JP4051157B2 - Neon transformer ground fault detection circuit - Google Patents

Neon transformer ground fault detection circuit Download PDF

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Publication number
JP4051157B2
JP4051157B2 JP19850799A JP19850799A JP4051157B2 JP 4051157 B2 JP4051157 B2 JP 4051157B2 JP 19850799 A JP19850799 A JP 19850799A JP 19850799 A JP19850799 A JP 19850799A JP 4051157 B2 JP4051157 B2 JP 4051157B2
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Prior art keywords
voltage
neutral point
detection circuit
ground fault
neon transformer
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JP19850799A
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JP2001028831A (en
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義広 松井
英幾 清水
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レシップ株式会社
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Priority to JP19850799A priority Critical patent/JP4051157B2/en
Priority to US09/613,734 priority patent/US6504691B1/en
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Description

【0001】
【発明の属する技術分野】
この発明はネオン管やアルゴン管を点灯させるためのネオン変圧器における2次側の地絡事故を検出する回路に関する。
【0002】
【従来の技術】
図6にこの種の従来のネオン変圧器の地絡事故検出回路を示す。漏洩変圧器(ネオン変圧器)11の1次巻線12の片端はスイッチ13を通じて入力端子14に接続され、1次巻線12のもう片端は入力端子15に接続されている。2個の2次巻線16,17の巻始め端Cは互いに接続されて、変圧器ケース36のアース端子18に接続され、つまりケース36に接続される。そして接地端子が大地に接地され2次巻線16,17の両巻き終わり端は出力端子21,22に接続され、出力端子21,22間に、ネオン管又はアルゴン管などのサイン灯23が接続される。入力端子14,15間に交流電力、例えば商用電力が入力され、これが変圧器11で昇圧されてサイン灯23が点灯される。
【0003】
サイン灯23やその配線がケース36などと接触し、つまり地絡事故が生じると、これを検出して、入力交流電力を遮断する保護回路10が設けられている。2次巻線16,17の近傍に、これらとそれぞれ磁気的に結合した3次巻線25,26が保護回路10の一部として、設けられる。通常は2次巻線16,17の最下層の下において、磁気コアに3次巻線25,26が巻かれて、2次巻線16,17と3次巻線25,26との間には耐圧が6000〜7000V程度の高耐電圧絶縁材層が介在されて電気的絶縁を大にし、かつ磁気的結合が十分大とされている。
【0004】
3次巻線25,26の一端は、その誘起電圧が互いに打消し合うように逆相に接続され、3次巻線25,26の両他端は整流平滑回路27の入力側に接続され、整流平滑回路27の出力側はツェナーダイオード28を通じて、抵抗器31、コンデンサ32の並列回路の両端に接続され、また、この両端はトライアック33のゲートと陰極とに接続される。トライアック33はリレー34を通じて入力端子14,15間に接続され、リレー34のリレー接点でスイッチ13が構成されている。
【0005】
正常な状態では3次巻線25,26に誘起される電圧はほぼ等しく、互いに逆相なので、整流平滑回路27の入力電圧はほぼゼロである。しかしサイン灯23、又はその配線が地絡すると、地絡された方の2次巻線の両端が短絡され、その2次巻線と結合している3次巻線の誘起電圧が著しく減少するため、他方の3次巻線の全誘起電圧が整流平滑回路27に印加されることになる。この電圧が整流平滑され、その出力電圧が上昇してツェナーダイオード28がオンとなる。その結果、トライアック33がオンとなりリレー34が動作し、スイッチ13が開となり、入力交流電力の変圧器11への供給が遮断される。スイッチ13のリレー接点は常開側NOに接続され、これを通じてリレー34に動作保持電流が流れる。
【0006】
【発明が解決しようとする課題】
先に述べたように2次側の地絡事故を検出するため、従来においては2つの3次巻線を用いていた。この3次巻線は、2つの2次巻線の最下層の下(内側)に高耐圧絶縁物を介して設けていた。このため、この3次巻線を設けるための手数がかかり、それだけネオン変圧器の生産効率を低くしていた。
【0007】
この発明の目的は3次巻線を用いることなく、地絡事故を検出できるネオン変圧器の地絡事故検出回路を提供することにある。
【0008】
【課題を解決するための手段】
この発明によれば2次巻線とアース端子との間に所定値以上の電圧が発生するとこれを検出する電圧検出手段が設けられ、この電圧検出手段の検出出力により1次巻線への電源電力の供給が遮断されるようになされる。
【0009】
【発明の実施の形態】
図1にこの発明の基本構成を示し、図6と対応する部分に同一番号を付けてある。この発明においては2次巻線16,17の接続点(2次巻線の中性点)Cと変圧器のアース端子18との間に電圧検出手段41が挿入される。電圧検出手段41としてしきい値素子としてのツェナダイオード42とホトカプラ43の発光素子43Lの直列回路が用いられた場合である。またこの例では電圧検出手段41と並列に抵抗素子44が接続されるとともに、電圧検出手段41と直列に整流用のダイオード45が接続される。またホトカプラ43の受光素子43Pとリレー34の直列回路が入力端子14,15間に接続される。入力端子14と1次巻線12との間にリレー34の接点13が挿入され、その常開接点NOはリレー34を通じて入力端子15と接続されている。
【0010】
この構成において変圧器11の2次側に地絡事故がない正常な状態にあれば、2次巻線16,17の中性点Cの電位はほぼゼロであって、中性点Cとアース端子18との間の電圧もほぼゼロである。従って電圧検出手段41は電圧を検出しない。また発光素子43Lに電流が流れないで、入力端子14,15より電源電力が1次巻線12へ供給される。
【0011】
いま変圧器11の2次側、つまりサイン灯23あるいはその配線が地絡すると、例えば出力端子21側が地絡すると、その地絡点が基準電位となり中性点Cに2次電圧が現われ、この電圧によりツェナダイオード42が導通し、発光素子43Lが発光し、受光素子43Pに電流が流れ、リレー34が動作し、接点13は常開側NOに切替り、1次巻線12への電源電力の供給が遮断され、またリレー34には自己保持電流が流れる。つまり地絡事故が発生すると、これが電圧検出手段41で検出され、1次巻線12への電源電力の供給が遮断され、地絡点に電流が流れ続けて火災が生じるようなことが避けられる。
【0012】
2次側配線を、火災防止の点から、メタルコンジットと呼ばれる可撓性チューブ内に通すことがある。この場合はメタルコンジットと配線との間の静電容量にもとづく高いインピーダンスが生じ、2次側電圧がこの静電容量インピーダンスと電圧検出手段41のインピーダンスとで分圧され、正常時においても電圧検出手段41で電圧を検出するような電圧が電圧検出手段41に印加され、誤動作するおそれがある。この誤動作が生じないように抵抗素子44の抵抗値を選定して、正常状態で、電圧検出手段41に印加される電圧が所定値以下、つまりツェナダイオード42が導通しないようにされる。この状態で地絡事故が生じると、その個所で前記静電容量インピーダンスがほぼゼロになり、電圧検出手段41には地絡事故を検出するに十分な電圧が印加される。
【0013】
図1に示した電圧検出手段41では発光素子43Lを確実に動作させるための電流が不足する場合がある。このような問題を解決するには例えば図2に示すように構成すればよい。
つまり、抵抗素子44の両端の電圧がダイオード45よりなる整流回路46で整流され、その整流出力が、しきい値素子としてのツェナダイオード42と抵抗素子47−48の直列回路に印加され、またトランジスタ49、発光素子43Lの直列回路に印加され、抵抗素子47,48の接続点がトランジスタ49のベースに接続される。トランジスタ49のコレクタ−エミッタ間にこのトランジスタ49を保護するためのツェナダイオード51が必要に応じて接続される。
【0014】
抵抗素子44の両端間の電圧が所定値を越えると、整流回路46の出力でツェナダイオード42が導通され、トランジスタ49にベース電流が供給され、トランジスタ49が導通して発光素子43Lが発光する。トランジスタ49が導通する電圧は、ツェナダイオード42、抵抗素子47,48により設定する。
電圧検出手段41としては図3に示すように、整流回路46内にコンデンサ52,抵抗素子53よりなる平滑回路を設け、整流出力を平滑してツェナダイオード42に印加してもよい。またトランジスタ49の代りにスイッチング素子としてサイリスタ54を用いてもよい。更に発光素子43Lはサイリスタ54のカソード側ではなくアノード側に接続する方がよい。つまり発光素子43Lをサイリスタ54のカソード側(トランジスタ49の場合はエミッタ側)に挿入すると、発光素子43Lのインピーダンスのばらつきにより、サイリスタ54(トランジスタ49)がオンする電圧が変化するからである。なおサイリスタ54のカソード側に挿入したツェナダイオード55は雑音でサイリスタ54が導通しないようにするもので省略してもよい。
【0015】
なお、2次側が地絡して、中性点Cが高電位になると、この電圧がホトカプラ43を介して商用電源の非接続側端子15との間に印加され、ホトカプラ43が破壊するおそれがある場合は、図1に示すように、中性点Cと入力端子15との間に接続した保護素子56が導通して、ホトカプラ43に対する保護がなされる。
【0016】
図1に示した構成において、負荷(サイン灯23)の中点を接地すると、2次側の地絡事故の検出が困難になる。この点で負荷の中点は接地しないことに決められている。しかし工事ミスで負荷の中点を接地してしまった場合に、前記電圧検出手段41を用いて、電源電力の1次巻線12への供給を停止して、ネオン塔が動作しないようにする。
【0017】
そのためネオン変圧器の2つの2次巻線16,17でそれぞれ構成される2つの磁気回路が互いに不平衡になるようにされる。例えば図4に示すように、ロ字状磁気コア61上に1次巻線12が巻装され、その1次巻線12の両側で磁気コア61上に2次巻線16,17がそれぞれ巻装され、1次巻線12と2次巻線16,17との各間において、ロ字状磁気コア61の磁路を分路するリーケージコア62,63が設けられている。この実施例でリーケージコア62,63の各幅t1,t2を互いに異ならせて、磁束漏洩特性を異ならせ、2次巻線16,17によりそれぞれ構成される磁気回路64,65を互いに不平衡とさせる。t1は例えばロ字状磁気コア61の幅tに対しその10〜30%程度小とし、t2はtに対し10〜30%程度大とする。
【0018】
このようなネオン変圧器11とし、図1に示したと同様に、図5に示すように中性点Cとアース端子18との間に、図1乃至図3に示した電圧検出手段41の何れかを接続する。この構成において、負荷側の中点が接地されず、かつ正常な状態であれば、中性点Cの電圧はほぼゼロであって電圧検出手段41は電圧を検出しない。しかし図5に示すように負荷の中点が接地されると、この接地点、アース端子18、各2次巻線16,17をそれぞれ通る電流66,67が流れ、これら電流66,67は前記磁気回路64,65の磁気特性の相異により、電流66,67の値が異なり、これらの差の電流、例えば数mA程度が中性点Cとアース端子18との間に流れ、これが電圧検出手段41により検出され、リレー34が動作して、電源電力の1次巻線12への供給が遮断される。
【0019】
リーケージコア62,63の磁束漏洩特性を異ならせるには、リーケージコア62,63の幅の変更の他に、磁気空隙の長さG1,G2を互いに異ならせてもよい。或は幅t1,t2と長さG1,G2の両方を互いに異ならせてもよい。要は磁気回路64,65の磁気特性を互いに異ならせればよい。ただし、この磁気回路64,65の不平衡を大きくし過ぎると、サイン灯の点灯特性に影響を与えることになる。よって幅についてみれば前述したように基準に対し各±10〜30%程度が好ましい。
【0020】
図5に示した構成によれば、前述したように負荷側の中点を接地すると、電源電力の供給が停止され、また図1乃至図3の説明から明らかなように、2次側で地絡事故が発生すると、これを検出して、電源電力の供給を停止することになる。電源電力供給の遮断はリレーによることなく、トライアックなどの半導体スイッチング素子を用いてもよい。
【0021】
【発明の効果】
以上述べたようにこの発明によれば、ネオン変圧器に3次巻線を設けることなく2次側の地絡事故を検出して、電源電力の供給を遮断することができる。従って、ネオン変圧器の作成が従来より簡単になり、生産性が向上する。
またネオン変圧器を図4に示したように、2つの2次巻線がそれぞれ構成する磁気回路を不平衡とすることにより、負荷の中性点を接地すると、電源電力の供給が停止される。
【図面の簡単な説明】
【図1】この発明の実施例を示す回路図。
【図2】図1中の電圧検出手段41の変形例を示す回路図。
【図3】図1中の電圧検出手段41の更に他の変形例を示す回路図。
【図4】2つの2次巻線の磁気回路を不平衡にしたネオン変圧器の例を示す図。
【図5】この発明の他の実施例を示す回路図。
【図6】従来のネオン変圧器の地絡事故検出回路を示す回路図。
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit for detecting a secondary ground fault in a neon transformer for lighting a neon tube or an argon tube.
[0002]
[Prior art]
FIG. 6 shows a ground fault detection circuit of this type of conventional neon transformer. One end of the primary winding 12 of the leakage transformer (neon transformer) 11 is connected to the input terminal 14 through the switch 13, and the other end of the primary winding 12 is connected to the input terminal 15. The winding start ends C of the two secondary windings 16 and 17 are connected to each other and connected to the ground terminal 18 of the transformer case 36, that is, connected to the case 36. Then, the ground terminal is grounded to the ground, both winding end ends of the secondary windings 16 and 17 are connected to the output terminals 21 and 22, and a sign lamp 23 such as a neon tube or an argon tube is connected between the output terminals 21 and 22. Is done. AC power, for example, commercial power, is input between the input terminals 14 and 15, which is boosted by the transformer 11 and the sign lamp 23 is lit.
[0003]
When the sign lamp 23 or its wiring comes into contact with the case 36 or the like, that is, when a ground fault occurs, a protection circuit 10 is provided to detect this and cut off the input AC power. In the vicinity of the secondary windings 16 and 17, tertiary windings 25 and 26 that are magnetically coupled thereto are provided as part of the protection circuit 10. Normally, under the lowermost layer of the secondary windings 16 and 17, the tertiary windings 25 and 26 are wound around the magnetic core, and between the secondary windings 16 and 17 and the tertiary windings 25 and 26. Is provided with a high withstand voltage insulating material layer having a withstand voltage of about 6000 to 7000 V to increase electrical insulation and sufficiently large magnetic coupling.
[0004]
One ends of the tertiary windings 25 and 26 are connected in opposite phases so that the induced voltages cancel each other, and the other ends of the tertiary windings 25 and 26 are connected to the input side of the rectifying and smoothing circuit 27. The output side of the rectifying and smoothing circuit 27 is connected to both ends of a parallel circuit of a resistor 31 and a capacitor 32 through a Zener diode 28, and both ends are connected to the gate and cathode of the triac 33. The triac 33 is connected between the input terminals 14 and 15 through a relay 34, and the switch 13 is configured by a relay contact of the relay 34.
[0005]
In a normal state, the voltages induced in the tertiary windings 25 and 26 are substantially equal and have opposite phases, so the input voltage of the rectifying and smoothing circuit 27 is substantially zero. However, when the sine lamp 23 or its wiring is grounded, both ends of the grounded secondary winding are short-circuited, and the induced voltage of the tertiary winding coupled to the secondary winding is significantly reduced. Therefore, the entire induced voltage of the other tertiary winding is applied to the rectifying / smoothing circuit 27. This voltage is rectified and smoothed, the output voltage rises, and the Zener diode 28 is turned on. As a result, the triac 33 is turned on, the relay 34 is operated, the switch 13 is opened, and the supply of input AC power to the transformer 11 is interrupted. The relay contact of the switch 13 is connected to the normally open side NO, and an operation holding current flows through the relay 34 through this.
[0006]
[Problems to be solved by the invention]
As described above, in order to detect a secondary side ground fault, two tertiary windings are conventionally used. The tertiary winding is provided under the lowermost layer (inside) of the two secondary windings via a high-voltage insulator. For this reason, it takes time to provide the tertiary winding, and the production efficiency of the neon transformer is lowered accordingly.
[0007]
An object of the present invention is to provide a ground fault detection circuit for a neon transformer that can detect a ground fault without using a tertiary winding.
[0008]
[Means for Solving the Problems]
According to the present invention, voltage detecting means for detecting when a voltage exceeding a predetermined value is generated between the secondary winding and the ground terminal is provided, and the power supply to the primary winding is detected by the detection output of the voltage detecting means. The power supply is cut off.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a basic configuration of the present invention, and the same reference numerals are given to portions corresponding to FIG. In the present invention, the voltage detection means 41 is inserted between the connection point (the neutral point of the secondary winding) C between the secondary windings 16 and 17 and the ground terminal 18 of the transformer. This is a case where a series circuit of a Zener diode 42 as a threshold element and a light emitting element 43L of a photocoupler 43 is used as the voltage detecting means 41. In this example, a resistance element 44 is connected in parallel with the voltage detection means 41, and a rectifying diode 45 is connected in series with the voltage detection means 41. A series circuit of the light receiving element 43P of the photocoupler 43 and the relay 34 is connected between the input terminals 14 and 15. The contact 13 of the relay 34 is inserted between the input terminal 14 and the primary winding 12, and the normally open contact NO is connected to the input terminal 15 through the relay 34.
[0010]
In this configuration, if the secondary side of the transformer 11 is in a normal state with no ground fault, the potential of the neutral point C of the secondary windings 16 and 17 is almost zero, and the neutral point C and ground The voltage between the terminals 18 is also almost zero. Therefore, the voltage detection means 41 does not detect the voltage. In addition, current does not flow through the light emitting element 43 </ b> L, and power is supplied from the input terminals 14 and 15 to the primary winding 12.
[0011]
If the secondary side of the transformer 11, that is, the sine lamp 23 or its wiring is grounded, for example, if the output terminal 21 side is grounded, the grounding point becomes the reference potential, and a secondary voltage appears at the neutral point C. The zener diode 42 is turned on by the voltage, the light emitting element 43L emits light, a current flows through the light receiving element 43P, the relay 34 operates, the contact 13 is switched to the normally open side NO, and the power supply power to the primary winding 12 And the self-holding current flows through the relay 34. That is, when a ground fault occurs, this is detected by the voltage detection means 41, the supply of power to the primary winding 12 is cut off, and it is avoided that a current continues to flow through the ground fault point and a fire occurs. .
[0012]
From the viewpoint of fire prevention, the secondary side wiring may be passed through a flexible tube called a metal conduit. In this case, a high impedance based on the electrostatic capacitance between the metal conduit and the wiring is generated, and the secondary side voltage is divided by the electrostatic capacitance impedance and the impedance of the voltage detecting means 41, and the voltage is detected even in the normal state. A voltage for detecting the voltage by the means 41 is applied to the voltage detecting means 41, and there is a risk of malfunction. The resistance value of the resistance element 44 is selected so that this malfunction does not occur, and the voltage applied to the voltage detection means 41 is not more than a predetermined value, that is, the Zener diode 42 is not conducted in a normal state. When a ground fault occurs in this state, the capacitance impedance becomes almost zero at that point, and a voltage sufficient to detect the ground fault is applied to the voltage detecting means 41.
[0013]
In the voltage detection means 41 shown in FIG. 1, there is a case where the current for reliably operating the light emitting element 43L is insufficient. To solve such a problem, for example, a configuration as shown in FIG.
That is, the voltage across the resistor element 44 is rectified by the rectifier circuit 46 including the diode 45, and the rectified output is applied to the series circuit of the Zener diode 42 as the threshold element and the resistor elements 47-48. 49, the light emitting element 43L is applied to the series circuit, and the connection point of the resistance elements 47 and 48 is connected to the base of the transistor 49. A Zener diode 51 for protecting the transistor 49 is connected between the collector and the emitter of the transistor 49 as necessary.
[0014]
When the voltage across the resistance element 44 exceeds a predetermined value, the Zener diode 42 is turned on by the output of the rectifier circuit 46, the base current is supplied to the transistor 49, the transistor 49 is turned on, and the light emitting element 43L emits light. The voltage at which the transistor 49 is conducted is set by the Zener diode 42 and the resistance elements 47 and 48.
As the voltage detecting means 41, as shown in FIG. 3, a smoothing circuit including a capacitor 52 and a resistance element 53 may be provided in the rectifying circuit 46, and the rectified output may be smoothed and applied to the Zener diode 42. Further, a thyristor 54 may be used as a switching element instead of the transistor 49. Furthermore, it is better to connect the light emitting element 43L to the anode side rather than the cathode side of the thyristor 54. That is, when the light emitting element 43L is inserted into the cathode side (emitter side in the case of the transistor 49) of the thyristor 54, the voltage at which the thyristor 54 (transistor 49) is turned on changes due to the impedance variation of the light emitting element 43L. The Zener diode 55 inserted on the cathode side of the thyristor 54 is to prevent the thyristor 54 from conducting due to noise and may be omitted.
[0015]
If the secondary side is grounded and the neutral point C is at a high potential, this voltage is applied to the non-connection side terminal 15 of the commercial power supply via the photocoupler 43, and the photocoupler 43 may be destroyed. In some cases, as shown in FIG. 1, the protection element 56 connected between the neutral point C and the input terminal 15 is turned on, and the photocoupler 43 is protected.
[0016]
In the configuration shown in FIG. 1, if the midpoint of the load (sign lamp 23) is grounded, it becomes difficult to detect a ground fault on the secondary side. At this point, it is determined that the midpoint of the load is not grounded. However, if the midpoint of the load is grounded due to a construction error, the supply of power to the primary winding 12 is stopped using the voltage detection means 41 so that the neon tower does not operate. .
[0017]
For this reason, the two magnetic circuits respectively composed of the two secondary windings 16 and 17 of the neon transformer are unbalanced from each other. For example, as shown in FIG. 4, the primary winding 12 is wound on the rectangular magnetic core 61, and the secondary windings 16 and 17 are wound on the magnetic core 61 on both sides of the primary winding 12. Leakage cores 62 and 63 are provided between the primary winding 12 and the secondary windings 16 and 17 to shunt the magnetic path of the rectangular magnetic core 61. In this embodiment, the widths t1 and t2 of the leakage cores 62 and 63 are made different from each other, the magnetic flux leakage characteristics are made different, and the magnetic circuits 64 and 65 respectively constituted by the secondary windings 16 and 17 are unbalanced. Let For example, t1 is about 10 to 30% smaller than the width t of the rectangular magnetic core 61, and t2 is about 10 to 30% larger than t.
[0018]
As in the case shown in FIG. 1, such a neon transformer 11, as shown in FIG. 5, any of the voltage detection means 41 shown in FIGS. 1 to 3 is interposed between the neutral point C and the ground terminal 18. Or connect. In this configuration, if the midpoint of the load side is not grounded and is in a normal state, the voltage at the neutral point C is almost zero and the voltage detection means 41 does not detect the voltage. However, when the middle point of the load is grounded as shown in FIG. 5, currents 66 and 67 passing through the grounding point, the ground terminal 18, and the secondary windings 16 and 17 flow, respectively. Due to the difference in magnetic characteristics of the magnetic circuits 64 and 65, the values of the currents 66 and 67 are different, and a current of these differences, for example, about several mA flows between the neutral point C and the ground terminal 18, which is voltage detection. Detected by the means 41, the relay 34 operates to cut off the supply of power to the primary winding 12.
[0019]
In order to make the leakage flux characteristics of the leakage cores 62 and 63 different, in addition to changing the width of the leakage cores 62 and 63, the lengths G1 and G2 of the magnetic gaps may be made different from each other. Alternatively, both the widths t1 and t2 and the lengths G1 and G2 may be different from each other. In short, the magnetic characteristics of the magnetic circuits 64 and 65 may be made different from each other. However, if the unbalance of the magnetic circuits 64 and 65 is increased too much, the lighting characteristics of the sign lamp will be affected. Therefore, in terms of width, as described above, each of about ± 10 to 30% is preferable with respect to the reference.
[0020]
According to the configuration shown in FIG. 5, when the midpoint of the load side is grounded as described above, the supply of the power supply is stopped, and as is clear from the description of FIGS. When an entanglement accident occurs, this is detected and supply of power supply is stopped. The power supply may be cut off without using a relay, and a semiconductor switching element such as a triac may be used.
[0021]
【The invention's effect】
As described above, according to the present invention, it is possible to detect a ground fault on the secondary side without providing a third winding in the neon transformer and to cut off the supply of power. Therefore, the production of the neon transformer becomes easier than before, and the productivity is improved.
In addition, as shown in FIG. 4, the supply of the power supply is stopped when the neutral point of the load is grounded by making the magnetic circuit formed by the two secondary windings unbalanced as shown in FIG. .
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of the present invention.
FIG. 2 is a circuit diagram showing a modification of the voltage detecting means 41 in FIG.
FIG. 3 is a circuit diagram showing still another modified example of the voltage detecting means 41 in FIG. 1;
FIG. 4 is a diagram showing an example of a neon transformer in which the magnetic circuit of two secondary windings is unbalanced.
FIG. 5 is a circuit diagram showing another embodiment of the present invention.
FIG. 6 is a circuit diagram showing a ground fault detection circuit of a conventional neon transformer.

Claims (6)

2次巻線の片点又は中性点を変圧器のアース端子に接続したネオン変圧器において、2次巻線の中性点と上記アース端子との間に設けられ、これら間に所定値以上の電圧が発生すると、これを検出する電圧検出手段と、上記電圧検出手段の検出出力により1次巻線への電源供給を遮断する電源遮断手段と、を具備し、上記ネオン変圧器の2つの2次巻線でそれぞれ構成される2つの磁気回路が互いに不平衡であるネオン変圧器の地絡事故検出回路。In a neon transformer in which one point or neutral point of the secondary winding is connected to the earth terminal of the transformer, it is provided between the neutral point of the secondary winding and the earth terminal, and a predetermined value or more between these points. Voltage detecting means for detecting this voltage, and power shut-off means for shutting off the power supply to the primary winding by the detection output of the voltage detecting means . A ground fault detection circuit for a neon transformer in which two magnetic circuits each composed of a secondary winding are unbalanced with each other . 上記2つの磁気回路にそれぞれ設けられたリーケージコアの磁束漏洩特性が互いに異ならされて、上記不平衡とされていることを特徴とする請求項記載のネオン変圧器の地絡事故検出回路。Flux leakage characteristics of the leakage core respectively provided to the two magnetic circuits is different from each other, ground fault detection circuit of neon transformer according to claim 1, characterized in that it is with the unbalanced. 上記電圧検出手段は上記中性点と上記アース端子との間の電圧が所定値以上になると、これら間に電流を流すしきい値手段であることを特徴とする請求項1乃至の何れかに記載のネオン変圧器の地絡事故検出回路。When the voltage between the above voltage detection means and said neutral point and said ground terminal is equal to or higher than a predetermined value, any one of claims 1 to 2, characterized in that the threshold means for flowing a current between these Neon transformer ground fault detection circuit described in 1. 上記電圧検出手段は上記中性点と上記アース端子との間の電圧を整流して上記しきい値手段に印加する整流回路と、上記中性点と上記アース端子との間に接続され、上記しきい値手段の所定値以上の電圧にもとづく出力によりオンにされるスイッチング素子とよりなることを特徴とする請求項記載のネオン変圧器の地絡事故検出回路。The voltage detecting means is connected between the rectifying circuit for rectifying the voltage between the neutral point and the ground terminal and applying the voltage to the threshold means, and the neutral point and the ground terminal. 4. The ground fault detection circuit for a neon transformer according to claim 3 , further comprising a switching element that is turned on by an output based on a voltage that is equal to or higher than a predetermined value of the threshold means. 上記電源遮断手段は、上記スイッチング素子の上記中性点側にホトカプラの発光素子が挿入され、1次巻線の一対の入力端子間に上記ホトカプラの受光素子とリレーの直列回路が接続され、そのリレーの接点が上記入力端子と1次巻線との間に直列に挿入され、そのリレー接点が断にされるとリレーに電源電力による自己保持電流が流れるように構成されていることを特徴とする請求項乃至記載のネオン変圧器の地絡事故検出回路。The power shut-off means includes a light emitting element of a photocoupler inserted on the neutral point side of the switching element, and a series circuit of a light receiving element of the photocoupler and a relay is connected between a pair of input terminals of a primary winding. The relay contact is inserted in series between the input terminal and the primary winding, and when the relay contact is cut off, a self-holding current by power supply flows through the relay. neon transformer ground fault detection circuit according to claim 3 or 4, wherein to. 上記電圧検出手段と並列に、上記中性点と上記アース端子との間に抵抗素子が接続されていることを特徴とする請求項1乃至の何れかに記載のネオン変圧器の地絡事故検出回路。In parallel with said voltage detecting means, ground faults neon transformer according to any one of claims 1 to 5 resistive element is characterized in that it is connected between the neutral point and the ground terminal Detection circuit.
JP19850799A 1999-07-13 1999-07-13 Neon transformer ground fault detection circuit Expired - Fee Related JP4051157B2 (en)

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JP19850799A JP4051157B2 (en) 1999-07-13 1999-07-13 Neon transformer ground fault detection circuit
US09/613,734 US6504691B1 (en) 1999-07-13 2000-07-11 Safety enhanced transformer circuit

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JP2003017287A (en) * 2001-07-02 2003-01-17 Lecip Corp Power supply device for lighting cold cathode discharge lamp having ground protection function
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