Power upgrade on SSL

I susoect that any power supply increase will be taken in hand with immunisation of the substations against any unwanted emissions from the traction package.

I heard somewhere that 95TS can run on 750V DC...

When Phil, stanmore K and BAET show up they will post lots of interesting formulae and mathematical data on the subject, but in simple terms, increasing the voltage decreases the amperage required by the trains.

Taking a potted example, suppose that a D stock requires 100 kilowatts (100,000 watts) to accelerate to a given speed (this of course discounts other electrical loads such as ETH, lighting, and so on).

At 630V, 100 kW requires 158.7 amps from the substation.
At 750V, 100 kW requires 133.3 amps from the substation - 83% of the original amperage.

When you now have as many as 8 D stocks accelerating within a given area, you can see that increasing the voltage and subsequently decreasing the amperage significantly lessens the load on the substation and increases the capacity of the electrification.

There is also the added safety aspect with regards to going on the track - "volts jolt, but amps kill."

fx: stampede of AETs and infracos and teachers....

maurits: Current (Amps) heats up its medium and thus a higher current means more energy is lost en route. This heat in the rails will warm the air underground. A higher voltage means a lower current is required, so less heating in the circuit will occur. This has the benefit of making it cooler underground but the system is more efficient also because less energy is lost between substation and train as heat. (I think, anyway)

This has been done before. The real issue was contractual. The power for LU is supplied through a PFI (A French company EDF) and when the idea of uplifting to 750v was discussed about 5 years ago, it went into the "too difficult" box because it required a contract variation and LU was pre-occupied with getting the PPP sorted out. Technically, I seem to recall something about insulation requirements and earthing in tunnels.

Who needs us when you've done so well yourself, TOK?

without using proper formulas, if you can halve the current (as you would do by doubling the voltage) the energy loss (as heat) is reduced to a quarter. More efficient use of power, less waste heat to dispose of.

So, applying this to a 630>750V change, the waste energy (heat) reduces by 31% - quite a saving.


Oh and for TOK's benefit, you would square his 83% (0.83²=0.69=69%) to get the energy saving using his figures, which makes the 31% saving

Indeed, as do all media that transfer electricity! (Which is why the voltage on the national grid is so high, to make the current really small so less energy is lost between generator and home/factory etc., because power lines emit heat too)

All media also transmit Electromagnetic radiation.

By the way has anyone seen the pratts crossing the line at Stonebridge Park in the photo on the penultimate page of RAIL this week? One idiot is actually stepping on a conductor rail. Am I right in saying that the rails ar bonded on the line? Does that increase the chances of an inadvertent electrocution?

Of course the voltage on the former SR varies considerably aswell.

"Until 1939 lines were electrified at 600V except for some in the inner suburban area. Lines in Kent south and east of Gillingham, Sevenoaks and Maidstone, that is those electrified by British Railways, have been at 750V since electrification. The Bournemouth line west of Pirbright Junction (Brookwood) is electrified at 850V. The Isle of Wight line is electrified at 630V while the Waterloo & City [now part of the London Underground] remained at 660V."

www.southernelectric.org.uk/seginfohistory4.html

Would a power upgrade improve the performances of the rolling stock, by say improving the accleration?

My guess would be yes because is it not one of the reasons used to improve the power from 750 V to 850 V on the old Eurostar 3rd rail route.