The Ericsson Group 1968 - History of Ericsson - History of Ericsson

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34 Supervision of Common Control Equipment Markers, registers, code senders etc. are continuously supervised by means of built-in supervisory circuits. All functional disturbances—due to faults in the device itself or in interworking devices, as also to a lack of devices—are recorded on statistical counters. For various groups of devices the numbers of occupations and disturbances of different kinds are recorded, and from these data one can obtain the average fault rate for the groups of devices, and so a measure of the reliability. Normally the fault rate is low and is caused by temporary faults which it is not worth while searching for. If a serious fault occurs, the fault rate rises abruptly. To obtain quick information of this situation, the common control devices arc equipped with an arrangement for disturbance ratio supervision. A disturbance memory in the form of a relay chain totals the number of disturbances. At the same time the number of occupations is totalled on a counter which can be preset. When this counter shows the preset number of occupations, the disturbance memory is zeroed. If the number of disturbances is too large before zeroing takes place, a service alarm is issued. The disturbance ratio, i.e. the number of permissible faults for a given number of occupations, is selected so that an alarm is not issued for temporary random faults but is issued in the event of an abrupt increase caused by permanent faults. The disturbance ratio can be set very much higher than the average fault rate. The following groups of devices are equipped with disturbance memories • Subscriber stage: one per marker for 1000-line groups © GV stage: one per two markers for 320 GV inlets • Register: one for one or more racks, but max. 10 REG • Code sender: one per 10 KS For zeroing of the disturbance memories only four occupation counters are required per 10,000-line exchange—one for each of the groups of devices above. The occupation counters are connected to devices which provide a representative picture of the variations in traffic intensity. Supervision of Outgoing Routes The junction relay sets are blocked in the event of a fault and an alarm is issued. For route supervision the blocking alarm circuit for all junction relay sets on a route is connected to a sensing relay in a route alarm relay set. A route alarm relay set contains circuits for 10 routes, and by means of strapping per route one can decide for what number of blocked devices a route alarm shall be issued. When a device on a route has been blocked its alarm lamp glows faintly, but changes to a bright light when the preset number of blocked junction relay sets has been reached. Only then is an alarm issued. Indication Equipments Alarm System This system is constructed so that the type of alarm—e.g. blown fuse, service alarm, blocking, locking—is indicated on lamps on the relay set or rack where the fault has occurred.
Fig. 3 Arrangement of supervisory panel for exchange with max. 5000 lines 35
Page 1: 2 1969
Page 4 and 5: Equipments for Maintenance of ARF 1
Page 6 and 7: 32 For each programme a maximum of
Page 10 and 11: Fig. 4 Supervisory panel for exchan
Page 12 and 13: Fig. 8 Fault tracing «ith manual .
Page 14 and 15: Fig. 12 MFC tester Fig. 13 Electron
Page 16 and 17: Fig. 16 Test set AHP 1622 42 via a
Page 18 and 19: 44 The following tests can be made:
Page 20 and 21: Fig. 20 Transmission of alarm 46 A
Page 22 and 23: 48 Exchanges A—D attended. Mainte
Page 24 and 25: 50 result in wrong connection. With
Page 26 and 27: Fig. 2 Insertion of tone generator
Page 28 and 29: Fig. 4 Exploded view of the push-bu
Page 30 and 31: Fig. 7 Push-button mechanism with l
Page 32 and 33: 58 registered by the V.F. code sign
Page 34 and 35: 60 Description of a Junction Networ
Page 36 and 37: Fig. 4 Kxample of cable runs in a l
Page 38 and 39: 64 Data for Programming The calcula
Page 40 and 41: Interesting New LME Items at "Prote
Page 42 and 43: New Head of Telecommunication Grouo
Page 44: The Ericsson Group Associated and c

The Ericsson Group 1968 - History of Ericsson - History of Ericsson

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