US3532976A - Fault detecting and correcting circuitry for crosspoint networks - Google Patents

Fault detecting and correcting circuitry for crosspoint networks Download PDF

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Publication number
US3532976A
US3532976A US698541A US3532976DA US3532976A US 3532976 A US3532976 A US 3532976A US 698541 A US698541 A US 698541A US 3532976D A US3532976D A US 3532976DA US 3532976 A US3532976 A US 3532976A
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Prior art keywords
marking
crosspoint
potential
relay
diode
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Expired - Lifetime
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US698541A
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English (en)
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Hans Helmut Adelaar
Jan Van Goethem
Marcel Arthur Van Brussel
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Alcatel Lucent NV
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International Standard Electric Corp
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Assigned to ALCATEL N.V., DE LAIRESSESTRAAT 153, 1075 HK AMSTERDAM, THE NETHERLANDS, A CORP OF THE NETHERLANDS reassignment ALCATEL N.V., DE LAIRESSESTRAAT 153, 1075 HK AMSTERDAM, THE NETHERLANDS, A CORP OF THE NETHERLANDS ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INTERNATIONAL STANDARD ELECTRIC CORPORATION, A CORP OF DE
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/0008—Selecting arrangements using relay selectors in the switching stages
    • H04Q3/0012—Selecting arrangements using relay selectors in the switching stages in which the relays are arranged in a matrix configuration

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  • a selected Br relay will be operated in series with the previous two and in turn, upon the closure of a selected marking contact ma and the reopening of the contact mb, a selected Ar relay will operate in series with the previous three. Closure of make contact ar will then lead to the energization of the desired cut-off relay Cor which is biased to negative battery.
  • make contact can be closed so that ground will be applied to the operated Dr relay through the decoupling diode GI and thereafter the marking contacts m' and ma. can also be reopened so that the operated connection is now held under the control of the closed jcontact.
  • FIG. 2 shows one of the 64 coordinate switches forming the B stage and it will be recognized to include 32 crosspoints of which only the four extreme ones involving relays Brll, Br14, Br81 and E184 are represented together with their associated make contacts and marking diodes.
  • This is secured by first providing a suitable ground potential at the marking lead ml which is multipled to the crosspoints in the same way as the corresponding outlet al, this being true for all outlets and marking leads.
  • This negative potential on marking lead m1 supplied through a relatively low resistance formed by the crosspoints thus simulates a permanent marking condition and this is applied to all the remaining 256 b-links such as link [24 through diode GB14 and relay winding Br14 if it is assumed that the links of the switching network of FIG. 1 including the b-links are normally biased by a positive potential through a relatively high resistance to indicate their availability.
  • FIG. 3 represents such a positive biasing arrangement. It is seen that each link, e.g. Z2, is connected to positive battery via two biasing resistors R1 and R2 in series. Thus, as long as the b-link is not involved in a connection in the switching network the only potential which it can receive is the positive biasing potential which is an indication that the link is available to establish a connection. Thus, a positive probe pulse may be applied through capacitor C to the junction of resistors R1 and R2 and this will pass through the decoupling rectifier G poled as shown to reach a common detector (not shown) and indicating that the link is available.
  • a positive probe pulse may be applied through capacitor C to the junction of resistors R1 and R2 and this will pass through the decoupling rectifier G poled as shown to reach a common detector (not shown) and indicating that the link is available.
  • the potential at the junction of resistors R1 and R2 will necessarily be lowered and it can be arranged that in this case the reading pulse is insufficient to trigger the detector, thereby indicating that the link is not available.
  • the positive biasing potential can be chosen with a much lower value egg. 6 volts, than the positive marking potential, e.g. 48 volts supplied through marking contact m, and R1/2 can be relatively high valued resistors as compared to the crosspoint resistances so that a negative potential or ground on a marking lead such as mil cannot send a significant current through a crosspoint relay.
  • FIG. 4 This is represented in FIG. 4 which will be recognized as being entirely similar to FIG. 3 except that the polarities of the battery, the reading pulse and the decoupling rectifier leading to the link-available detector (not shown) have all been reversed.
  • the short-circuited diode GB11 will thus be unable to block the whole exchange because the negative potential present at b1 on the holding connection and which it transmits to the marking lead m1 will not create a busy condition on all the other b-links since such diodes as GB14 will now remain blocked.
  • marking and holding switching arrangements described form part of a telephone exchange so that the crosspoint relays shown have their windings inserted in the test wire of a telephone connection and in addition to their make contacts shown, to hold the connection, are provided with two additional make contacts to establish the speech wire connections, it is clear that such double connections will play havoc with the telephone traffic.
  • the fault detection circuit FD of FIG. 1 will prevent such undesirable situations and with simple means limit the inconvenience to subscribers on the whole, to a minim-um.
  • the circuit FD provides for each of the l6+8+4+4 multiple marking wires to be connected to a common detector DET. As shown the multiple marking wires on the side of the marking contacts away from the marking ground are connected through a decoupling diode, e.g. diode SA for the multiple marking wire shown connected to a marking contact ma, to the terminal of the detector DET away from ground through a break contact detO pertaining to a relay (not shown) part of this detector.
  • a decoupling diode e.g. diode SA for the multiple marking wire shown connected to a marking contact ma
  • the short-circuited marking diode GB11 cannot transmit an interfering negative potential to its multiple marking conductor since the connection involving this faulty crosspoint is forcedly released.
  • the gro rid provided by the detector DET means that the potential on link [11 will be sufficiently raised, i.e. close to ground, with respect to the negative biasing potential (FIG. 4) to cause an artificial busying of this b1 link whereby the latter can no longer be selected until the fault is cleared.
  • possibility Xx creates no effective disturbance upon affected connection which will be normally released at the end of the conversation.
  • case Yx will arise in a transient manner, since the reopening of make contact j will be followed by the subsequent release of relays Dr and Cr.
  • condition Yy will automatically arise because the current supplied from ground at the detector DET and passing through the short-circuited marking diode GB11 will flow through the winding of the faulty cross point relay Brl l in series with the operated crosspoint relay Br81 which will thus remain held in that connection in series with the other two relays Ar and Car.
  • the faulty crosspoint happens to be in the A switching stage, when it operates in the manner described, irrespective of whether the cut-off relay Cor was operated or not, i.e. irrespective of whether the line circuit was free or busy, the operation of a faulty Ar crosspoint by closing make contact ar will apply ground to the cut-off relay and always operate the latter.
  • the invention provides an artificial busy potential on half of the links of a stage including the faulty diode to thereby assure that the remaining half of the stage will remain operating until the shorted diode is located.
  • the invention relates to crosspoint network formed by coordinate arrangements of crosspoints each of which includes asymmetrically conducting impedances used to establish an operating path for the crosspoint, and more particularly to fault detecting and clearing circuitry for such networks.
  • marking potentials applied to the diodes have the same value for all the switching stages, before a relay can be operated in a given stage, it is evident that the marking potential applied to the diode in the preceding switching stage must be disconnected, so as to remove the short circuit on the relay which then operates in series with the previously operated relay in the preceding stage.
  • This sequential withdrawal of the marking potential may in fact be avoided by using different marking potentials in each switching stage, the potential difference between successive stages corresponding substantially to the voltage needed to operate a relay plus a blocking voltage for the marking diode.
  • Silicon diodes can be used for the marking diodes needed for each crosspoint but although these are generally very reliable, one may not absolutely exclude one of said diodes becoming short circuited. With the present reliability figures, such an occurrence will ve very rare, but it is clear that in a relatively large exchange, the correspondingly large number of crosspoints implies that over the years, such a fault cannot be dismissed entirely and may have unfortunate results.
  • test impedance must be relatively low valued to enable the desired shortcircuit but this is not the only way to realize the test detector which may also have a relatively high impedance in accordance with another aspect of the invention.
  • the switch inlets i.e. the links between switching stages
  • the switch inlets are permanently biased to a positive potential to readily indicate when these links are not involved in a connection. They are then idle and available for the establishment of a new connection.
  • all the diodes multipled to a faulty short-circuited one are effectively conductive.
  • all links lead ing to the preceding stage will now assume a false potential indicating that they are busy, i.e. a negative potential, if the impedance through which the positive bias is provided is substantially larger than that of the holding connection seen from the link. This means that no new connection can be established until the faulty crosspoint is released.
  • a general object of the invention is to remedy these disadvantages in a simple way and produce an arrangement in which short-circuited diodes can be readily detected and the faulty conditions cleared in a simple and effective manner.
  • one end of the crosspoint impedances is coupled to a test potential via test impedance, associated with a plurality of crosspoints, in such a way that upon one of the asymmetrically conducting impedances becoming conductive in both directions, a common detector is operated.
  • said couplings to the test potential are provided through asymmetrically conducing test impedances oppo-- 3 sitely poled with respect to the crosspoint asymmetrically conducting impedances.
  • said asymmetrically conducting impedances include a relay winding in series with a diode, a holding connection may be provided through a plurality of crosspoints in series with a hold potential source, each crosspoint holding circuit comprising the relay winding in series with a make contact of the relay connected to the junction of the winding with the diode, and said test impedance being chosen high enough to allow a short-circuited diode coupled to a holding connection to communicate a potential different from said test potential to a marking lead connected to the end of said short-circuited diode away from the relay winding.
  • free links can again be made artificially busy due to a fault by biasing them with a positive potential, so that the negative potential passed by the short-circuited diode may cause the links connected thereto through a cross-point winding in series with a diode to assume a potential near that communicated from the holding connection whereby they are no longer treated as free.
  • the cross-points giving access, when operated, to a predetermined switch outlet are divided in at least two groups whose diodes are multipled to separate marking conductors, whereby a short-circuited diode renders only part of the links unavailable.
  • the low impedance fault current detector is coupled via diodes to the various marking leads, the diodes from the detector being oppositely poled with respect to the crosspoint marking diodes multipled to the marking leads. If a short-circuited marking diode is involved in a holding connection, this will immediately cause the detector to react and the latter may in turn apply short-circuiting potential to all the marking diodes in one stage of the network causing thereby the release of all established connections. Thereafter, this shortcircuit is suppressed and new connections may be established with the sole exception of those using the inlet directly coupled to the faulty marking diode, which inlet is now marked as artificially busy due to the test potential supplied through the detector.
  • FIG. 1 a four stage switching network to which the fault detecting and clearing circuits of the invention are applied;
  • FIG. 2 a coordinate switching stage part of the network of FIG. 1;
  • FIG. 3 a way to bias the links of the network of FIG. 1 with a positive potential to indicate their availability
  • FIG. 4 a way to bias the links of the network of FIG. 1 with a negative potential to indicate their availability.
  • the latter represents in diagrammatical form a four-stage switching network enabling connections to be established between any one out of 1024 external outlets and any one out of 128 external inlets, there being a unique path for every possible interconnection.
  • the external outlets may be telephone line circuits while the external inlets may be telephone junctor circuits and particularly an input thereof.
  • the line circuit cut-off relay Cor conected to negative battery will be operated from a ground supplied at make contact j in the junctor circuit and passing through the decoupling diode G] in the junctor circuit and the four switching stages labelled A, B, C and D starting from the cut-off relay Cor side.
  • the A and B switching stages form a series of 16 socalled concentration planes because they enable to couple the 1024 line circuits to a smaller number of 256 so-called b-links which are the interconnections between the B and C switching stages.
  • the quantities of each element shown in FIG. 1 are each time indicated between brackets next to the various elements so that it is clear that in addition to these b-links, there are 512 a-links between the A and B stages and 256 c-links between the C and D switching stages.
  • the latter constitute so-called mixing planes because they enable the traffic from all the 16 concentration planes (A/B) to be mixed towards any desired mixing plane (C/D) out of a set of also 16 planes.
  • the relay winding terminals away from the common point may be considered as the switch inlets whereas the make contact armatures away from the common point can be considered as the switch outlets.
  • the multiplying arrows at the inlet and outlet conductors indicate to how many crosspoints an inlet or an outlet is multipled in a switch.
  • a similar reasoning can be readily made for the C and D switches, but for the A switches this is an incompletely filled rectangular coordinate arrangement of 16 8 and there are only 64 crosspoints.
  • Each A switch has 8 a-link inlets and 16 line circuit outlets leading to the cut-off relay windings Cor.
  • two of the 8 a-links inlets to an A switch come from each of the four B switches while two of the 8 a-links outlets from a B these conductors so that for example the multiple marking conductor mil would only serve the crossp-oints (FIG. 2) leading to the links b1 and b2 only the first of which is shown, while a separate multiple marking lead ml would serve the crosspoints coupled to the remaining links, i.e. b3 and b4- only the last of which is shown.
  • FIG. 2 crossp-oints
  • the current detector DET may be arranged, when it reacts to a fault, i.e. a short-circuited marking diode, to break down all existing connections through the network and completely clear the latter. This may occur manually due to an alarm being given by DET or automatically. As shown in FIG. 1, it suffices that upon such an alarm being given or upon a monostable device operating in the detector, that the ground provided through the latter be temporarily interrupted at break contact detO and on the other hand through four make contacts det1/4 of the same monostable relay device, that negative battery be applied to the four multiple marking wires for the C switching stage. For all established connections this will short-circuit the Cr and Dr relays whereby all existing connections will be interrupted. Admittedly, the final interruption of all existing telephone communications is a serious disturbance but since the event will be very rare it can be considered as a minor evil as compared to the danger of an unchecked number of double connections.
  • break jacks may be provided in all or in major branches of each marking wire.
  • the automatic one-shot detecting device will be particularly desirable in an unattended exchange so that communications may be immediately resumed after clearing down the network and without waiting for maintenance action to be carried out.
  • An alternative fault detection arrangement may however keep the network operative at all times, though on a reduced grade of service basis. Thus, this alternative solution could at worst cause only congestion during peak traffic hours if a fault occurred at that time.
  • a detector DET should still be connected via decoupling diodes such as SA to the various multiple marking conductors, but this time the impedance of the detector should be relatively high, instead of relatively low to supply a clamping ground.
  • the multiple marking wires like the 8 marking conductors ml to m8 for the B switching stage are split in at least two parts as indicated in FIG. 2 by the two short lines crossing the corresponding lines will be blocked, i.e. they can neither make a call nor be called.
  • the close to ground marking potential appearing on lead m1 is a faulty permanent marking condition which may again lead to double connections being set up in the manner previously explained.
  • the fourth case Xy has yet to be considered, i.e the holding current in the right-hand path of the holding connection remains sufficient to hold the connection but the current through the faulty crosspoint is also suflicient to cause its operation.
  • a path will be closed from b1 to al through the winding of Br11 in series with make contact br11 and this may result in a double connection if a1 is already involved in an established connection.
  • the connection involving b1 and a8 is releaased due potential on all the b-links coupled via a crosspoint relay winding in series with a marking diode to the multiple marking wire m1.
  • the network represented in FIG. 1 only illustrates the way in which the fault detection and clearing circuits of the invention can be applied.
  • the dotted line connection included in the positive potential marking branch on the right-hand side of FIG. 1 may incorporate not only a junctor selecting marking contact such as m but also transistor switches to apply the potential after closure of such a contact and to remove it after opening thereof so as to avoid such relay contacts as m from establishing or breaking a current path.
  • a constant current regulating device may also be inserted in this branch.
  • the same switching stage D may of course also be used to provide a path between the opposite side of the junctor circuit and the c-links in which case the number of crosspoints in the D switches would be doubled and if the same marking contact m is used for the input or the output of a junctor circuit, distinct marking contacts md being used for such input and output connections, a decoupling diode would be inserted in series with contact m.
  • the fault detection measures disclosed herein may also be coupled with other measures of like nature such as a vertification of the correct operation of each crosspoint each time this is required for a new connection.
  • said networks comprising a plurality of stages
  • each of said stages having a plurality of switching blocks formed by a plurality of coordinately arranged horizontal and vertical multiples, crosspoints comprising reed relays extending between the horizontal and vertical multiples at the overlapping of the horizontal and vertical multiples,
  • operating circuit means comprising marking means for supplying a marking potential at one side of said reed relays to prepare an operating path at selected ones of each of said crosspoints,
  • said marking means including asymmetrically conducting marking impedance means connected to one side of said reed relays,
  • first potential means applied to selected inputs of the last stage of said plurality of stages for providing sufficient potential difference in cooperation with said marking potential for operating selected crosspoints stage by stage
  • hold circuit means operated responsive to a series of crosspoints switching through said stages so that a path is established from one end of said network to the other end of said network, said hold circuit means comprising an output hold potential difference across said established path, and
  • fault detecting means coupled to one side of the asymmetrically conducting marking impedance means at each of said crosspoints for detecting a short condition in any of said asymmetrically conducting marking impedance means.
  • fault detecting and clearing circuitry of claim 1 wherein said fault detecting means comprises asymmetrically conducting test impedance means coupled to said crosspoint asymmetrically conducting marking impedance means,
  • test impedance means being poled opposite to said marking impedance means
  • test potential means coupled to said test impedance means at the side thereof opposite the coupling to the said crosspoint impedance means.
  • marking diode means serially connected with said windeach crosspoint comprising the reed relay winding, a
  • the fault detecting and clearing circuitry of claim 3 including network clearing means operated responsive to the operation of said detecting means to temporarily prevent all crosspoint reed relay operations so that the temporary operation of said clearing means causes the interruption of all crosspoint connections established through the network.
  • said clearing circuitry includes means to connect a release potential to all of the marking diodes to a selected one of said switching stages, so that at least one of the crosspoint reed relay windings in the hold circuit means is short-circuited thereby causing the release of the serial connection.
  • each switching stage of said plurality of said switching stages the crosspoints giving access, when operated, to a predetermined switch outlet, are divided in at least two groups, means for multipling the marking diodes to separate marking conductors, whereby a shortcircuited diode renders only part of the links unavailable.
  • test impedance means has a relatively low impedance value and thereby causes a short-circuited marking diode to indicate that a link connected thereto via a crosspoint is busy.
  • test impedance means has a relatively high impedance value and thereby enables the potential of a busy link coupling said switch blocks to be transmitted through a shortcircuited marking diode coupled thereto to all free links connected to said short-circuited diode via a crosspoint impedance whereby the potential of said free links assumes a value indicating that they are busy.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)
  • Lubricants (AREA)
US698541A 1967-01-23 1968-01-17 Fault detecting and correcting circuitry for crosspoint networks Expired - Lifetime US3532976A (en)

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Application Number Priority Date Filing Date Title
NL6701055A NL6701055A (ja) 1967-01-23 1967-01-23

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US698541A Expired - Lifetime US3532976A (en) 1967-01-23 1968-01-17 Fault detecting and correcting circuitry for crosspoint networks

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US (1) US3532976A (ja)
AT (1) AT296396B (ja)
BE (1) BE709718A (ja)
CH (1) CH477789A (ja)
DE (1) DE1562121B2 (ja)
DK (1) DK141590B (ja)
ES (1) ES349621A1 (ja)
FI (1) FI53642C (ja)
FR (1) FR1565457A (ja)
GB (1) GB1147572A (ja)
IE (1) IE31817B1 (ja)
NL (1) NL6701055A (ja)
NO (1) NO129068B (ja)
SE (1) SE368314B (ja)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3731275A (en) * 1971-09-03 1973-05-01 Stromberg Carlson Corp Digital switching network
US4231017A (en) * 1978-02-22 1980-10-28 Hitachi, Ltd. Switching matrix equipment having a series circuit of relay coil and self-holding diode at each crosspoint
US20100061024A1 (en) * 2008-09-11 2010-03-11 General Electric Company Micro-electromechanical switch protection in series parallel topology

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL6701052A (ja) * 1967-01-23 1968-07-24

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2978641A (en) * 1956-10-31 1961-04-04 Siemens And Halske Ag Berlin A Circuit ambiguity testing apparatus
US3084326A (en) * 1958-12-01 1963-04-02 Transitron Electronic Corp Means for measuring and testing components
US3200392A (en) * 1960-12-02 1965-08-10 Ite Circuit Breaker Ltd Counting circuit for counting cell railures in a rectifier system
US3206729A (en) * 1960-12-22 1965-09-14 Daniel Roger Hegelbacher System for ascertaining from a distance the electrical conditions of a switching device
US3363064A (en) * 1964-02-29 1968-01-09 Telefunken Patent Matrix means circuit tester

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2978641A (en) * 1956-10-31 1961-04-04 Siemens And Halske Ag Berlin A Circuit ambiguity testing apparatus
US3084326A (en) * 1958-12-01 1963-04-02 Transitron Electronic Corp Means for measuring and testing components
US3200392A (en) * 1960-12-02 1965-08-10 Ite Circuit Breaker Ltd Counting circuit for counting cell railures in a rectifier system
US3206729A (en) * 1960-12-22 1965-09-14 Daniel Roger Hegelbacher System for ascertaining from a distance the electrical conditions of a switching device
US3363064A (en) * 1964-02-29 1968-01-09 Telefunken Patent Matrix means circuit tester

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3731275A (en) * 1971-09-03 1973-05-01 Stromberg Carlson Corp Digital switching network
US4231017A (en) * 1978-02-22 1980-10-28 Hitachi, Ltd. Switching matrix equipment having a series circuit of relay coil and self-holding diode at each crosspoint
US20100061024A1 (en) * 2008-09-11 2010-03-11 General Electric Company Micro-electromechanical switch protection in series parallel topology
US8687325B2 (en) * 2008-09-11 2014-04-01 General Electric Company Micro-electromechanical switch protection in series parallel topology

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Publication number Publication date
DK141590B (da) 1980-04-28
IE31817B1 (en) 1973-01-10
BE709718A (ja) 1968-07-23
DK141590C (ja) 1980-10-06
CH477789A (de) 1969-08-31
AT296396B (de) 1972-02-10
FI53642B (ja) 1978-02-28
NO129068B (ja) 1974-02-18
DE1562121B2 (de) 1973-04-26
NL6701055A (ja) 1968-07-24
ES349621A1 (es) 1969-04-01
FR1565457A (ja) 1969-05-02
SE368314B (ja) 1974-06-24
IE31817L (en) 1968-07-23
DE1562121A1 (de) 1970-02-19
GB1147572A (en) 1969-04-02
FI53642C (fi) 1978-06-12

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Owner name: ALCATEL N.V., DE LAIRESSESTRAAT 153, 1075 HK AMSTE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INTERNATIONAL STANDARD ELECTRIC CORPORATION, A CORP OF DE;REEL/FRAME:004718/0023

Effective date: 19870311