JP2861696B2 - Instrument transformer - Google Patents
Instrument transformerInfo
- Publication number
- JP2861696B2 JP2861696B2 JP5001220A JP122093A JP2861696B2 JP 2861696 B2 JP2861696 B2 JP 2861696B2 JP 5001220 A JP5001220 A JP 5001220A JP 122093 A JP122093 A JP 122093A JP 2861696 B2 JP2861696 B2 JP 2861696B2
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- Prior art keywords
- current
- transformer
- secondary winding
- value
- impedance
- Prior art date
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- Transformers For Measuring Instruments (AREA)
- Thermistors And Varistors (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、電力回路に用いる計器
用変圧器に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an instrument transformer used in a power circuit.
【０００２】[0002]
【従来の技術】計器用変圧器（いわゆるＶＴ）は、図５
に示したように、１次コイル１と２次コイル２とを鉄心
に巻装したものからなっていて、１次コイル１に被測定
電圧が印加され、２次コイル２にはヒューズ３を通して
２次負担４が接続される。２次負担４は通常電圧計（メ
ータ）や種々の継電器（リレー）等からなっている。2. Description of the Related Art An instrument transformer (so-called VT) is shown in FIG.
As shown in (1), a primary coil 1 and a secondary coil 2 are wound around an iron core, a voltage to be measured is applied to the primary coil 1, and a secondary coil 2 is connected to the secondary coil 2 through a fuse 3. Next burden 4 is connected. The secondary burden 4 usually comprises a voltmeter (meter), various relays, and the like.
【０００３】計器用変圧器は、２次側で短絡事故が生じ
ると、その２次回路に定格電流の数10倍ないし数100 倍
の過電流が流れ、２次コイル２が焼損する。これを防ぐ
ため、２次コイル２と２次負担４との間にヒューズ３が
挿入されている。When a short circuit accident occurs on the secondary side of an instrument transformer, an overcurrent of several tens to several hundred times the rated current flows through the secondary circuit, and the secondary coil 2 is burned out. To prevent this, a fuse 3 is inserted between the secondary coil 2 and the secondary burden 4.
【０００４】[0004]
【発明が解決しようとする課題】図５に示したように、
２次コイルの焼損を防止するためにヒューズ３を用いた
場合には、該ヒューズが溶断した後、計器用変圧器を復
帰させる際にヒューズを交換する必要があるため面倒で
あった。As shown in FIG. 5,
When the fuse 3 is used to prevent the secondary coil from burning, the fuse must be replaced when the instrument transformer is restored after the fuse is blown, which is troublesome.
【０００５】またヒューズは経年劣化により自然断線す
ることがあるため、その保守点検が面倒であった。特に
最近増加する傾向にある無人変電所では、上記ヒューズ
が保守上の問題になっていた。[0005] Further, since the fuse may be naturally disconnected due to aging, maintenance and inspection thereof are troublesome. Particularly in unmanned substations, which tend to increase in recent years, the fuse has become a maintenance problem.
【０００６】本発明の目的は、２次側で生じた短絡事故
が解消したときに、２次回路を自然に正常な状態に復帰
させることができるようにした計器用変圧器を提供する
ことにある。An object of the present invention is to provide an instrument transformer capable of returning a secondary circuit to a normal state spontaneously when a short circuit accident occurring on the secondary side is eliminated. is there.
【０００７】[0007]
【課題を解決するための手段】本発明は１次巻線と２次
負担が接続された２次巻線とを有する計器用変圧器に係
わるもので、請求項１に記載した発明においては、２次
巻線の通電電流が定格値以下のときに微小な抵抗値を示
し、２次巻線の通電電流が定格値より大きく設定された
設定値を超えたときには温度上昇により抵抗値が急上昇
する特性を有する過電流抑制インピーダンスを２次巻線
と２次負担とに対して直列に接続した。また請求項２に
記載した発明においては、変流器の１次コイルを２次巻
線と２次負担とに対して直列に接続し、２次巻線の通電
電流が定格値以下の場合に変流器の２次側に誘導する電
流が通電されたときには微小な抵抗値を示し、２次巻線
の通電電流が定格値より大きく設定された設定値を超え
た場合に変流器の２次側に誘導する電流が通電されたと
きには温度上昇により抵抗値が急上昇する特性を有する
過電流抑制インピーダンスを変流器の２次コイルの両端
に接続した。Means for Solving the Problems The present invention is the primary winding and the secondary
The present invention relates to a transformer for an instrument having a secondary winding to which a load is connected, and in the invention described in claim 1, when a current flowing through the secondary winding is equal to or less than a rated value, a small resistance value is set. When the current flowing through the secondary winding exceeds a set value larger than the rated value, an overcurrent suppression impedance having a characteristic that the resistance value rises sharply due to a temperature rise is applied to the secondary winding and the secondary load. Connected in series. Further, in the invention described in claim 2, the primary coil of the current transformer is connected in series to the secondary winding and the secondary load, and the current flowing through the secondary winding is equal to or less than the rated value. When a current induced on the secondary side of the current transformer is applied, the resistance value is very small. When the current supplied to the secondary winding exceeds a set value larger than the rated value, the resistance of the current transformer is reduced. An overcurrent suppression impedance having a characteristic that a resistance value sharply rises due to a temperature rise when a current induced on the next side is supplied is connected to both ends of the secondary coil of the current transformer.
【０００８】上記過電流抑制インピーダンスは、感温抵
抗素子と固定抵抗素子とを並列に接続して構成した並列
抵抗体を複数個直列に接続したものにより構成するのが
好ましい。It is preferable that the overcurrent suppressing impedance is formed by connecting a plurality of parallel resistors connected in series with a temperature-sensitive resistor and a fixed resistor.
【０００９】尚本発明において、「微小な抵抗値」と
は、定常時に２次負担に印加される電圧に悪影響を及ぼ
さない程度に小さい抵抗値であることを意味する。In the present invention, "small resistance value" means a resistance value that is small enough not to adversely affect the voltage applied to the secondary load in a steady state.
【００１０】また本発明において、抵抗値が「急上昇す
る」とは、２次巻線に過電流が流れ始めてから該２次巻
線の温度が許容限界に達するまでの短い時間内に、過電
流抑制インピーダンスの抵抗値が２次巻線の通電電流を
許容限界値以下に制限し得る値まで上昇することを意味
する。[0010] In the present invention, the "rapid rise" of the resistance value means that the overcurrent occurs within a short time after the overcurrent starts flowing in the secondary winding until the temperature of the secondary winding reaches an allowable limit. This means that the resistance value of the suppression impedance rises to a value that can limit the energizing current of the secondary winding to an allowable limit value or less.
【００１１】[0011]
【作用】請求項１に記載した発明のように、計器用変圧
器の２次電流が定格値以下のときに微小な抵抗値を示
し、２次電流が定格値より大きく設定された設定値を超
えたときには温度上昇により抵抗値が大幅に増大する特
性を有する過電流抑制インピーダンスを２次巻線と２次
負担とに対して直列に接続すると、２次短絡事故が発生
して過電流が流れようとしたときに過電流抑制インピー
ダンスの抵抗値が増大して電流を抑制するため、２次巻
線に過電流が流れるのを防ぐことができ、２次巻線の焼
損を防止することができる。As described in the first aspect of the present invention, when the secondary current of the instrument transformer is equal to or less than the rated value, it exhibits a small resistance value, and the secondary current is set to a value larger than the rated value. When it exceeds, the overcurrent suppression impedance having the characteristic that the resistance value greatly increases due to the temperature rise is connected to the secondary winding and the secondary
If it is connected in series with the burden, the resistance value of the overcurrent suppression impedance increases when an overcurrent is about to flow due to a secondary short circuit accident. Current can be prevented from flowing, and burning of the secondary winding can be prevented.
【００１２】請求項２に記載した発明のように、計器用
変圧器の２次巻線と２次負担とに対して直列に変流器の
１次コイルを接続して該変流器の２次側に過電流抑制イ
ンピーダンスを接続すると、過電流抑制インピーダンス
と計器用変圧器の２次巻線とを変流器により絶縁するこ
とができるため、信頼性を向上させることができる。ま
た変流器の変流比を変えることにより、過電流抑制イン
ピーダンスに流れる電流を適値に調整できるため、過電
流抑制インピーダンスの標準化を図ることができる。According to a second aspect of the present invention, the primary coil of the current transformer is connected in series with the secondary winding and the secondary load of the transformer for the instrument. When the overcurrent suppression impedance is connected to the secondary side, the overcurrent suppression impedance and the secondary winding of the instrument transformer can be insulated by the current transformer, so that the reliability can be improved. Further, by changing the current transformer ratio of the current transformer, the current flowing through the overcurrent suppression impedance can be adjusted to an appropriate value, so that the overcurrent suppression impedance can be standardized.
【００１３】更に変流器の変流比をｎとすると、２次巻
線に短絡電流Ｉo が流れたときに変流器の２次側に流れ
る電流は、Ｉo ／ｎとなるため、過電流抑制インピーダ
ンスでの発熱を少なくして、該インピーダンスの小形化
を図ることができる。Further, assuming that the current transformer has a current transformer ratio of n, the current flowing on the secondary side of the current transformer when the short-circuit current Io flows in the secondary winding is Io / n, so that the overcurrent Heat generation at the suppressed impedance can be reduced, and the impedance can be reduced in size.
【００１４】また請求項３に記載した発明のように過電
流抑制インピーダンスを構成すると、比較的耐電圧性能
が低い感温抵抗素子を用いて、所定の耐電圧性能を有す
る過電流抑制インピーダンスを構成することができる。Further, when the overcurrent suppressing impedance is configured as in the third aspect of the present invention, the overcurrent suppressing impedance having a predetermined withstand voltage performance is configured using a temperature-sensitive resistance element having relatively low withstand voltage performance. can do.
【００１５】[0015]
【実施例】図１は請求項１に記載した発明の実施例を示
したもので、同図において１及び２はそれぞれ計器用変
圧器ＶＴの１次巻線及び２次巻線、４は２次負担であ
る。本発明においては、２次巻線２に対して直列に過電
流抑制インピーダンス５が接続されている。過電流抑制
インピーダンス５は、２次巻線２の通電電流が定格値以
下のときには微小な抵抗値を示し、２次巻線２の通電電
流が定格値よりも大きく設定された設定値を超えたとき
には温度上昇により抵抗値が大幅に増大する特性を有す
るインピーダンスで、所定値以上の電流が流れたときに
抵抗値が急上昇する特性を有する感温抵抗素子を用いて
構成することができる。このような特性を有する感温抵
抗素子としては、例えばポリスイッチの商品名で知られ
ているものを用いることができる。ポリスイッチは、温
度が上昇すると抵抗値が増加するＰＴＣ特性を有するポ
リマー系のＰＴＣサーミスタで、導電性のカーボンと、
ポリオレフィン、フッ素樹脂等のポリマーとの特殊な配
合からなる、正の温度係数を有する抵抗素子である。こ
のポリスイッチにおいては、通電による発熱により温度
がポリマーの融点に達したときに該ポリマーが融解し、
その大きな体積変化によりカーボンの導電性パスが切断
されるため、抵抗値が飛躍的に増加する。ポリスイッチ
の抵抗値対温度特性の一例を図４に示した。この例で
は、温度が低い領域で１０-2のオーダーの微小な抵抗値
を示し、温度が８０℃を超えたあたりから、抵抗値が急
上昇する。抵抗値が急上昇するのに要する時間は数10ミ
リ秒程度まで短くすることができるため、ヒューズの代
りに十分使用することができる。またこのポリスイッチ
は、温度上昇によりその抵抗値が急上昇した後、その温
度を下げると自然に抵抗値が小さい状態に復帰する特性
を有している。FIG. 1 shows an embodiment of the invention described in claim 1. In FIG. 1, reference numerals 1 and 2 denote primary and secondary windings of an instrument transformer VT, respectively, and Next burden. In the present invention, an overcurrent suppression impedance 5 is connected in series to the secondary winding 2. The overcurrent suppression impedance 5 shows a small resistance value when the current flowing through the secondary winding 2 is equal to or less than the rated value, and the current flowing through the secondary winding 2 exceeds a set value which is set to be larger than the rated value. Sometimes, it is possible to use a temperature-sensitive resistance element having an characteristic having a characteristic that the resistance value greatly increases due to a temperature rise, and having a characteristic that the resistance value rapidly rises when a current of a predetermined value or more flows. As the temperature-sensitive resistance element having such characteristics, for example, an element known under the trade name of a polyswitch can be used. The polyswitch is a polymer-based PTC thermistor having PTC characteristics in which the resistance value increases as the temperature rises.
This is a resistance element having a positive temperature coefficient, which is made of a special combination with a polymer such as polyolefin or fluororesin. In this polyswitch, the polymer melts when the temperature reaches the melting point of the polymer due to heat generated by energization,
Since the conductive path of carbon is cut by the large volume change, the resistance value is dramatically increased. FIG. 4 shows an example of the resistance value versus temperature characteristic of the polyswitch. In this example, a small resistance value of the order of 10 -2 is shown in a low temperature region, and the resistance value rises rapidly when the temperature exceeds 80 ° C. Since the time required for the resistance value to rise rapidly can be reduced to about several tens of milliseconds, it can be sufficiently used in place of a fuse. Further, this polyswitch has a characteristic that after a resistance value rises sharply due to a rise in temperature, when the temperature is lowered, the resistance value naturally returns to a small state.
【００１６】感温抵抗素子の耐電圧性能及び電流容量が
不足するために、感温抵抗素子を単独で計器用変圧器Ｖ
Ｔの２次巻線に直列に接続することが困難な場合には、
複数の感温抵抗素子を並列に接続するこおとにより電流
容量を増大させ、複数の感温抵抗素子を直列に接続する
ことにより所定の耐電圧性能を得るようにすればよい。
複数の感温抵抗素子を直列に接続する場合、各感温抵抗
素子の抵抗値が上昇した状態で各感温抵抗素子が負担す
る電圧を均一にして、特定の感温抵抗素子に過電圧が印
加されるのを防止するため、各感温抵抗素子に並列に固
定抵抗素子を接続するのが好ましい。Since the withstand voltage performance and the current capacity of the temperature-sensitive resistance element are insufficient, the temperature-sensitive resistance element is used alone for the measuring transformer V.
If it is difficult to connect in series to the secondary winding of T,
The current capacity may be increased by connecting a plurality of temperature-sensitive resistance elements in parallel, and a predetermined withstand voltage performance may be obtained by connecting the plurality of temperature-sensitive resistance elements in series.
When multiple temperature-sensitive resistance elements are connected in series, the voltage borne by each temperature-sensitive resistance element when the resistance value of each temperature-sensitive resistance element is increased is equalized, and an overvoltage is applied to a specific temperature-sensitive resistance element. It is preferable to connect a fixed resistance element in parallel with each of the temperature-sensitive resistance elements in order to prevent the occurrence of such a phenomenon.
【００１７】図３（Ａ）は図１の実施例で用いるのに好
適な過電流抑制インピーダンス５の構成例を示したもの
で、この過電流抑制インピーダンスは、ポリスイッチ等
からなる感温抵抗素子５０１，５０１´と固定抵抗素子
５０２とを並列に接続して構成した並列抵抗体５ａ〜５
ｃを直列に接続したものからなっており、固定抵抗素子
５０２により、各感温抵抗素子の分担電圧の均一化が図
られている。FIG. 3A shows an example of a configuration of an overcurrent suppressing impedance 5 suitable for use in the embodiment of FIG. 1. The overcurrent suppressing impedance is a temperature-sensitive resistance element such as a polyswitch. Parallel resistors 5a to 5 'each formed by connecting 501, 501' and fixed resistance element 502 in parallel.
c are connected in series, and the fixed resistance element 502 makes the shared voltage of each temperature-sensitive resistance element uniform.
【００１８】過電流抑制インピーダンスの抵抗値は、定
格電流通電時には感温抵抗素子の定抵抗値で決まり、２
次短絡時には固定抵抗素子の抵抗値で決まる。固定抵抗
素子の抵抗値は、２次短絡時に２次巻線２に流れる短絡
電流を許容限界値以下に抑制するように設定する。例え
ば、計器用変圧器の２次定格電圧をＶ2 、２次短絡電流
の許容限界値をＩosとし、図３（Ａ）に示すように過電
流抑制インピーダンスを構成する場合、固定抵抗素子５
０２の抵抗値Ｒは、Ｖ2 ／３Ｒ≦Ｉosを満足するように
設定する。The resistance value of the overcurrent suppression impedance is determined by the constant resistance value of the temperature-sensitive resistance element when the rated current is applied.
At the time of the next short circuit, it is determined by the resistance value of the fixed resistance element. The resistance value of the fixed resistance element is set so that the short-circuit current flowing through the secondary winding 2 at the time of the secondary short-circuit is suppressed to an allowable limit value or less. For example, when the secondary rated voltage of the instrument transformer is V 2 , the allowable limit value of the secondary short-circuit current is Ios, and the overcurrent suppression impedance is configured as shown in FIG.
The resistance value R of 02 is set so as to satisfy V 2 / 3R ≦ Ios.
【００１９】尚各並列抵抗体を構成する感温抵抗素子の
数及び直列に接続する並列抵抗体の数は、感温抵抗素子
の耐電圧性能及び電流容量、計器用変圧器の２次定格電
圧、２次短絡電流の許容限界値等により適宜に設定す
る。The number of temperature-sensitive resistance elements constituting each parallel resistance element and the number of parallel resistance elements connected in series are determined by the withstand voltage performance and current capacity of the temperature-sensitive resistance element, the secondary rated voltage of the instrument transformer. It is set appropriately according to the allowable limit value of the secondary short-circuit current and the like.
【００２０】例えば、感温抵抗素子の電流容量が十分な
場合には、図３（Ｂ）に示すように、１つの感温抵抗素
子５０１と固定抵抗素子５０２とを並列に接続して構成
した並列抵抗体５ａ〜５ｃを直列に接続するようにして
もよい。For example, when the current capacity of the temperature-sensitive resistance element is sufficient, as shown in FIG. 3B, one temperature-sensitive resistance element 501 and a fixed resistance element 502 are connected in parallel. The parallel resistors 5a to 5c may be connected in series.
【００２１】上記実施例の計器用変圧器において、２次
巻線２に流れる電流が定格値以下である場合には、過電
流抑制インピーダンス５の抵抗値が微小であるため、該
インピーダンスが２次負担の印加電圧に影響を与えるこ
とはない。定格電流通電時における過電流抑制インピー
ダンス５の抵抗値は0.1 ［Ω］以下程度であれば問題が
ない。In the instrument transformer of the above embodiment, when the current flowing through the secondary winding 2 is equal to or less than the rated value, the resistance value of the overcurrent suppressing impedance 5 is very small. It does not affect the applied voltage of the burden. There is no problem if the resistance value of the overcurrent suppression impedance 5 when the rated current is applied is about 0.1 [Ω] or less.
【００２２】過電流抑制インピーダンス５と２次負担４
との間の回路で短絡事故が生じると２次巻線２に定格電
流の数10倍ないし数100 倍の短絡電流が流れるが、この
とき過電流抑制インピーダンス５を構成する感温抵抗素
子が発熱してその抵抗値が急上昇するため、２次巻線２
に流れる電流が抑制される。感温抵抗素子の抵抗値が上
昇した状態では、固定抵抗素子５０２に電流が流れるた
め、各感温抵抗素子の分担電圧が均一になり、特定の感
温抵抗素子に過電圧が印加されるのが防止される。Overcurrent suppression impedance 5 and secondary burden 4
If a short-circuit fault occurs in the circuit between the two, a short-circuit current of several tens to several hundreds times the rated current flows through the secondary winding 2, and at this time, the temperature-sensitive resistance element constituting the overcurrent suppression impedance 5 generates heat. And the resistance value rises sharply,
The current flowing through is suppressed. In the state where the resistance value of the temperature-sensitive resistance element is increased, a current flows through the fixed resistance element 502, so that the shared voltage of each temperature-sensitive resistance element becomes uniform, and an overvoltage is applied to a specific temperature-sensitive resistance element. Is prevented.
【００２３】通常の計器用変圧器ＶＴの２次電圧は110
［ボルト］または110 ／√3 ［ボルト］（＝63.5［ボル
ト］）であるが、この場合、２次短絡時の過電流抑制イ
ンピーダンス５の抵抗値を3 〜20［Ω］程度に選べば、
短絡電流を3 〜40アンペア程度に抑制することができる
ため、２次巻線２の温度上昇は問題がない範囲に抑えら
れる。The secondary voltage of a normal instrument transformer VT is 110
[Volt] or 110 / √3 [volt] (= 63.5 [volt]). In this case, if the resistance value of the overcurrent suppression impedance 5 at the time of the secondary short circuit is selected to be about 3 to 20 [Ω],
Since the short-circuit current can be suppressed to about 3 to 40 amps, the temperature rise of the secondary winding 2 can be suppressed to a range where there is no problem.
【００２４】２次短絡事故が解消した後は、自然冷却に
より過電流抑制インピーダンス５の温度が所定値まで低
下した時点で２次回路が正常状態に復帰する。従って、
ヒューズを用いた場合のように、素子の交換を行う必要
がなく、保守作業が容易となる。After the secondary short-circuit accident is resolved, the secondary circuit returns to the normal state when the temperature of the overcurrent suppression impedance 5 drops to a predetermined value due to natural cooling. Therefore,
Unlike the case where a fuse is used, there is no need to replace elements, and maintenance work is facilitated.
【００２５】図２は請求項２に記載した発明の実施例を
示したもので、この実施例では、計器用変圧器ＶＴの２
次巻線２に直列に、変流器６の１次コイル６ａが直列に
接続され、変流器６の２次コイル６ｂの両端に過電流抑
制インピーダンス５が接続されている。この実施例で用
いる過電流抑制インピーダンス５は、２次巻線２の通電
電流が定格値以下のときに変流器６の２次側に誘導する
電流が通電されたときには微小な抵抗値を示し、２次巻
線２の通電電流が定格値より十分大きく設定された設定
値を超えたときに変流器６の２次側に誘導する電流が通
電されたときには温度上昇により抵抗値が急激に上昇す
る特性を有するようにしておく。その他の点は図１の実
施例と同様である。FIG. 2 shows an embodiment of the invention described in claim 2. In this embodiment, the second embodiment of the instrument transformer VT is shown.
A primary coil 6 a of a current transformer 6 is connected in series with the secondary winding 2, and an overcurrent suppression impedance 5 is connected to both ends of a secondary coil 6 b of the current transformer 6 . The overcurrent suppression impedance 5 used in this embodiment indicates a small resistance value when a current induced on the secondary side of the current transformer 6 is applied when the current flowing through the secondary winding 2 is equal to or less than the rated value. When the current flowing through the secondary side of the current transformer 6 is energized when the current flowing through the secondary winding 2 exceeds a set value sufficiently larger than the rated value, the resistance value sharply increases due to temperature rise. It should have ascending properties. Other points are the same as the embodiment of FIG.
【００２６】図２の実施例において、計器用変圧器ＶＴ
の２次巻線に定格電流が流れているときには、変流器６
の２次出力電流が小さく、過電流抑制インピーダンス５
に通電される電流が小さいため、該インピーダンスの抵
抗値は十分に低い値を示している。このとき変流器を１
次側から見たインピーダンスは十分に小さいため、２次
負担に印加される電圧には影響がない。In the embodiment of FIG. 2, an instrument transformer VT
When the rated current is flowing through the secondary winding of the current transformer 6
Has a small secondary output current and an overcurrent suppression impedance of 5
, The impedance has a sufficiently low resistance value. At this time, the current transformer
Since the impedance seen from the secondary side is sufficiently small, there is no effect on the voltage applied to the secondary load.
【００２７】計器用変圧器ＶＴの２次回路で短絡が生
じ、２次巻線２に短絡電流Ｉo が流れると、変流器６の
２次側に接続された過電流抑制インピーダンス５には、
Ｉo ／ｎ（ｎは変流比）の電流が流れる。これにより過
電流抑制インピーダンス５を構成する感温抵抗素子が発
熱し、その抵抗値が急上昇する。このとき変流器６を１
次側から見たインピーダンスが急上昇するため、短絡電
流が抑制され、２次巻線の温度上昇が抑制される。When a short circuit occurs in the secondary circuit of the instrument transformer VT and a short-circuit current Io flows through the secondary winding 2, the overcurrent suppression impedance 5 connected to the secondary side of the current transformer 6 has
A current of Io / n (n is a current transformation ratio) flows. As a result, the temperature-sensitive resistance element constituting the overcurrent suppression impedance 5 generates heat, and its resistance value rises sharply. At this time, the current transformer 6
Since the impedance seen from the secondary side rises sharply, the short-circuit current is suppressed, and the temperature rise of the secondary winding is suppressed.
【００２８】今図２の実施例において、図３（Ｂ）に示
す過電流抑制インピーダンス５が用いられているものと
し、計器用変圧器の２次定格電圧が63.5［ボルト］のと
きに、２次短絡時の短絡電流を40［アンペア］以下に制
限するものとすると、３個の固定抵抗素子５０２の合成
抵抗値は、（63.5／40）×（１／ｎ）2 ［Ω］でよい。
また変流器６の２次側に流れる電流値は（40／n)［アン
ペア］となるため、各感温抵抗素子５０１の発熱量は、
（63.5／40）×（1/n)2 ×（40/n）2 ＝（63.5×40）×
（1/n)4 ［ワット］となる。図１の実施例において、計
器用変圧器の２次定格電圧が63.5［ボルト］のときに、
２次短絡時の短絡電流を40［アンペア］に制限する場合
の過電流抑制インピーダンスの発熱量は、（63.5／40）
×402 ＝60.5×40［ワット］となる。従って、図２の実
施例によれば、過電流抑制インピーダンスでの発熱量
を、図２の実施例の場合の１／ｎ4 にすることができ、
過電流抑制インピーダンスの小形化を図って、装置全体
の小形化を図ることができる。また過電流抑制インピー
ダンスを小形に構成すると、その熱容量が小さくなるた
め、該インピーダンスを短時間で冷却して正常状態への
復帰を速やかに行わせることができる。In the embodiment of FIG. 2, it is assumed that the overcurrent suppression impedance 5 shown in FIG. 3B is used, and that the secondary rated voltage of the instrument transformer is 63.5 [volts]. Assuming that the short-circuit current at the time of the next short-circuit is limited to 40 [Amps] or less, the combined resistance value of the three fixed resistance elements 502 may be (63.5 / 40) × (1 / n) 2 [Ω].
In addition, since the value of the current flowing on the secondary side of the current transformer 6 is (40 / n) [ampere], the calorific value of each temperature-sensitive resistance element 501 is
(63.5 / 40) × (1 / n) 2 × (40 / n) 2 = (63.5 × 40) ×
(1 / n) 4 [Watts]. In the embodiment of FIG. 1, when the secondary rated voltage of the instrument transformer is 63.5 [volt],
When the short-circuit current at the time of secondary short-circuit is limited to 40 [Amps], the calorific value of the overcurrent suppression impedance is (63.5 / 40)
× 40 2 = 60.5 × 40 [watt]. Therefore, according to the embodiment of FIG. 2, the amount of heat generated at the overcurrent suppression impedance can be reduced to 1 / n 4 of the case of the embodiment of FIG.
The overcurrent suppression impedance can be reduced in size, and the entire device can be reduced in size. Further, when the overcurrent suppression impedance is configured to be small, the heat capacity thereof is reduced, so that the impedance can be cooled in a short time and the normal state can be quickly restored.
【００２９】図２の実施例のように、２次巻線に変流器
を介して過電流抑制インピーダンスを接続するようにす
ると、変流器の変流比を調整することにより、過電流抑
制インピーダンスを流れる電流を調整できるため、同じ
過電流抑制インピーダンスを種々の異なる計器用変圧器
に適用することが可能になる。従って過電流抑制インピ
ーダンスの標準化が可能になり、そのコストの低減を図
ることができる。When an overcurrent suppression impedance is connected to a secondary winding via a current transformer as in the embodiment of FIG. 2, the overcurrent suppression is performed by adjusting the current transformer ratio of the current transformer. Because the current flowing through the impedance can be adjusted, the same overcurrent suppression impedance can be applied to various different instrument transformers. Therefore, the overcurrent suppression impedance can be standardized, and the cost can be reduced.
【００３０】上記の実施例では、分圧コンデンサを用い
ずに、１次側に被測定電圧が直接印加される計器用変圧
器（いわゆるＶＴ）を例にとったが、分圧コンデンサに
より分圧された電圧を１次側に印加するコンデンサ形の
計器用変圧器（ＣＶＴ）にも本発明を適用することがで
きるのはもちろんである。In the above-described embodiment, an example of an instrument transformer (so-called VT) in which a voltage to be measured is directly applied to the primary side without using a voltage dividing capacitor is taken as an example. Needless to say, the present invention can be applied to a capacitor-type instrument transformer (CVT) that applies the applied voltage to the primary side.
【００３１】[0031]
【発明の効果】以上のように、本発明によれば、通電電
流が所定値を超えたときに抵抗値が急上昇する特性を有
する過電流抑制インピーダンスを２次巻線と２次負担と
に対して直列に接続するか、または該過電流抑制インピ
ーダンスを、２次巻線と２次負担とに対して１次コイル
を直列に接続した変流器の２次側に接続したので、２次
短絡事故が生じたときに、過電流抑制インピーダンスの
抵抗値の増大により、２次巻線を流れる短絡電流を抑制
することができ、ヒューズを用いることなく２次巻線を
過電流から保護することができる利点がある。As described above, according to the present invention, the overcurrent suppressing impedance having the characteristic that the resistance value rises sharply when the flowing current exceeds a predetermined value is reduced by the secondary winding and the secondary load. Or the overcurrent suppression impedance is connected to the secondary side of the current transformer in which the primary coil is connected in series to the secondary winding and the secondary load . In the event of a secondary short-circuit accident, the short-circuit current flowing through the secondary winding can be suppressed by increasing the resistance value of the overcurrent suppression impedance, and the secondary winding can be removed from the overcurrent without using a fuse. There are advantages that can be protected.
【００３２】また過電流抑制インピーダンスの抵抗値は
冷却により自然復帰させることができ、ヒューズを用い
る場合のように、素子の交換を必要としないため、保守
作業を簡単にすることができる利点がある。Further, the resistance value of the overcurrent suppression impedance can be spontaneously restored by cooling, and since there is no need to replace elements as in the case of using a fuse, there is an advantage that maintenance work can be simplified. .
【００３３】特に請求項２に記載した発明によれば、計
器用変圧器の２次巻線と２次負担とに対して直列に変流
器の１次コイルを接続して該変流器の２次側に過電流抑
制インピーダンスを接続すると、過電流抑制インピーダ
ンスと計器用変圧器の２次巻線とを変流器により絶縁す
ることができるため、信頼性を向上させることができる
利点がある。In particular, according to the second aspect of the present invention, the primary coil of the current transformer is connected in series with the secondary winding and the secondary load of the instrument transformer. When the overcurrent suppression impedance is connected to the secondary side, the overcurrent suppression impedance and the secondary winding of the instrument transformer can be insulated by the current transformer, so that there is an advantage that reliability can be improved. .
【００３４】また請求項２に記載した発明によれば、変
流器の変流比を変えることにより、過電流抑制インピー
ダンスに流れる電流を適値に調整できるため、過電流抑
制インピーダンスの標準化を図ることができる。According to the second aspect of the present invention, the current flowing through the overcurrent suppression impedance can be adjusted to an appropriate value by changing the current transformer ratio of the current transformer, so that the overcurrent suppression impedance is standardized. be able to.
【００３５】更に請求項３に記載した発明では、変流比
をｎとすると、過電流抑制インピーダンスに流れる電流
は２次巻線に流れる電流の１／ｎになるため、２次短絡
時に過電流抑制インピーダンスで生じる発熱を少なくし
て、該インピーダンスの小形化を図り、装置全体の小形
化を図ることができる。According to the third aspect of the present invention, assuming that the current transformation ratio is n, the current flowing in the overcurrent suppression impedance is 1 / n of the current flowing in the secondary winding, so that the The heat generated by the suppression impedance can be reduced, the impedance can be reduced, and the entire device can be reduced in size.
【図１】本発明の実施例を示した回路図である。FIG. 1 is a circuit diagram showing an embodiment of the present invention.
【図２】本発明の他の実施例を示した回路図である。FIG. 2 is a circuit diagram showing another embodiment of the present invention.
【図３】（Ａ）及び（Ｂ）はそれぞれ本発明で用いる過
電流抑制インピーダンスの異なる構成例を示した回路図
である。FIGS. 3A and 3B are circuit diagrams each showing a configuration example in which an overcurrent suppression impedance used in the present invention is different.
【図４】本発明の実施例で用いるのに適した感温抵抗素
子の特性の一例を示した線図である。FIG. 4 is a diagram showing an example of characteristics of a temperature-sensitive resistance element suitable for use in an embodiment of the present invention.
【図５】従来の計器用変圧器を示した回路図である。FIG. 5 is a circuit diagram showing a conventional instrument transformer.
ＶＴ 計器用変圧器 １ １次巻線 ２ ２次巻線 ４ ２次負担 ５ 過電流抑制インピーダンス ６ 変流器 ６ａ １次コイル ６ｂ ２次コイル VT instrument transformer 1 Primary winding 2 Secondary winding 4 Secondary burden 5 Overcurrent suppression impedance 6 Current transformer 6a Primary coil 6b Secondary coil
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) H01F 38/24 H01C 7/02──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 6 , DB name) H01F 38/24 H01C 7/02
Claims (3)
線とを有する計器用変圧器において、 前記２次巻線の通電電流が定格値以下のときには微小な
抵抗値を示し、前記２次巻線の通電電流が定格値よりも
大きく設定された設定値を超えたときには温度上昇によ
り抵抗値が急上昇する特性を有する過電流抑制インピー
ダンスを前記２次巻線と前記２次負担とに対して直列に
接続したことを特徴とする計器用変圧器。1. An instrument transformer having a primary winding and a secondary winding connected to a secondary load , wherein when a current flowing through the secondary winding is equal to or less than a rated value, a small resistance value is exhibited. When the current flowing through the secondary winding exceeds a set value larger than a rated value, an overcurrent suppression impedance having a characteristic that a resistance value sharply rises due to a temperature rise is provided between the secondary winding and the secondary load. A transformer for an instrument, which is connected in series with the transformer.
線とを有する計器用変圧器において、 変流器の１次コイルを前記２次巻線と前記２次負担とに
対して直列に接続し、 前記２次巻線の通電電流が定格値以下のときに前記変流
器の２次側に誘導する電流が通電されたときには微小な
抵抗値を示し、前記２次巻線の通電電流が定格値よりも
大きく設定された設定値を超えたときに前記変流器の２
次側に誘導する電流が通電されたときには通電による温
度上昇により抵抗値が急上昇する特性を有する過電流抑
制インピーダンスを前記変流器の２次コイルの両端に接
続したことを特徴とする計器用変圧器。2. An instrument transformer having a primary winding and a secondary winding connected to a secondary load , wherein a primary coil of a current transformer is connected to the secondary winding and the secondary load . Connected in series with each other, and when a current induced on the secondary side of the current transformer is applied when the current flowing through the secondary winding is equal to or less than a rated value, the secondary winding has a small resistance value. When the current flowing through the wire exceeds a set value larger than the rated value, the current
An overcurrent suppression impedance having a characteristic that a resistance value sharply rises due to a temperature rise due to energization when a current to be induced on the secondary side is applied, is connected to both ends of a secondary coil of the current transformer. vessel.
抵抗素子と固定抵抗素子とを並列に接続して構成した並
列抵抗体を複数個直列に接続したものからなっている請
求項１または２に記載の計器用変圧器。3. The overcurrent suppression impedance according to claim 1, wherein a plurality of parallel resistors configured by connecting a temperature-sensitive resistance element and a fixed resistance element in parallel are connected in series. An instrument transformer as described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5001220A JP2861696B2 (en) | 1993-01-07 | 1993-01-07 | Instrument transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5001220A JP2861696B2 (en) | 1993-01-07 | 1993-01-07 | Instrument transformer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06204060A JPH06204060A (en) | 1994-07-22 |
| JP2861696B2 true JP2861696B2 (en) | 1999-02-24 |
Family
ID=11495390
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5001220A Expired - Fee Related JP2861696B2 (en) | 1993-01-07 | 1993-01-07 | Instrument transformer |
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| Country | Link |
|---|---|
| JP (1) | JP2861696B2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006145478A (en) * | 2004-11-24 | 2006-06-08 | Tyco Electronics Raychem Kk | Temperature abnormality detection method and system |
| JP5575046B2 (en) * | 2011-04-07 | 2014-08-20 | 三菱電機株式会社 | Grid connection power conditioner |
| CN103093949B (en) * | 2013-02-21 | 2016-03-30 | 上海磊跃自动化设备有限公司 | A kind of mutual inductance device for temperature-control-low-voltage low-voltage circuit breaker |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5014937U (en) * | 1973-06-06 | 1975-02-17 | ||
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1993
- 1993-01-07 JP JP5001220A patent/JP2861696B2/en not_active Expired - Fee Related
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| Publication number | Publication date |
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| JPH06204060A (en) | 1994-07-22 |
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