Tom
Administrator
Signalfel?
Posts: 4,196 
|
Post by Tom on May 20, 2014 21:13:56 GMT
Not sure on the currents drawn, but I do know that the standard traction cable size is 950mm 2. I'm sure there is a way to work out the relationship between cable CSA and rated current, but I can't remember it. Didn't traction cabling used to be 935mm 2, is it 950mm 2 because aluminium is being used instead of copper? You may well be right there, it was certainly in excess of 900mm 2 and we still use copper. |
|
Tom
Administrator
Signalfel?
Posts: 4,196
|
Post by Tom on May 20, 2014 21:17:15 GMT
Exposed steel toecaps can also be fatal, in fact safety boots can be dangerous in other ways too as wearers automatically assume a level of protection without checking their boots before wearing them! People never saw the dangers, I recall one T5M years ago who deliberately exposed the toecaps of his boots and had them chromed like his Tilley lamp, he was an accident waiting to happen! We're not allowed steel toecaps now for that very reason. |
|
Ben
fotopic... whats that?
Posts: 4,282
|
Post by Ben on May 21, 2014 8:39:17 GMT
Now thats interesting. What re-enforcement do they use if not steel?
It must have been far more interesting dealing with the supplies on LT before standardisation and the move to digital - what a variety! There must have been a few awkward moments where nominally similar frequencies/voltages, where meant to interface, were found to be very different!!
|
|
|
|
Post by domh245 on May 21, 2014 8:58:36 GMT
I've seen Kevlar reinforced boots before, so that could be what they use, or indeed any strong, rigid, non-conductive material
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 21, 2014 15:16:52 GMT
We do indeed use Kevlar toe cap and a Kevlar re-inforced sole
|
|
|
|
Post by railtechnician on May 22, 2014 1:21:42 GMT
Now thats interesting. What re-enforcement do they use if not steel? It must have been far more interesting dealing with the supplies on LT before standardisation and the move to digital - what a variety! There must have been a few awkward moments where nominally similar frequencies/voltages, where meant to interface, were found to be very different!! Yes indeed, parts of the system AFAIAA still use 33 1/ 3 Hz signal supplies and in the odd place it was also used to supply 240v lighting. Years ago when enhanced line clear was instigated the tunnel telephones had to have maintenance free rechargeable standby batteries to ensure that T/T circuits would reset in the morning. The old lead acid cells were replaced as they would not have survived the T/T drawing current all night if working parties had looped the tunnel wires as per procedure. At one of the substations the battery charge controller had been wired to the only available 240v outlet and that happened to be a 33 1/ 3 Hz supply rather than 50Hz. The upshot was that some months after on a routine T/T maintenance inspection the rechargeable batteries were seen to be physically oscillating when on charge. This was a rare occurrence although there were other places where 'stick' telephone 24v supplies were derived from local signal supplies, they didn't matter because it was dc being supplied although it was derived from 33 1/ 3 Hz or 125 Hz signal supplies. |
|
