JPH05316184A - Lightning resistance test method for telephone set with extension function - Google Patents

Lightning resistance test method for telephone set with extension function

Info

Publication number
JPH05316184A
JPH05316184A JP4122173A JP12217392A JPH05316184A JP H05316184 A JPH05316184 A JP H05316184A JP 4122173 A JP4122173 A JP 4122173A JP 12217392 A JP12217392 A JP 12217392A JP H05316184 A JPH05316184 A JP H05316184A
Authority
JP
Japan
Prior art keywords
impedance
ground
line
earth
lightning
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
Application number
JP4122173A
Other languages
Japanese (ja)
Other versions
JP2751730B2 (en
Inventor
Masaharu Sato
正治 佐藤
Takeshi Ideguchi
健 井手口
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Telegraph and Telephone Corp
Original Assignee
Nippon Telegraph and Telephone Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nippon Telegraph and Telephone Corp filed Critical Nippon Telegraph and Telephone Corp
Priority to JP4122173A priority Critical patent/JP2751730B2/en
Publication of JPH05316184A publication Critical patent/JPH05316184A/en
Application granted granted Critical
Publication of JP2751730B2 publication Critical patent/JP2751730B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00Adapting or protecting infrastructure or their operation

Abstract

PURPOSE:To execute the lightning test excellent fault reproducibility by connecting an impedance equivalent to an earth feedback circuit while taking the earth feedback circuit of an extension cable together with a subscriber line and a power source line into consideration. CONSTITUTION:An impedance element 11 having an impedance equivalent to earth return impedance is inserted to a power source earth line 48, a resistor 12 simulating an earth resistance of a 3rd class ground to a 3rd class connection line 49 and an impedance element 13 equivalent to an earth feedback impedance of an extension cable is connected between the extension cable 43 and ground. Furthermore, since the resistor 12 simulates the 3rd class grounding for protection of a human body, when the device adopts a double insulation structure, the connection is not required because no frame ground terminal is used, and when the double insulation structure is not adopted, the earth connection is required. Furthermore, the most severe condition for the ground resistance of the 3rd class ground has the resistance of 100 ohms by taking the potential rise in the telephone set frame into account.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は、雷サージに対する内線
機能付電話機の耐力を試験する内線機能付電話機の耐雷
試験方法に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning resistance test method for a telephone with an extension function for testing the proof strength of the telephone with an extension function against a lightning surge.

【0002】[0002]

【従来の技術】図4は、内線機能付電話機に対する従来
の耐雷試験回路の構成を示す図である。
2. Description of the Related Art FIG. 4 is a diagram showing a configuration of a conventional lightning protection test circuit for a telephone with an extension function.

【0003】図において、内線機能を有する主電話機4
0には、加入者線41を介して交換機を擬似した加入者
回路42が接続され、内線ケーブル43を介して副電話
器44が接続される。また、主電話機40には、電源ス
イッチ45,絶縁トランス46および電源線47を介し
てAC100 Vの電源が供給される。電源線47の一線は
電源接地線48を介して接地され、主電話機40のフレ
ームは第三種接地線49を介して接地される。このよう
な電話機の基本構成に対して、一端が接地された雷サー
ジ発生器50は、結合回路51を介して加入者線41に
雷サージを印加する。なお、交換機を擬似した加入者回
路42はバッテリーで動作させ、接地に対して十分に絶
縁されているものとする。
In the figure, a main telephone 4 having an extension function
A subscriber circuit 42 simulating an exchange is connected to 0 through a subscriber line 41, and a sub telephone 44 is connected through an extension cable 43. Further, the main telephone 40 is supplied with power of AC 100 V through a power switch 45, an insulating transformer 46 and a power line 47. One line of the power line 47 is grounded via a power ground line 48, and the frame of the main telephone 40 is grounded via a third type ground line 49. In contrast to the basic configuration of such a telephone, the lightning surge generator 50, one end of which is grounded, applies a lightning surge to the subscriber line 41 via a coupling circuit 51. The subscriber circuit 42 simulating the exchange is operated by a battery and is sufficiently insulated from the ground.

【0004】この耐雷試験回路では、まず加入者回路4
2を動作させて主電話機40の加入者線41側を給電状
態にするとともに、電源スイッチ45をオンにしてAC
100Vの電源供給系も給電状態とする。次に、雷サージ
発生器50で発生させた雷サージを結合回路51を介し
て加入者線41に印加する。加入者線41に印加された
雷サージは、加入者回路42側からの流出経路がないの
で、すべて主電話機40に流入し、電源接地線48およ
び第三種接地線49を経由して接地に流出し、雷サージ
発生器50に戻る。
In this lightning protection test circuit, first, the subscriber circuit 4
2 is operated to set the subscriber line 41 side of the main telephone 40 to the power supply state, and the power switch 45 is turned on to turn on the AC.
The 100V power supply system is also in the power supply state. Next, the lightning surge generated by the lightning surge generator 50 is applied to the subscriber line 41 via the coupling circuit 51. Since the lightning surge applied to the subscriber line 41 does not have an outflow route from the subscriber circuit 42 side, it all flows into the main telephone 40 and is grounded via the power supply ground line 48 and the third type ground line 49. It flows out and returns to the lightning surge generator 50.

【0005】[0005]

【発明が解決しようとする課題】ところで、従来の耐雷
試験回路では加入者線41から雷サージを印加している
が、流出経路になるのは電源接地線48および第三種接
地線49であり、内線系には雷サージ電流が回り込まな
い構成になっている。すなわち、このような回路で耐雷
試験を実施しても、主電話機40の内線系インタフェー
ス回路や副電話器44に雷サージ電流が流れることはな
かった。
By the way, in the conventional lightning protection test circuit, the lightning surge is applied from the subscriber line 41, but the power supply ground line 48 and the third type ground line 49 are the outflow paths. , The extension system is configured so that the lightning surge current does not flow into it. That is, even if the lightning protection test is performed with such a circuit, no lightning surge current flows in the extension interface circuit of the main telephone 40 or the sub telephone 44.

【0006】しかし、内線機能付電話機が一般家庭や工
場,事務所などの実環境下で雷による被害を受けたとき
の故障状況をみると、故障が最も多い箇所は主電話機4
0の内線系インタフェース回路であった。すなわち、従
来の耐雷試験回路の構成では実際の現場の状況と耐雷試
験結果が一致せず、耐雷試験による故障再現性が極めて
低い状況にあった。
However, when looking at the failure situation when the telephone with extension function is damaged by lightning in a real environment such as a general home, a factory, an office, etc., the most frequent location is the main telephone 4
It was 0 extension interface circuit. That is, in the conventional lightning protection test circuit configuration, the actual situation at the site does not match the lightning protection test result, and the failure reproducibility due to the lightning protection test is extremely low.

【0007】本発明は、現場の実態に即して良好な故障
再現性を得ることができる内線機能付電話機の耐雷試験
方法を提供することを目的とする。
It is an object of the present invention to provide a lightning protection test method for a telephone with an extension function, which can obtain good failure reproducibility according to the actual situation at the site.

【0008】[0008]

【課題を解決するための手段】本発明は、主電話機に電
源を供給する電源線の一線と接地との間に、電源線の大
地帰路インピーダンスに相当する第一のインピーダンス
素子を接続し、内線ケーブルと接地との間に、内線ケー
ブルの大地帰路インピーダンスに相当する第二のインピ
ーダンス素子を接続して耐雷試験を行うことを特徴とす
る。
According to the present invention, a first impedance element corresponding to a ground return impedance of a power supply line is connected between one line of a power supply line for supplying power to a main telephone and ground, and an extension line is connected. A lightning resistance test is performed by connecting a second impedance element corresponding to the earth return impedance of the extension cable between the cable and the ground.

【0009】[0009]

【作用】本発明では、電源線の接地をより実態に近いイ
ンピーダンスで接地するとともに、従来は接地に対して
絶縁されていた内線ケーブルもその大地帰路インピーダ
ンスで接地することにより、内線機能付電話機の実際の
設置状況に近い電気回路条件を設定することができる。
したがって、耐雷試験において内線機能付電話機の実際
の雷害状況の再現を図ることができる。
In the present invention, the ground of the power supply line is grounded with a more realistic impedance, and the extension cable, which has been conventionally insulated from the ground, is also grounded with the earth return impedance, so that the extension function telephone It is possible to set electrical circuit conditions close to the actual installation conditions.
Therefore, it is possible to reproduce the actual lightning damage situation of the telephone with extension function in the lightning resistance test.

【0010】[0010]

【実施例】図1は、本発明の耐雷試験方法を実現する耐
雷試験回路の実施例構成を示す図である。
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an embodiment configuration of a lightning protection test circuit for implementing the lightning protection test method of the present invention.

【0011】図において、主電話機40,加入者線4
1,加入者回路42,内線ケーブル43,副電話器4
4,電源スイッチ45,絶縁トランス46,電源線4
7,電源接地線48,第三種接地線49,雷サージ発生
器50および結合回路51は、従来のものと同様の配置
である。
In the figure, main telephone 40 and subscriber line 4
1, subscriber circuit 42, extension cable 43, sub telephone 4
4, power switch 45, isolation transformer 46, power line 4
7, the power supply ground line 48, the third type ground line 49, the lightning surge generator 50, and the coupling circuit 51 have the same arrangement as the conventional one.

【0012】本発明の特徴とするところは、本実施例で
は電源接地線48にその大地帰路インピーダンスに相当
するインピーダンス素子11を挿入し、第三種接地線4
9に第三種接地の接地抵抗を模擬する抵抗器12を挿入
し、内線ケーブル43と接地間に内線ケーブルの大地帰
路インピーダンスに相当するインピーダンス素子13を
接続する構成にある。
A feature of the present invention is that in this embodiment, the impedance element 11 corresponding to the ground return path impedance is inserted in the power source ground line 48, and the third type ground line 4 is inserted.
A resistor 12 simulating the grounding resistance of the third type ground is inserted in 9 and an impedance element 13 corresponding to the ground return impedance of the extension cable is connected between the extension cable 43 and the ground.

【0013】なお、抵抗器12は、人体保安用の第三種
接地を模擬するものであるので、機器が二重絶縁構造に
なっている場合には、フレームの接地端子がないのでそ
の接続は不要であるが、二重絶縁構造になっていない機
器の場合には接続する必要がある。また、この第三種接
地の接地抵抗は、電気設備技術基準により 100Ω以下と
定められているので、抵抗器12の抵抗値は0〜 100Ω
の範囲をとることができるが、電話機フレームの電位上
昇を考慮すると抵抗値は 100Ωとするのが最も厳しい条
件となる。
Since the resistor 12 simulates the third type grounding for human body safety, when the device has a double insulation structure, the grounding terminal of the frame is not provided, so that the connection is not made. It is not necessary, but it must be connected if the device does not have a double insulation structure. In addition, the ground resistance of this type 3 ground is defined as 100Ω or less according to the electrical equipment technical standard, so the resistance value of the resistor 12 is 0 to 100Ω.
However, considering the rise in the potential of the telephone frame, the most severe condition is to set the resistance value to 100Ω.

【0014】電源接地線48に挿入されるインピーダン
ス素子11は、高周波の妨害波の場合と同様に、50Ω/
50μHの擬似電源回路網を用いてもよいが、電源線47
が雷サージ電流の最も流出しやすい経路であることか
ら、短絡状態にしておくことが最も厳しい条件となる。
The impedance element 11 inserted in the power ground line 48 has a resistance of 50 Ω / similar to the case of the high frequency interference wave.
Although a pseudo power supply network of 50 μH may be used, the power supply line 47
Is the path through which lightning surge currents are most likely to flow out, so the shortest condition is the most severe condition.

【0015】内線ケーブル43に接続されるインピーダ
ンス素子13は、大地帰路回路の抵抗r(Ω/km)、大
地帰路回路のインダクタンスl(H/km)、大地帰路回
路の漏洩量g(モー/km)、大地帰路回路の静電容量c
(F/km)とすると、その特性インピーダンスZ0 が、 Z0 ={(r+jωl)/(g+jωc)}1/2 …(1) となる。
The impedance element 13 connected to the extension cable 43 includes a ground return circuit resistance r (Ω / km), a ground return circuit inductance l (H / km), and a ground return circuit leakage amount g (mho / km). ), Capacitance of earth return circuit c
If (F / km), the characteristic impedance Z 0 is Z 0 = {(r + jωl) / (g + jωc)} 1/2 (1)

【0016】雷サージ電圧の周波数範囲が数10kHz〜数
100kHzであり、この周波数帯域では、r<jωl,g
=0の関係があるので、 (1)式は Z0 =(1/c)1/2 +r/jω2(lc)1/2 …(2) と近似することができる。この (2)式は、図2に示すよ
うに、(1/c)1/2 の値の抵抗Rと、2(lc)1/2/r
の値のコンデンサCの直列回路のインピーダンスで近似
できることを示している。
Frequency range of lightning surge voltage is from several tens of kHz to several
100 kHz, and in this frequency band, r <jωl, g
Since there is a relation of = 0, the equation (1) can be approximated as Z 0 = (1 / c) 1/2 + r / jω2 (lc) 1/2 (2). As shown in FIG. 2, the equation (2) is obtained by using the resistance R having a value of (1 / c) 1/2 and 2 (lc) 1/2 / r.
It can be approximated by the impedance of the series circuit of the capacitor C having the value of.

【0017】宅内あるいは構内系には、主に導体径 0.4
〜0.65mmφのケーブルが用いられるので、 (2)式のr,
l,cの値は、それぞれ 53 〜 139(Ω/km)、0.3 〜
0.7(H/km)、 50 〜 100(nF/km)の範囲にある
と考えられる。
Conductor diameters of 0.4
Since a cable of ~ 0.65mmφ is used, r,
The values of l and c are 53-139 (Ω / km), 0.3-
It is considered to be in the range of 0.7 (H / km) and 50-100 (nF / km).

【0018】また、 (2)式の関係から図2の抵抗Rおよ
びコンデンサCの値を求めると、それぞれ 50 〜 120
(Ω)、0.08〜 0.2(μF)の範囲になる。ここで、本
発明を実際の電話機に適用したときの実験結果を図3に
示す。内線機能付電話機としてA,B,Cの3種類のホ
ームテレホンを選定し、それぞれ内線系に副電話機1台
とドアホン1台を接続して図1に示すような耐雷試験回
路を構成し、内線ケーブルの大地帰路インピーダンスと
して図2に示す回路を接続した場合と、接続しない場合
の雷サージ耐力を比較した。なお、接続時の雷サージ耐
力をとし、無接続(絶縁)時の雷サージ耐力をとす
る。
Further, when the values of the resistor R and the capacitor C of FIG. 2 are obtained from the relationship of the equation (2), they are 50 to 120, respectively.
(Ω), in the range of 0.08 to 0.2 (μF). Here, FIG. 3 shows an experimental result when the present invention is applied to an actual telephone. Three types of home telephones, A, B, and C, are selected as telephones with extension functions, and one auxiliary telephone and one intercom are connected to each extension system to configure a lightning protection test circuit as shown in Fig. 1, and an extension cable As a ground return impedance of, the lightning surge withstand capability was compared between the case where the circuit shown in FIG. 2 was connected and the case where it was not connected. The resistance to lightning surges when connected and the resistance to lightning surges when not connected (insulated).

【0019】実験に使用した電話機A,Bは、加入者線
41から電源線47間のみに雷サージ対策を実施し、内
線系インタフェース回路は未対策とし、従来の耐雷試験
で20〜30(kV)以上の雷サージ耐力を有していたが、
現場に導入されると雷による故障が頻発した電話機であ
る。一方、電話機Cは、加入者線41から電源線47間
および内線系インタフェース回路の両方について雷サー
ジ対策を実施しておいたもので、現場に導入後も雷によ
る故障が少なかった電話機である。
In the telephones A and B used in the experiment, lightning surge countermeasures are implemented only between the subscriber line 41 and the power line 47, and the extension interface circuit is not treated. In the conventional lightning resistance test, 20 to 30 (kV) ) It had the lightning surge resistance above,
It was a telephone that was frequently damaged by lightning when it was introduced to the site. On the other hand, the telephone set C is a telephone set which has taken measures against lightning surges both between the subscriber line 41 and the power supply line 47 and in the extension system interface circuit, and has been less prone to damage due to lightning even after being introduced to the site.

【0020】本実験で使用したインピーダンス素子13
は、最もインピーダンスが小さく電流が流れやすくなる
条件を考慮し、R=50(Ω)、C=0.2(μF)を選定し
た。なお、この実験に用いたホームテレホンはいずれも
二重絶縁構造になっているので、第三種接地は不要であ
り、抵抗器12を接続しないで実験を行った。また、電
源接地線48に挿入するインピーダンス素子11は、最
も厳しい状態を想定して短絡状態にした。
Impedance element 13 used in this experiment
, R = 50 (Ω) and C = 0.2 (μF) were selected in consideration of the condition that the impedance is smallest and the current easily flows. Since all the home telephones used in this experiment have the double insulation structure, the third type grounding is unnecessary, and the experiment was conducted without connecting the resistor 12. Further, the impedance element 11 to be inserted into the power supply ground line 48 is short-circuited assuming the most severe condition.

【0021】本実験の結果は、内線ケーブル43にイン
ピーダンス素子13を接続しない場合は、電話機A,
B,Cともに20〜30(kV)の雷サージ耐力を有してい
るが、インピーダンス素子13を接続すると、電話機
A,Bは4〜5(kV)の雷サージ耐力しかなくなり、
電話機Cに比べて耐力が約1/5に低下することがわか
る。雷サージ印加時の故障状況は、電話機A,B,Cと
もにインピーダンス素子13を接続しない場合はフュー
ズ断など主に電源回路の故障であるが、インピーダンス
素子13を接続すると内線系インタフェース回路の故障
が多くなり、現場の故障状況とよく一致することが確認
された。
The results of this experiment show that when the impedance element 13 is not connected to the extension cable 43, the telephone set A,
Both B and C have a lightning surge resistance of 20 to 30 (kV), but when the impedance element 13 is connected, the telephones A and B have only a lightning surge resistance of 4 to 5 (kV),
It can be seen that the yield strength is reduced to about 1/5 as compared with the telephone C. The failure condition at the time of applying the lightning surge is mainly a power supply circuit failure such as a fuse disconnection when the impedance elements 13 are not connected to all the telephones A, B, and C. However, when the impedance element 13 is connected, the extension interface circuit fails. It was confirmed that the number increased and that it was in good agreement with the on-site failure situation.

【0022】このことから、内線機能付電話機の場合
は、内線ケーブル43の大地帰還回路も考慮し、それに
相当するインピーダンスの接続が不可欠であることがわ
かる。
From this, it is understood that in the case of a telephone with an extension function, it is necessary to consider the ground return circuit of the extension cable 43 and connect an impedance corresponding to it.

【0023】[0023]

【発明の効果】以上説明したように本発明は、耐雷試験
を実施するに当たり、雷サージの直接の流入および流出
経路となる加入者線や電源線とともに、内線ケーブルの
大地帰還回路も考慮してそれに相当するインピーダンス
を接続しているので、回路構成が従来構成に比べて現場
の設置状態に近くなり、故障再現性の非常に良好な耐雷
試験を行うことができる。
As described above, in carrying out the lightning resistance test, the present invention takes into consideration the ground return circuit of the extension cable as well as the subscriber line and the power line which are the direct inflow and outflow paths of the lightning surge. Since the impedance corresponding to that is connected, the circuit configuration becomes closer to the installation state at the site compared to the conventional configuration, and a lightning resistance test with extremely good failure reproducibility can be performed.

【0024】また、本耐雷試験方法は雷サージに限ら
ず、伝導妨害波等のイミュニティ試験を行う際の試験方
法にも応用することが可能である。
Further, the present lightning resistance test method can be applied not only to lightning surge, but also to a test method for conducting an immunity test such as conducted interference waves.

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明の耐雷試験方法を実現する耐雷試験回路
の実施例構成を示す図。
FIG. 1 is a diagram showing an embodiment configuration of a lightning protection test circuit for realizing a lightning protection test method of the present invention.

【図2】内線ケーブルに接続するインピーダンス素子1
3の等価回路図。
FIG. 2 Impedance element 1 connected to an extension cable
3 is an equivalent circuit diagram.

【図3】本発明を実際の電話機に適用したときの実験結
果を示す図。
FIG. 3 is a diagram showing an experimental result when the present invention is applied to an actual telephone.

【図4】内線機能付電話機に対する従来の耐雷試験回路
の構成を示す図。
FIG. 4 is a diagram showing a configuration of a conventional lightning protection test circuit for a telephone with an extension function.

【符号の説明】[Explanation of symbols]

11 インピーダンス素子 12 抵抗器 13 インピーダンス素子 40 主電話機 41 加入者線 42 加入者回路 43 内線ケーブル 44 副電話器 45 電源スイッチ 46 絶縁トランス 47 電源線 48 電源接地線 49 第三種接地線 50 雷サージ発生器 51 結合回路 11 Impedance element 12 Resistor 13 Impedance element 40 Main telephone 41 Subscriber line 42 Subscriber circuit 43 Extension cable 44 Sub telephone 45 Power switch 46 Insulation transformer 47 Power line 48 Power ground line 49 Third type ground line 50 Lightning surge occurrence Device 51 coupling circuit

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 内線ケーブルを介して副電話機が接続さ
れる内線機能付電話機に対して、加入者線から雷サージ
を印加してその耐力を試験する耐雷試験方法において、 前記主電話機に電源を供給する電源線の一線と接地との
間に、電源線の大地帰路インピーダンスに相当する第一
のインピーダンス素子を接続し、 前記内線ケーブルと接地との間に、内線ケーブルの大地
帰路インピーダンスに相当する第二のインピーダンス素
子を接続して耐雷試験を行うことを特徴とする内線機能
付電話機の耐雷試験方法。
1. A lightning protection test method for applying a lightning surge from a subscriber line to test the proof strength of a telephone with an extension function, to which a sub telephone is connected via an extension cable. A first impedance element corresponding to the earth return impedance of the power supply line is connected between one line of the power supply line to be supplied and the ground, and corresponds to the earth return impedance of the extension cable between the extension cable and the ground. A lightning protection test method for a telephone with extension function, comprising performing a lightning protection test by connecting a second impedance element.
JP4122173A 1992-05-14 1992-05-14 Lightning resistance test method for telephones with extension functions Expired - Lifetime JP2751730B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4122173A JP2751730B2 (en) 1992-05-14 1992-05-14 Lightning resistance test method for telephones with extension functions

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4122173A JP2751730B2 (en) 1992-05-14 1992-05-14 Lightning resistance test method for telephones with extension functions

Publications (2)

Publication Number Publication Date
JPH05316184A true JPH05316184A (en) 1993-11-26
JP2751730B2 JP2751730B2 (en) 1998-05-18

Family

ID=14829382

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4122173A Expired - Lifetime JP2751730B2 (en) 1992-05-14 1992-05-14 Lightning resistance test method for telephones with extension functions

Country Status (1)

Country Link
JP (1) JP2751730B2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6426924B1 (en) 1993-04-12 2002-07-30 Olympus Optical Co., Ltd. Apparatus for recording and/or reproducing information and/or from optical information record disk
WO2022170592A1 (en) * 2021-02-10 2022-08-18 华为技术有限公司 Outdoor electronic device having function of non-grounded lightning protection, and power source module

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6426924B1 (en) 1993-04-12 2002-07-30 Olympus Optical Co., Ltd. Apparatus for recording and/or reproducing information and/or from optical information record disk
WO2022170592A1 (en) * 2021-02-10 2022-08-18 华为技术有限公司 Outdoor electronic device having function of non-grounded lightning protection, and power source module

Also Published As

Publication number Publication date
JP2751730B2 (en) 1998-05-18

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