Patent GB-904567-A (GB)
Title: Improvements in or relating to circuit arrangements in telephone systems for controlling the operation of mixed service connector switches
IPC: H04Q3/42
Filed: 1959-08-10
Abstract: 904,567. Automatic-exchange systems. SIEMENS & HALSKE A.G. Aug. 10, 1959 [Aug. 20, 1958], No. 27253/59. Class 40 (4). A final selector having access to subscribers on single lines, party lines, and PBX lines, is controlled by a circuit which marks the selector and sets it to a position before a wanted group of outlets in response to the tens digit, connects the switch to step directly in response to the units digit, and also controls a relay set to provide code ringing for party lines. Layout of exchange.-As seen in Fig. 1, a subscriber TnA has access over finder AS to a register controller UeA with an electromechanical impulse repeater JW. Receipt of the first digit causes seizure of control circuit ES 1 which over AW1 hunts for the pertinent first group selector IGW. When AW1 connects with IGW a signal is reverted to UeA which sends the first digit to ES1 where it is stored to mark the wanted outlet group of IGW. When IGW finds an outlet the connection is similarly extended over group selector IIGW to the final selector the control circuit ES3 of which stores the tens digit to mark an outlet in the contact bank of LW preceding the group containing the wanted outlet. When the tens mark is found ES3 is released but the relay set UeB stores a condition which causes ES3 to step LW directly in response to the units digit to reach the wanted outlet or first line of a PBX group. Incoming trunks VL2 and outgoing trunks VL1 are shown, but only the circuits controlling the final selector LW are described in detail. The switches are motor uni-selectors. Final selection of single subscriber line.- Fig. 3 shows the relay set UeB, Fig. 4 shows the final selector switch, and Fig. 5 shows the control circuit ES3 and switch AW3; the top right-hand corner of Fig. 5 duplicates part of Fig. 4. To seize the final, selector the register UeA puts battery on the upper speech conductor R and over contact 1c to the start wire operates relay RS in the control circuit where relay US is normally energized. A relay Ut in register UeA, shown in Fig. 3, is not operated in this circuit as RS has high resistance. Relay RS brings up relays S and V in the control circuit to drive magnets N1 and N2 of switch AW3 which finds start potential on wiper nII and operates relay AP. With AP operated, low resistance is returned over the start wire to relay Ut in the register and this operates to send the tens digit. Operation of AP also energizes AS and CS which energizes L and causes slow-release of RS and consequent slow-release of S and V. Relays AP and AS repeat the tens digit, contacts of AS feeding the impulses to a relay chain I to V, each relay of which has two windings a and b and contacts of which connect a test relay BP to outlets x1 to x0 of the final selector. At the end of the tens digit relays V and AP restore bringing up relays M and D. With D energized magnets M1 and M2 of the final selector LW are driven over wipers nVI to nVIII of AW3 to set LW on the marked outlet. Capacitor Co6, Fig. 5, which is normally charged over a contact of M, discharges over wiper d of LW in circuit with relay BP when the marked outlet is found and BP locks up to the impulse to stop LW and restore the control circuit by releasing AS, CS, D, M, L, and itself. Relay US holds up throughout the operation until D falls back and with CS back RS is again connected to the start conductor. Switch AW3 may restore though it is not necessary that it should. When relay L was energized, before the tens digit was sent, it was connected over wiper nV of AW3 in series with winding I of relay T in the relay set of Fig. 3, where relay Ra is normally energized. In the relay set relays U and Rb energize with T, U releasing T which causes slow release of U. When BP responds to release the control circuit of Fig. 5, it puts earth on the wiper nV of switch AW3 before relays CS and L fall back to energize relays E and C which lock up. When U falls back, E and C release. Due to the fact that Rb holds up in the relay set, relay L is connected in series with relays E and C which are connected to battery and when relays AP, AS, V, and CS, respond in the control circuit preparatory to receiving the units digit, L does not operate. With L back relay TS operates to connect up magnets M1, M2, of the final selector which are driven by relays AP and AS as they repeat the units digit. When AP and AS release to the first impulse both magnets M1 and M2 are energized with windings I and II of relay TS driven in opposition. At the end of the impulse restoration of AS and AP disconnects magnet M2, stepping LW with M1 and changing over contacts ml, m2. With the second impulse the current in winding I of TS is reversed and TS operates so that at the end of the inpulse release of AS and AP disconnects magnet M1 and steps LW with M2. With the third impulse relay TS releases and the circuit responds as to the first impulse. At the end of the train. V falls back, bringing up M which connects BP into the test circuit with capacitor Co6. Over the wire x13 connected to ordinary outlets of LW relay BP responds to release the control circuit and by putting earth on wiper nV of AW3 operates relays E and C in the relay set of Fig. 3. Contacts of C prepare a test circuit for relay P over wire S and wiper c of LW. With C operated relay A responds to the calling loop and T falls back with U following slowly. Response to busy, idle, and non-existent conditions.-If the called line is idle, battery is found on wire S and relay P responds, locking up over the P wire in series with magnet Ad which presses the speech wipers of LW on to their contacts. Relay Ra responds with P to hold U before its release and to operate Q. Continuous ringing current is now connected to the called loop over capacitor Co4 in shunt with ring trip relay F. If answer is made quickly F operates to the called loop, releasing relays Ra and Q. If answer is delayed, relay U falls back as thermistor HL removes the shunt from reverse winding II and Ra is energized by an impulsing cam every 6 secs. to make ringing intermittent. Answer now releases Ra and Q. With Q back relay B energizes to feed the called loop and causes Z to respond, reversing the line wires for metering. If the called line is busy P does not respond but U falls back with Rb. Earth found on the S wire energizes Q before Rb releases so that busy tone from source BT is fed to the A relay. If the number is non-existent neither P nor Q respond but when U releases with Rb relay X energizes to connect a recorded message from ANS to the line. Release.-Breaking of the calling and called loops releases A and B which restore the relay set. If only the called loop is broken B falls back and relay TH is connected up to force the release of C and restore the relay set. If only the calling loop is broken A falls back, operating TH and U to disconnect B and restore the relay set. Release by calling subscriber in face of busy tone releases A to disconnect C, Q and E. PBX hunting.-If the call is to a PBX line in a group, say, having a first line marked by wire x21 and a last line marked by wire x24 in the final selector LW, the tens and units digits set LW as for an ordinary line but the units digit sets LW on the first outlet of the group causing relay H to respond and lock up to discharge of capacitor Co5 in the control circuit of Fig. 5. With H operated, relay D responds and if the first outlet is free relay AP in the control circuit energizes to battery on the S wire over wiper nIV of switch AW3. If the first line is busy TS interacts with magnets M1, M2, of LW to step the selector over the group until an idle outlet is found and AP responds. With AP energized earth is placed on the wiper nV of AW3 to energize relays E and C in the relay set of Fig. 3 to transfer control and testing to the relay set as for an ordinary line. If no outlet of the group is idle relay BP responds to discharge of capacitor Co6 over the last outlet of the group marked by wire x24 and control and testing is transferred to the relay set to revert busy tone. Party line calls.-Each party line subscriber in a group of no more than ten, has an individual outlet in the final selector LW. As shown in Fig. 4, party line outlets are shown marked by wires x12 and x53 in the final selector which is controlled as for an ordinary line by the tens and units digits except that BP does not respond at the end of the units digit. Resistance earth is, however, returned over wiper nV to the relay set of Fig. 3 such that relay C, but not high resistance relay E, responds. With C operated, relays T, U, and Rb restore while relay P tests the S wire. If the line is busy, earth on the S wire operates Q to return busy tone. If the line is idle, P responds with magnet Ad while Q is energized by a 6 second impulse cam to connect ringing. A timing cam Unt12 or Unt53, Fig. 4, connects 50 volts positive or negative over wiper d of LW depending on whether the ringing code of the wanted party line is applied as a long burst or a pair of short bursts in each cam cycle. Positive 50 volts, which may be associated with either a short or a long burst ringing cam, operates relay Ra, negative 50 volts operates relay Rb to connect up ringing tone leads Ltl or Lt2 having access to frequency generators f1 to f3 and f4 and f5, respectively. The timing cams, such as Unt12 and Unt53, operate contacts such as NKa1 to connect a particular frequency generator to the line. With five generators and two types of interruption, ten ringing codes are provided. Each party line subset has a filter to receive its particular ringing code. Reply and release are the same as for an ordinary line.