JPH02215235A - Protection circuit for communication equipment - Google Patents

Abstract

PURPOSE:To protect an internal circuit against a high voltage such as lightning by connecting a protective element having a discharge start voltage slightly higher than a signal voltage generated between terminals of windings of a transformer connecting to a communication line side. CONSTITUTION:When in-phase high voltage invades between connecting terminals 15, 16 with a communication line via a communication line, ground voltage protective elements 4, 5 start discharging. When there is any 'dispersion' in the discharge start voltage of the elements 4, 5, a high voltage is generated between the terminals 15 and 16. The line voltage protective element 3 starts discharge by the high voltage, but the line voltage does not decrease below various voltages in existence on the communication line. In this case, a high voltage exist among terminals 8-1 to 8-4 of a transformer 8. However, since the elements 1, 2 exist, a high voltage is generated in a DC interruption high breakdown capacitor 9, only a low voltage is generated among the terminals 8-1 to 8-2 and terminals 8-3 to 8-4. Thus, only a low voltage is generated between terminals 8-5 to 8-6.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は通信線から通信機器に侵入してくる雷などのサ
ージ電圧に対する防護回路に係シ、特に情報信号以外に
直流電流を流している平衡形通信線からのサージ電圧に
対する通信機器の防護回路に関するものである。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a protection circuit against surge voltages such as those caused by lightning intruding into communication equipment from communication lines, and particularly relates to a circuit for protecting against surge voltages such as those caused by lightning that intrude into communication equipment from communication lines. This invention relates to a protection circuit for communication equipment against surge voltages from balanced communication lines.

〔従来の技術〕[Conventional technology]

従来の通信機器の防護回路の一例を第２図に示し説明す
る。An example of a conventional protection circuit for communication equipment is shown in FIG. 2 and will be described.

従来の通信機器では、通信線から侵入してくるサージ電
圧に対し、この第２図に示すようか回路構成で防護を行
っている。In conventional communication equipment, protection is provided against surge voltages that enter through communication lines using a circuit configuration as shown in FIG.

第２図に示す４．５は縦電圧用防護素子で各通信線と大
地間に挿入され、３は横電圧用防護素子で通信線間に接
続され、６，７は通信機器内の電子回路の防護素子であ
る。In Figure 2, 4.5 is a vertical voltage protection element inserted between each communication line and the ground, 3 is a horizontal voltage protection element connected between the communication lines, and 6 and 7 are electronic circuits in communication equipment. It is a protective element.

８はトランス、８−１　、８−２・・・・・・８−６は
トランス８の端子、９は直流遮断用高耐圧コンデンサ、
１０は電子回路の送信回路、１１は電子回路の受信回路
、１２は電子回路の電源電圧端子、１３は電子回路の電
源アース、１４は避雷用グランド、１５．１６は通信線
との接続点端子、１７は送信信号の入力点、１８は受信
信号の出力点である。8 is a transformer, 8-1, 8-2...8-6 is a terminal of transformer 8, 9 is a high-voltage capacitor for DC cutoff,
10 is a transmission circuit of the electronic circuit, 11 is a reception circuit of the electronic circuit, 12 is a power supply voltage terminal of the electronic circuit, 13 is a power supply ground of the electronic circuit, 14 is a ground for lightning protection, and 15.16 is a connection point terminal with a communication line. , 17 is an input point for a transmitted signal, and 18 is an output point for a received signal.

そして、この第２図に示す回路構成の場合、通信線を通
る信号電圧が数Ｖ以下であれば、縦電圧用および横電圧
用防護素子４．５および３の放電開始電圧を低くするこ
とができる。よって、通信線に高電圧がかかつてもトラ
ンス８を介して電子回路側へ伝わる電圧は低くてすむた
め、電子回路部品が壊れる可能性は非常に低いので問題
は危い。In the case of the circuit configuration shown in FIG. 2, if the signal voltage passing through the communication line is several volts or less, it is possible to lower the discharge starting voltage of the protective elements 4.5 and 3 for vertical voltage and horizontal voltage. can. Therefore, even if a high voltage is applied to the communication line, the voltage transmitted to the electronic circuit side via the transformer 8 is low, and the possibility of breaking the electronic circuit components is extremely low, which is a dangerous problem.

しかし、実際の通信線には、情報信号だけでなく、給電
やシーリング電流等を通すために、また、ケーブルや通
信機器の試験用に直流あるいは低周波電圧が信号線間あ
るいは信号線と大地間に存在する□そのため、これらの
直流あるいは低周波電圧に対して反応しない縦電圧用お
よび横電圧用防護素子４，５および３を通信線に挿入し
なければいけない。However, in actual communication lines, not only information signals but also direct current or low-frequency voltages are passed between signal lines or between the signal line and the ground for power supply, ceiling current, etc., and for testing cables and communication equipment. Therefore, it is necessary to insert vertical voltage protection elements 4, 5, and 3 into the communication line, which do not react to these direct current or low frequency voltages.

〔発明が解決しようとする課題〕[Problem to be solved by the invention]

上述した従来の通信機器の防護回路では、通信線に高電
圧がかかった場合、トランスを介して電子回路側にも数
１０ｖの電源電圧に対して数倍の電圧がかかり、電子回
路に防護素子があっても常、源部に大電流が流れ、電子
回路部品を壊す可能性が高くなるという課題があった。In the conventional protection circuit for communication equipment described above, when a high voltage is applied to the communication line, a voltage several times higher than the power supply voltage of several tens of volts is applied to the electronic circuit via the transformer, and the protective element is applied to the electronic circuit. However, there was a problem in that large currents always flowed through the power source, increasing the possibility of damaging electronic circuit components.

〔課題を解決するための手段〕[Means to solve the problem]

本発明の通信機器の防護回路は、トランスを用いて平衡
伝送を行う通信機器の通信線側に接続されたトランスの
各巻線毎に、これらの巻線の端子間に発生する信号電圧
よりわずかに高い放電開始電圧をもつ防護素子を接続す
ることによシ、通信線から侵入してくる高電圧から通信
機器内部の電子回路を防護するようにしたものである。The protection circuit for communication equipment of the present invention has a voltage slightly lower than the signal voltage generated between the terminals of each winding of a transformer connected to the communication line side of a communication equipment that performs balanced transmission using a transformer. By connecting a protective element with a high firing voltage, the electronic circuit inside the communication device is protected from the high voltage that enters from the communication line.

〔作用〕[Effect]

本発明においては、通信線から侵入してくる高電圧から
通信機器内部の電子回路を防護する。In the present invention, electronic circuits inside communication equipment are protected from high voltages that enter from communication lines.

〔実施例〕〔Example〕

以下、図面に基づき本発明の実施例を詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

第１図は本発明による通信機器の防護回路の一実施例を
示す回路図である。FIG. 1 is a circuit diagram showing an embodiment of a protection circuit for communication equipment according to the present invention.

この第１図において第２図と同一符号のものは相当部分
を示し、１，２はトランス８の端子間に発生する信号電
圧よシわずかに高い放電開始電圧を持つ防護素子（横電
圧用防護素子）で、これらはトランス８を用いて平衡伝
送を行う通信機器の通信線側に接続されたトランス８の
各巻線毎、すなわち、トランス８の端子８−１．８−２
問およびトランス８の端子８−３．８−４間にそれぞれ
接続されている。In Fig. 1, the same numbers as in Fig. 2 indicate corresponding parts, and 1 and 2 are protective elements (transverse voltage protective These are for each winding of the transformer 8 connected to the communication line side of a communication device that performs balanced transmission using the transformer 8, that is, the terminals 8-1, 8-2 of the transformer 8.
and terminals 8-3 and 8-4 of the transformer 8, respectively.

つぎにこの第１図に示す実施例の動作を説明する０ まず、第１図に示す回路構成において、横電圧用防護素
子１，２は信号電圧程度の放電開始電圧を持ち、横電圧
用防護素子３は通信線上に存在する各種電流あるいは低
周波電圧を越える放電開始電圧および放電維持電圧を持
つ。そして、直流遮断用高耐圧コンデンサ９は横電圧用
防護素子３の放電開始電圧よシ高い電圧の耐力を持つ。Next, the operation of the embodiment shown in FIG. 1 will be explained. First, in the circuit configuration shown in FIG. The element 3 has a discharge starting voltage and a discharge sustaining voltage that exceed various currents or low frequency voltages existing on the communication line. The DC interrupting high voltage capacitor 9 has a voltage resistance higher than the discharge starting voltage of the lateral voltage protection element 3.

つぎに、通信線を介して通信線との接続点端子１５．１
６に同相の高電圧が侵入した場合を考える０ この場合、縦電圧用防護素子４，５が放電を開始する。Next, the connection point terminal 15.1 with the communication line is connected to the communication line via the communication line.
Let us consider the case where a high voltage of the same phase enters into 6. In this case, the vertical voltage protection elements 4 and 5 start discharging.

そして、この縦電圧用防護素子４，５の放電開始電圧に
「ばらつき」があった場合通信線との接続点端子１５．
１６の間に高電圧が発生する。この高電圧により、横電
圧用防護素子３が放電を開始するが、通信線上に存在す
る各種電圧以下には下げられない。このとき、トランス
８の端子８−１〜Ｂ−４間に高電圧が立つが、横電圧用
防護素子１，２があるために、直流遮断用高耐圧コンデ
ンサ９には高電圧が発生するが、トランス８の端子８−
１〜８−２問および端子８−３〜８−４間には低い電圧
しか発生しない。したがって、トランス８の端子８−５
〜８−６間に発生する電圧は、トランスの巻線比、端子
８−１〜Ｂ−２間・８−３〜８−４間の電圧およびトラ
ンスの周波数特性で決まるため、信号電圧よシわずかに
高い電圧が非常に短時間にしか発生しなくなる。そのた
めに、電子回路用防護素子６．７には小電流しか流れな
くなシ、電子回路部品を壊す可能性は非常に低くなる０ 同様に１通信線との接続点端子１５．１６に逆位相の高
電圧が侵入した場合も同様に横電圧用防護素子３−．−
直流遮断用高耐圧コンデンサ９の両端に高電圧が発生す
るが、横電圧用防護素子１，２があるために、トランス
８の端子８−１〜８−２間。If there is a "discrepancy" in the discharge starting voltage of the vertical voltage protective elements 4 and 5, the connection point terminal 15 with the communication line.
A high voltage is generated between 16 and 16. This high voltage causes the lateral voltage protection element 3 to start discharging, but the voltage cannot be lowered below the various voltages present on the communication line. At this time, a high voltage is generated between terminals 8-1 to B-4 of the transformer 8, but due to the presence of the lateral voltage protection elements 1 and 2, a high voltage is generated in the high voltage withstand voltage capacitor 9 for DC interruption. , terminal 8- of transformer 8
Only a low voltage is generated between questions 1 to 8-2 and terminals 8-3 and 8-4. Therefore, terminals 8-5 of transformer 8
The voltage generated between 8-6 and 8-6 is determined by the turns ratio of the transformer, the voltage between terminals 8-1 and B-2 and between 8-3 and 8-4, and the frequency characteristics of the transformer. A slightly higher voltage will only occur for a very short time. Therefore, only a small current flows through the electronic circuit protection element 6.7, and the possibility of damaging the electronic circuit components is extremely low.Similarly, the connection point terminal 15.16 with the 1 communication line Similarly, when a high voltage enters the lateral voltage protection element 3-. −
A high voltage is generated across the high-voltage capacitor 9 for DC interruption, but because of the lateral voltage protection elements 1 and 2, the voltage between the terminals 8-1 and 8-2 of the transformer 8 is high.

８−３〜８−４間、８−５〜８−６間に高電圧は発生し
々くなる。したがって、電子回路部品を壊す可能性は低
くなる。High voltages tend to occur between 8-3 and 8-4 and between 8-5 and 8-6. Therefore, the possibility of damaging electronic circuit components is reduced.

〔発明の効果〕〔Effect of the invention〕

以上説明したように本発明は、トランスを用いて平衡伝
送を行う通信機器の通信線側に接続されたトランスの各
巻線毎にこれらの巻線の端子間に発生する信号電圧よシ
わずかに高い放電開始電圧を持つ防雁素子を接続するこ
とによシ、通信線から通信機器に侵入してくる雷等の高
電圧に対し、通信機器の内部回路を係挿することができ
る効果がある。As explained above, the present invention has the advantage that the signal voltage generated between each winding of a transformer connected to the communication line side of a communication device that performs balanced transmission using a transformer is slightly higher than the signal voltage generated between the terminals of these windings. By connecting a wild goose protection element having a discharge starting voltage, there is an effect that the internal circuit of the communication device can be protected against high voltages such as those caused by lightning that enter the communication device from the communication line.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明による通信機器の防護回路の一実施例を
示す回路図、第２図は従来の通信機器の防護回路の一例
を示す回路図である。 １〜３・φ・・横電圧用防護素子、４，５・・−・縦電
圧用防護素子、６，７・・拳・電子回路用防護素子、８
・・・・トランス、９・・・・直流遮断用高耐圧コンデ
ンサ、１０・・・・電子回路の送信回路、１１・・・・
電子回路の受信回路、１２命・・φ電子回路の電源電圧
端子、１３・・・・電子回路の雷、源アース、１４・・
・・避雷用グランド、１５，１６・・―・通信線との接
続点端子、１７・・・−送信信号の入力点、１８・・・
・受信信号の出力点。FIG. 1 is a circuit diagram showing an embodiment of a protection circuit for a communication device according to the present invention, and FIG. 2 is a circuit diagram showing an example of a conventional protection circuit for a communication device. 1-3・φ・・Protective element for horizontal voltage, 4, 5・・・Protective element for vertical voltage, 6, 7・・・・・Protective element for electronic circuit, 8
...Transformer, 9...High voltage withstand capacitor for DC cutoff, 10...Electronic circuit transmission circuit, 11...
Receiving circuit of electronic circuit, 12 life... φ Power supply voltage terminal of electronic circuit, 13... Lightning of electronic circuit, source ground, 14...
... Ground for lightning protection, 15, 16... Connection point terminal with communication line, 17... - Input point of transmission signal, 18...
・Output point of received signal.

Claims (1)

【特許請求の範囲】[Claims] トランスを用いて平衡伝送を行う通信機器の、通信線側
に接続されたトランスの各巻線毎に、これらの巻線の端
子間に発生する信号電圧よりわずかに高い放電開始電圧
をもつ防護素子を接続することにより、通信線から侵入
してくる高電圧から通信機器内部の電子回路を防護し得
るようにしたことを特徴とする通信機器の防護回路。For communication equipment that performs balanced transmission using a transformer, a protective element with a discharge starting voltage slightly higher than the signal voltage generated between the terminals of these windings is installed for each winding of the transformer connected to the communication line side. 1. A protection circuit for communication equipment, characterized in that when connected, electronic circuits inside the communication equipment can be protected from high voltage intruding from communication lines.