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Question on Caternary

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  • Member since
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Posted by tree68 on Saturday, January 14, 2017 6:39 AM

There are, as I recall, some transit systems using (or planning to use) an inductive method of power transfer, but I can't remember who or where.  In their case, the power source is in the ground, between the rails.

I would opine that the apparatus to make this possible might be too cumbersome to elevate.

LarryWhistling
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Posted by Norm48327 on Saturday, January 14, 2017 6:21 AM

100 year old wire.

Norm


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Posted by tdmidget on Saturday, January 14, 2017 12:58 AM

NP Red
  Centenary wire"??? What is that?

It really is not possible.  In essence, you are making an air core transformer where the primary loop is the centenary wire and the secondary loop would be a length of wire the total length of the train. Even with this, the efficiency of power transfer would be very poor at power line frequencies.  That is why low frequency transformers have an iron cores. The iron core concentrates the magnetic flux around the wires. Out in the open air, most of the power would be lost. Furthermore, the centenary wire would need  to be a closed AC current loop. You would source electric current into the centenary wire at one place and somehow it needs to return back to the original place to complete the loop. This would be a nightmare to design.

 

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Posted by NP Red on Saturday, January 14, 2017 12:16 AM

It really is not possible.  In essence, you are making an air core transformer where the primary loop is the caternary wire and the secondary loop would be a length of wire the total length of the train. Even with this, the efficiency of power transfer would be very poor at power line frequencies.  That is why low frequency transformers have an iron cores. The iron core concentrates the magnetic flux around the wires. Out in the open air, most of the power would be lost. Furthermore, the caternary wire would need  to be a closed AC current loop. You would source electric current into the caternary wire at one place and somehow it needs to return back to the original place to complete the loop. This would be a nightmare to design.

(Thanks a lot spell check)

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Posted by erikem on Friday, January 13, 2017 11:41 PM

It could be doe, but somewhat educated guess is that it would add about an order of magntdue more cost to the overhead. "Somewhat educated guess" is from working on a contactless power transfer system.

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Question on Caternary
Posted by ORNHOO on Friday, January 13, 2017 4:58 PM

This year's snowpocalypse seems to be bringing the usual problems to electric traction systems; increased tension due to cold weather, ice buildup on conductors, etc. In good weather conductors on pantographs are subject to wear and need frequent replacement. Has anyone built a system where electricity is "harvested" from the caternary by electromagnetic induction without direct physical contact?

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