JPH0242367A - Optical fiber type minute-current detector - Google Patents
Optical fiber type minute-current detectorInfo
- Publication number
- JPH0242367A JPH0242367A JP19317188A JP19317188A JPH0242367A JP H0242367 A JPH0242367 A JP H0242367A JP 19317188 A JP19317188 A JP 19317188A JP 19317188 A JP19317188 A JP 19317188A JP H0242367 A JPH0242367 A JP H0242367A
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- circuit
- capacitor
- emitting diode
- optical fiber
- 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.)
- Granted
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 18
- 239000003990 capacitor Substances 0.000 claims abstract description 25
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000001514 detection method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
- 239000012212 insulator Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 230000004397 blinking Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
Landscapes
- Measurement Of Current Or Voltage (AREA)
Abstract
Description
【発明の詳細な説明】
Ａ、産業上の利用分野
本発明は検電碍子などの高電圧微少電流の検知に適した
光ファイバー式微少電流検出器に関する。DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an optical fiber type minute current detector suitable for detecting high voltage minute currents such as in a voltage detecting insulator.
Ｂ８発明の概要
本発明は微少電流回路内に全波整流回路を設けて、その
整流電流でコンデンサを充電し、コンデンサに発生する
電圧ｅのＶ＋、Ｖｚの２点電圧値でヒステリシス特性を
有するマイクロ・パワー電圧検出器回路で電圧−周波数
変換を行うと共に、この電圧−周波数変換回路中に転送
用発光グイオードを設けて、この発光ダイオードの点滅
回数を光ファイバーを介して受信側で数えることにより
、微少電流の平均値を求めるようにしたものである。B8 Summary of the invention The present invention provides a full-wave rectifier circuit in a micro current circuit, charges a capacitor with the rectified current, and has a hysteresis characteristic at two voltage values of V+ and Vz of the voltage e generated in the capacitor.・A power voltage detector circuit performs voltage-frequency conversion, and a light-emitting diode for transfer is provided in this voltage-frequency conversion circuit, and the number of blinks of this light-emitting diode is counted on the receiving side via an optical fiber. This method calculates the average value of the current.
Ｃ１従来の技術
従来、高電圧検知装置は、コンデンサ型又は高抵抗型検
電碍子を用いて第３図のように高電圧ＶＨをコンデンサ
、高抵抗などの高インピーダンスＺ１２．Ｚｎで分圧し
て、インピーダンスＺｎに生ずる電圧Ｖｏを、■電圧計
、■入力段に絶縁アンプを用いたデジタル電圧計、■ボ
ッケル素子を用いた光ファイバー式電圧計などを用いて
測定している。C1 Prior Art Conventionally, a high voltage detection device uses a capacitor-type or high-resistance type voltage detecting insulator to detect a high voltage VH as shown in FIG. The voltage Vo generated at the impedance Zn is measured by using a voltmeter, 2 a digital voltmeter using an insulated amplifier at the input stage, and 2 an optical fiber voltmeter using a Bockel element.
Ｄ０発明が解決しようとする課題
しかし■のアナログ電圧計は定期点検用には便利である
が、自動計測用の常時監視には不適である。D0 Problems to be Solved by the Invention However, although the analog voltmeter (2) is convenient for periodic inspection, it is not suitable for constant monitoring for automatic measurement.
■のデジタル電圧計は絶縁アンプの入・出力間や人力−
電源間の絶縁に限界があり、更に人力信号線から処理回
路へのノイズが進入するのを防ぐには完全ではない。■The digital voltmeter can be used between the input and output of an isolated amplifier or
There is a limit to the insulation between the power supplies, and it is not perfect to prevent noise from entering the processing circuit from the human input signal line.
■の光ファイバー式電圧計は光学系部品を用いており、
価格の点で問題がある。■The optical fiber type voltmeter uses optical parts.
There is a problem with the price.
又、■の場合、ノイズを処理回路本体に進入させない方
法として、第４図のように検知器である送信部７と受信
部８との間を光ファイバー９によりつなぐことが考えら
れるが、この場合、絶縁アンプｌＯの出力電圧を周波数
に変換する電圧−周波数変換回路Ｖ／Ｆには、安定した
電源を供給する必要があるため、送信部７に別電源Ｅｓ
を設ける必要がある。In addition, in the case of (2), as a way to prevent noise from entering the processing circuit main body, it is possible to connect the transmitting section 7 and the receiving section 8, which are the detectors, with an optical fiber 9 as shown in Fig. 4, but in this case. , it is necessary to supply a stable power supply to the voltage-frequency conversion circuit V/F that converts the output voltage of the isolation amplifier 1O into a frequency, so a separate power supply Es is provided to the transmitting section 7.
It is necessary to provide
ところで、前記高電圧検知装置の高電圧は高インピーダ
ンスに流れる微小電流を検知しても知ることができる。Incidentally, the high voltage of the high voltage detection device can also be detected by detecting a minute current flowing through a high impedance.
本発明は高電圧検出装置の微少電流の検出に適しており
、この微少電流の検出に用いた場合、前記高電圧検知装
置の欠点を解決できる光ファイバー式微少電流検出器を
提供することを目的としている。The present invention is suitable for detecting a minute current in a high voltage detection device, and an object of the present invention is to provide an optical fiber type minute current detector that can solve the drawbacks of the high voltage detection device when used for detecting this minute current. There is.
９１課題を解決するための手段
本発明は微少電流回路と直列に全波整流回路を設け、こ
の全波整流回路の出力側にコンデンサを接続し、このコ
ンデンサと並列にその充電電圧を電源とすると共にその
充電電圧が所定の電圧に達したことを検出してそれより
低い所定の電圧までその充電電荷を放電させる２点電圧
値でヒステリシス特性を有するマイクロ・パワー電圧検
出器を用いた電圧−周波数変換回路を設け、この変換回
路の放電回路中に発光ダイオードを接続し、この発光ダ
イオードの点滅回数を光ファイバーを介して受信側で一
定時間計数するようにしたものである。91 Means for Solving the Problems The present invention provides a full-wave rectifier circuit in series with a minute current circuit, connects a capacitor to the output side of this full-wave rectifier circuit, and uses the charging voltage in parallel with the capacitor as a power source. voltage-frequency using a micro-power voltage detector with hysteresis characteristics at two-point voltage values that detects when the charging voltage reaches a predetermined voltage and discharges the charged charge to a lower predetermined voltage. A conversion circuit is provided, a light emitting diode is connected to the discharge circuit of the conversion circuit, and the number of blinks of the light emitting diode is counted on the receiving side for a certain period of time via an optical fiber.
Ｆ９作用
全波整流回路の出力側に接続されたコンデンサの充電速
度は微少電流に比例する。２点電圧値でヒステリシス特
性した比較回路であるマイクロ・パワー検出器を用いた
電圧−周波数変換回路によって前記コンデンサの充電電
圧が所定値に達するとそれより低い所定値までその充電
電荷が放電され、又充電により充電電圧が所定値に達す
ると放電するという動作を繰返す。しかして所定時間内
の放電回数は微少電流に比例するので、放電回路内に設
けた発光ダイオードの所定時間内の発光を光ファイバー
を介して受光し計数することにより微少電流値を知るこ
とができる。The charging speed of the capacitor connected to the output side of the F9 action full-wave rectifier circuit is proportional to the minute current. When the charging voltage of the capacitor reaches a predetermined value, the charged charge is discharged to a lower predetermined value by a voltage-frequency conversion circuit using a micro power detector, which is a comparison circuit with hysteresis characteristics at two-point voltage values, Further, when the charging voltage reaches a predetermined value due to charging, the operation of discharging is repeated. Since the number of discharges within a predetermined time is proportional to the microcurrent, the microcurrent value can be determined by receiving and counting the light emitted from a light emitting diode provided in the discharge circuit within a predetermined time via an optical fiber.
Ｇ、実施例
実施例について図面を参照して説明すると、第１図にお
いて、Ｚは検電碍子の高インピーダンス、１は高インピ
ーダンＺと直列に接続された全波整流回路、Ｃｏは全波
整流回路１の出力側に接続されたコンデンサ、２はコン
デンサＣＯΩ端子電圧を電源とし、この端子電圧を検出
するマイクロ・パワー電圧検出器、３はコンデンサＧｏ
の端子電圧を電源とし、マイクロ・パワー電圧検出器２
の出力で制御されるトランジスタ、Ｒは抵抗、４はトラ
ンジスタ３のコレクタ回路に抵抗Ｒと共に直列に接続さ
れた発光ダイオード、５は光ファイバー、６は内部にカ
ウンタを有する受光回路である。G. Embodiment The embodiment will be explained with reference to the drawings. In FIG. 1, Z is the high impedance of the voltage detecting insulator, 1 is the full-wave rectifier circuit connected in series with the high-impedance Z, and Co is the full-wave rectifier. A capacitor connected to the output side of circuit 1, 2 a micro power voltage detector which uses the capacitor COΩ terminal voltage as a power source and detects this terminal voltage, 3 a capacitor Go
Micro power voltage detector 2
R is a resistor, 4 is a light emitting diode connected in series with the resistor R to the collector circuit of transistor 3, 5 is an optical fiber, and 6 is a light receiving circuit having a counter inside.
次に第１図の動作を説明するに、高電圧ＶＨにより高イ
ンピーダンスＺに流れる微少電流１ｏが全波整流回路１
で整流され、コンデンサＣＯを充電する。Next, to explain the operation of FIG.
is rectified by and charges the capacitor CO.
一方、マイクロ・パワー電圧検出器２は第２図に示すよ
うにヒステリシス特性をもった電圧比較回路である。し
かしてコンデンサＣｏの充電電圧ｅがＶｌに達すると、
マイクロ・パワー電圧検出器２に出力が出てトランジス
タ３をＯＮさせて発光ダイオード４をＢのＯＦＦ状態か
らＣのＯＮ状態にする。このためコンデンサｃｏは発光
ダイオードを通じて放電し、コンデンサＣｏの電圧ｅが
Ｖ、よりＶｔに下がると、検出器２の出力は停止してト
ランジスタ３をＯＦＦとするので、発光ダイオード４は
ＤのＯＮ状態からＥのＯＦＦ状態となる。On the other hand, the micro power voltage detector 2 is a voltage comparison circuit having hysteresis characteristics as shown in FIG. However, when the charging voltage e of the capacitor Co reaches Vl,
An output is output to the micro power voltage detector 2, turning on the transistor 3, and changing the light emitting diode 4 from the OFF state of B to the ON state of C. Therefore, the capacitor co is discharged through the light emitting diode, and when the voltage e of the capacitor Co drops from V to Vt, the output of the detector 2 is stopped and the transistor 3 is turned off, so the light emitting diode 4 is in the ON state of D. From then on, E becomes OFF state.
コンデンサｃｏは充電され続けているので、充電電圧ｅ
はＶ、より再びＶｌに上がるので、前記同様にして発光
ダイオード４はＯＮ、ＯＦＦを繰り返して点滅する。Since the capacitor co continues to be charged, the charging voltage e
Since the voltage rises from V to Vl again, the light emitting diode 4 repeatedly turns ON and OFF and blinks in the same manner as described above.
コンデンサＧｏの充電の速さは微少電流Ｉｏの大きさ、
即ち、高電圧ＶＨに比例するので、コンデンサＧｏの電
圧ｅがＶ、よりｖＩになる充電時間は高電圧ｖＨの電圧
に比例して早くなる。このため一定時間の発光ダイオー
ド４の点滅回数は高電圧Ｖ Ｈ（平均値）に比例する。The charging speed of the capacitor Go is determined by the magnitude of the minute current Io,
That is, since it is proportional to the high voltage VH, the charging time for the voltage e of the capacitor Go to become VI becomes faster in proportion to the voltage of the high voltage VH. Therefore, the number of blinks of the light emitting diode 4 during a certain period of time is proportional to the high voltage VH (average value).
しかして、発光ダイオード４の点滅を光ファイバー５を
介して送り、これを先受回路６で受光して電圧に変換し
、点滅に応じた電気パルスを受光回路６内のカウンタで
一定時間カウントすることにより、微少電流１ｏ又は高
電圧Ｖ）ｌの平均値を知ることができる。Thus, the blinking of the light emitting diode 4 is sent via the optical fiber 5, this is received by the pre-receiving circuit 6 and converted into voltage, and the electric pulse corresponding to the blinking is counted for a certain period of time by a counter in the light receiving circuit 6. Accordingly, the average value of the minute current 1o or the high voltage V)l can be known.
Ｈ１発明の効果
本発明は、以上説明したように構成されているので、以
下に記載されるような効果を奏する。H1 Effects of the Invention Since the present invention is configured as described above, it produces the effects described below.
（１）コンデンサの充・放電のくり返し動作により放電
で消費するエネルギを用いて転送用の発光ダイオードを
発光させているので、検知する電流が極めて微少な電流
でも確実に動作する。(1) Since the energy consumed by discharging the capacitor through repeated charging and discharging operations is used to cause the light emitting diode for transfer to emit light, it operates reliably even when the detected current is extremely small.
（２）検知する電流回路内に整流回路を設けてコンデン
サを充電しているので、検知する電流は交流、直流どち
らでもコンデンサに充電される電荷量に比例した発振周
波数が得られる。(2) Since a rectifier circuit is provided in the current circuit to be detected to charge the capacitor, an oscillation frequency proportional to the amount of charge charged in the capacitor can be obtained whether the current to be detected is AC or DC.
（３）電源電圧変化に対しヒステリシス特性をもった電
圧比較回路であるマイクロ・パワー電圧検出器を使用し
て、コンデンサの充電電圧を電源とし、コンデンサの充
・放電を制御しているので、従来必要であった検出器側
の一定した電圧の電源が不要となる。(3) A micro-power voltage detector, which is a voltage comparison circuit with hysteresis characteristics in response to changes in power supply voltage, is used to control the charging and discharging of the capacitor using the capacitor's charging voltage as the power source. This eliminates the need for a constant voltage power source on the detector side.
（４）部品点数が少なく、低価格、高信頼性のものがで
きる。(4) A product with a small number of parts, low cost, and high reliability can be produced.
（５）周波数に変換した信号が光ファイバーによりノイ
ズ・フリーで長距離で送ることが可能であるから、監視
システムのＣＰＵへ信号を取り込み易くなる。(5) Since the signal converted into a frequency can be sent noise-free over a long distance using an optical fiber, it becomes easier to take the signal into the CPU of the monitoring system.
（６）真空バルブの真空度低下時の放電電荷の測定にも
利用が可能である。(6) It can also be used to measure the discharge charge when the degree of vacuum in a vacuum valve decreases.
（７）光フアイバ一方式なので、相間電圧の測定のよう
に検知側を大地間に対して浮かせた測定も可能である。(7) Since it is an optical fiber type, it is also possible to perform measurements with the detection side floating relative to the ground, such as in the measurement of phase-to-phase voltage.
第１図は本願発明の一実施例を示す回路図、第２図はマ
イクロ・パワー電圧検出器の動作説明図、第３図は従来
検電碍子の説明図、第４図は従来光ファイバー転送型デ
ジタル電圧計の回路図である。
ｌ・・・余波整流回路、２・・・マイクロ・パワー電圧
検出器、４・・・発光ダイオード、５，９・・・光ファ
イバー、６・・・受光回路、７・・・送信部、８・・・
受信部、ＩＯ・・・絶縁アンプ。Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of a micro-power voltage detector, Fig. 3 is an explanatory diagram of a conventional voltage detection insulator, and Fig. 4 is a conventional optical fiber transfer type It is a circuit diagram of a digital voltmeter. 1... Aftermath rectifier circuit, 2... Micro power voltage detector, 4... Light emitting diode, 5, 9... Optical fiber, 6... Light receiving circuit, 7... Transmitting unit, 8...・・・
Receiving section, IO...isolated amplifier.
Claims (1)
全波整流回路の出力側にコンデンサを接続し、このコン
デンサと並列にその充電電圧を電源とすると共にその充
電電圧が所定の電圧に達したことを検出してそれより低
い所定の電圧までその充電電荷を放電させる２点電圧値
でヒステリシス特性を有するマイクロ・パワー電圧検出
器を用いた電圧−周波数変換回路を設け、この変換回路
の放電回路中に発光ダイオードを接続し、この発光ダイ
オードの点滅回数を光ファイバーを介して受信側で一定
時間計数するようにした光ファイバー式微少電流検出器
。(1) A full-wave rectifier circuit is provided in series with the minute current circuit, a capacitor is connected to the output side of this full-wave rectifier circuit, and the charging voltage is used as a power source in parallel with this capacitor, and the charging voltage is a predetermined voltage. A voltage-to-frequency conversion circuit is provided using a micro-power voltage detector having hysteresis characteristics at a two-point voltage value that detects when the voltage has reached the specified voltage and discharges the charged charge to a lower predetermined voltage. A fiber-optic microcurrent detector that connects a light-emitting diode to the discharge circuit, and counts the number of times the light-emitting diode blinks over a certain period of time on the receiving side via an optical fiber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63193171A JP2701343B2 (en) | 1988-08-02 | 1988-08-02 | Optical fiber micro-current detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63193171A JP2701343B2 (en) | 1988-08-02 | 1988-08-02 | Optical fiber micro-current detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0242367A true JPH0242367A (en) | 1990-02-13 |
| JP2701343B2 JP2701343B2 (en) | 1998-01-21 |
Family
ID=16303478
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63193171A Expired - Lifetime JP2701343B2 (en) | 1988-08-02 | 1988-08-02 | Optical fiber micro-current detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2701343B2 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0897210A2 (en) * | 1997-08-12 | 1999-02-17 | General Electric Company | Control circuit for distributed electrical equipment |
| WO1999041618A1 (en) * | 1998-02-12 | 1999-08-19 | Furukawa Electric Co., Ltd. | Instrument for measuring alternating current |
| FR2839763A1 (en) * | 2002-05-16 | 2003-11-21 | Freudenberg Carl Kg | Rubber engine mounting includes hydraulic mounting including two interconnected liquid chambers providing axial damping, and rubber bushing providing radial damping |
| FR2840042A1 (en) * | 2002-05-24 | 2003-11-28 | Freudenberg Carl Kg | Hydraulic damper rubber support comprises interior and exterior fixing parts enclosing elastomer body forming two liquid chambers communicating through liquid channel |
| US6831130B2 (en) | 2000-05-24 | 2004-12-14 | Kaneka Corporation | Composition of crosslinkable polyether, crosslinkable vinyl polymer and compatibilizer |
| EP2354799A1 (en) * | 2010-02-08 | 2011-08-10 | Schneider Electric Industries SAS | Device and method for metering electric energy |
| CN106597063A (en) * | 2017-01-25 | 2017-04-26 | 杭州士兰微电子股份有限公司 | Current detecting circuit and current detecting method |
| US11018332B2 (en) | 2017-05-18 | 2021-05-25 | Panasonic Intellectual Property Management Co., Ltd. | Lithium secondary battery including lithium metal as negative electrode active material |
| US11031584B2 (en) | 2017-05-18 | 2021-06-08 | Panasonic Intellectual Property Management Co., Ltd. | Lithium secondary battery including lithium metal as negative electrode active material |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5663264A (en) * | 1979-10-29 | 1981-05-29 | Furukawa Electric Co Ltd:The | Current detecting method |
-
1988
- 1988-08-02 JP JP63193171A patent/JP2701343B2/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5663264A (en) * | 1979-10-29 | 1981-05-29 | Furukawa Electric Co Ltd:The | Current detecting method |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0897210A2 (en) * | 1997-08-12 | 1999-02-17 | General Electric Company | Control circuit for distributed electrical equipment |
| EP0897210A3 (en) * | 1997-08-12 | 2000-10-11 | General Electric Company | Control circuit for distributed electrical equipment |
| WO1999041618A1 (en) * | 1998-02-12 | 1999-08-19 | Furukawa Electric Co., Ltd. | Instrument for measuring alternating current |
| GB2339295A (en) * | 1998-02-12 | 2000-01-19 | Furukawa Electric Co Ltd | Instrument for measuring alternating current |
| US6831130B2 (en) | 2000-05-24 | 2004-12-14 | Kaneka Corporation | Composition of crosslinkable polyether, crosslinkable vinyl polymer and compatibilizer |
| FR2839763A1 (en) * | 2002-05-16 | 2003-11-21 | Freudenberg Carl Kg | Rubber engine mounting includes hydraulic mounting including two interconnected liquid chambers providing axial damping, and rubber bushing providing radial damping |
| FR2840042A1 (en) * | 2002-05-24 | 2003-11-28 | Freudenberg Carl Kg | Hydraulic damper rubber support comprises interior and exterior fixing parts enclosing elastomer body forming two liquid chambers communicating through liquid channel |
| EP2354799A1 (en) * | 2010-02-08 | 2011-08-10 | Schneider Electric Industries SAS | Device and method for metering electric energy |
| FR2956212A1 (en) * | 2010-02-08 | 2011-08-12 | Schneider Electric Ind Sas | DEVICE AND METHOD FOR ELECTRIC POWER COUNTING |
| RU2554607C2 (en) * | 2010-02-08 | 2015-06-27 | Шнейдер Электрик Эндюстри Сас | Device and method to measure electric capacity |
| CN106597063A (en) * | 2017-01-25 | 2017-04-26 | 杭州士兰微电子股份有限公司 | Current detecting circuit and current detecting method |
| US11018332B2 (en) | 2017-05-18 | 2021-05-25 | Panasonic Intellectual Property Management Co., Ltd. | Lithium secondary battery including lithium metal as negative electrode active material |
| US11031584B2 (en) | 2017-05-18 | 2021-06-08 | Panasonic Intellectual Property Management Co., Ltd. | Lithium secondary battery including lithium metal as negative electrode active material |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2701343B2 (en) | 1998-01-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5363047A (en) | Portable ground fault detector | |
| US5726901A (en) | System for reporting computer energy consumption | |
| KR100232437B1 (en) | Current measuring apparatus for solid state motor controller | |
| JPH0242367A (en) | Optical fiber type minute-current detector | |
| JPH0311591B2 (en) | ||
| US3816812A (en) | Portable apparatus for measuring load resistance | |
| GB2339295A (en) | Instrument for measuring alternating current | |
| US4277683A (en) | X-ray diagnostic generator with a measuring arrangement for the x-ray tube current | |
| US5153502A (en) | Low noise charge ramp electrometer | |
| US5164660A (en) | True, power, RMS current, and RMS voltage measuring devices | |
| JP3155311B2 (en) | Micro ammeter and micro current measurement method | |
| JP3116411B2 (en) | Optical fiber micro-current detector | |
| GB2177805A (en) | Supply meter | |
| JPH0568663B2 (en) | ||
| US6218808B1 (en) | Micro-peak detection quick charger | |
| US4956600A (en) | High frequency current detector for a low frequency line | |
| US2800191A (en) | Sparking rate meter | |
| JPS5682455A (en) | High voltage direct current measuring apparatus | |
| JP3340509B2 (en) | Humidity element driving device and humidity measuring device | |
| SU983579A1 (en) | Device for checking cable article insulation resistance | |
| JPH0524182Y2 (en) | ||
| SU1597780A1 (en) | Converter of difference of impedances of two-terminal networks to voltage | |
| JPS62175678A (en) | Charging state detector for battery | |
| JPS5663215A (en) | Electrostatic capacity type fuel meter | |
| JPH0697250B2 (en) | Partial discharge charge measurement device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20071003 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20081003 Year of fee payment: 11 |
|
| EXPY | Cancellation because of completion of term |