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| Communication, thirties style 17/05/2015 at 11:49 #72343 | |
maxand
1637 posts |
Quote:If necessary the driver of a tube train can cut off the supply of electric current on any section of the line by pinching together two bare wires which run the length of the tunnel. The driver can then speak to the power substation by clipping a portable telephone to the wires."Railway Wonders of the World" magazine, ca. 1930s. Log in to reply |
| Communication, thirties style 17/05/2015 at 11:58 #72345 | |
headshot119
4869 posts |
" said:Quote:and a system still in use to this day!If necessary the driver of a tube train can cut off the supply of electric current on any section of the line by pinching together two bare wires which run the length of the tunnel. The driver can then speak to the power substation by clipping a portable telephone to the wires."Railway Wonders of the World" magazine, ca. 1930s. "Passengers for New Lane, should be seated in the rear coach of the train " - Opinions are my own and not those of my employer Log in to reply |
| Communication, thirties style 17/05/2015 at 12:13 #72346 | |
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metcontrol
227 posts |
If we're speaking about London Underground, the system is indeed still in use today, but may be phased out in the not too distant future when each line gets upgraded. The system is only found in tunnel sections. It is usually (but not always) 2 copper wires fixed to the tunnel wall, at a height a driver can reach when opening a their cab door. The wires are linked to the substation which feeds the section of current the train is currently on. They have a low voltage running through them, and when pinched together they cause a short-circuit at the substation, which drops out a circuit breaker which is connected to the main traction current feed. The only person that can be spoken to (when a suitable telephone handset is fitted to the wires) is the Line / Service Controller. When the wires are operated, an alarm will sound in the relevant line control room, and on receiving this alarm the controller will acknowledge it and then make contact with the Power Control Room to confirm if current has been discharged (it won't always trip fully by the operation of the wires alone, so may need to be manually tripped). Once confirmation is received, the controller will try to make contact with whoever has operated the wires. The advent of secure radio systems mean that it is rare for this type of operation to be used. It can also be fairly unreliable. The wires are fixed to our old Victorian tunnel walls, and water ingress and the like often weaken the brackets, leaving the wires dangling on the floor (often tripping the current as they fall!) In almost 10 years as a controller, I have had only 2 activations by people needing the current off in an emergency. I have had many more activations caused through unknown means. Last edited: 17/05/2015 at 12:17 by metcontrol Log in to reply The following users said thank you: belly buster, maxand |