the contact between 2B and 2B is maintained sufficiently, the electric circuit is closed, so turn on the high frequency power supply E.
By doing so, coil magnetic flux is generated from both heating conductors 1A and 1B, and the coil magnetic flux is transmitted to the search coil 2 attached to each heating conductor 1A and 1B.
A high frequency current proportional to the coil magnetic flux is induced in A and 2B, and the high frequency current is converted to DC voltage and input to each meter relay, but the input DC is within the preset upper and lower limit voltage values. Therefore, both meter relays do not work.
もし図視加熱導体１Ａの如く、例えば接点部分
の摩耗・接点間にゴミ等の介挿あるいは変位機構
の不調など諸要因から電気回路が閉成されなかつ
た場合、当該加熱導体１Ａからはコイル磁束が発
生しないので、貼着されたサーチコイル２Ａに高
周波電流は誘起されず、従つてメータリレーに
は直流電圧が入力されず、また電気回路の閉成が
不完全であつた場合、当該加熱導体１Ａから発生
するコイル磁束は常態時より少であるので、当該
コイル磁束に比例してサーチコイル２Ａに誘起す
る高周波電流も常態時より少となり、従つてメー
タリレーには上記プリセツト下限電圧値以下の
電圧が入力されるので、いづれの場合もメータリ
レーは高周波電源ＥのON後、直ちに動作して
例えば高周波電源ＥをOFFとするなどの信号を
出力し、所謂片焼き等の事故を防止する。 If the electric circuit cannot be closed due to various reasons such as wear of the contact parts, dirt or the like interposed between the contacts, or malfunction of the displacement mechanism, as in the heating conductor 1A shown in the figure, the coil magnetic flux will be released from the heating conductor 1A. Since no high-frequency current is induced in the attached search coil 2A, no DC voltage is input to the meter relay, and if the electric circuit is incompletely closed, the heating conductor Since the coil magnetic flux generated from 1A is less than the normal state, the high frequency current induced in the search coil 2A in proportion to the coil magnetic flux is also smaller than the normal state, so the meter relay has a voltage below the preset lower limit voltage. Since voltage is input, in either case, the meter relay operates immediately after the high-frequency power supply E is turned on, and outputs a signal to turn off the high-frequency power supply E, for example, to prevent accidents such as so-called one-sided burning.
また加熱進行中に、例えば熱歪等で被処理材Ｗ
が曲つて加熱導体１と接触したような場合等、加
熱導体１に異常大電流が流れたようなときには、
コイル磁束は瞬間的に常態時より大となり、サー
チコイル２には常態時より大なる高周波電流が誘
起され、メータリレーには上記プリセツト上限
電圧値以上の電圧が入力し、当該メータリレー
は直ちに動作となり、高周波電源Ｅ OFF信号
等を出力するので、加熱導体１の焼損や電源構成
部材の破壊等に至らぬ前に対処する。 Also, during heating, the material to be treated W may be damaged due to thermal strain, etc.
When an abnormally large current flows through the heating conductor 1, such as when the
The coil magnetic flux momentarily becomes larger than the normal state, a higher frequency current is induced in the search coil 2 than the normal state, a voltage higher than the preset upper limit voltage value is input to the meter relay, and the meter relay immediately operates. Since the high frequency power supply E OFF signal etc. are outputted, measures can be taken before the heating conductor 1 is burnt out or the power source components are destroyed.
従つて、高周波電源Ｅに並列接続された加熱導
体１Ａ・１Ｂそれぞれはいづれか一方の加熱導体
１に異常があつても、直ちに当該異常が検出され
所定の処置がとられるので、他方の加熱導体１の
加熱のみが進行するような不測の事態が回避され
ることとなる。 Therefore, even if there is an abnormality in one of the heating conductors 1A and 1B connected in parallel to the high-frequency power source E, the abnormality is immediately detected and prescribed measures are taken, so that the other heating conductor 1 This will avoid an unforeseen situation where only the heating progresses.
本考案において用いられるHF／DCコンバータ
３は上記実施例の構成に限られるものではなく、
他の構成としてもよい。 The HF/DC converter 3 used in the present invention is not limited to the configuration of the above embodiment,
Other configurations may also be used.
また上記実施例では高周波電源Ｅに並列接続さ
れる加熱導体が１Ａ・１Ｂの２ケである場合を挙
げて説明したが、加熱導体がさらに多い場合でも
それぞれの加熱導体に本考案にかゝるコイル電流
監視回路を付加すれば、そのなかのいづれの加熱
導体に異常を生じてもこれが検出され対応処置を
施し得ること上記実施例と同様である。 Furthermore, in the above embodiment, the case where the number of heating conductors connected in parallel to the high frequency power source E is two, 1A and 1B, was explained, but even if there are more heating conductors, each heating conductor can be connected according to the present invention. If a coil current monitoring circuit is added, even if an abnormality occurs in any of the heating conductors, this can be detected and appropriate measures can be taken, as in the above embodiment.
本考案を実施することにより、
(1) 従来の監視装置では、複数の被焼入れ部中の
１ケ処が加熱処理されていないにも拘らずこの
異常を発見し得ず、このため正常処理品として
生産ライン上を流れて完成品となり、未焼入れ
部が摩耗や折損の事故を惹起するような虞れが
あつたが、本考案では高周波電源に並列接続さ
れた複数の加熱導体それぞれのコイル磁束を直
接箇々に監視するので、上記の如き異常は直ち
に検出され対処されるため一切発生せず、従つ
て信頼をもつてライン生産がなしうる。 By implementing the present invention, (1) Conventional monitoring equipment could not detect this abnormality even though one of the plurality of parts to be quenched had not been heat treated, and therefore However, in this invention, the coil magnetic flux of each of multiple heating conductors connected in parallel to a high frequency power source was Since the above-mentioned abnormalities are directly monitored, they will not occur at all because they will be immediately detected and dealt with, and therefore line production can be carried out with confidence.
(2) 加熱不足や加熱過剰等のバラツキがなくなり
焼入れ品質の均一性が保証される。(2) Uniformity of quenching quality is ensured by eliminating variations such as under-heating or over-heating.
(3) 焼入れ装置や高周波電源の不調が直ちに検出
されるとともに初期に対処しうる。(3) Malfunctions in the hardening equipment or high-frequency power supply can be detected immediately and can be dealt with at an early stage.
などそのもたらされる効果は顕著である。The effects brought about are remarkable.
図は本考案誘導加熱コイルのコイル電流監視回
路の一実施例回路図である。
１Ａ，１Ｂ……加熱導体、２，２Ａ，２Ｂ……
サーチコイル、３，３Ａ，３Ｂ……HF／DCコン
バータ、Ｅ……高周波電源、……メータリレ
ー。
The figure is a circuit diagram of an embodiment of the coil current monitoring circuit of the induction heating coil of the present invention. 1A, 1B... Heating conductor, 2, 2A, 2B...
Search coil, 3, 3A, 3B...HF/DC converter, E...High frequency power supply,...Meter relay.
Claims (1)
れぞれに貼着したサーチコイル、各サーチコイル
に誘起する高周波電圧を直流に変換するHF／DC
コンバータ、当該HF／DCコンバータの出力が入
力するメータリレーとからなり、当該メータリレ
ーは入力直流がプリセツトされている所定上下限
電圧値を超えた場合に動作となるように設定する
ことによつて、複数の加熱導体それぞれの状態を
検知し、かつ異常に対処するようにした誘導加熱
コイルのコイル電流監視回路。 Search coils attached to each of multiple heating conductors connected in parallel to a high frequency power supply, HF/DC that converts the high frequency voltage induced in each search coil into direct current.
It consists of a converter and a meter relay into which the output of the HF/DC converter is input, and the meter relay is set to operate when the input DC exceeds preset upper and lower voltage limits. , a coil current monitoring circuit for an induction heating coil that detects the status of each of multiple heating conductors and handles abnormalities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16760383U JPS6075996U (en) | 1983-10-31 | 1983-10-31 | Coil current monitoring circuit for induction heating coil |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16760383U JPS6075996U (en) | 1983-10-31 | 1983-10-31 | Coil current monitoring circuit for induction heating coil |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6075996U JPS6075996U (en) | 1985-05-28 |
| JPS625024Y2 true JPS625024Y2 (en) | 1987-02-04 |
Family
ID=30366638
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16760383U Granted JPS6075996U (en) | 1983-10-31 | 1983-10-31 | Coil current monitoring circuit for induction heating coil |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6075996U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9451068B2 (en) | 2001-06-21 | 2016-09-20 | Oakley, Inc. | Eyeglasses with electronic components |
| US9494807B2 (en) | 2006-12-14 | 2016-11-15 | Oakley, Inc. | Wearable high resolution audio visual interface |
-
1983
- 1983-10-31 JP JP16760383U patent/JPS6075996U/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9451068B2 (en) | 2001-06-21 | 2016-09-20 | Oakley, Inc. | Eyeglasses with electronic components |
| US9494807B2 (en) | 2006-12-14 | 2016-11-15 | Oakley, Inc. | Wearable high resolution audio visual interface |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6075996U (en) | 1985-05-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8988035B2 (en) | System for determining a magnetizing curve and rotor resistance of an induction machine and method of making same | |
| EP3928402A1 (en) | Method and apparatus for controlling a power supply to a protected electrical load | |
| US4114010A (en) | Test circuit and method for matching an induction load to a solid state power supply | |
| JPS625024Y2 (en) | ||
| JP2800383B2 (en) | High frequency inverter | |
| US2352779A (en) | Motor testing apparatus | |
| JP2745101B2 (en) | High frequency heating equipment | |
| US3007105A (en) | Electrical control apparatus | |
| JPS6280567A (en) | Deterioration diagnosing method for power converting element | |
| US2352371A (en) | Magnetic testing apparatus and method of magnetizing | |
| JP2878333B2 (en) | Unburned detector for induction heating | |
| US1647295A (en) | Control system | |
| JPH0731222B2 (en) | Disconnection detection device for synchronous machine field winding | |
| JPH0814596B2 (en) | Winding abnormality determination method for electric equipment having windings | |
| JPH0753822Y2 (en) | Monitoring device for primary cable for resistance welding machine | |
| US4228388A (en) | Control circuit responsive to utility voltage level | |
| US701886A (en) | Synchronizing alternators. | |
| JP2597592B2 (en) | Superconducting transformer monitoring device | |
| SU1137415A1 (en) | Method of checking contact connections in circuits of consecutive-excitation ac electric machines | |
| JPS61269079A (en) | Temperature rise test for transformer | |
| JPS6013242Y2 (en) | overcurrent detector | |
| SU1185218A2 (en) | Apparatus for remote-control of pipelines | |
| SU964483A2 (en) | Device for measuring electric machine winding temperature | |
| US1728803A (en) | Temperature-indicating device | |
| USRE17041E (en) | Automatically-controlled vapor-converter substation |