DE907310C - Circuit arrangement in at least semi-automatic telecommunications office systems - Google Patents

Description

Circuit arrangement in at least semi-automatic telecommunication exchange equipment Additional patent 880: 322 Patent 880 322 relates to -a arrangement for detecting the presence of a predetermined over-limit signal voltage by means of a gas discharge tube and connected in series with the discharge path of this tube signal receiving apparatus. The arrangement is characterized in that a signal voltage which exceeds the predetermined limit host activates a static switch to transmit an alternating voltage to the control electrode of the gas discharge tube and thereby cause the same to ignite.

The invention now relates to an application of those described in the main patent Arrangement to use different line classes in telecommunications exchange systems, in which lines, z. B. subscriber or other lines of an automatic telephone system divided are, or different classes of compounds through which the different Types of lines are occupied. can distinguish and corresponding operations to be able to control in the office equipment.

It is well known that a line is idle or busy to be identified by applying different voltages to one of their conductors. For example, when a line is in the free state, a battery voltage can be applied to the test conductor of such a high value that a test relay one seeking selector switch can respond at this voltage while in the busy state the line this voltage to the value zero or at least to such a low Value is reduced that the test relays of the searching selector switch to this Voltage can no longer respond.

It is also known to arrange the test director so that, in order to detect two different Types of lines to be able to identify the voltage present on it two different resistances can be applied. In such cases, the am Test director according to the occupancy of the line by a selector switch still available Voltage different according to the type of line, and this voltage difference can be used to assign a specific display to a searching selector give. For example, the first line of a group of extension lines lead a battery voltage to their test conductor, which is applied via a resistor which is lower than an ordinary single line, so that if a Selector switch checks the first line of an extension group, he checks this in theirs Occupied state as such by noticing that the voltage on the test conductor then is higher than in the case of a single line. This distinguishing signal can do this can be used to initiate the selector switch with the search process in the extension line group if the first line in the group turns out to be busy.

The present invention relates to similar arrangements, in but for which the range of voltages used is significantly wider, so that between a greater number of different lines or different Types of connections through which a line can be occupied, or a distinction between both can be. According to the invention, this is done using those described in the main patent Arrangement achieved by a) that in a first group of line classes the Test lead across a resistor assigned to each class, including the resistance value Zero, to which one battery pole is connected, b) that for another group of line classes according to which lines connections are not established the test director of individual classes can use a resistor assigned to each class is connected to the other battery pole, the test lead of another class from this group remains open, and c) that with a number of different classes of connections a voltage across a resistor assigned to each connection class is connected from the last-named battery terminal to the relevant test conductor, in such a way that that for every possible combination of line and connection classes on the test director there is a different and characteristic tension and that it is in the office equipment existing, the gas discharge tube and the static switch containing arrangement responds to this voltage and for everyone on the test conductors. possible electrical State controls a corresponding process in the automatic equipment.

According to a further embodiment of the invention, the arrangement can except their use to determine the voltages present on the test director be used either the, value: of the resistance over which the one voltage is present on the test conductor corresponding to the battery poles, or the presence or lack of a rectifier in a test director to determine which rectifier serve as a further means of displaying a certain state of the line can.

The invention further describes means by which different classes of compounds the line can be indicated by the fact that a busy voltage over different Resistance values can be applied to the line and that the corresponding electrical states in the line circuit can be used under to bring about a change in the line class under certain conditions.

The invention is exemplified below with reference to the drawing described in more detail. In the drawing, Fig. R shows the line circuit at the top left of a calling party, this line circuit via a call finder is connected to a register device, a part of which in the lower part of this Figure is shown, Fig. 2 the line circuit of a called party and Parts of local and remote connection devices and a register device for Establishing local connections, Fig.3 shows a circuit arrangement similar to that Fig. 2, in which the register device for the establishment of remote connections , is set up, and Fig. q. the connections according to the test directors of a number of subscriber lines that are set up to search for specific Line classes in a group of line classes is restricted.

In the illustrated embodiment of the invention, the following six classes of power through different electrical states, in particular indicated by DC voltages (or lack thereof) on one of the test conductors become: a) Individual line or line of an extension group with the exception of first and last line of the extension group, b) first line of an ancillary bell group, c) last line of an extension group, d) line of an absent subscriber., e) line with changed number, f) unused line.

As for cases a), b) and c), @so are already different Proposals become known, according to which extension lines from individual lines can be distinguished. All of these proposed arrangements,. Those with differential voltages or resistance to work on a leader of the subscriber line suffer from parallel a direct earth connection to the resistance on the test conductor Manufactures ladder. On the other hand, if the line is in the state for a long time should remain for absent participants, the direct grounding of the test lead through various means can be effected, such as by replacing the resistor with a direct earth connection or by short-circuiting this resistor.

The usual arrangement up to now was made in such a way that one participant, whose line is in the state for absent participants when making of a call from his station by means of a special search and connection device is connected to the above-mentioned officer and can ask her to direct him return to normal. According to the one shown in the drawing Embodiment of the present invention is the existence of the condition for absent participants also perceived on the call side, through the Register as soon as this is connected to the calling line. In such a After this perception, Ida's register causes the automatic production of the trap a connection to the workplace for absent participants, via the normal dialing and connection equipment and without the participation of the subscriber. In this way, there is no need for special search and connection equipment provide for calls from lines that are in the state for absent subscribers are to redirect to the workplace for such participants. The only measure to set a normal subscriber line to the state for absent subscribers, there is only a direct connection to be established with the test director after Earth.

On the other hand, there is another one in contrast to the grounding of the test conductor The possibility of differentiation is that the test conductor is connected to the battery will. This can be used for lines whose number has been changed as mentioned above under e). This state is different from any of the states a) to @d), in that in the latter states, when there is a busy voltage from the automatic equipment seizing the line applied to the test conductor, the voltage on the test conductor never equals the value of the voltage the office battery can reach as the test lead in the line circuit either connected directly or through a resistor to earth and the busy voltage is applied over a certain resistance value. Only if the test conductor of the line circuit is connected to the battery voltage via a resistor, which applies to case e), the automatic equipment can find a voltage on this conductor that is the same the battery voltage is. This state becomes the one shown in the drawing Example used to show a changed number, i. H. to indicate that a particular subscriber number is no longer used for a particular subscriber so that all calls directed there are diverted to an officer, or that a certain display occurs, for example in the form of a buzzing tone for unavailable numbers. By applying full battery voltage to the Test director of such a line can this condition through the automatic equipment are perceived, which can then ensure that the calling subscriber connected as requested. In this case, too, the connection becomes clear The line of the dialed number is automatically terminated.

The embodiment shown in the drawing shows only one Line class whose test conductor has a resistor with the negative pole of the Battery is connected. However, there is still the option to choose between more than to distinguish a class of lines of this type, namely that the Test lead is connected to the battery through resistors of various sizes, as shown in a similar manner for lines, their test leads via resistors are grounded of different sizes.

Another state f) can be created by the test director is left open in the line circuit so that it is neither connected to earth nor to a Battery voltage leads. In the exemplary embodiment shown, this is used for display purposes an unused subscriber number is used, so that connections to such Lines have to be resolved and the calling party sends a special signal to receive or to be connected to a workplace.

According to the invention, in addition to the display of a certain line class, z. B. a subscriber line, given the possibility of the connection class a connection occupying a line by means of the one on the test director voltage present in the line: in many countries it is required that between different classes of compounds are to be distinguished; for example between Local and long-distance connections, and there should be the possibility of a long-distance connection to be able to give preference if the requested subscriber line turns out to be locally manned proves. For this reason it is necessary to make an electrical distinction between to enable the manned and the remote-manned state. In certain cases this is done by means of a buzzing tone which the test director is created and by an officer who makes a long-distance connection to this line to make wishes can be heard. If the officer hears this tone, she should you refrain from switching the connection through. In other cases, the Difference between the local and the remotely occupied state due to such an arrangement the remote connection device achieved that after the attempt wire separation of a An existing connection is checked to see if this attempt is made was successful. Since disconnection is only possible in the case of a local connection, to the Disadvantage that only two displays are possible. For example, one of these is Suggestions for the voltage for individual lines or the last lines of extension groups connected to the test leads of these lines via resistors of the same size, while for all other lines of an extension group, the voltage via resistors of a different size. When dialing a busy line the latter Kind is determined by the presence of the resistance of a certain size of the search process initiated after a free line. This arrangement has the disadvantage that the Search process initiated for all lines in the group with the exception of the last line will, if @these lines are busy so that it is not possible, certain Lines of the group for night duty in such a way with certain subscriber stations to connect the extension switchboard, .that they called individually during the night without initiating a free choice among the other lines, if they are occupied.

In another arrangement, it is only activated when a line is busy , one conductor of this line is grounded, and in addition, the grounding is only used for branch lines made except for the last one. This grounding thus indicates that the line is busy and belongs to an extension line group and that therefore a free choice should be initiated.

Furthermore, an arrangement is known in which a voltage across resistors one size with all individual lines and all lines of extension groups except for the first and last line connected while the voltage the first and the last lead of the group via a resistance from another Size is fed. In this way it is possible to use the intermediate lines, i. H. those between the first and last line of an extension group Lines to call during the night without the line selector when busy Intermediate line to carry out a free election, because these intermediate lines have the same marking status as individual cables. The line voter However, dst is set up so that if he is to dial a busy first line an extension group is caused, forced to carry out a free dialing and continues this until he finds a free line or the last one Management of the group reached which has the same identification status like the first line and thus differs from the intermediate lines. Such an arrangement has the disadvantage that, if a calling party directly dials the last line of an extension group and if so this line is busy, the line selector starts free selection and thus on the contact set of the wrong participant.

In the illustrated embodiment of the present invention, resistances of three different sizes are provided for the above-mentioned cases a), b) and c), so that it is possible to call an intermediate line individually in the same way as a single line while the electrical state of the last line of a group is different from that of any other line type, so that if the last line is dialed individually, no free dialing is initiated. This last line can therefore also be dialed directly without having to initiate free dialing when the line is busy. In the embodiment shown in the drawing, the various above-mentioned states are indicated by a grounding via Wiiderstäüd @ e of 19,000, 4300 and rooo ohms for .die three connection classes a), b) and c), as can be seen in the table below : Local tension Head of the busy remote busy Subscriber line resistance Type of line 5700 ohms 2400 ohms Last line a group. . rooo ohms 7.2 volts 14.1 volts First line a group .. 430o - 2o, 6 - 3o, 8 - Single line and Intermediate line a group .. rgooo - 36.9 -, ¢ 2.7 - A further distinction can be made by direct grounding of the test conductor without using a series wIderstantdes and used, for example, to display the line of an absent participant, as indicated under d). If such a line is called by another subscriber, this condition is sensed by the automatic equipment, which, as soon as it detects that the test director of the subscriber line is directly earthed, disconnects the connection to the called subscriber and automatically sets up another connection leading to an officer specifically designated to deal with such compounds.

It can be seen that it is very convenient to run a to indicate absent participants by direct earthing of the test lead of this line, because this grounding can be done without affecting the resistance across the test lead normally grounded when the participant is present, must be removed. If a participant informs the officer that his line is in the state of a Line of an absent participant is to be relocated, then only has to the test lead of the line must be connected directly to earth. If the line is continuous for this possibility is set up, which will be the case when the line is often to be put into this state, then the line can, for example a relay can be assigned from a central point by the desire the official receiving the participant can be excited or de-excited and that not but in the case of a long-distance connection holding the line busy, it indicates failure of disconnection indicates that the line is remote. But this will only be known if the officer attempted to disconnect; and immediately after connecting to the line there is no such indication obtain.

In the illustrated embodiment of the present invention is a permanent one between the test directors of local and remote lines electrical difference present, so that when continuing a long-distance connection after a line already in use by a remote connection, this state of the Official can be reported immediately, and the order can be trained be sure that any attempt to terminate the existing connection is prevented. At the same time the arrangement is such that local and long-distance connections via one common electoral train can be established at least in the line electoral stage.

In order to be able to differentiate between local and long-distance connections at the test conductor, the busy voltage for local connections is applied via a resistor which is different from that for long-distance connections, so that the values of the voltages generated by the application of the busy voltage for local and long-distance connections are different from one another . In the embodiment shown, the busy voltage supplied by a local connection circuit is applied via a resistor of 5700 ohms and that supplied by a remote connection circuit is applied via a resistor of 2400 ohms. If an office battery of 48 volts is used, the voltages on the test conductors of the subscriber lines for the various line classes are the values given in the table above. This table shows that each line class on the test conductor can have two different voltage values, depending on whether the line is manned locally or remotely. For example, the voltage on the test lead of the last line in a group of extensions is 7.2 volts when the line is manned and 14.1 volts when the line is remote.

It can be seen that it is not necessary in the case of local calls the difference between a remote and a remote connection to know. This is only necessary if an attempt is made to obtain a Continue the remote connection after the existing connection. For this reason are only the remote connection circuits that allow verification of the voltage condition on the test director of the subscriber line so that they for each line class between voltages for the locally manned and the remotely manned State. The location registers only have between the different To distinguish between voltages for the various cable classes. For this reason the arrangement of the resistors is such that the six different voltages for, the three line classes a), b) and c), according to which connections are switched through should occur in pairs, so that starting with the lowest voltage and in ascending order, each pair belongs to a line class. That way it is possible to arrange the means by which these tensions are checked in such a way, that they only differentiate between pairs and thus between different classes of line. This distinction is made using an elimination process. Let it be B. assumed that a single line is occupied. The discriminator begins verify that the 7.2 and 14.1 volts are present, setting them up so is that it can respond at any voltage below, for example, 15 volts. in the assumed case it does not address, so that the possibility of what the called line could be the last line of an extension group is. The device is then set up to work with any of the for example 32 volts lying voltage can respond, so that if the Line would be a first extension line and its voltage would therefore be between 15 and 32 volts would respond. In the assumed case, however, she speaks not to and therefore includes the possibility that the called line is a first Extension line could be off. Thereupon the discriminating device becomes adjusted so that it can respond to voltages, for example below 43 volts lie. The facility will now operate accordingly, regardless of whether the line is occupied locally (voltage 36.9 volts) or remotely occupied (voltage 42.7 Volt) was. Only in the case of a remote call and only after it has been finally determined has been that the line is a single line and busy, or after the Line selector has arrived on a busy last extension line, investigated the remote automatic equipment, as detailed below, whether the line is manned locally or remotely.

On the other hand, the class of a busy line can thereby be determined turn when the discriminator s0 is switched; d @ she ate the off of the various possibilities one after the other, from breath to the highest tension pair starting out.

As mentioned above, the arrangement is such that local and remote connections can be completed via a joint voter train. This is in itself already known, however, has the use of combined local and remote dialers in the known systems a considerable repercussion on the possibilities of Free extension dialing. It is clear that if an entire leadership group is occupied there is a tendency to post a new incoming remote call for this group the last line, and that a local connection, .the last, Line may be present in favor of the long-distance connection separated will. If another remote call for this group arrives in this state, then this is usually also routed to the last line,: and both The officer at the transfer will determine the busy status of this line the remote connection, regardless of the fact that several other of the lines; the group can lead local connections that are separated can. About the tendency to forward long-distance calls after the last line To prevent the group, orders have been proposed through which the free election in the group in the event that the last line is remote, to free or Busy lines are restricted.

This is achieved by means of a relay, which only applies to remote calls responds and, if a last line is remote occupied, on the last but one line creates the condition for the last lines. If this line is also occupied remotely is or will, so speaks a; Relay for this line and creates the same State on the previous line, and so on. This procedure was only This enables separate line selectors for local and long-distance connections are used so that the relay indicating the remote busy status: is in series can be inserted multiple times between the local and trunk line selectors could. Such arrangements cannot therefore be used when combined Local and trunk line selectors are used as it is important to to give the line an electrical label indicating that it is remotely manned has been. In the illustrated example of the present invention, the electrical! Indication by the fact that the busy voltage for remote connections via the Pxüfleiter @ a resistor, the value of which is the same as the resistance for local connections is different,, applied wind, and this enables the free dialing of the extension restricted to idle or busy lines, even if combined Local and long-distance line selectors are used.

Another possibility of the arrangement is; that the presence a rectifier in one of the conductors of the subscriber line which rectifier can be provided, can be to a certain state a line, which is a common characteristic of some of those discussed so far Line classes with the exception of unused lines. This rectifier can be in series for connection to earth or battery, either directly or is connected to the test conductor via a resistor, or it can be on the other hand in series with one of the other conductors of the subscriber line's exchange equipment be according to which the distinguishing device in the register required for verification the electrical condition in the test director is used, can gain access. When described The embodiment is a rectifier in the conductor c of the subscriber line (Fig. I) inserted for a line with limited traffic. When a call is made on such a line, the registry checks -to the presence of this rectifier, and he, if it is present, takes care of it that certain types of connection cannot be carried out, or that, ß the calls are diverted in a predetermined manner.

The following is a detailed description of the operation.

If i a call is initiated in the arrangement awake Fig. Over the top left shown line, so the voltage at the connection point zw-regard Iden with the conductor of the subscriber line b connected resistors 15 ooo and 30,000 ohms to a lower value, whereby the actual Initiation takes place in a known manner. The reduced voltage also occurs in many cases the conductor c to the subscriber line, which extends to all first call viewfinder. The figure only shows such a call finder.

Position i: Control of the search process #, in the first call seeker If a register has been occupied by the call and put into the state in which it can control the search process of the first call seeker for the calling line, a relay Ut, not shown, speaks effected on which ut at its working contact 3 d @ ate the switch PM, which belongs to the register is incremented from the rest position to the position i: earth, normally closed contact A 3, make contact ut 3, rest position contact and switching arm d of the switch PM, Switching magnet and series resistor of this switch, battery. The switching magnet works and energizes the relay via its break contact. This opens the circuit described above tau its normally closed contact A 3 , so: that the switching magnet and the relay Pkr de-energized and thereby the switching arms of the switch PM are moved to the position i. In position i of the switch, the following circuit is closed for the first caller: earth, break contacts fti and pk4, switching arm a and contact i of switch PH, switching magnet LF of the first caller belonging to the machine dialer type, battery. _ The call seeker turns his switching arms until they find the calling line, at which moment the voltage on the conductor c is switched through via the switching arm, c of the first call seeker to the register, via the switching arm e of the switch PM to the midpoint of the Secondary winding of the transformer T i. This transformer forms part of a static switch of a known type. The occurrence of this voltage causes a direct current to flow through the static switch via the center point of the primary winding of the transformer T z and the switching arm f of the switch PM, which is in position i with a voltage of -37 volts leading point of a potentiometer is connected. It should be mentioned that, as long as the calling line was not reached, the voltage at the center of the transformer T i was kept at -q.8 volts via a resistor of 500,000 ohms, so that the rectifiers Re i and Re 2 were in a non-conductive state. As soon as the seeker reaches the calling line, these rectifiers become conductive, so that an alternating current of q.5o Hz can flow via the two transformers to the control electrode of the tube Tu , which works with cold cathode, whereby the tube ignites and the excitation of the relay Ftr causes. The circuit of this relay. runs from the --i5o-volt battery via the resistor of 35oo ohms and the shunt capacitor C over the main section of the tube Tu, winding of the relay Ftr, break contact pk 2, make contact uf 5 to earth, assuming that this working contact is already closed in this state of the arrangement. The relay Ftr responds, and its normally closed contact ft i opens the circuit of the call seeker magnet LF, so that the switch arms of the call seeker are stopped on the calling line. The relay Ftr closes the following circuit at its normally open contact: normally open contact ft i, switching arm b of switch PM, winding of the switching magnet of this switch, series resistor, battery. The switching magnet responds and energizes the relay Pkr. At the contact pk 2 the circuit of this relay Ftr and the Stromfluss.in the main section of the tube Tu is interrupted, so that the relay Ftr is de-energized and the tube is extinguished. But since the contact pk q. is opened, the call finder solenoid cannot be re-energized. The switching magnet of the switch PM is de-energized by the contact ft i, so that the switch continues to switch to position 2, the relay: Pkr also being de-energized. Position 2: Check for a line with limited connectivity In position 2, a check is made to see whether there is a rectifier in conductor c of the subscriber line, which would indicate a line with limited connectivity. This check is carried out by reversing the connection after the static switch in such a way that the switching arm c dos call seeker is now connected to the center of the transformer T 2, while the center of the transformer T i via the switching arm e and contact 2 of the switch PM is directly earthed. This has the effect that the rectifiers Re i and 'Reg only become conductive when a current can flow from conductor c of the subscriber line to the negative pole of the battery. This cannot be the case if there is a rectifier in conductor c, since this is connected in such a way that it only lets the current through if the voltage in the register is negative with respect to the voltage on conductor c. If an earth is connected in the register, then the rectifier Re3 in conductor c prevents the passage of current, so that the static switch does not work. And the relay Ftr keeps its normally closed contact closed. On the other hand, in the case of lines with unrestricted traffic, where there is no rectifier, the static switch works and the relay Ftr responds. Let us now assume the case of a line with limited connectivity. In this case the relay Rsr responds in position 2 of the switch 1'M: earth, normally closed contacts ft i and pk q., Switching arm a and contact 2 of the switch PM, winding of the relay Rsr, battery. The relay. Rsr holds itself through its contact rs i and closes at its contact rs 5 a circuit leading to the switching arm d d es switch PM for the further switching of this switch, which is advanced in the same way as when switching from the rest position N out was the case.

If the line is not subject to any restrictions, the relay Rsr cannot work, because before it can be energized, the relay Ftr responds and closes a direct circuit for switching the switch PM out of position 2, in the same way as this was the case when forwarding from position i. This circuit runs via switch arm b of switch PM.

The relay Rsr indicates by its energization that restrictions are placed on the line, so that, if certain types of connection are selected, the register can take the necessary measures for rerouting. Position 3: Checking this call status In position 3, it is checked again whether the line is in the call status in order to determine whether the test switch arm of the call seeker has also been correctly stopped on the corresponding bank contact of the calling line. The conditions in position 3 are exactly the same as in position i, with the exception that the circuit of the call seeker's switching magnet cannot be closed. If the caller has been stopped correctly, the relay Ftr will respond and the switching of the switch PM to position q. cause. Position ¢: Check the line for the free or busy status In position q. it is checked whether the line has not been seized by a line selector, namely in the period between the moment the telephone is picked up and the seizure by a caller. In such a case, the battery voltage would be switched through via the line selector switch arm d to id; em conductor d of the calling line, and since this is connected through to earth via a resistor r in a normal line; as can be seen from the table above, a voltage of at least -7.2 volts would be present on conductor d, depending on the blind or line class. If the line is free, then the voltage on conductor d is zero. This is checked by keeping the conductor d in position q. is connected to the center of the transformer T i of the static switch, while the center of this transformer T.2 is connected to the voltage -5 volts via the switching arm f of the switch FM. The state is now such that the current can only flow in the static switch when the conductor d is connected to Erdre, ie when the line is free. Assume that this is the case. In this case the relay Ftr responds and closes a circuit via the switching arm b , which is in position 4, for the relay Psr, which responds via the contact pst unid at the contact PS 3 a circuit for switching the switch PM off position 4 closes after position 5.

If the relay Ftr does not respond, ie if the line is busy, the switch PM stops in position 4 until the register has dropped out, which occurs automatically because the call state disappears. Position 5: Check the status for absent participants In position 5, it is checked whether conductor d is directly connected to earth, which is the case when the line is in the status for absent participants. The connections with the static switch are the same in position 5 as in position 4, so that the static switch should always work, @ because it knew how to work in position 4. The inferential arrangement is used, however, in order to ensure that it only works when there is a direct grounding, while when the conductor d is grounded via a resistor r, the static switch cannot respond. When the relay Psr responded, it closed a power circuit from the battery to the contact PS i via a resistance of 100 ohms to the contacts 4 and 5 of the bank contact row e of the switch PM. This battery has no effect in position 4, since the relay Psr only works after the tube and the relay Ftr has already worked. In position 5, however, the presence of this battery prevents the static switch from responding as soon as the earth potential present on conductor d is applied via a resistor, dpa in this case the voltage on the conductor reaches such a high negative value that it is higher than that at the midpoint of the Transformer T 2 occurring voltage becomes negative. Therefore, only when the conductor d is directly earthed, the voltage at the center point of the transformer T i is positive compared to the voltage v011-5 volts and causes the static switch to work. It is assumed that: this! Is the case. In this case, a circuit is closed in position 5 via the normally open contact ft i and the bank row b of the switch & PM for the excitation of the relay Asr, which is maintained via its contact a.12, while at its contact as 5 the excitation of the relay Ltr is effected. If the line is not in the state for absent subscribers, the relay Ftr remains de-energized and the relay Ltr responds by itself, via the normally closed contacts of the relays Ftr and Pkr and the bank row a. The response of the relay Ltr indicates d.that the checking of the line of the calling subscriber has ended, u-ud puts the register in the state in which it can receive the requested subscriber number and dial the requested line. However, if the relay Asr has responded, the automatic selection of an officer can be initiated by measures not shown in the register, without the participant having to dial any number. In this way, a participant can join. When he returns home, he can automatically be connected to the officer designated for handling connections to and from lines of absent subscribers by picking up his receiver: The relay Ltr closes a circuit at contact 14 for switching the switch PM from position 5 to position 6, with the switching in the same whiteness takes place as from the rest position N. Mode of operation on called subscriber line In Fig. 2, a subscriber line circuit is shown at the top left and a part of a location register is shown in the remaining part. The resistor x 'inserted in the conductor d of the subscriber line can have different values, as can be seen from the table above. It can be connected to earth or not connected at all, as has been described for the various types of line. If a subscriber is in a local connection, a battery is connected via a resistor of 5700 ohms and the switching arm d of the line selector. For this purpose it should be assumed that the point x is connected to the point zer. The relay Rlr, which is connected in the local cord line parallel to the resistance of 5700 ohms; is in series with a rectifier in such a way that a current only flows through this relay when the voltage on the switch arm d of the selector receives a higher negative value than the normal voltage of the office battery. Accordingly, no current flows through this relay when the line is connected to a local cord circuit. The relay can be made to work by a remote officer who, when attempting to disconnect a local connection, causes a high negative voltage of, for example, -6o, volts to be connected to conductor d of the subscriber line for a short period of time. The excitation of the relay Rlr then causes the dissolution of the local connection. With a battery connected via a resistor of 570 ohms, the voltages around conductor d are given the values given under the column “Occupied” in the table.

If a subscriber line is remotely busy, then the practicing conflict is over Battery connected by 24oo ohms to the remote connection equipment via the switch arm d of the line selector switched through to the conductor d of the subscriber line. the correspond to the voltages occurring on this conductor for the various cable classes then the values given in the "Remote occupied" column.

The various possible cases will now be described in order will.

Local call on free line The switch PM (finger 2) corresponds to that of FIG. For the sake of simplicity, however, the first five positions have been omitted, so that the figure begins at position 6. It is assumed that after the selection of a subscriber, the switch PM is in S ± .oitun @ 6, so that when the selection is completed, after energizing the relay Esr (not shown), the following circuit for switching the switch from position 6 to 7 closed << ird: break contact pk 3, make contacts ut 3 and es i, contact 6 and switching arm d of switch PM, switching magnet, series resistor, battery. The solenoid works and energizes the relay Pky, which opens the circuit of the solenoid. This is de-energized and switches its switching arms to position 7, whereby the relay Pky is de-energized. Position 7: Check for a free called line In position 7, the conductor d of the called subscriber line is connected to the center of the transformer T i via the switching arm e, it being assumed that the point w is connected to the point z. At the same time will. the midpoint of the transformer T 2 is connected to the voltage -5 volts, so that the static switch only responds when the voltage on the conductor d is significantly less negative than -5 volts, which is the case when the line is free or when the conductor d is connected directly to earth. It is assumed that the line is free. In this case the relay Ftr responds as described. The relay Sfr responds to this via the switching arm b in position 7. The relay Sfr holds itself via its contact sf 9 and causes the switching of the switch PM @ by closing the contact sf 7, and via the switching arm d. Position 8: Checking a called line that is in the state for absent subscribers In position 8, the battery is connected to the center of the transformer T i via the switching arm e and the normally open contact sf 2 and a resistance of 100 ohms. Otherwise, the conditions in the static switch are unchanged, so that, as has been explained above for the case of checking a calling line in the state for absent subscribers, the static switch can only work if the conductor d of the subscriber line is directly grounded .. The fact that the battery has a. Resistance of 100 ohms connected would normally produce a voltage which is negative in relation to the voltage of -5 volts present at the midpoint of the transformer T2, if the conductor d, of the subscriber line across a resistance of one of the three for normal Lines provided for the sizes provided. Since it was assumed that the call was initiated on a normal line, the static switch will obviously not work and the Relaris Ftr remains de-energized, so that the following circuit is now closed: earth, normally closed contacts ft i and pk q., Switch PM in position 8, normally open contact sf 3, normally closed contact as9, winding of relay Sbr, battery.

In this condition considered, the relays Sfy and Sbr are excited. The relay Sby switches the cord circuit and switches off the register. The relays energized at the same time. Sfr causes the cord circuit to be put into the state in which the called subscriber is called, and the calling subscriber receives the ringing tone. The switch PM holds in position 8 until the register is switched off, whereupon it is switched back to the rest position by a switch 0M located in position i via its switching arm c and the switching arm e. Local connection after a line in the state for absent subscribers If the noble switch PM arrives in position 8 as with a call for a free line, it is checked whether the line is in the state for absent subscribers. If this is the case, ie if the d wire is directly earthed, the static switch and the relay Ftr respond, so that the circuit of the relay Sbr cannot be closed as with a free line. On the other hand, a circuit for the relay Asr is closed: earth, working contact ft i, switch arm b in position 8, working contact sf 5, winding .des relay Asr, battery. The relay Asr responds, holds itself through the contact as i and closes a circuit running through the switching arm d, through which the switch PM is switched from the position 8 to the position 9. The other tasks to be fulfilled by the relay Ars will not be described since they do not belong to the present invention. It should only be mentioned that the switch AM goes to position 9 while the register, under the control of the relay Asr, establishes a connection to an officer, whereupon the switch PM returns to the rest position and the register is switched off. Local call to a busy line of an extension line group When the selection has been made, the relay Esr responds and switches the PM switch to position 7, as has been described for a call to a free line. In position 7 it is checked whether the subscriber line is free. But since the voltage on conductor d of the subscriber line is more negative than the voltage of -5 volts present in position 7 at the center of the transformer T2, the static switch and the relay Ftr cannot respond, so that the following circuit is now closed : Earth, normally closed contacts ft i and pk 4, switching arm a in position 7, switching magnet of switch PM, series resistor, battery. The switch PM moves its switch arms to Stelhing 8; without the relay Sf r being energized.

Position 8: Repeated test Since Lias relay Sf r is not energized, the arrangement is in position 8 of the switch PM in exactly the same state as in position 7, so that the relay Ftr again does not 'respond and' therefore on via the switch arm a. and the normally closed contact sf 3 running circuit for the Switching the PM switch to position 9 is closed.

Position 9: Run through Position 9 is run through, as there is a circuit for the switching magnet of the switch FAl via the switch arm d and the normally closed contact as3.

Position i o: Check the last line in an extension group on busy The voltage on a last busy line can go up given table have either the value of -7.2 or -14.1 volts. In Stel - long 1o is a test with a connected to the midpoint of the transformer T: 2 Voltage of -17, q. Volts made so that the static switch can work, if one of the first two voltages on conductor d of the subscriber line there is what should now be assumed. The excitation of the relay Ftr in position io closes the following circuit: earth, normally open fti, switching arm b and contact i o, normally closed contact as9, winding of the relay Sbr; Battery. Dias relay: Sbr responds.

As mentioned above, the excitation has .this relay Sbr the advancement of the cord circuit and the release of the register for Episode. But since this relay is excited without the relay Sfr, the cord circuit is now put in a state in which he gives the busy signal to the calling subscriber releases: and terminates the connection established after the called line. The desk P.11 stops in position i o until it is released by a is moved into the rest position via its switching arm c extending circuit.

Local call to a busy single line According to the table, can the voltage present on conductor d in the case of an occupied single line is the value of -36.9 or -q.2.7 volts.

As in the case of a busy last extension line, the Switch PAJ advanced to the position io, in which the static switch with a voltage of -17, q. Volts is at the center of the transformer T2. in the The static switch indicates the present state when a single line is busy not on and accordingly there is a circuit for switching the switch PM closed, which runs over the switching arm a in position io, as already done has been described.

Position i i: Check for busy first extension line In position i i there is a voltage of -3q., 2 volts at the midpoint of transformer T2, and since this voltage is less negative than that which is present when a single line is occupied Voltage, the static switch will not respond this time either, and the switch PM is switched from position i i to position i2 via switch arm a. Position 12: Check for occupied single line In position 12, the center point is given of the transformer T2 has a voltage of -46.1 volts. The static switch speaks in this case on, the relay Ftr also, it being the following circuit closes: earth, normally open contact fti, switching arm b and contact 12, normally closed contacts pb 7 and as 9, winding of the relay Sbr, battery. The relay Sbr responds and fulfills the same functions as in the case of a busy last extension line, so that the calling subscriber receives the busy signal and the register is released will.

Local call for an unused line or a subscriber with a changed number. In the case of a changed number, conductor d is connected to the 48 volt office battery via a 10000 ohm resistor. In the case of an unused line, conductor d is open. In both cases, the same processes take place up to position 12 as with a local call for a busy line. Position 12: Run through When testing in position 12 and a voltage of -46.1 volts at the midpoint of transformer T2, the static switch cannot respond, because if the number is changed, the voltage on conductor d is compared to that at the midpoint of transformer T2 Voltage is negative, while in the case of an unused line the conductor d is open, so that no current can flow on it. On the other hand, a battery voltage is connected to the center of the transformer T i via a resistor of 500,000 ohms, so that in this case too the voltage at this point is negative with respect to the voltage at the center of the transformer T: 2. A circuit is therefore closed in the manner described via the switching arm a for the switching magnet of the switch PtbI, so that the latter leaves the position 12. Position 13: Check for unused line or line with a changed number In position 13, the connections after the static switch are swapped, so that the conductor d is now with the center point of the transformer T 2 and the center point of the transformer T i with a voltage of - 43 volts is connected. Under these circumstances, the static switch can only respond when the voltage on conductor d is negative compared to the voltage of -43 volts. However, this is only the case with a call to a line with a changed number. The operation of the static switch and relay Ftr in position 13 therefore indicates that the call is directed to such a line, while failure to respond to these parts indicates that conductor d is open and the call is therefore directed to an idle line. The latter becomes clear when one considers that the conductor d successively indicates the presence of a voltage that is less negative than -46.1 volts (position 12) and a voltage that is more negative than -43 volts (position 13), is checked. If the static switch does not respond in one or the other case, this only indicates an interruption in the circuit. If the static switch and the relay Ftr do not respond, the relay Dlr responds in position 13 via the normally closed contact pb 3 , while the response of the relay Ftr indicates that a line with a changed number has been selected and causes the relay Cnr to use the switching arm b responds. The excitation of either of these two relays causes the switch PM to switch from position 13 to position 14, the switching magnetic circuit leading via the switching arm d. In this position, the switch PM waits, while either the relay Dlr or the relay Cnr the termination of the connection to the called subscriber and the rerouting of the call to an officer intended for such connection classes. causes. After the connection with this officer has been established, the register is released, the switch PM being returned to the rest position by a circuit passing through the switching arm c. Local call making an occupied first extension line The voltage present on conductor d of an occupied first extension line is either -2o, 6 or -3o, 8 volts according to the table. From the description of a call to a busy line it can be seen that if a test with a voltage of -3 , ,, 2 volts is made at the center of the transformer T2 in position ii, the static switch and the relay Ftr work if the Conductor d carries a voltage with one of the values specified for a first extension line. Position ii: Check for busy first extension line Therefore, after the connection has progressed to position ii as described, a circuit for relay Pbr is closed by energizing relay Ftr: earth , normally open contact ft i, switching arm b and contact ri, Winding of relay Pbr, battery. The relay Pbr is maintained via its contact pb 5 and closes a circuit at contact pb 2 via the switching arm d for switching the switch PM from position ii to position 12.

Position 12: Run through As in the case of a call to a single line, the test is now carried out with a voltage of -46.1 volts present at the center of the transformer Tz, and in the case under consideration, the static switch and the relay Ftr will respond, but this remains Excitation of this relay has no effect, as the connection from switching arm b in position 12 on normally closed contact pb7 is open. A circuit for switching the switch PM from position 12 is closed via the contact pb 2 and the switching arm d. Position 13: Run through As in the case of a line that is not in use or whose number has been changed, the conditions in position 13 are such that the static switch can only work if conductor d of the subscriber line has the full battery voltage of - 48 volts leads. In the present case, the static switch cannot respond, and therefore the following circuit is closed for switching the switch PM to position 14: earth, normally closed contacts ft i and pk4, switching arm a and contact 13, normally open contact pb 3, switching magnet, series resistor , Battery. Position 14: Run through Position 14 is run through because a circuit for the switching magnet is closed via the normally closed contacts cn3 and d13 and the switching arm d.

Position 15: Free extension selection In position 15, a circuit is closed to switch the line selector on from the first line of the extension groupa and to freely select a free line or, if there is no free line, to initiate switching to the last line in the group. The circuit of the line selector solenoid is as follows: earth; Normally closed contacts ft i and pk 4, switching arm a and bank contact 15, normally open contact pb i, normally closed contact ph i, switching magnet; Battery. The line selector searches until his switching arm d finds a line whose test conductor is grounded and thus indicates a free line or whose test conductor indicates that it is the last line in the group. For this purpose, the switching arm d of the line selector is connected to the static switch, while the center point of the transformer T2 is connected to a point that carries a voltage of 7.4 volts. Under these circumstances, the static switch cannot respond to the voltage present on the first line in the group, since this line is busy and carries either a voltage of −20, 6 or −30.8 volts. Likewise, the static switch cannot respond if the intermediate line in the group is occupied, as it carries a voltage of -36.9 or -42.7 volts, according to the table. However, the line selector may stop on a free intermediate line or the last line of the group, since ° such an intermediate line is connected via a resistor of 1 9 ooo ohm to ground, while the .besetzte last line to either a voltage of 7.2 or more - i4 ;, i volts leads. The free selection is therefore terminated as soon as the line selector hits a free intermediate line or arrives on the last line of the group, the relay Ftr responding and the stopping of the line selector and the activation of the relay Phr via the switching arm b of the switch PM in position 1 5 causes. The relay Plar effected via the contact plag the handoff of the switch PM in the position 16, position 16: Check for free or busy line in position 16 is in turn connected to a voltage of an exam - made 5 volts at the midpoint of the transformer T 2. Under these circumstances, the static switch can only work when the line selector has found a free line. In this case, the excitation -of the relay Ftr causes the excitation of the relay Sfr via -den; Switch arm b in position 16. The relay Sfr causes the excitation ide-s. Relay Sbr: earth, normally open contacts ph4 and sf i, normally closed contacts as9, winding of relay Sbr, battery. As already described, the simultaneous excitation of the relays Sbr and Sfr causes the line circuit to be switched to the call position and the register is released.

If the static switch does not respond in position 16, then shows this indicates that the line dialer has stopped on the last line and that this is busy. In this case, a circuit is set in position 16 via the switching arm a closed only for the relay Sbr, which responds and the incremental switching of the cord circuit in the occupied position and the release of the register. Long-distance connections Long-distance connections are treated in a very similar way to local connections, however, to distinguish between the locally busy and the remote busy status in different approaches must be taken in certain cases. The remote registers are used for this purpose specially set up in such a way that they are in the event of an occupied line or the last The line of an extension group determine whether the line is local or remote and send the officer a corresponding signal.

The lower half of Figure 3 shows part of a remote register. The arrangement shown is the one! 2 very similar, with the exception of the Numbering of the positions of the switch P1LT, in which the rest position N in FIG. 3 corresponds to position 6 in FIG. In addition, three test positions have been added, in which a distinction is made between locally busy and remote busy status. Because only Calls to busy lines cause the remote register to work differently, are only intended to describe these cases below. Remote connection after a occupied single line When the election is over, the contact is closed, and the switch PM goes from position N to position i. Position i: check on free called line In this position, a test with a voltage made of -5 volts at the center of the transformer T2, so that the static Switch only responds when the line is free. In the case under consideration speaks the relay Ftr does not come on and the switch goes to position 2. Position 2: Check on called line in the state for absent subscribers or run through if If the line proves to be free, then position 2 is used to check for a direct grounded test director d be used, which state an absent participant indicates. If such a line is found, the relay r4sr responds, as described for a local call. If the study director isn't direct is grounded, the relay Lbr responds, which in the remote register has the same task fulfilled like the relay Sbr in the location register.

For the case under consideration, an occupied single line was. the relay Sfr is not energized in position i, and therefore the test conditions are the same in position 2 as in position i, and the Sehalter PM is advanced in a circuit leading via the normally closed contact of the relay Ftr. Position 3: Run through Position 3 is only used in the event that the line is in the state for absent subscribers. In the present case, the switch PM passes through this position in a circuit leading via the normally closed contact as3 and the switching arm d. Position 4 .: Check for busy last line In position 4, a voltage of -17.4 volts is tested at the midpoint of transformer T2, and the static switch only works if the line is the last extension line and is busy. In the present case it does not respond, so that the switch PM passes through position 4 in a circuit leading via the switching arm a and the normally closed contact ft i. Position 5: Run through Position 5 is only used to check the difference between busy and remote if a last extension line has been dialed. In the present case, the position 5 is passed through by a circuit leading via the switching arm a and the break contact sb 3. Position 6: Check for busy first extension line In position 6, a voltage of -34.2 volts at the center of transformer T 2 is used to test so that the static switch does not respond. The switch PM passes through this position as a result of a circuit running over the switch arm a. Position 7: Check for an occupied single line In this position, a voltage of - 46.1 volts is tested at the midpoint of transformer T2 so that the static switch responds. A circuit for the excitation of the relay Sbr is thus closed via the: switching arm in position 7 and the normally closed contacts pb7 and as9. This indicates that a busy subscriber line has been selected and causes the switch PM to be switched to the next position, in which a distinction is made between local and remote busy status. In the present case, a circuit for switching the switch PM from position 7 to position 8 is closed, via the contact sb2 and the switching arm d. Position 8: Check for local or remote occupancy of a single line In position 8, the test is carried out with a voltage of -q.0.5 volts at the center of transformer T2. Since the voltage on conductor d of the subscriber line is 3.6.9 volts in the case of local occupancy and 42.7 volts in the case of remote occupancy, the static switch does not respond in the first case. When responding, the relay Ftr closes a circuit via the normally closed contact pb 6 for the relay Lbr, which responds and causes the remote connection circuit to be advanced and the remote register to be released. The remote connection circuit is placed in a state in which it indicates to the officer that the called line is busy and in which the officer can disconnect the local connection. As has already been mentioned, the dissolution can be brought about by the officer by temporarily connecting a high negative voltage to the conductor d of the subscriber line, which causes the dissolution relay Rlr to be energized in the local connection circuit. After the local connection has been terminated, the remote cord circuit can remotely occupy the called line by applying a voltage of -48 volts across a resistor of 2400 ohms to conductor d of the subscriber line. If the called line is already remotely occupied, the static switch does not work at the moment in which the switch PM in position 8 initiates the test, and the relay Tbr responds via the switching arm a and the normally open contact sb 3. The relay Tbr causes the remote connection circuit to be advanced and the register released, whereby the remote connection circuit is put into a state in which it reports that the called line to the officer is remote and makes any attempt at disconnection by the officer impossible. Remote connection after a busy last extension line If a busy last extension is dialed directly, then the same processes take place as with a connection after a busy individual line, up to position 4 of the switch PM. In this position, the test is carried out with a voltage of - 17.4 volts at the center of transformer T2. If the last extension line is occupied, the static switch responds and causes the relay Ftr and the relay Sbr to be excited in position 4 via the switching arm b and the normally closed contact as9 of the relay Asr.

As already mentioned, the relay Sbr is intended to initiate the check for local and remote occupancy, for which purpose the Sehalter PM is switched to the next position by a circuit leading via the normally closed contact sb 2 and the switching arm d. Position 5: Distinction between the last extension line manned locally and remotely. In position 5, the test is carried out with a voltage of - 10.9 volts at the center of the transformer T 2. Since the voltage on conductor d of the subscriber line when the last extension line is occupied is -7.2 volts and when the last extension line is remote is -14.1 volts, the static switch only responds in the first case. When the line is occupied, the relay Lbr is energized and, when the line is remote, the relay Tbr, this is exactly the same as in the case of an occupied line in position B. The two relays perform the tasks described for that case and cause the register to be released. Remote connection after a busy extension group If a busy extension group is called by dialing the first line of an extension group, the same processes take place up to position 6 of the PM switch as with a remote call after a busy individual line. In this position the test is carried out with a voltage of -34.2 volts at the center of the transformer T2, and accordingly the static switch works if the first extension line is busy, in which case the voltage on conductor d is either -20, 6 or 30.8 volts amounts to. When it responds, the relay Ftr causes the relay Pbr to be excited in position 6 in a circuit leading via the switching arm b. In a circuit leading via the normally open contact pb 2 and the switching arm d, the switch P.11 is switched from position 6. Position 7: run through In position 7, a voltage of -46, z volts is tested at the midpoint of the transformer T2, and the static switch responds. The excitation of the relay Ftr, however, remains ineffective, since the circuit has been opened via the normally open contact ft i at the normally closed contact pb 7 , so that the relay Sbr cannot respond. The relay Pby also causes the switching .des switch P II out of position 7, for which purpose; a circuit running through the contact pb 2 and the switching arm d is closed. Position 8: run through In position 8, a voltage of -40.5 volts at the center of the transformer T: z. Is tested and the static switch works again, but the excitation of the relay Ftr remains ineffective again because the relay via its normally open contact leading circuit at contact pb 6 is interrupted, so that the relay Lb.r can not respond. The switch Pill is activated by a via the contact pb 4; and the switching arm d running circuit switched out of position 8.

Position 9: run through In position 9 the state is such that the static switch can only respond when conductor d is at full voltage of -48 volts of the official battery leads. In the present case, therefore, speaks the static Switch not on, and by one via the normally open contact Pb 3 and the switching arm d leading circuit, the switch Pll is advanced.

Position 1o: run through The position io is also run through, since a circuit leading via the normally closed contacts cft 3 and d13 and the switching arm d is closed. Position ii: Free extension dialing In position ii, the free extension dialing is controlled, the circuit for the line selector magnet running through the contacts ph i and pb i and the switching arm a of the switch PM, while the static switch is connected in such a way that it responds as soon as a free one or the last line: the group is reached, ie the test is carried out with a voltage of r 17.4 volts at the center of the transformer T 2. In the case under consideration, in which all lines are assumed to be occupied, the line selector stops on the last line in the group and switches the switch P31 to position 12 as soon as the circuit leading via a contact of the relay Phr and the switching arm d is closed .

Position ia: Differentiation between free line and the last extension line that is busy The test for the free or busy state of the line is carried out with a voltage of -5 volts at the midpoint of transformer T2. The static switch only responds to a free line and in this case causes the relays Sfr and Lbr to be excited, while if the last extension line is occupied, the relay Sb-r is excited via the switching arm a and the normally closed contact as 9. This relay has the effect, as described, that the switch in the next position differentiates between local and remote line. The switch is advanced to the next position by a circuit leading via contact sb 4 and switching type d. Position 13: Distinction between local and remote lines In position 13, a voltage of -1039 volts is tested at the center point of the transformer T2. Since the voltage on conductor d of a last busy extension line is either -7.2 volts for a busy line or -143i volts for a remote line, the static switch only responds in the former case and causes the relay Lbr to be energized in the case of a busy line Line via the switching arm b and, in the case of a remote line, the excitation of the relay Tby via the switching arm a and the normally open contact sb 3. The relays Lbr and Tbr fulfill the same tasks as in the case of a remote call to an occupied line. Subscriber lines with limited traffic possibilities The invention is not limited to the arrangement shown in the drawing, but the principle described can also be applied to other tasks. For example, a distinction can be made between lines with restricted and those with unrestricted traffic in a way other than by checking for the presence or absence of the rectifier Re 3 in conductor c of the subscriber line. This is because the line circuit can be set up in such a way that the call voltage occurring in multiple of the conductors c is substantially different for the two cases. The drawing shows the in-office part of the line circuit of the subscriber line as being built up only from resistors. With such a line circuit, the voltage that occurs when making a call in conductor e is in the vicinity of -24 volts, as the total resistance across which the earth is connected via the subscriber loop to the connection point between the resistances of 15,000 and 30,000 ohms is switched through, is approximately 30,000 ohms, so that this connection point carries half the battery voltage. Lines with restricted traffic can be differentiated by means of a different arrangement of the subscriber line, with the call voltage being significantly less negative: if it fails, for example: has a value of -8 volts. This can be achieved by increasing the resistance specified as 30,000 ohms to about 150,000 ohms. The presence of a line with restricted or unrestricted traffic can then be verified by checking the voltage present on conductor c of the subscriber line using the static switch with interchanged connections, in position 2 this check using a voltage present at the center of transformer T i of -io volts in place of the earth shown in Fig. i. In these circumstances, the static switch will not work when the voltage on conductor c of the subscriber line is near -24 volts, but will work when that voltage is approximately -8 volts. This voltage difference on conductor c can of course also be caused in other ways. For example, in subscriber line circuits in which the usual call and cut-off relays are used in place of the resistors, the excitation of the line relay can cause a circuit leading to a potentiometer to close, which has either a voltage of -8 or -24 volts on the multiple of the conductor c gives up. Restriction of free extension selection FIG. 4 shows a number of test conductors for a number of lines which are numbered from i to 6. Leads i and 6 are unit leads, and their test leads are grounded through 19,000 ohms resistors, as also indicated in the table above. Lines 2, 3, 4 and 5 represent a group of extensions, and in the normal state the first line, namely # 2, is grounded through a resistor of 4300 ohms, and the last line (# 5) is through the resistor of 100 ohms of the winding of the relay Lar grounded, so that these lines have the properties of a first and a last line of a group of extensions. The intermediate lines are grounded through a 9,000 ohm resistor, as is necessary for such lines. The drawing also shows that the switch arm d of a selector is connected to a voltage source either through a resistor of 570 ohms or 2400 ohms, the voltage above 570 ohms being used for local connections and that above 2400 ohms for long-distance connections. As long as not all lines are busy, the processes for any call take place as has been described for FIGS. This also applies in the event that all lines are busy and the last line is occupied by a local connection. In this state the relay Zar, through which the test conductor no: 5 is grounded, is not energized. If another remote call is routed to an extension group during this last-mentioned state, the line selector goes to line no. 5 and the officer can disconnect the local connection in favor of the long-distance connection. At the moment when this line is made remotely occupied, the relay Zar responds, since it is set so that it can respond in series with the resistance of 2400 ohms, via which the battery is connected in the remote occupied state. It then earths the test contact of the penultimate line of the group in parallel with the resistance of 9,000 ohms via the contact la i and the winding of io5o ohms of the relay Lbr. The test director of this line is therefore now grounded via a total resistance of 100 ohms, and further calls to this group terminate this free selection on this line. If it is assumed that the penultimate line is or is occupied by a remote connection, then the relay Lbr responds and grounds the test contact of the third last line via the contact Ib i and the resistance of 1050 ohms of the relay Lcr. In this way, idle extension can be restricted so that idle dialing stops either on an idle line or on the last line in the group that is busy. The relay connected to the second line of the group switches a resistance of 1300 ohms parallel to the resistance of 4300 ohms already connected to the test conductor of the first line of the group when it is energized during a remote connection, i.e. when all following lines are already remotely occupied . Therefore: if all lines with the exception of the first are remote-occupied, this first line is grounded via a total resistance of 100 ohms, and a register that finds this state does not initiate free selection, regardless of whether this line is free or occupied. The registry can find this line in a local or remote state and send a corresponding signal to the remote officer.

Claims (1)

PATENT CLAIMS: i. Use of an arrangement for determining a signal voltage exceeding a predetermined limit value by means of a gas discharge tube and a signal receiving device connected in series to the discharge path of the same in cooperation with a static switch which causes the gas discharge tube to ignite; according to patent 880 322 in a circuit arrangement in telecommunications office systems, in particular telephone systems with dialer operation, in which different line classes and operating states of the lines are distinguished with the aid of the electrical state of the test conductor present in the office equipment of each line, characterized in that a) that in a first group of line classes of the test conductors via a resistance assigned to each class, including the resistance value o, to which a battery pole is connected, b) that in another group of line classes, according to whose lines connections cannot be made, the test conductor of individual classes via one of each class assigned resistor is connected to the other battery pole, but the test conductor of a further class from this group remains open, and c) that with a number of different classes of connections a voltage across a W resistance from the last-mentioned battery terminal to the test conductor concerned is placed in such a way that a different and characteristic voltage is applied to the test conductor for every possible combination of line and connection classes and that the arrangement present in the office equipment, including the gas discharge tube and the static switch, is applied to this Voltage responds and controls a corresponding process in the automatic equipment for each possible electrical condition on the test conductors. a. Switching arrangement according to claim i, characterized in that different voltages which can occur on the test conductor of a line are achieved by the switchable connection of one side of the direct current path of the static switch to said conductor and the successive connection of a number of reference direct voltages to the other side of that direct current path be determined, each of these voltages has a different value than the previous one, until a current flows through the static switch and causes the discharge tube to work, the static switch being connected in such a way that a current only passes if the reference voltage has a more negative value than the voltage present on the test lead, and that, if the aforementioned connection is reversed, a current will only pass if the reference voltage has a less negative value than the voltage present on the test lead, and d The reference voltage at which the continuity occurs is a measure of the voltage present on the test conductor. 3. Circuit arrangement according to claim i, characterized in that the presence of an open test conductor by the lack of current passage through the static; Switch is displayed in each of the following two cases, namely when, firstly, the static switch is connected in one direction and to a reference voltage of an arbitrarily chosen value X in such a way that a St.romdurcli.gang. Takes place through the static switch, if on Test conductor any voltage with a value between X and the voltage of one pole @ it of the battery is applied, and if, secondly, the static switch is connected in the reverse direction and to a reference voltage, which is at least the value. X and at most the value of the voltage of said one battery pole, so that a Sbrom @ passage through the static switch takes place, if any voltage is applied to the test conductor, which at most the value of that reference voltage and at least the value of the voltage of the other battery pole owns. q .. Circuit arrangement according to claim i, characterized in that the value of the resistance via which a test conductor is connected to only one pole of the battery, by switching on the direct current path of the static switch between the test conductor and a reference voltage, with an additional path via a Resistance from the other battery pole to that side of the static switch that is connected to the test conductor is closed, and by the successive connection of different reference voltages, this is determined until a current passage occurs in the static switch, the reference voltage at which a passage of current occurs, forms a measure for the resistance value to be determined. 5. Circuit arrangement according to claim i, characterized in that firstly individual lines and extension intermediate lines, secondly first extension lines and thirdly last N, 'benstel'lenrnlinien characterized in that the voltage of a battery terminal is present via a resistor on its test probe, the value of which for each of these line classes is characteristic, and in which a line in the state for absent subscribers is also characterized by the direct connection of its test conductor to that battery terminal. Circuit arrangement according to Claim i, in which the free dialing of the extension is terminated when the extension group is fully occupied on the last line of the group, characterized in that only the electrical status found on the test conductor of an occupied first extension line by the automatic switching equipment can cause this equipment to be freely dialed and that the Electrical status at the test director of a busy intermediate line or last extension line, if such a line is not reached by free dialing but by direct dialing, causing the equipment to transmit a busy signal to the calling subscriber. 7. A circuit arrangement according to claim i, characterized in that the means for perceiving the 'condition present on the test conductor of the calling and the called subscriber line of a connection are provided in each register and control device of a group of such devices which jointly control all selection levels of a Office are provided. B. Circuit arrangement according to claim i, characterized. characterized in that after the initiation of a connection on a line, the electrical identification of which indicates the status for absent subscribers; the register and control device, after having gained access to this line and determined its status, establishes a connection to an officer designated for absent participants via the normal dialer and connection line equipment. G. Circuit arrangement according to Claim i, characterized in that for calls to a line which has one of the electrical states on its test conductor which indicates either an absent subscriber or another class of lines to which no connections can be made, the register and After this state has been determined, the control device releases all voters that it occupied for the connection and redirects the call via the normal voter and connection line equipment to an officer provided for such calls. ok Circuit arrangement according to Claim i, in which at least the line selector stage is used jointly for local and remote connections, characterized in that the busy voltage applied to the test conductor from the automatic switching equipment for local connections is supplied via a resistor whose value is different from the resistance for remote connections, and that the register and control means for remote connections are set up so that they can distinguish between the different voltages occurring for each class of local or remote lines, with the exception of first extension lines, and that after the completion of the dialing and possibly the free dialing after a such occupied line or line group report the local or remote state of the called line or line group to the remote official and allow the forwarding of the remote connection in such a case only in preference to local connections. i i. Circuit arrangement according to Claims 1 to 5 and 7, in which connections from or to a line in the state for absent subscribers are automatically routed to a workstation provided for such connections, characterized in that the line is solely by creating an electrical state characterizing this state is set to the status for absent participants on the line's test director. 1a. Circuit arrangement according to. Claims i to 5, 7 and ii, characterized in that each line which can use this service is individually assigned a relay which, under the control of means, can be brought into an actuating position and in this position the line is in this state offset, this relay creating the state characteristic of this state on the test director via its own contact, and d: aß the state for absent participants can be deleted by causing the return to the rest position of this relay by means of the means mentioned. 13. Circuit arrangement according to claim i and io, characterized in that the winding of a relay, the excitation of which causes the dissolution of a local connection, is connected in parallel to the resistor, via which the busy voltage for a local connection is given to the test conductor of a calling or called line, that further a rectifier is inserted in this parallel circuit that no current flows through the relay winding, except when the test conductor connected to it is brought to a more negative voltage than that of the battery terminal supplying the occupied voltage, and that this more negative voltage can be applied to the test director by an officer who wishes to disconnect an existing local connection on this line. 1q .. Circuit arrangement according to claim i and 7, characterized in that a further subdivision of each of these classes of lines is carried out according to common characteristics of lines of several classes, namely by inserting a rectifier in series with a conductor (c) of the lines of a Subclass, the presence of this rectifier being detected by the automatic equipment, whereupon it selects its mode of operation accordingly. 15. Circuit arrangement according to claim i, 7 and 1q., Characterized in that the presence of a rectifier in series with a conductor (c-conductor) firstly by connecting the static switch in such a direction that a current flows through the rectifier, if one such is present, and by determining the voltage present on the conductor in this state and, secondly, by connecting the static switch in the opposite direction and to a reference voltage, it is checked which reference voltage has such a value that one can be derived from the difference between this voltage and that The current resulting at the said conductor flows through the conductor if there is no rectifier in this conductor, but a current cannot flow when a rectifier is switched on, so that the lack of current flow in the latter state indicates the presence of a rectifier. 16. Circuit arrangement according to claim i, in which after the continuation of a preferential connection after a line which turns out to be the last line of a group, the line immediately preceding this line behaves like the last line of the group during its test and in which to effect the on the preceding line required change of the state a relay provided for a line appearing as the last line is made to respond as soon as the line is occupied for a preferential connection, characterized in that this relay is in the test conductor circuit, that also the automatic equipment dem Test conductor applied busy voltage for a preferential connection is supplied via a resistor which has a lower value than for any other class of connection, and that the relay is set so that it can only respond in the event of a preferential connection.