Earthing in electric traction

Them steel thingys the car runs on conduct electricity. There is no danger to passengers when there is an earth fault (unless you mean the San Andreas earth fault).

In a normal step-down transformer for a residence the higher voltage 11,500-14,500 is brought down to 220(110 x 2). If you look closely at the transformer you will see a wire running down the pole to a ground rod or other type of path.

This allows the return path that is needed on that side of the system. I have always specified 2-3 grounding systems in a residence for safety. Inour area there have been some of those grounding conductors cut and stolen off of poles, apparently for the copper scrap. If there were no other path for the hot to go, it would be very hazardous for the users should they provide the ground path. Equipment failures could also result if they were not adequately isolated.

I'm not too sure what the "traction' part means. The only time I have heard it used is in EV's. Maxozone@comcast.net

The track provides the earth system with many earth paths.

Traction refers to electric traction, engines powered by electricity, whether by overhead conductor, third rail conductor or batteries. They are used from local services to high speed Shinkansen in Japan and very high speed TGV in Europe. Low DC voltage was first used but very high AC voltage is taking over as controls systems evolve. The first battery powered 'locomotive' was in 1837. In the USA street tramways evolved in the 1880s and heavy duty electric traction evolved on rapid transit railways in the 1890s. The first railway with real electric power carriages was the London underground in 1890 followed, I think, by the Prague underground in 1893, of which one of the first lengths and station is open to the public.

Electric traction = all vehicles powered by electric motors ; DC or AC.

To make this subject more interesting: everybody, please give your info about:

1. Your country

2. Voltage and frequency ( 0 - ??? Hz)

3. Other details for comparing how far are Engineers of the World in designing their public transportation.

In my state no more tramways, el-street-busses etc. Everything runs on gas-oline or diesel.

Guest, (whoever you are,)

You remind me of the famous saying:

"I have all the answers, it's the questions that I don't understand"

It is evident that you haven't got a clue of what this question is all about. Why than make yourself ridiculous?

Wangito.

In 25KV 1 phase electric traction earting is done through the railway track,in which railway track is connected through the thick metallick strips to the poles on which there is wiring.and many poles in the way gives a good return path.

There are at least two ways of applying power to the Overhead traction system. Transformers are used and the easiest system to explain is the Autotransformer system used for long distance and heavy freight.

Power comes from the transmission system at high voltage (132kv or higher) to a feeder substation where a 50kv centre tapped single phase supply is derived (25kv to earth). At the feeder station the phase imbalance is taken up by a large C/R network. The centre tap is earthed to multiple points including the rails, the equipotential bonds and the overhead earth conductor (lightning conductor). All structures are bonded to this earth reticularion. There are autotransformers every 10 km or so which are also centre tapped 50kv. One live leg is connected to the Catenary / Conductor group (Cat/Con) to power the train via the pantograph and the other live leg is carried on insulators along the structures to the Autotransformers. At the Auto transformer sites the current in induced onto the two live legs. The Autotransformers (approx 10 Mva each) are in parallel along the section of traction circuit providing a low impedance supply to the train which is often of 20 Mva capacity (5 locos and a 15,000 tonne, 2 kilometre train).

Suburban passenger rail is slightly different in the use of transformers (compensation transformers) to induce the earth current onto the outside live conductor. One reason to induce the current into the live conductor is the effect that heavy earth currents have on communication equipment in the area including railway signalling gear.

As you can see the current doesn't always merely return via the rails although a system of that type can work but has problems as listed above, You've asked a good question.