Rules regarding power socket use on the 378s?

Most of the trains should have a not for public use sticker on them. With a charger it shouldn't be too bad as it's just supplying power to a battery, but if something was directly plugged into it (for example a standard computer, or a laptop without a battery in) the equipment would probably be damaged at any section gaps where the power supply changes from one substation to another! (commonly identified by the aircon turning off and on again, or a massive thump if you're under the pantograph on a Desiro!)

I am surprised that 16A sockets are not used. I noticed these at stations (incl Farringdon) and assumed they were for the cleaners - not that they needed the higher power rating, but to restrict the use of the socket.

I've never seen this on LUL property (that's not to say that it doesn't exist), but I have at Harrow Bus Station - must get a photo next time I'm passing through

I have seen BS546 plugs on tube platforms, typically (might be always, I can't remember) at 110V. It's of course not at all implausible that someone could obtain a suitable phone charger

EDIT: I'm told that this is called Walsall gauge


I believe that this is the case on some (most? all?) stock

110v DC, or AC? If AC: 50Hz, 60Hz or ? Photo?

I'm remembering back to 1985/6 and what I saw at Farringdon and elsewhere. I assumed they were 16A square pattern, but I could have been wrong. If 110v, why?

This depot mode - is it something LU trains have. ?

3-pin, so single phase.

The idea of a -55v = 0v = +55v for AC as posted by JohnW is new to me. On a 3-pin plug, it means that Earth is the Neutral with 2 Active cores at 180 deg out of phase. Somehow doesn't gel with my (albeit limited) knowledge of electricity.

That sounds like DC to me, as per the 3rd and 4th rail system (-210/+420v). Haven't heard of it for AC before. How do you get the 180deg out of phase supply? Is this something an auto transformer does? What would the description be if I was to search the net about it?

This is also the reason why building sites tend to use 110v tools (I can't remember if they're obliged to do so or not, but it's good practice) - building sites being more prone to have an accident where the cable gets nicked.

I also seem to remember being told that 240v 50Hz AC is particularly bad for the heart due to the frequency, which 110v isn't.

dw54: You have to stop thinking in "Voltage". Think instead of electrical potential diference. In normal households, we say that "voltage" is 230V, which means that a live conductor has a potential of 230V in relation to neutral (which by it's own definition is at 0V), so 230-0=230V. Here we have +55 and -55, so: +55 - - 55 = 55+55 = 110. As you can see there is no "neutral" but an opposite electrical potential. The same goes for the fouth rail system LU uses: +420 - - 210 = 420 + 210 = 630V.

Split phase power supply

Electric power distribution

Electrical potential difference

Cheers, thanks for the links.

That's all OK, except that AC isn't steady voltage, but by definition alternates. So the PD is say 110v RMS. The actual peak momentary voltage is much higher. And the unit for Potential Difference is Volt. I've already mentioned the +420, -210v DC for 4-rail systems with a net voltage of 630vDC - I'm across that.

Will read up the wiki links offline from DD's.

Perhaps they are, and the person was blissfully unaware that their battery was running down rather than being charged up!

it is kind of hard to word this to make sense, but neither is actually to stop unauthorised use, but intended for the opposite logic, to only permit authorised equipment, although it happens to have the first purpose as a side effect.


According to the interweb those plugs with the rotated pins (Walsall plugs) has every site saying it is an LU and/or BBC idea, and LU use them. Well for the post 6 years I have been in and out of IMRs SERs CERs SCRs and other machine rooms with test equipment that needs plugging in to mains power, as well as to numerous offices, and I have yet to come across either a plug or a socket in that format, inside or outside of any equipment rack or cabinet.


We do use T earth plugs in a few places where portable test equipment needs to use the local clean filtered supply; all the locations I have seen usually have a dedicated UPS/filter and sockets local to that supply, in one case physically on it,


AFAIK none of these outlets are supposed to be any place other than secure rooms, where only authorised personnel are supposed to be, but no doubt as I've said that people will start listing places that don't follow this.


They are really used to demarcate dedicated clean power supplies that should only have specific and usually calibrated test or reference equipment plugged in to them.


The idea is where there is a clean supply to stop say a building contractor working in the room plugging in an electric drill or to stop a cleaner using a vacuum cleaner in one. You don't really want a local site computer to crash when some one plugs in a drill that kills the supply. To go back to my opening words, the contractor working in such a room is authorised to be there, and authorised to uses his drill , but that drill is not authorised to go itno certain specfic supplies.




--
Nick

Hello,

What about linking these plugs with a meter and a coin box, as for heating in the old days ?

Shh! You'll give Southeastern ideas.... We'll soon be seeing the 395s fitted with Oyster/ITSO readers next to the between seats power sockets - pay per charge. ;-)