JPH09232145A - Surge preventing transformer for signal cable and signal cable connection structure using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surge preventing transformer for a signal cable which prevents breakage of a semiconductor device due to surge and which can be inserted even in the middle of a communication line without causing impedance mismatch. SOLUTION: A primary and secondary coils, made of a high withstand voltage wire and the same in number, are formed around a ferrite core 1. The primary and secondary coils are respectively connected to connectors 5 and 6. A surge blocking transformer 16 is detachably attached between one end of a signal cable and a communication terminal device. A surge absorber is provided at the previous stage of the surge blocking transformer 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can reduce surge and noise intrusion from a signal cable by retrofitting it to a connector for connecting to a signal cable of a device for data communication. The present invention relates to a surge prevention transformer for signal cables.

[0002]

2. Description of the Related Art Conventionally, in a device for performing data communication such as a communication terminal device or a LAN (local area network), when a surge from a signal cable is considered (for example, outdoor overhead wiring), a surge absorber and a ground are provided. Has taken the method of bypassing the surge to the ground.

As one of the countermeasure methods, there is one as shown in FIG. In FIG. 3, the surge (or common mode noise) induced in the signal cable (data communication line) 103 is the external surge absorber 10 of the terminal device 102.
Assuming that the surge absorber is added to the surge absorber 4, the surge absorber operates when the surge (or common mode noise) voltage is higher than its operation start voltage (DC discharge start voltage in the case of arrester, varistor voltage in the case of varistor), and surge ( Or, common mode noise) current is discharged to the ground to reduce damage to the pulse transformer and semiconductor device in the subsequent stage. The level at which the surge absorber 104 reduces the surge (or common mode noise) is almost determined by the operation start voltage.
Countermeasures are taken by setting the value to a value lower than the surge withstand strength of the pulse transformer 105 and the semiconductor element in FIG.

Further, as seen when the outer coating of the signal cable is broken and a ground fault (contact with the ground) is seen, a closed circuit (ground loop) is formed through the ground, and noise from the signal cable is prevented from entering. Possible equipment was re-sequencing of signal cables.

[0005]

However, such a conventional signal cable has the following problems regarding surge and noise.

That is, regarding the surge, the above method has a problem that the operation start voltage of the surge absorber becomes too low, and the surge absorber is easily burned due to the leakage of the power line. Therefore, if the operation start voltage is raised to a value that does not operate due to leakage of power lines in order to prevent the surge absorber from being burnt out, the surge absorber will not operate and the leakage component of induced noise of power equipment and lightning surge will not occur. Even with such a low voltage surge, the insulation between the windings of the pulse transformer 105 shown in FIG. 3 may be destroyed, and the semiconductor element in the subsequent stage may be damaged.

On the other hand, in recent years, the data transmission speed has been increased, which means that a signal having a high frequency component passes through the signal cable. For the surge absorber used in this signal cable, a gas arrester that has a small stray capacitance and uses the characteristics of air discharge is used in order to prevent waveform distortion due to stray capacitance on the signal. For example, even if an arrester with a DC discharge start voltage (operation start voltage) of 90V operates due to a surge, it does not operate at 90V at the rising portion of the surge, but in reality, due to the delay characteristic that is the property of the gas arrester, Several hundred V (for example, 1.2 / 50 μs, which is a position delayed from 90 V,
When the voltage surge of 6 kV reaches about 700 V), the operation starts. Therefore, an impulse of several hundreds V may be applied to the device at the latter stage of the gas arrester. With the recent progress in fine processing and speeding up of semiconductor elements, there have been cases where they cannot withstand this impulse and are damaged.

Next, noise will be described. As described above, when the outer coating of the signal cable is broken and a ground loop is formed due to a ground fault, a noise current flows into the signal cable, causing noise interference. There is a problem in that the countermeasure for re-installing the signal cable is costly because of the construction work.

FIG. 11 is a graph showing the magnitudes of surge and noise corresponding to their frequencies. In the figure,
Reference numeral 111 indicates an induced lightning surge, and reference numeral 112 indicates a voltage remaining due to the delay characteristic of the arrester against the surge. Such a voltage causes damage to the semiconductor. 110 indicates a voltage corresponding to AC leakage. As described above, when the operation start voltage of the surge absorber is lowered, the surge absorber is burned out due to the leakage of the power line. Reference numeral 113 indicates common mode noise that exceeds the threshold of the semiconductor element.

The present invention has been made in view of such a problem, and prevents the semiconductor element from being destroyed by a surge, and does not cause the problem of impedance mismatch even if it is inserted in the middle of the communication line. The present invention provides a surge prevention transformer for a signal cable that can be used as well as a signal cable connection structure using the same.

[0011]

In order to solve the above problems, the present invention relates to a core having a high magnetic permeability, a primary winding made of high withstand voltage wire wound around the core at a winding ratio of 1: 1, and A surge prevention transformer for a signal cable, which is configured by a secondary winding and is arranged between a signal cable and a communication terminal device.

Since the primary and secondary windings made of high withstand voltage wire are used, the withstand voltage against surge is improved, and even if the operation start voltage of the surge absorber arranged in the preceding stage is increased, the semiconductor element in the succeeding stage due to the surge is It is possible to prevent destruction.

Further, since the turns ratio is 1 to 1, even if it is inserted in the input circuit, the adverse effect due to the impedance mismatch does not affect the circuit in the subsequent stage. Therefore, a circuit for matching the impedance is unnecessary.

As the high withstand voltage wire, for example, a wire covered with polytetrafluoroethylene can be used.

Preferably, a housing for accommodating the core around which the primary winding and the secondary winding are wound, and first and second fixed to the housing and connected to the primary winding and the secondary winding, respectively. And a second connector. This allows the signal cable surge prevention transformer of the present invention to be easily detachably attached to the target device.

Further, the present invention is a signal cable connection structure for connecting a signal cable for transmitting data to a communication terminal device, which comprises a pulse transformer provided at an input stage of the communication terminal device, a signal cable and a ground. A surge absorber provided therebetween, a core having a high magnetic permeability provided between the surge absorber and the pulse transformer, and a primary winding made of high withstand voltage wire wound around the core at a winding ratio of 1: 1. There is provided a signal cable connection structure comprising: a signal cable surge prevention transformer configured by a wire and a secondary winding.

The withstand voltage of the insulating coating of the winding of the signal cable surge prevention transformer is higher than that of the winding of the pulse transformer.

In the present invention, a transformer having a winding ratio of 1: 1 whose insulation strength is matched to the operation start voltage of the surge absorber and the voltage depending on the operation characteristics is preferably attached to the signal cable plug portion of the device. The signal (normal mode) can be transmitted with extremely low loss, and the surge (common mode) and the common mode noise current can be significantly increased in loss.

According to another aspect, the surge prevention transformer for a signal cable according to the present invention is formed by a transformer having an effect of reducing a common mode signal having a frequency of about 10 MHz or less to about ½ or less. It is arranged between the communication terminal device and the communication terminal device.

According to yet another aspect, the surge prevention transformer for a signal cable according to the present invention comprises a transformer having a withstand voltage higher than a withstand voltage of a pulse transformer incorporated in the communication terminal device, and the signal cable and the communication terminal device. It is characterized by being placed between and.

According to another aspect, the surge prevention transformer for a signal cable according to the present invention comprises a transformer having a withstand voltage (dielectric strength) of about 2 kV and is arranged between the signal cable and the communication terminal device. Is characterized by.

According to yet another aspect, a surge prevention transformer for a signal cable according to the present invention is a surge prevention transformer for a signal cable arranged between a signal cable and a communication terminal device, wherein A first connector that is attachable to and detachable from a plug portion of the communication terminal device, a second connector that is attachable and detachable to a tangential portion of the signal cable removed from the communication terminal device, and the first and second connectors It is characterized by being configured with a transformer connected in between.

According to another aspect, the signal cable connection structure according to the present invention suppresses a common mode signal having a frequency of about 10 MHz or less to about 1/2 or less, and has a winding ratio of 1 :.
By connecting a plurality of transformers of No. 1 and arranging them between the communication terminal device and the signal cable, the effect of suppressing the common-mode high-voltage surge is provided.

According to yet another aspect, the signal cable connection structure according to the present invention has a turn ratio M: N (M ≠ N) for suppressing a common mode signal having a frequency of about 10 MHz or less to about ½ or less. Multiple transformers are combined and connected so that the input impedance on one end side and the output impedance on the other end side are equal, and the transformer is placed between the communication terminal device and the signal cable to prevent common mode high voltage surges. It is characterized by having a suppressing effect. In this case, in addition to combinations such as M: N and N: M,
A combination such as 1: N and N: M and M: 1 may be used.

In still another surge arrester for signal cables according to the present invention, a plurality of transformers having a winding ratio of 1: 1 for suppressing a common mode signal having a frequency of about 10 MHz or less to about ½ or less are connected and connected. One is characterized by being built into a housing having connectors at both ends.

In the present specification, the term "communication terminal device" includes, in a broad sense, any terminal device connected to both ends of the signal cable, and also includes a terminal control device described later.

Specifically, this surge prevention transformer has one
Between the secondary winding and the secondary winding, it has an AC withstand voltage of 2.5 kV for 1 minute and, as shown in FIG. 4, a common mode noise removal characteristic up to a frequency of about 10 MHz. "Gain" on the vertical axis of Fig. 4
Indicates the current between secondary winding and ground / current between primary winding and ground.

The reason for exhibiting the noise elimination characteristics as shown in FIG. 4 will be described below. The transformer originally has a property of canceling out common mode signals (because of the same phase, same waveform and same level). Ideally, it should exhibit infinite removal (or attenuation or suppression) characteristics regardless of frequency. However, this is not the case, and the frequency characteristics as shown in FIG. 4 (removal characteristics (or attenuation rate,
Or, the characteristic that the suppression ratio) decreases and rises upward is because stray capacitance (capacitor component) exists between the primary winding and the secondary winding. Therefore, it can be said that the noise removal characteristic is a characteristic of the stray capacitance existing between the primary winding and the secondary winding.

Further, this noise elimination characteristic is guaranteed at a voltage within a range where the dielectric breakdown does not occur between the primary winding and the secondary winding of the transformer. (This is because when the insulation breakdown occurs, the mode in which the signal is transmitted from the primary winding to the secondary winding is not the stray capacitance mode but the insulation breakdown mode, and there is almost no attenuation.) The operation start voltage of the surge absorber If the voltage of the power line is lower than the peak value (140V at the peak value), the burning of the power line at the time of an electric leakage accident becomes a problem.
At the occurrence of the electric leakage accident, the potential of the voltage stabilizing ground 107 on the terminal control device 101 side rises to about 100 V, and the surge absorber 10 passes through the signal cable ground.
4, the signal cable is insulated (cut) between the primary winding and the secondary winding because the surge prevention transformer 16 is attached as shown in FIG. Therefore, the potential difference does not occur at both ends of the surge absorber 104, and the burnout is avoided (by the way, the voltage (peak value 140 V) due to the leakage accident is applied between the primary winding and the secondary winding of this surge prevention transformer. .
However, this surge prevention transformer will not be damaged due to dielectric strength). The surge absorber operates with a conventional operation start voltage against the surge generated in the signal cable, and reduces the surge (or common mode noise) current by discharging it to the ground. This surge prevention transformer has an effect of further reducing the surge reduced by the surge absorber.

The operation start voltage of the surge absorber is a voltage (eg 150
V: When the voltage is changed to a voltage that does not operate even at a peak value of 140 V of AC 100 V), a surge (or common mode noise) that does not cause the surge absorber to operate becomes a problem. Suppose now that in FIG. 3, the surge (less than 150 V) that does not cause the surge absorber to operate is the terminal device 102.
Assuming that the surge prevention transformer is attached as shown in FIG. 2, the common mode noise elimination characteristics reduce the damage. Therefore, in this case as well, damage to the pulse transformer 15 and the semiconductor in the subsequent stage is reduced. Can be prevented. Similarly, impulses of several hundreds of V due to the delay characteristics of the gas arrester are also reduced by the common mode noise removal characteristics to prevent damage. The surge absorber operates against a surge (or common mode noise) of 150 V or more generated in the signal cable, and reduces the surge (or common mode noise) current by discharging it to the ground. This surge prevention transformer has an effect of further reducing the surge reduced by the surge absorber.

As to the problem of common mode noise, as described above, the noise current that penetrates into the signal cable is reduced by the noise elimination characteristic between the primary winding and the secondary winding of the surge prevention transformer. Can prevent damage.

However, for the signal, the frequency band is 80 as shown in the frequency characteristics of the surge prevention transformer of FIG.
Since it is 0 Hz to 12 MHz, a signal having a frequency in this range can be transmitted without waveform distortion. In addition, compared with the coaxial cable, there is no need to amplify the signal because the attenuation is extremely small. The “gain” on the vertical axis in FIG. 5 indicates the secondary winding output current / primary winding input current.

[0033]

1 shows the configuration of a first embodiment of a surge prevention transformer according to the present invention.

In FIG. 1, reference numeral 16 indicates a surge prevention transformer. Reference numeral 1 is a high-permeability magnetic material such as a ferrite core used for the core of the surge prevention transformer 16. The shape is mainly a toroidal shape, but may be another shape. Reference numeral 2 is a high withstand voltage wire material in which the conductor wire 3 used for the winding of the surge prevention transformer 16 is covered with a high withstand voltage insulating material 4 of, for example, Teflon (polytetrafluoroethylene). The high withstand voltage wire 2 on the input side and the high withstand voltage wire 2 on the output side are arranged in parallel and wound around the ferrite core 1 the same number of times (here, 20 times) in one layer. That is, the turn ratio is 1: 1. The ferrite core 1 wound with the high withstand voltage wire 2 in this manner is used for the housing 7
It is housed in and is connected to the outside with connectors 5 and 6. In this example, the connector 5 is BNC-J (B
NC jack) connector, and connector 6 is BNC-
It is a P (BNC plug) connector. However, the type of connector (plug) is not limited to this. The housing 7 may be configured by molding with a resin while the transformer is included. The stray capacitance between the primary winding and the secondary winding of the surge prevention transformer 16 is about one-tenth that of the stray capacitance of the pulse transformer.

FIG. 2 shows a mode of use in which the surge prevention transformer 16 is mounted between the signal cable 13 and the device housing. The output signal from the pulse transformer 15 in the terminal control device 11 is output from the connector fixed to the housing. One end of the secondary winding of the pulse transformer 15 is grounded. Further, the surge prevention transformer 16 of FIG. 1 is detachably connected to the connector of the terminal control device 11. On the other hand, the pulse transformer 15 is also provided in the terminal device 12 that receives the signal output from the terminal control device 11, and the surge prevention transformer 16 is detachably connected to the connector fixed to this housing. A signal cable 13 is detachably connected between both transformers 16. The surge absorber 14 is connected to the front stage (on the signal cable 13 side) of the transformer 16 of the terminal device 12. The surge absorber 14 preferably has a relatively high operation starting voltage (for example, 150 V) so that the surge absorber 14 is not easily burnt out due to leakage of the power line.

In FIG. 2, when the leak voltage (about AC 100 V) of the power line generated on the terminal control device 11 side is applied via the signal cable 13 and the ground, this voltage is the primary voltage of the surge prevention transformer 16 and Add between secondary windings. For this voltage, surge prevention transformer 1
In 6, the voltage appearing on the secondary side due to the stray capacitance between the primary winding and the secondary winding is almost 0V.

Next, when a high-voltage induced lightning surge is induced in the signal cable 13, the voltage due to the surge absorption characteristic of the surge absorber 14 (usually 1 kV or less, 500 kH
z) is applied between the primary and secondary windings of the surge prevention transformer 16. Therefore, if the withstand voltage between the primary and secondary windings of the surge prevention transformer 16 is 1 kV or more (actually measured AC 2.5 kV for 1 minute), it is necessary and sufficient, and this also applies to the voltage appearing on the secondary side. (Voltage between the secondary winding and ground) is attenuated to about 3%. In addition, the surge prevention transformer 16 is connected to the signal cable 13
By providing it between the housing and the housing, an effect of attenuating high-frequency noise up to 10 MHz is exerted.

As described above, in the structure shown in FIG. 1, the toroidal ferrite core of high permeability magnetic material is
Primary and secondary made of high voltage insulation with Teflon coating
Transformer 1 formed by winding the next winding 20 times each
6 was used to measure the following surge blocking ability.

For this measurement, as shown in FIG. 6, a surge simulator 61 (Big Burn Co., 3230), an oscilloscope 62 (Tektronix 2430A), a current probe amplifier 63 (Tektronix AM).
503), a current probe 65 (AM503 manufactured by Tektronix) and a pressure tester (TO manufactured by Kikusui Electronics Co., Ltd.)
S5051) was used. A plotter H180 manufactured by Epson Corporation was used for printing out the waveform output of the oscilloscope 62. From the surge simulator 61, 1.2 (wave front length) / 50 (wave tail length) μs as shown in FIG.
The lightning voltage surge waveform of was output.

At the time of measurement, first, the surge simulator 6
The SURG terminal and the GND terminal of No. 1 were short-circuited, and the current flowing at this time was observed by the oscilloscope 62 via the current probe 65 and the amplifier 63. The results are shown in the graph of FIG.

Next, the surge prevention transformer 16 is connected as shown in FIG. 6, and the lightning surge voltage waveform of FIG.
6 between the primary and secondary windings. At this time, the primary side and the secondary side of the surge prevention transformer 16 were short-circuited in advance. The current flowing at this time was observed by the oscilloscope 62 via the current probe 65 and the amplifier 63. The graph of the result is shown in FIG. From this graph, it can be seen that the peak-to-peak current value is 14.5A. It can be seen that this current value is attenuated to almost 8% in comparison with the peak current value 190A in FIG.

This is a characteristic of the surge prevention transformer alone. In the configuration in which the pulse transformer is connected in the subsequent stage as shown in FIG. 2, how it can be considered will be described below. Considering the surge (common mode signal),
It looks like a circuit in which the stray capacitance between the primary winding and secondary winding of the surge prevention transformer and the stray capacitance between the primary winding and secondary winding of the pulse transformer are connected in series. In the case of such a circuit, the voltage applied to the pulse transformer is divided by the ratio of the impedance generated by the stray capacitance of each transformer. The impedance of stray capacitance (capacitor) is proportional to the inverse ratio of capacitance. Therefore, the impedance ratio is also the inverse ratio of the stray capacitances of the surge prevention transformer and the pulse transformer. Therefore, since the stray capacitance of the surge prevention transformer is about 1/10 of that of the pulse transformer, the impedance ratio is about 10: 1 and only about 1/10 of the voltage is applied to the pulse transformer.
(In addition, connecting n surge prevention transformers is nothing but reducing the stray capacitance to 1 / n. As a result, the impedance becomes n times higher.) Also, the primary of this surge prevention transformer 16 When the voltage waveform between the side winding and the secondary side winding was observed with the oscilloscope 62, a graph as shown in FIG. 9 was obtained. From this result, it is understood that the surge prevention transformer 16 withstands a lightning surge of 2.5 kV by its dielectric strength. This is because the voltage in FIG. 9 should break down to 0 V at the time of dielectric breakdown, but it is not so.

Further, when the dielectric strength between the primary and secondary windings of the surge prevention transformer 16 was tested by using a withstand voltage tester, it was confirmed that it could withstand an application of AC 2.5 kV for 1 minute. .

FIG. 12 is a graph showing the effect when the surge prevention transformer of FIG. 1 is used in combination with a surge absorber. It should be noted that the frequency on the horizontal axis of FIG. 12 is the same as that of FIG. 11, but the voltage on the vertical axis is scaled up. As can be seen from FIG. 12, both surge and noise are significantly reduced in the frequency range of 10 MHz or less.

FIG. 13 shows a second embodiment of the present invention. FIG. 13 shows a state in which n (n is a plurality) transformers 208 having a winding ratio of 1: 1 are connected and connected. This electrical configuration is as shown in FIG.

In FIG. 15, a plurality of such transformers 208 connected to each other are shown in FIG.
Instead of the signal cable 203 and the terminal control device 201
Between the signal cables 203 and the terminal device 202. In this example, in order to facilitate the handling and attachment / detachment of the individual transformers 208, the transformer is built in a housing in which female connectors 5 and male connectors 6 (BNC connectors are shown in the figure) are fixed at both ends. The transformer 208 is realized. Again,
The housing may include a transformer and be molded with resin. Further, a plurality of such transformers connected to each other may be built in a housing having connectors at both ends.

Assuming that a high-voltage induced lightning surge has occurred in the signal cable 203, the surge is bypassed to the ground by the external surge absorber 204, but in the case of an element having a delay characteristic such as an arrester. ,
At the steep rising part, only the operation delay (1k
V or so) Terminal device 202 side (or terminal control device 20)
It goes out to 1). However, the winding ratio mentioned above is 1: 1.
By connecting and arranging n transformers 208, the surge voltage that has come out is dispersed to 1 / n of the individual transformers. Since the insulation withstand voltage of each transformer is larger than the distributed surge voltage,
Dielectric breakdown does not occur. (Conversely, if the sum of the insulation withstand voltage of n transformers with a winding ratio of 1: 1 is larger than the surge voltage that has come out, no dielectric breakdown occurs.) As a method of connecting the transformers 208, FIG. In addition to the direct connection as shown, it may be performed via a relay data line.

Next, referring to FIG. 16, as a third embodiment of the present invention, a transformer 209 having a winding ratio of 1: N and a winding ratio N:
The external view when the transformer 210 of No. 1 is connected by the signal cable 211 whose characteristic impedance is the square of N of that of the signal cable 203 is shown. The transformers 209 and 210 may be, for example, so-called baluns (BALance to UNbalan).
ce) An existing transformer with a coaxial line pair impedance matching function called a transformer can be used.

In FIG. 16, the transformer 209 is temporarily assumed.
It is assumed that a signal flows from the left side of the to the right side of the transformer 210. Transformer 209 whose signal turns ratio is 1: N
After passing through, the output side impedance becomes the square (N squared) times the turns ratio of the input side impedance. The signal reaches the transformer 210 through the connection cable 211 having the characteristic impedance of the same value as the output impedance. When the signal passes through the transformer 210, the output side impedance becomes the square of the turns ratio (1 / N 2) times, and therefore has the same value as the impedance on the left side of the transformer 209. Therefore, the signal cable originally used is removed, and the transformer of the combination shown in FIG. 16 is arranged between the terminal control device 201 and the signal cable 203 and between the signal cable 203 and the terminal device 202. Also, without distortion due to impedance unmatching,
It becomes possible to transmit a signal. As a matter of course,
By combining two 1: N transformers, the total withstand voltage improves. If a plurality of combinations of the transformers of FIG. 16 are connected and used, the withstand voltage can be further improved.

In FIG. 16, since the transformers having the same winding ratio are used, two transformers (even number) are combined. However, for example, a transformer having a winding ratio of 1: N, N:
Any number of combinations may be used as long as the product of the winding ratio is 1, such as M transformer and M: 1 transformer.

Although the transformer 209 and the transformer 210 are connected by the signal cable 211 in FIG. 16, the transformer 209 and the transformer 210 may be connected by a connector.

The same effects as described above can be expected by these embodiments.

[0053]

As described above, according to the present invention,
Prevents burnout of the surge absorber at the time of electrical leakage, attenuates surges at levels that the surge absorber cannot operate, and also has the effect of attenuating high-frequency noise, and requires an extra circuit for impedance matching. Not.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a surge prevention transformer for a signal cable according to the present invention.

FIG. 2 is a diagram showing a utilization mode of the surge prevention transformer for the signal cable of FIG.

FIG. 3 is an explanatory diagram regarding a surge countermeasure of a conventional signal cable input circuit.

FIG. 4 is a graph showing measurement results of noise removal characteristics of the signal cable surge prevention transformer of FIG. 1.

5 is a graph showing measurement results of frequency characteristics of the signal cable surge prevention transformer of FIG. 1. FIG.

FIG. 6 is a diagram showing a configuration of a measurement system for measuring a surge blocking capability of the signal cable surge blocking transformer of FIG. 1;

FIG. 7 is a graph showing an output voltage waveform of the lightning surge simulator used for measuring the surge blocking capability.

FIG. 8 is a graph showing an output current waveform of the lightning surge simulator of FIG.

9 is a graph showing voltage waveforms between the primary and secondary windings of the transformer when a surge is applied to the signal cable surge prevention transformer of FIG. 1. FIG.

10 is a graph showing current waveforms between the primary and secondary windings of the transformer when a surge is applied to the signal cable surge prevention transformer of FIG.

FIG. 11 is a graph showing the magnitudes of surge and noise corresponding to their frequencies.

FIG. 12 is a graph showing an effect when the signal cable surge prevention transformer of FIG. 1 is used in combination with a surge absorber.

FIG. 13 is a diagram showing a second embodiment of a signal cable surge prevention transformer according to the present invention.

FIG. 14 is a circuit diagram showing an electrical configuration of the surge suppression transformer connected and connected in FIG.

FIG. 15 is a diagram showing a configuration in which the surge blocking transformer connected in FIG. 13 is arranged between a signal cable and a terminal control device (and a terminal device) instead of the surge blocking transformer of FIG. 1.

FIG. 16 is a diagram showing a third embodiment of a signal cable surge prevention transformer according to the present invention.

[Explanation of symbols]

1 ... Ferrite core, 2 ... High-voltage wire, 3 ... Conductor wire, 4 ...
High-voltage insulating material, 5 ... BNC-J (BNC jack) connector, 6 ... BNC-P (BNC plug) connector, 1
1, 101, 201 ... Terminal control device, 12, 102, 2
02 ... Terminal device, 13, 103, 203 ... Signal cable (data communication line), 14, 104, 204 ... External surge absorber, 15, 105, 205 ... Pulse transformer, 16 ... Surge prevention transformer, 17, 107 ... Voltage Stabilizing ground, 208 ... Turn ratio 1: 1 transformer, 209
... turn ratio 1: N transformer, 210 ... turn ratio N: 1 transformer, 211 ... data communication line.

Front Page Continuation (72) Inventor Hiromi Yamaguchi 504, Shinanomachi, Totsuka-ku, Yokohama, Kanagawa 2 Hitachi Electronic Services Co., Ltd. (72) Inventor Susumu Ebihara 504, Shinano-machi, Totsuka-ku, Yokohama, Kanagawa 2 Hitachi Electronics Service Co., Ltd. In the company

Claims (13)

[Claims] 1. A high-permeability core and a winding ratio of 1: 1 to the core.
A surge prevention transformer for a signal cable, comprising a primary winding and a secondary winding made of a high withstand voltage wire wound around, and arranged between a signal cable and a communication terminal device. 2. The surge prevention transformer for a signal cable according to claim 1, wherein the high withstand voltage wire is a conductor covered with polytetrafluoroethylene. 3. A housing for accommodating a core around which the primary winding and the secondary winding are wound, and a first and a first fixed to the housing and connected to the primary winding and the secondary winding, respectively. The surge prevention transformer for signal cables according to claim 1 or 2, further comprising two connectors. 4. A signal cable connection structure for connecting a signal cable for transmitting data to a communication terminal device, the signal transformer being provided between a pulse transformer provided at an input stage of the communication terminal device and the signal cable and ground. A surge absorber, a high-permeability core provided between the surge absorber and the pulse transformer, and a primary winding and a secondary winding made of high withstand voltage wire wound around the core at a winding ratio of 1: 1. A signal cable connection structure comprising: a surge prevention transformer for signal cable, which is composed of a winding wire. 5. The signal cable connecting structure according to claim 4, wherein the withstand voltage of the insulating coating of the winding of the signal cable surge prevention transformer is higher than that of the winding of the pulse transformer. 6. A signal comprising a transformer having an effect of reducing a common mode signal having a frequency of about 10 MHz or less to about ½ or less, and arranged between a signal cable and a communication terminal device. Surge prevention transformer for cables. 7. A surge arrester for a signal cable, comprising a transformer having a withstand voltage higher than a withstand voltage of a pulse transformer built in the communication terminal device, and being arranged between the signal cable and the communication terminal device. Trance. 8. A surge prevention transformer for a signal cable, comprising a transformer having a withstand voltage (dielectric strength) of about 2 kV and arranged between a signal cable and a communication terminal device. 9. The surge prevention transformer for a signal cable according to claim 6, wherein the surge prevention transformer is arranged inside the communication terminal device. 10. A surge prevention transformer for signal cables arranged between a signal cable and a communication terminal device,
A first connector detachably attached to a plug portion of the communication terminal device from which the signal cable is detached, a second connector detachable to a contact portion of the signal cable detached from the communication terminal device, and And a transformer connected between the second connector and a surge prevention transformer for signal cables. 11. A turns ratio of 1: 1 for suppressing a common mode signal having a frequency of about 10 MHz or less to about 1/2 or less.
A signal cable connection structure characterized in that a plurality of transformers of (1) are connected and connected, and are arranged between a communication terminal device and a signal cable to have a suppressing effect on a common mode high voltage surge. 12. A turns ratio M: N for suppressing a common mode signal having a frequency of about 10 MHz or less to about ½ or less.
By connecting a plurality of (M ≠ N) transformers so that the input impedance on one end side and the output impedance on the other end side are equal and arranging them between the communication terminal device and the signal cable. , A signal cable connection structure characterized by suppressing the high-voltage surge of common mode. 13. A turns ratio of 1: 1 for suppressing a common mode signal having a frequency of about 10 MHz or less to about ½ or less.
A surge prevention transformer for signal cables, characterized in that a plurality of transformers of (1) are connected and connected to each other and are built into a housing having connectors at both ends.