JPH0412764Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a safety device that improves the ability to absorb surges induced in transmission lines such as communication lines.

[Conventional technology]

FIG. 3 is a diagram showing a surge protection circuit for a repeater connected to a transmission line using a conventional balanced line.
1, 101' and the output terminal 102, 1 on the output side
02' through series resistors 106, 106' and 107, 107', respectively, and input transformer 103 and output transformer 104, and input terminal 10
1,101'
9 and the midpoint of this discharge coil 109 is the varistor 1
10 to ground 117, a second lightning arrester circuit consisting of a varistor 113 connected between both terminals of the primary winding of the input transformer 103, and output terminals 102 and 102'. A drain coil 111 is connected between the drain coil 111 , a third lightning arrester circuit that connects the middle point of the drain coil 111 to ground 118 via a varistor 112 , and both terminals of the secondary line of the output transformer 104 . A fourth lightning arrester circuit consisting of a varistor 114, a resistor 116 and a Zener diode 108 connected between the midpoint of the primary winding of the input transformer 103 and the midpoint of the secondary winding of the output transformer 104. and an overvoltage protection element connected in parallel to this series circuit, such as a gas arrester 1.
15 is shown.
Note that the Zener diode 108 is connected to the power supply section of the repeater 105.

In the security device shown in FIG.
The surge that entered from 1,101' is discharged from the discharge coil 1.
09 and ground 117 via varistor 110
flows to Further, when a lateral surge occurs between the input terminals 101 and 101' due to line imbalance, etc., the varistor 113 connected between the lines of the input transformer 103 absorbs the lateral surge. Similarly, the surge that enters from the output terminals 102, 102' flows to the ground 118 via the discharge coil 111 and the varistor 112. Further, when a lateral surge occurs between the output terminals 102 and 102' due to line imbalance, etc., the varistor 114 connected between the lines of the output transformer 104 absorbs the lateral surge. The series resistors 106, 106' and 107, 107' are current limiting resistors for the varistors 113 and 114, respectively, and the resistor 116 is a Zener diode 1.
08 current limiting resistor. Furthermore, earth 117
and 118 are commonly connected.

[Problem that the invention attempts to solve]

In the above conventional safety device, each varistor 1
10, 112, 113, and 114 must have a sufficiently high operating voltage with respect to the signal during normal operation, so the operating voltage cannot be lowered particularly, so input/output transformer 1 may be damaged due to surge intrusion.
Zener diode 108 via 03, 104
The Zener diode 108 may be destroyed due to an overcurrent flowing through it, and the repeater 105 may become unable to operate. In addition, the positive surge that enters from the input terminals 101 and 101' flows from the middle point of the discharge coil 109 to the ground 117 via the varistor 110. If a large surge enters the varistor, the varistor voltage will become quite high (about several hundred volts).
This voltage remains at the input terminals 101, 101',
The surge further passes through the resistors 106 and 106', the input transformer 103, the resistor 116 and the Zener diode 108, and then the output transformer 104, the resistor 107, and the zener diode 108.
From 107', it reaches the output terminals 102, 102' and flows into the line. At this time, if the peak value of the surge current is low, the voltage drop across the resistor 116 will be low and the gas arrester 115 will not operate. In that case, if the time width of the surge current is long, the Zener diode 10
8 has low surge current resistance, so it may be destroyed. Further, the negative polarity surge from the output terminals 102, 102' is similar to the positive polarity surge from the input terminals 101, 101', and the direction of surge intrusion is from the output terminals 102, 102' side to the input terminals 101, 1.
Since the rest is the same except that it advances to the 01' side, the explanation thereof will be omitted.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and to provide a safety device that can operate reliably even against surges that are lower than the operating voltage of the overvoltage protection element, and can improve its protection ability.

[Means for solving problems]

In order to achieve the above object, the present invention provides an input transformer and an output transformer connected to the input and output sides of a repeater connected to a communication transmission line, respectively, and a primary transformer of the input transformer. A resistor connected in series between both ends of the winding and a transmission line connected to both ends of the winding, and a transmission line connected to both ends of the secondary winding of the output transformer. The input end side of the resistor is configured by combining a resistor connected in series with each other, an overvoltage protection element, and another element, and is connected in series with both ends of the primary winding of the input transformer. and a first lightning arrester circuit provided between the overvoltage protection element and the ground such that one terminal of the overvoltage protection element is connected to the ground;
A second lightning protection circuit connected between both ends of the primary winding of the input transformer, an overvoltage protection element and other elements, and a second lightning protection circuit connected between both ends of the secondary winding of the output transformer, respectively. a third lightning arrester circuit provided between the output end side of the resistor connected in series and the ground so that one terminal of the overvoltage protection element is connected to the ground; and a third lightning protection circuit of the output transformer. a fourth lightning protection circuit connected between both ends of the secondary winding; and a fourth lightning protection circuit connected between the midpoint of the primary winding of the input transformer and the midpoint of the secondary winding of the output transformer. In a safety device comprising a series circuit of a resistor and a Zener diode, and an overvoltage protection element connected in parallel to the series circuit, the other terminal of the overvoltage protection element in the first lightning arrester circuit and the first The present invention is characterized in that another overvoltage protection element is connected between the other terminal of the overvoltage protection element in the lightning arrester circuit of No. 3.

[Effect]

According to the present invention, when the potential difference between the other terminal of the overvoltage protection element in the first lightning arrester circuit and the other terminal of the overvoltage protection element in the third lightning arrester circuit is about to exceed a certain value, Another overvoltage protection element connected between the terminals of the repeater can be operated, and the voltage applied to the input and output terminals of the repeater can be suppressed to a low voltage. The current flowing through the connected Zener diode is also suppressed to a low current, which can protect it from destruction.

〔Example〕

FIG. 1 is a diagram showing the configuration of one embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of another embodiment of the present invention. Identical parts in FIG. 1 and FIG. and explain.

A safety device according to an embodiment of the present invention shown in FIG.
Input terminals 1 and 1' of the transmission line on the input side of the repeater 5
and input transformer 3 and output transformer 4, which are connected to output terminals 2 and 2' on the output side via series resistors 6, 6' and 7, 7', respectively, and input terminals 1 and 1'. a first lightning arrester circuit that connects the discharge coil 9 to the ground 17 through a biristor 10, and a first lightning protection circuit that connects the middle point of the discharge coil 9 to the
A second lightning protection circuit consisting of a biristor 13 connected between both terminals of the next winding, a discharge coil 11 connected between output terminals 2 and 2', and a midpoint of this discharge coil 11. Earth 1 via biristor 12
8, a fourth lightning arrester circuit consisting of a biristor 14 connected between both terminals of the secondary winding of the output transformer 4, and a midpoint of the primary winding of the input transformer 3. A series circuit of a resistor 16 and a Zener diode 8 connected between the middle point of the secondary winding of the output transformer 4, an overvoltage protection element such as a gas arrester 15 connected in parallel to this series circuit, and a first An overvoltage protection element, such as a gas arrester 1, connected between the midpoint of the lightning arrester circuit and the midpoint of the third lightning arrester circuit.
9. Note that the Zener diode 8 is connected to the power supply section of the repeater 5. Furthermore, earth 17 and earth 18 are connected identically.

To explain the operation of one embodiment of the present invention shown in FIG. 1, in FIG. The structure and operation of the remaining parts are the same as those explained with reference to FIG. 3, so their explanation will be omitted. In one embodiment shown in FIG. 1, the gas arrester 1 is added to the conventional example shown in FIG.
9 is added, so for example input terminals 1, 1'
The surge voltage that enters from the varistor 10 and is limited by the operation of the varistor 10 is transferred from the input terminal 1, 1' to the resistor 6,
6' → midpoint of input transformer 3 → resistor 16 → Zener diode 8 → midpoint of output transformer 4 → resistor 7,
7'→A surge tries to flow to output terminals 2, 2', but the voltage of the sum of resistors 6, 6', resistors 16, and resistors 7, 7' is applied to the gas arrester 19, and this gas arrester 19 operates. This reduces the current flowing through the Zener diode 8 and protects it from destruction. For example, resistors 6 and 6' are each 6Ω,
Resistor 16 is 6Ω and resistors 7 and 7' are each 6Ω.
Ω and the surge current is 20A, a voltage of 240V is applied to the gas arrester 19;
This gas arrester 19 operates much faster than the gas arrester 15, and the Zener diode 8
can prevent the destruction of

In another embodiment of the present invention shown in FIG. 2, the difference from the embodiment shown in FIG. In contrast, in FIG. 2, the first lightning arrester circuit connects the input terminal 1 to the ground, whereas in FIG. , 1' between diodes 20, 21
a first series circuit connected in series with opposite polarities to each other; a second series circuit connected in opposite polarity to this first series circuit and having diodes 22 and 23 connected in series with opposite polarities; A third lightning arrester circuit is constructed by connecting the midpoints of the diodes of the first and second series circuits to earth 17 via overvoltage protection elements such as gas arresters 24 and 25, and a third lightning arrester circuit is configured by connecting the midpoints of the diodes of the first and second series circuits to ground 17 via overvoltage protection elements such as gas arresters 24 and 25. a third series circuit in which diodes 26 and 27 are connected in series with opposite polarities; and a fourth series circuit in which diodes 28 and 29 are connected in series with opposite polarities to the third series circuit. The connection midpoint between the circuit and each of the diodes of these third and fourth series circuits is connected to an overvoltage protection element such as a gas arrester 3.
0, 31 to the ground 18, and further connects the middle point of the connection between the diodes 20 and 21 of the first series circuit in the first lightning protection circuit, and the third
Diode 28 of the fourth series circuit in the lightning protection circuit of
An overvoltage protection element, such as a gas arrester 32, is connected between the connection midpoint between the diodes 22 and 23 of the first lightning protection circuit, and
An overvoltage protection element, such as a gas arrester 33, is connected between the connection midpoint between the diodes 26 and 27 of the third lightning arrester circuit.

The operation of the embodiment shown in FIG. 2 is substantially similar to that of FIG. In other words, in the case of FIG. 2, the surge and the direction of the surge flowing to the diode are different, but the others are almost the same. For example, the surge passes through the diodes 20 and 21, passes through the gas arrester 32, and reaches the diode 28. , 29, the surge passes through diodes 22 and 23,
Diodes 26, 27 via gas arrester 33
, respectively, to protect the Zener diode 8 from surges.

In the embodiment shown in FIG. 1, when the surge current is large, the varistor voltage due to the resistance of the varistors 10 and 12 becomes high, so that the Zener diode 8
The action of the gas arrester 19 is used to prevent the Zener diode 8 from being destroyed, and even when the voltage is such that the varistors 10 and 12 do not operate, the action of the gas arrester 19 is used to prevent the Zener diode 8 from being destroyed. On the other hand, in the embodiment shown in FIG.
Since the first and third lightning arrester circuits each use a gas arrester that tends to cause operational delays and operational variations, the Zener diode 8 is Gas arrester 32,
It is applied to prevent by the operation of 33.

In each of the above embodiments, a discharge coil and a varistor (Fig. 1) are used in the first and third lightning arrester circuits, or a diode and a gas arrester (Fig. 2) are used.
It goes without saying that other lightning arrester circuits may also be used. For example, a lightning arrester circuit as shown in FIG. 4 may be used instead of the first lightning arrester circuit in FIG. 2. In FIG. 4, 20 to 23 are diodes,
40 and 41 are diodes 20 and 21, respectively.
A diode 42 is connected between the connection midpoint of diodes 20 and 21 and ground 17 and between the connection midpoint of diodes 22 and 23 and ground 17.
A gas arrester is connected between the connection midpoint of the diodes 22 and 23 and the connection midpoint of the diodes 22 and 23.

[Effect of idea]

According to the present invention, by operating reliably even in the case of large surges that occur on the transmission line or surges that are below the operating voltage of the overvoltage protection element, the Zener diode connected between the input and output transformers of the repeater can be destroyed. It is possible to reliably prevent this, and as a result, excellent effects such as being able to avoid the occurrence of operation stoppage of the transmission line can be achieved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the configuration of one embodiment of the present invention, Figure 2 is a diagram showing the configuration of another embodiment of the invention, and Figure 3 is a diagram showing the configuration of another embodiment of the invention.
The figure shows a conventional example, and FIG. 4 shows a modification of the first lightning arrester circuit in FIG. 2. 3...Input transformer, 4...Output transformer, 5...
Repeater, 8... Zener diode, 19... Gas arrester, 32, 33... Gas arrester.

Claims (1)

[Scope of utility model registration request] An input transformer and an output transformer connected to the input and output sides of a repeater connected to a communication transmission line, respectively, and both ends of the primary winding of the input transformer, and a transmission connected to both ends of the primary winding of the input transformer. a resistor connected in series between both ends of the secondary winding of the output transformer and a transmission line connected to both ends of the secondary winding of the output transformer; One of the overvoltage protection elements is connected between the input end side of the resistor, which is configured by a combination of a protection element and another element, and is connected in series with both ends of the primary winding of the input transformer, and the ground. a first lightning arrester circuit provided such that the terminal thereof is connected to the ground; a second lightning arrester circuit connected between both ends of the primary winding of the input transformer; One terminal of the overvoltage protection element is connected to the ground between the output end side of the resistor, which is connected in series to both ends of the secondary winding of the output transformer, and the ground. a fourth lightning arrester circuit connected between both ends of the secondary winding of the output transformer; and a fourth lightning arrester circuit connected to the primary winding of the input transformer. and a series circuit of a resistor and a Zener diode connected between the point and the middle point of the secondary winding of the output transformer, and an overvoltage protection element connected in parallel to this series circuit. The device includes an overvoltage protection element connected between the other terminal of the overvoltage protection element in the first lightning arrester circuit and the other terminal of the overvoltage protection element in the third lightning arrester circuit. A security device featuring: