Do sockets on trains have rcds?............

[Gavin John Hyde]

Currently on train to paddington to get to gatwick.
Using socket to charge my phone and tablet.
Wondered if sockets have rcd protection on the train?
Is each carriage on its own board or breaker?
The amount of people plugged in I imagine there is quite a bit of earth leakage. One woman has hair irons plugged in! And mirror on table in front of her. It hasnt overloaded sockets despite signs saying phones and laptops only.
Just curious and bored so got me thinking.

 

[FatAlan]

Third rail is 650V DC. Interesting reading about the different systems that have evolved in the U.K. since the late 19th century. Dying to make some sort of jokey reference to Pete999 but I think I’ll leave him alone tonight.

 

[StephenRowley]

I do know that the railway supply sites only has two phases from the grid

 

[Strima]

Judging by the age of some of the rolling stock I’d be surprised if the even had electric, normally the conductor on our trains goes round lighting the lamps at dusk...

 

[hasel5]

So all the people on this train have desktops ?

 

[Gavin John Hyde]

So all the people on this train have desktops ?

Not every one in the literal sene. But plenty of phones and tablets.

 

[BeardyJaws]

I’m not sure about the trains themselves, however all power sockets fed from the rail networks power supplies and any buildings within 30meters of line side have DC immune RCD’s made by Blakley Electronics and they protect against earth leakage from the 3rd rail. It would stand to reason that similar protected would be fitted to the trains themselves, will try and find out next time I’m on a site.

 

[davesparks]

I think trains fed from the third rail DC supply use motor-generator sets to produce their AC supplies so they could have neither Pole referenced to earth.
On the trains round here you can see therows of Mcbs in the drivers cabs when you walk through trains made up of multiple units. If I remember correctly they are DP mcbs which leads me to think it may be set up as an IT system.

 

[freddo]

Certainly newer trains have RCDs for parts of the trains electrical equipment, so it would be very likely the sockets are too.

 

[freddo]

6:40 It doesn't mention sockets though...

 

[pirate]

Crikey! How does the Gatwick Airport shuttle between North and South terminals ever work, given it is unmanned?

 

[45140]

As a railway engineer, I can perhaps help with the answer.

Trains such as the original High Speed train, and the Mk3 and Mk 4 (used on East Coast Main Line only) rolling stock provide a 415 AC supply which is intended for what are known as "hotel services" - air con, doors, lighting, restaurant vehicles, PA, etc. In the case of diesel powered trains (HST and locomotive hauled Mk3) the supply is derived from the traction unit main generator, and in the case of electric rolling stock (mainly ECML Mk4 now) the 415 volt supply is drawn from a tap from the main transformer at 25kV.

The power supply is then reduced down to 230 volts as required. For obvious reasons to supply is known as a "dirty" supply because it is not controlled and can be variable The sockets that you see principally in the luggage area intended ONLY for use when the train is switched onto a stabilised shore supply or when the train is stabled during a turn-round period and we can be certain that the power supply should be relatively stable. The sockets are there for cleaning equipment and any powered maintenance equipment.

These sockets are NOT under any circumstances to be used for passengers personal items such as mobile phones, laptops, etc, etc because the supply could suddenly surge and fry the item plugged in.

Newer trains have protected dedicated supply circuits that are safe for passengers to use and these can be found at seat points and table ends/table bays.

Hope this helps ?

 

[Shoei]

From the Association of Train Operating Companies. (ATOC) 'Key Train Requirements. (pdf)
For 'Passenger Power Supplies', nothing about RCDs and a modest spec of 70mA per socket. They mention supply from an inverter, which should give a reasonably regulated 230V regardless of voltage on the train power distribution. They do mention 'how the system can be reset' but don't say what event would need a reset.

3.17 Passenger power supplies
3.17.1 For refurbishments where power constraints may limit 230V supplies consider a USB outlet for each seat.
3.17.2 For new-build consider a mix of 230V supply & USB outlet.
Note that USB outlets were never designed for such use, merely as part of a computer. They are now used for many applications, but the connecting arrangement is not necessarily robust for this type of railway vehicle use. Consideration for easy change out of broken ones should be considered.
3.17.3 For a 230V power supply system the following shall be provided:
 Sockets should be to “BS 1363: 13A plugs, socket-outlets, adaptors and connection units. Specification for rewirable and non-rewirable 13A fused plugs”.
 The output from the socket should suit the type of equipment for which it is to be used.
 The reliability of the inverter to be as high as possible to reduce failures.
3.17.4 When designing the 230V power supply system the following should be considered:
 The power consumption and diversity and number of outlets to be installed. Typically 70mA per socket is a reasonable value to use.
 Whether the outlets have a switch or not, having switches may lower the reliability and are not essential.
 Inclusion of an indicator on each socket to show the system is live.
 How the system can be reset, by whom.
 Auto-resetting could be an option, with a timeout before it tries again on the assumption that what caused the trip had been removed.
 How the system is earthed, how the wires are retained as sockets may not meet the railway vibration requirements.
 The splitting of supplies to each side of the carriage will increase availability but means two inverters will be needed. Alternating sockets from each inverter along each side of the carriage could lead to fault-finding issues.