CA1270300A - Safety circuit system for overvoltage protection of multiwire lines - Google Patents
Safety circuit system for overvoltage protection of multiwire linesInfo
- Publication number
- CA1270300A CA1270300A CA000471240A CA471240A CA1270300A CA 1270300 A CA1270300 A CA 1270300A CA 000471240 A CA000471240 A CA 000471240A CA 471240 A CA471240 A CA 471240A CA 1270300 A CA1270300 A CA 1270300A
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- Prior art keywords
- overvoltage
- line
- earth
- circuit system
- energy dispersing
- Prior art date
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Abstract
SAFETY CIRCUIT SYSTEM FOR
OVERVOLTAGE PROTECTION OF
MULTIWIRE LINES
ABSTRACT OF THE DISCLOSURE
A safety circuit system for overvoltage protection of multiwire lines (an, bn), in particular, of lines for telecommunication and the like.
The protective system comprises a device (P1) for dispersing the overvoltage energy, connected between the various line wires (an, bn) and, respectively, between each line wire (an, bn) and earth wire (T) by means of a composite bridge of diodes (Dk, Dr, Dt, D't) or overvoltage-activated solid-state switch means in which the energy dispersing device (P1) lies on a common diagonal of the bridge.
OVERVOLTAGE PROTECTION OF
MULTIWIRE LINES
ABSTRACT OF THE DISCLOSURE
A safety circuit system for overvoltage protection of multiwire lines (an, bn), in particular, of lines for telecommunication and the like.
The protective system comprises a device (P1) for dispersing the overvoltage energy, connected between the various line wires (an, bn) and, respectively, between each line wire (an, bn) and earth wire (T) by means of a composite bridge of diodes (Dk, Dr, Dt, D't) or overvoltage-activated solid-state switch means in which the energy dispersing device (P1) lies on a common diagonal of the bridge.
Description
~;~7~
SAFETY CIRCUIT SYSTEM FOR
OVERVOLTAGE PROT~CTION OF
HULTIVIRE LINES
A sa~ety circuit system ~or overvoltage protection of multiwire lines (an, bn), in particular, of lines for telecommunication and the like.
The protective system comprises a device (P1) for dispersing the overvol~age energy, connected between the various line wires (an, bn) and1 respectively, between each line wire (an, bn) and earth wire (T) by means of a composite bridge of diodes (Dk, Dr, Dt, D't) or overvoltage-activated solid-state switch means in which the energy dispersing device (P1) lies on a common diagonal of the bridge.
This invention concerns a safety circuit system ~or protecting two-wire or multiwire lines against overvoltage, for example or ~ t
SAFETY CIRCUIT SYSTEM FOR
OVERVOLTAGE PROT~CTION OF
HULTIVIRE LINES
A sa~ety circuit system ~or overvoltage protection of multiwire lines (an, bn), in particular, of lines for telecommunication and the like.
The protective system comprises a device (P1) for dispersing the overvol~age energy, connected between the various line wires (an, bn) and1 respectively, between each line wire (an, bn) and earth wire (T) by means of a composite bridge of diodes (Dk, Dr, Dt, D't) or overvoltage-activated solid-state switch means in which the energy dispersing device (P1) lies on a common diagonal of the bridge.
This invention concerns a safety circuit system ~or protecting two-wire or multiwire lines against overvoltage, for example or ~ t
2- ~.2~3~
protecting telecommunication lines and the like.
It is a known fact that modern electronic equipment, especially when it is connected to very long metal lines (as in the case of telecommunication`equipment and the like) can be quite easily damaged by any overvoltage which may occur on-the lines.
This due to the fact that, whilst on the one hand the latest elec-tronic components used in manu~acturing the equipment offer bet ter and better performances thanks to their increasing integra-tion and the reduction in cost for each single ~unction, on th~
other hand they are are becoming more and more vulnerable to overvoltages due to the continuous reduction in the însulating distances as a result of greater miniaturi~ation, and to an in-crease in the response rates.
Overvoltages are generally caused by atmospheric phenomena, for example, by electric discharge between clouds and the earth or between one cloud and another, and can also be caused by varia-tions in the electromagnetic ~ield produced by adjacent electric lines during operations or breakdowns on the lines themselves.
Whenever the line subjected to overvoltage is made up o~ two or more conductors, it is possible to distinguish "differential mode overvoltages", that is to say, between conductor and conductor, and "common mode overvoltages", that is to say, between the same conductors and the earth.
,' ~': ,
protecting telecommunication lines and the like.
It is a known fact that modern electronic equipment, especially when it is connected to very long metal lines (as in the case of telecommunication`equipment and the like) can be quite easily damaged by any overvoltage which may occur on-the lines.
This due to the fact that, whilst on the one hand the latest elec-tronic components used in manu~acturing the equipment offer bet ter and better performances thanks to their increasing integra-tion and the reduction in cost for each single ~unction, on th~
other hand they are are becoming more and more vulnerable to overvoltages due to the continuous reduction in the însulating distances as a result of greater miniaturi~ation, and to an in-crease in the response rates.
Overvoltages are generally caused by atmospheric phenomena, for example, by electric discharge between clouds and the earth or between one cloud and another, and can also be caused by varia-tions in the electromagnetic ~ield produced by adjacent electric lines during operations or breakdowns on the lines themselves.
Whenever the line subjected to overvoltage is made up o~ two or more conductors, it is possible to distinguish "differential mode overvoltages", that is to say, between conductor and conductor, and "common mode overvoltages", that is to say, between the same conductors and the earth.
,' ~': ,
- 3 In order to prevent the above-mentioned problems, use is made o~
suitable protective devices or the purpose of absorbing the ener-gy which accompanies overvoltages, or ~or enabling it to be ab~
sorbed by the portion o~ the line upstream to the device itsel, thereby preventing their output voltages from reaching values which could cause damage to the adjoining equipmentO
Among the know protective devices, for electronic circuits7 men-tion can be made, ~or example, of: gas arresters~ variable resi-stors (varistors~, semiconductor suppressors (normal or special, unidirectional or bidirectional Zener diodes, integrated circuits with the ~unction of crowbar-type discharger and other functions).
According to the circumstances and the desired degree of protec-tion, these devices are situated between one conductor and ano-ther and between the conductor and the earth.
However, the use o~ protective devices, in the per sè known man-ner, gives rise to considerable problems~ both Prom the point o~
view of higher costs and also ~rom the point of view of Pull and adequate protection. In Pact, in the case of a line with only two conductors, at least three overvoltage energy dispersing de-vices must be used. ~oreover, the various protective devices used on the same line usually have characteristics which are not perPectly identical, with the disadvantage o~ giving rise to cross components even in the presen~e of longitudinal overvoltages.
71D3~
Consequently, in the case o~ lines with several pairs or with a great number o conductors, it would be necessary to use an ex-tremely large number of energy dispersing devices, resulting in considerably high costs and lengthy installation times.
A scope of this invention is to provide a saPety circuit system for protecting two-wire and multiwire lines against overvoltages which is capable oP remedying the drawbacks o~ known devices.
A ~urther scope o~ this inventi~n is to provide a ci:rcuit system ~or protecting against overvoltage which, although it makes use of known ~ypes of energy dissipating devices~ is extremely in-expensive, can be m~de in the Porm of an integrated circuit and provides the best possible protection on lines with two or more conductors Por telecommunication and the like.
These scopes are achieved by the circuit system Por overvoltage protection oP two-wire and multiwire electric lines, comprising an overvoltage energy dispersing device, in which said energy dispersing device is connected between the line conductors and, respectively, between each line conductor and the ear-th, by means o~ a composite bridge oP diode means, said energy dispersing de-~LZ'7~3~
vice being inserted in the common diagonal of said compositebridge~
The invention will be described in greater detail hereunder, with re~erence to the accompanyi~ drawings, and maXing a comparison with the known systems. In the drawings:
~ig. 1 shows the conventional use of known devices, in the case o~ a line with only two conductors;
Fig. 2 shows the use of the protective system according to the invention, also in the case o a line with only two conductors;
Fig. 3 shows the conventional use o known devices, in the case of a line with several conductors;
Fig. 4 shows the use o~ the protective syste~ according to this invention, in the case of a line with several conductors.
DESCRI ION Or~ly ~ L~
With reerence to ~igures 1 and 2, we will illustrate the case o~ the protection o~ an apparatus or group of apparatuses U-con-. .. .
;' ~ '', ~ "' : . .' .
- 6 ~ 3~
nected to a line with only two conductors a and b; the reference T in both ~igures indicates the ground or earth conductor, in a per sè known way, whilst the re~erence P in Pigure 1 indicates the devices Por dispersing or dissipating the overvoltage energy, both in the direction o the earth and between conductors a and b. In the same figure, it can be seen that the conventional systems for a line with two conductors, require at least three overvoltage energy dispersing devices P, inserted as shown in the diagram.
Contrary to the above, and as shown by the continuous line in Pig. 2, the circuit system according to this invention, also in the case of a line with only two conductors, comprises only one energy dispersing device P1, being identical or similar ~o the devices P according to the known systems of figure 1, said ener-gy dispersing device P1 being inserted in the common diagonal oP a composite bridge oP diodes according to the wiring diagram shown in Pigure 2.
The composite bridge o~ diodes comprisest respectively, on the sides oP the device P1, a irst set oP line diodes D1, D2 on one side and a second set oP line diodes D4, D5 on the other, oP
which the diodes D1 and D2 have their anode connected to the conductors a and b respectively, and their cathode connected to a Pirst common node, whereas the diodeq 4 and 5 are connected, '~' '`::, ` '' :
: .
:~
~ 7 ~
in th~ opposite way9 that is to say~ with their cathodes to the conductors a and bl and wi~h their anode connected ~o a second common node. The bridge circuit also comprises the earth diodes D3 and D6 o~ which the diode D3 forms part of the first set o~
diodes and is connected by its anode to the earth T and by its cathode to the a~oresaid first node, whereas the earth diode D6 orms part of the second set of diodes and is connected by its cathode to the earth T and by its anode to the aÇoresaid second node, on the opposite sidP o~ the ove~voltage energy dispersing device.
Comparing the ~igures 1 and 2, it can be seen that in the latter case the same protection o~ the conductors a and b is achieved, both against dl~ferential mode and common mode overvoltages, by using just one energy dispersing device and six bridge-connected diodes~ the aoresaid device P1 lying in the common diagonal of the latter. Since it is possible to use low-cost common diodes o a type capable of withstanding high impulsive currents, with respect to the normal permanent currents for which the diodes are normally designed, it is obvious that the solution shown in figure 2 implies a considerable reduction in costs, an advantage which is even more appreciated as the cost o~ the energy disper sing devices continues to increase, as a result o~ the use o~
combined devicès, ~or example, gas arresters plus a variator.
' ';;:, .
.
~ 8 ~ 3~
A further advantage derives ~rom the fact that, according to this invention, it is possible to use energy dispersing or dissipating devices P1, o~ the unidirectional type, even in the presence o~
alternative voltage signals in ~he two line conductors; lastly, by using a single overvoltage energy dispersing device P1, the circuit system o4 ~igure 2 eliminates any problems ~hich may occur in the Xno~ systems, as a result o possible di~erences in the characteristics o one protective device P and the other.
Furthermore, in the case o~ the device P1 being o~ the crowbar type (liXe gas-arresters or integrated circuits with similar ~unc-tion) a simultaneous common safety short-circuit between all the involved conductors and earth takes place during overvoltage transients, thereby granting the maximum degree o~ protection for the electronic equipment.
This can also apply in the case in which several protective de-vices are used in cascade, on the s~me line, as shown by the dotted lines in ~igures 1 and 2; in order to achieve a more e~i-cient protection. In this case, the ~nown system would be ~ound to require the use o~ six overvoltage energy dispersing devices P, as opposed to the two devices P1 of figure 2.
As mentioned previously, the invention can easily be extended to the case o lines with more than two conductors, as shown schematically in Pig~re 4. In this igure, it can be seen that ~27~0~
in the case in which there is any given number o~ pairs o~ con-du~tors a1, b1, a2, b2, an, bn~ the layout oP the protective de-vice remains substantially unchanged, with the overvoltage ener-gy dispersing device P1 always inserted in ~he common diagonal o the composite bridge of two sets of diodes, the only dif~er-ence being that on both the input and the ou~put sides o~ this device P1, there will be a number of line diodes DX and Dr equal to the number o~ line conductors, each of which connected to its respective conductor as indicated previously9 and a single earth diode Dt, D't per side. In said figure 4, the references n, k, and r may assume any given numerical value over two.
The comparison between Pigure 3 which shows a conventional sys-tem for a line made up oP two pairs of conductors a1, b1 and a2, b2, and ~igure 4 for the same number of pairs, shows that in the ~irst case six overvoltage enFrgy dispersing devices P are required, as opposed to the use o~ only one device P1 according to this invention; in this case too, the cost of the diodes is considerably lower than the cost o~ the various devlces P.
Moreover, it can be seen that the solution in figure 3 does not o~er protection agalnst diPPerential mode overvoltages between the conductors of one pair and the conductors of the other, un-less a larger number o~ dispersing devices P are used. In the case in ~igure 4, according to the invention, such protection .:.
:. ;" ~ '' 1 0 ~70:300 between pairs o~ diferent conductors is achieved automatically by means o~ the single device P1 and the t~o sets of diodes Dk and Dr; in other wor~s, with the circuit system according to this invention, cirtually total protection is achieved without having to resort to additional devices.
According to a further scope and possible application of the pre-viously described circuit, the invention can also be used in place o ~nown protective devices, for telecommunication circuits using self-piloting multiple gas arresters, usually o~ the tri-polar type (two line and one earth electrodes) or pentapolar type (four line and one earth electrodes, the latter sometimes dis~
tributed over two or more connecting elements).
Said arresters represent a technically advantageous solution, as compared to the use of separate bipolar gas arresters inserted between each wire and the earth, in that it enables the discharge ~rom any given electrode to "pilot" ~that is to say, to help) the sparking off of the remaining electrodes, due to the fact that thetemporary gas ionization produced by the initial discharge gives rise to an immediate and considerable reduction in the value of their break-down voltage.
So it is evident that a "self-piloting" effect also proves to be intrinsically inherent in the circuit system embodied accord-ing to the invention and represented in eigs. 2 and 4, since the .~
. . .
2 703~0 break-down o~ the overvoltage energy despersing device P1 (device consisting ~or example o~ a simple bipolar gas arrester) is si-multaneously made use of by all the line conductors~ irrespective o the pair of elements (wire/wire or wire/earth) in which the overvoltaye which started the spark takes place.
Other embodiments are possible within the sphere of this inven-tion, or example, the diodes o~ the two sets which constitute the composite bridge connecting the overvoltage energy dispers-ing device P1 to the line and earth conductors, may be replaced by transistors or, more generally, by overvoltage-con~rolled so-lid-state switch means, so as to enable the embodiment of the entire circuit system claimed herein in the ~orm o~ an integra~
ted circuit. Alternatively, or in comhinatian, the earth diodes D't or the controlled switch means connected to the earth, could be replaced by other overvoltage energy dispersing devices.
According to a ~urther embodiment, it is also possible to use two or more diodes or controlled switch means, connected parallel with one another, ~or each line conductor and earth7 without de-viating ~rom the innovatory principles o~ this invention.
It will be clear, ~rom what has been described and shown in the accompanying drawings, that the invention consists in a particu-lar system for protecting against overvoltages in lines with se-veral conductcrs, comprising a single overvoltage energy dispers---:~ , : ' . :
.
... .. .
:, '' ,, : "
- 12 ~ 3~
ing device inserted in the common diagonal o~ a composite bridge of diod~s, which ca~ be used irrespective of the number 0~ COn-ductors making up ~he line. Therefore, wha~ has been described and shown in the accompanying dr~wings, is given merely in order to illustrate the invention and is understood as extended to all the cases that may occur in practice.
suitable protective devices or the purpose of absorbing the ener-gy which accompanies overvoltages, or ~or enabling it to be ab~
sorbed by the portion o~ the line upstream to the device itsel, thereby preventing their output voltages from reaching values which could cause damage to the adjoining equipmentO
Among the know protective devices, for electronic circuits7 men-tion can be made, ~or example, of: gas arresters~ variable resi-stors (varistors~, semiconductor suppressors (normal or special, unidirectional or bidirectional Zener diodes, integrated circuits with the ~unction of crowbar-type discharger and other functions).
According to the circumstances and the desired degree of protec-tion, these devices are situated between one conductor and ano-ther and between the conductor and the earth.
However, the use o~ protective devices, in the per sè known man-ner, gives rise to considerable problems~ both Prom the point o~
view of higher costs and also ~rom the point of view of Pull and adequate protection. In Pact, in the case of a line with only two conductors, at least three overvoltage energy dispersing de-vices must be used. ~oreover, the various protective devices used on the same line usually have characteristics which are not perPectly identical, with the disadvantage o~ giving rise to cross components even in the presen~e of longitudinal overvoltages.
71D3~
Consequently, in the case o~ lines with several pairs or with a great number o conductors, it would be necessary to use an ex-tremely large number of energy dispersing devices, resulting in considerably high costs and lengthy installation times.
A scope of this invention is to provide a saPety circuit system for protecting two-wire and multiwire lines against overvoltages which is capable oP remedying the drawbacks o~ known devices.
A ~urther scope o~ this inventi~n is to provide a ci:rcuit system ~or protecting against overvoltage which, although it makes use of known ~ypes of energy dissipating devices~ is extremely in-expensive, can be m~de in the Porm of an integrated circuit and provides the best possible protection on lines with two or more conductors Por telecommunication and the like.
These scopes are achieved by the circuit system Por overvoltage protection oP two-wire and multiwire electric lines, comprising an overvoltage energy dispersing device, in which said energy dispersing device is connected between the line conductors and, respectively, between each line conductor and the ear-th, by means o~ a composite bridge oP diode means, said energy dispersing de-~LZ'7~3~
vice being inserted in the common diagonal of said compositebridge~
The invention will be described in greater detail hereunder, with re~erence to the accompanyi~ drawings, and maXing a comparison with the known systems. In the drawings:
~ig. 1 shows the conventional use of known devices, in the case o~ a line with only two conductors;
Fig. 2 shows the use of the protective system according to the invention, also in the case o a line with only two conductors;
Fig. 3 shows the conventional use o known devices, in the case of a line with several conductors;
Fig. 4 shows the use o~ the protective syste~ according to this invention, in the case of a line with several conductors.
DESCRI ION Or~ly ~ L~
With reerence to ~igures 1 and 2, we will illustrate the case o~ the protection o~ an apparatus or group of apparatuses U-con-. .. .
;' ~ '', ~ "' : . .' .
- 6 ~ 3~
nected to a line with only two conductors a and b; the reference T in both ~igures indicates the ground or earth conductor, in a per sè known way, whilst the re~erence P in Pigure 1 indicates the devices Por dispersing or dissipating the overvoltage energy, both in the direction o the earth and between conductors a and b. In the same figure, it can be seen that the conventional systems for a line with two conductors, require at least three overvoltage energy dispersing devices P, inserted as shown in the diagram.
Contrary to the above, and as shown by the continuous line in Pig. 2, the circuit system according to this invention, also in the case of a line with only two conductors, comprises only one energy dispersing device P1, being identical or similar ~o the devices P according to the known systems of figure 1, said ener-gy dispersing device P1 being inserted in the common diagonal oP a composite bridge oP diodes according to the wiring diagram shown in Pigure 2.
The composite bridge o~ diodes comprisest respectively, on the sides oP the device P1, a irst set oP line diodes D1, D2 on one side and a second set oP line diodes D4, D5 on the other, oP
which the diodes D1 and D2 have their anode connected to the conductors a and b respectively, and their cathode connected to a Pirst common node, whereas the diodeq 4 and 5 are connected, '~' '`::, ` '' :
: .
:~
~ 7 ~
in th~ opposite way9 that is to say~ with their cathodes to the conductors a and bl and wi~h their anode connected ~o a second common node. The bridge circuit also comprises the earth diodes D3 and D6 o~ which the diode D3 forms part of the first set o~
diodes and is connected by its anode to the earth T and by its cathode to the a~oresaid first node, whereas the earth diode D6 orms part of the second set of diodes and is connected by its cathode to the earth T and by its anode to the aÇoresaid second node, on the opposite sidP o~ the ove~voltage energy dispersing device.
Comparing the ~igures 1 and 2, it can be seen that in the latter case the same protection o~ the conductors a and b is achieved, both against dl~ferential mode and common mode overvoltages, by using just one energy dispersing device and six bridge-connected diodes~ the aoresaid device P1 lying in the common diagonal of the latter. Since it is possible to use low-cost common diodes o a type capable of withstanding high impulsive currents, with respect to the normal permanent currents for which the diodes are normally designed, it is obvious that the solution shown in figure 2 implies a considerable reduction in costs, an advantage which is even more appreciated as the cost o~ the energy disper sing devices continues to increase, as a result o~ the use o~
combined devicès, ~or example, gas arresters plus a variator.
' ';;:, .
.
~ 8 ~ 3~
A further advantage derives ~rom the fact that, according to this invention, it is possible to use energy dispersing or dissipating devices P1, o~ the unidirectional type, even in the presence o~
alternative voltage signals in ~he two line conductors; lastly, by using a single overvoltage energy dispersing device P1, the circuit system o4 ~igure 2 eliminates any problems ~hich may occur in the Xno~ systems, as a result o possible di~erences in the characteristics o one protective device P and the other.
Furthermore, in the case o~ the device P1 being o~ the crowbar type (liXe gas-arresters or integrated circuits with similar ~unc-tion) a simultaneous common safety short-circuit between all the involved conductors and earth takes place during overvoltage transients, thereby granting the maximum degree o~ protection for the electronic equipment.
This can also apply in the case in which several protective de-vices are used in cascade, on the s~me line, as shown by the dotted lines in ~igures 1 and 2; in order to achieve a more e~i-cient protection. In this case, the ~nown system would be ~ound to require the use o~ six overvoltage energy dispersing devices P, as opposed to the two devices P1 of figure 2.
As mentioned previously, the invention can easily be extended to the case o lines with more than two conductors, as shown schematically in Pig~re 4. In this igure, it can be seen that ~27~0~
in the case in which there is any given number o~ pairs o~ con-du~tors a1, b1, a2, b2, an, bn~ the layout oP the protective de-vice remains substantially unchanged, with the overvoltage ener-gy dispersing device P1 always inserted in ~he common diagonal o the composite bridge of two sets of diodes, the only dif~er-ence being that on both the input and the ou~put sides o~ this device P1, there will be a number of line diodes DX and Dr equal to the number o~ line conductors, each of which connected to its respective conductor as indicated previously9 and a single earth diode Dt, D't per side. In said figure 4, the references n, k, and r may assume any given numerical value over two.
The comparison between Pigure 3 which shows a conventional sys-tem for a line made up oP two pairs of conductors a1, b1 and a2, b2, and ~igure 4 for the same number of pairs, shows that in the ~irst case six overvoltage enFrgy dispersing devices P are required, as opposed to the use o~ only one device P1 according to this invention; in this case too, the cost of the diodes is considerably lower than the cost o~ the various devlces P.
Moreover, it can be seen that the solution in figure 3 does not o~er protection agalnst diPPerential mode overvoltages between the conductors of one pair and the conductors of the other, un-less a larger number o~ dispersing devices P are used. In the case in ~igure 4, according to the invention, such protection .:.
:. ;" ~ '' 1 0 ~70:300 between pairs o~ diferent conductors is achieved automatically by means o~ the single device P1 and the t~o sets of diodes Dk and Dr; in other wor~s, with the circuit system according to this invention, cirtually total protection is achieved without having to resort to additional devices.
According to a further scope and possible application of the pre-viously described circuit, the invention can also be used in place o ~nown protective devices, for telecommunication circuits using self-piloting multiple gas arresters, usually o~ the tri-polar type (two line and one earth electrodes) or pentapolar type (four line and one earth electrodes, the latter sometimes dis~
tributed over two or more connecting elements).
Said arresters represent a technically advantageous solution, as compared to the use of separate bipolar gas arresters inserted between each wire and the earth, in that it enables the discharge ~rom any given electrode to "pilot" ~that is to say, to help) the sparking off of the remaining electrodes, due to the fact that thetemporary gas ionization produced by the initial discharge gives rise to an immediate and considerable reduction in the value of their break-down voltage.
So it is evident that a "self-piloting" effect also proves to be intrinsically inherent in the circuit system embodied accord-ing to the invention and represented in eigs. 2 and 4, since the .~
. . .
2 703~0 break-down o~ the overvoltage energy despersing device P1 (device consisting ~or example o~ a simple bipolar gas arrester) is si-multaneously made use of by all the line conductors~ irrespective o the pair of elements (wire/wire or wire/earth) in which the overvoltaye which started the spark takes place.
Other embodiments are possible within the sphere of this inven-tion, or example, the diodes o~ the two sets which constitute the composite bridge connecting the overvoltage energy dispers-ing device P1 to the line and earth conductors, may be replaced by transistors or, more generally, by overvoltage-con~rolled so-lid-state switch means, so as to enable the embodiment of the entire circuit system claimed herein in the ~orm o~ an integra~
ted circuit. Alternatively, or in comhinatian, the earth diodes D't or the controlled switch means connected to the earth, could be replaced by other overvoltage energy dispersing devices.
According to a ~urther embodiment, it is also possible to use two or more diodes or controlled switch means, connected parallel with one another, ~or each line conductor and earth7 without de-viating ~rom the innovatory principles o~ this invention.
It will be clear, ~rom what has been described and shown in the accompanying drawings, that the invention consists in a particu-lar system for protecting against overvoltages in lines with se-veral conductcrs, comprising a single overvoltage energy dispers---:~ , : ' . :
.
... .. .
:, '' ,, : "
- 12 ~ 3~
ing device inserted in the common diagonal o~ a composite bridge of diod~s, which ca~ be used irrespective of the number 0~ COn-ductors making up ~he line. Therefore, wha~ has been described and shown in the accompanying dr~wings, is given merely in order to illustrate the invention and is understood as extended to all the cases that may occur in practice.
Claims (9)
1. Overvoltage protection circuit system for two-wire and multi-wire electric lines including an overvoltage energy dispersing device, said energy dispersing device being connected between line conductors and, respectively, between each line conductor and the earth by means of a composite bridge of diode means, said energy dispersing device being inserted in the common diagonal of said composite bridge, said system further including a first set of diodes having as many line diodes as there are line conductors, and an earth diode, in which the anode of each line diode is connected to a corresponding line conductor and, respectively, the anode of the earth diode is connected to the earth, and in which the cathode of all the diodes in the set are connected to a first common node; a second set of diodes comprising the same number of line diodes as that of the previous set and an earth diode, in which the cathode of each line diode is connected to a respective line conductor and, respectively, the cathode of the earth diode is connected to the earth, and in which the anodes of all the diodes in the second set are connected to a second common node; and in which an overvoltage energy dispersing device is connected between the aforesaid first and second nodes.
2. Overvoltage protection circuit system as claimed in claim 1, wherein said overvoltage energy dispersing device is of the type capable of directly absorbing the energy of the overvoltage.
3. Overvoltage protection circuit system as claimed in claim 1, wherein said overvoltage energy dispersing device is of the type capable of allowing the, aforesaid energy to be absorbed mainly by the line situated upstream to the circuit system itself.
4. Overvoltage protection circuit system as claimed in claim 1, wherein said overvoltage energy dispersing device is of the unidirectional type.
5. Overvoltage protection circuit system as claimed in claim 1, wherein said overvoltage energy dispersing device is of the bidirectional type.
6. Overvoltage protection circuit system as claimed in claim 1, in which further energy dispersing devices are provided in place of the earth diodes.
7. Overvoltage protection circuit device for two-wire and multi-wire lines comprising at least one overvoltage energy dispersing device comprising in combination: - a first and at least a second set of overvoltage-controlled solid-state switch means; in which each set of controlled switch means comprises as many controlled line switches as the number of the line conductors, and at least a controlled earth switch in which one side of the controlled switch means, in each set, is connected to a line conductor and respectively to the earth whilst the other side is connected to a common node; and in which the overvoltage energy dispersing device is connected between the nodes connecting the two aforesaid sets of switch means.
8. Circuit system as claimed in claim 7, in which each set of controlled line switch means is connected to the earth by means of a further overvoltage energy dispersing device.
9. Circuit system as claimed in claim 1, in which the entire circuit system is in the form of integrated circuit equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000471240A CA1270300A (en) | 1984-12-31 | 1984-12-31 | Safety circuit system for overvoltage protection of multiwire lines |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000471240A CA1270300A (en) | 1984-12-31 | 1984-12-31 | Safety circuit system for overvoltage protection of multiwire lines |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1270300A true CA1270300A (en) | 1990-06-12 |
Family
ID=4129487
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000471240A Expired - Fee Related CA1270300A (en) | 1984-12-31 | 1984-12-31 | Safety circuit system for overvoltage protection of multiwire lines |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1270300A (en) |
-
1984
- 1984-12-31 CA CA000471240A patent/CA1270300A/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |