Melbourne Telephone Exchange Jan 1911

https://trove.nla.gov.au/newspaper/article

Sat 21 Jan 1911 "The New Telephone Exchange"

Planned Design in 1908


Melbourne telephone users will be glad to know that the new Telephone Exchange adjoining the Crown Law offices in Lonsdale Street, has been completed by the contractors, the Western Electric Company of London. The new building is a handsome two story structure, with a bold front, of Pyrmont free stone, it extends about 200 feet to Little Bourke Street, this position being in brick and reinforced concrete. It was expressly designed for a telephone exchange conducted on the most modern principles, and cost just on £20,030. Premises have been made thoroughly fireproof, they contain large and commodious rooms, possessing the latest appointments.
The manager and his clerical staff will occupy rooms on the ground floor, there will be a public inquiry room and several telephones for the use of the public. On the first floor the telephonists (operators) will be provided with luncheon rooms, cloak rooms and lockers.

The operating room, which is on the second floor, is 150 feet x 33 feet, it is lofty, well lighted and ventilated, and provided with a fire escape. It is in this room the common battery switchboard has been erected and equipped for the present 9000 subscribers' lines, but which can be readily extended to serve an additional 2700. It is claimed to be the largest yet installed by the Post Office department, and the latest in switchboard design. The main portion of the switchboard is placed on the east side of the room, it is 137 feet long and arranged for 21 telephonists to operate 567 junction lines connected with suburban exchanges, and 39 telephonists to attend to the wants of subscribers numbering from 1 to 4000. The second portion of the switchboard, which is at present only 65 feet long, is on the west side of the operating room, and equipped for 5003 subscribers, which will require the attention of 30 telephonists.

It is estimated that the traffic arising from the 9000 lines and the incoming traffic from the various suburban exchanges will require 90 telephonists to handle it during busy portions of the day. Each telephonist will wear a head telephone, and will have charge of from 100 to 180 lines. Should it be found, due to a sudden rush of business, that the traffic on any position is too much for any operator, it can at short notice be transferred to another.
The telephone user, when making a call on this new exchange, will do so by simply removing the receiver from the hook of his telephone; the hook thus released automatically connects his line with its relay at the exchange; glows the associated line lamp in the face of the switchboard in front of the telephonist, thus indicating the number calling, 8990 for instance.

The telephonist now takes up one of the answering cords, inserts its plug into the answering jack immediately under the lamp glowing, and extinguishes the lamp. She then pushes over the listening key connected with the particular cord in use and listens for the number required. On receiving this number —say 100 — she takes up the twin cord and plug of the one in use, then finds number 100 in the multiple field, tests same for engaged— gets no engaged click— inserts the plug and operates the ringing key, which rings the bell at number 100's premises. Assuming that number 100 responded to the call and is conversing with number 8990, the supervisory lamps associated with the connecting cords do not glow, but should either person hang up permanently or temporarily, the lamp of that respective cord will instantly glow.



1. The New Central Telephone Exchange in Lonsdale-Street. 2. Eastern Section of Main Switchboard, Showing Officers Testing. 3. Mr. O. A. Junck, Departmental Officer in Charge. 4. Mr. E. H. Minnes, Contractor's Representative. 5. A Rear View of Switchboard, Showing Multiple and Other Cabling. 6. Entrance to Five Miles of Tunnels Under Melbourne. 

When both hang up, then the two lamps glow, but before the telephonist makes the disconnection she presses the meter key, which will register a call against number 8990.
There are 400 outgoing junction wires connected with other exchanges, by which means the city telephone users can reach their suburban clients. The multiple field is the means by which it is possible for any operator to connect with any line. Each of the 9000 subscribers lines appears in the answering jack-field in the form of a 24-volt lamp and jack. Each of the 9000 again appears in the multiple field in 30 different portions of the whole switchboard; There are no fewer than 276.000 connecting jacks in the "multiple." Nine hundred cables, containing 64 wires each, are required to connect the multiple jacks with the answering jacks.

The apparatus room is on the first floor, and immediately under the operating room. Here the main frame, provided with 12.500 lightning protectors, and intermediate distributing frame, which is for the purposes of regulating the telephonists' load according to the state of business, also for the purpose of receiving and distributing the 900 multiple cables, 450 answering cables, 450 relay cables, 450 main frame cables, 90 meter cables, &c., are situated. No less than 3000 miles of silk and cotton covered copper wire laid up in cable form was necessary for the various circuits. Each cable has its color scheme of 20 distinctive colors.

An important feature of the new service will be the 9000 meters, that register the calls made by the subscribers. All lines for subscribers and operating circuits within the exchange are "fused"; whenever a fuse is "blown" by an excessive current it gives an automatic signal to the exchange officers. There are provided repeating coils, which repeat the voice currents from one line to the other, three dynomotors and power board, that generate an alternating current at 75 volts at about 16 cycles with an output of 2 amps. It is this current that the telephonists draw from when ringing subscribers telephone bells. These ringing machines have attached high and low speed battery interrupters, the current from which when used by the operator gives the familiar signals which signify that the line is either "busy" or "does not answer." There is a testing desk for the purpose of making rapid tests of any lines faulty or otherwise, locating same by a voltmeter and other apparatus, also for the purpose of calling by means of a "Howler set" any subscriber who has inadvertently left the receiver off his hook.

The accumulators and the 20 h. p. charging machine are on the ground floor. The batteries are of the chloride type, they are in duplicate, each set consists of 15 cells, the main battery, has eleven cells, giving 24 volts for signalling, speaking, &c. It has a capacity of 3910 ampere hours (10 hour rated). Lead covered cables are now being run through the underground tunnels, which will connect the subscribers with a new switchboard. The contract for the switchboard, apparatus, &c., amounted to £43,000, the installing of which required the services of hundreds of fitters for 13 months.
The contractors' engineer, Mr. E. H. Minnes, of London, is well pleased with the manner in which the work has been done, and quite recently handed the exchange over to the Postal department at being completed.
Departmental officers are at present engaged in making searching tests of every cable and piece of apparatus for efficiency, before accepting the same from the Western Electric Company.
The Postmaster-General and his Melbourne Deputy are very anxious to let the telephone users enjoy the benefits of the new service as early as possible. With that object in view, Mr. Hesleeth, the Chief Electrical Engineer, and Messrs. Jenvey, Howard, Howson, the Melbourne electrical engineers, are doing everything that is possible to have the "change-over" made at the earliest date that can be arranged.
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