Why Do Railroad Tracks Experience Voltage and Current from Nearby Power Lines?

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Discussion Overview

The discussion revolves around the phenomenon of voltage and current being detected on railroad tracks that run parallel to nearby power lines. Participants explore potential causes, measurement techniques, and possible solutions related to this electrical coupling, with a focus on both theoretical and practical implications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant describes measuring 20 volts and 4 amps on isolated sections of railroad track, noting that these readings disappear when the 12 kV line is deenergized.
  • Another participant humorously suggests cutting the track or using fiber optic transceivers as potential solutions, though these would disrupt the signal system.
  • A question is raised about the method of measurement, specifically whether the voltage and current are measured between tracks or from each track to ground.
  • It is mentioned that railroads maintain a potential across tracks for signaling purposes, which could be related to the observed measurements.
  • A participant provides details on their measurement technique, indicating that they use a Fluke 187 volt meter and a clamp-on amp probe, and notes that contacting the railroad has not resolved the issue.
  • Another participant expresses surprise at the amount of power coupling to the tracks and inquires about the distance of the transmission lines from the tracks.
  • One participant questions whether better impedance matching of power lines to the load could affect coupling to the rails, suggesting that they have already achieved a high power factor with capacitor banks.

Areas of Agreement / Disagreement

Participants express varying opinions on the causes and solutions for the voltage and current on the tracks. There is no consensus on the underlying mechanisms or the best approach to resolve the issue, indicating multiple competing views remain.

Contextual Notes

Participants mention specific technical details such as the use of capacitor banks for impedance matching and the design limitations of couplers used by the railroad, highlighting the complexity of the situation. The discussion does not resolve the mathematical or technical uncertainties involved.

jburgess56
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I have a parallel 69KV and 12KV line that runs parallel to a railroad track. Also, this system has a static on top for the system neutral. We are getting 20 plus volts and 4 amps on each track in an isolated section of track. We have deenergized the 12 kv and the volts and amps went away. The volts and amps returned no matter which 7200 volt phase that I reenergized first. I have jumpered out all of the static connections and the volts and amps remain. I have deenergized every single phase lateral that is in this section one at a time and the volts and amps remain. (Both circuits are on the same pole as well.)The isolated section of track is part of the signal circuit for the railroad. The railroad uses fiberglass connections to isolate from the rest of the track. Any ideas on how to figure out and to fix this problem would be greatly appreciated...Jburgess56
 
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lol, i'd say either run the current perpendicular to the track, increase its distance from the track, or cut the track. that cut would stop your signal, of course. maybe you could put in a fiber optic transceiver, tho.
 
Exactly how are you measuring the 20 volts and 4 amps? Between tracks or from each track to ground? What do you measure between tracks?

You may want to contact the railroad and work with them to correct the problem. If you give me the lat and lon of that section of track I can tell you which railroad it is and possibly who to contact. The railroads share engines and cars so just looking at the markings on the engines or cars is not a reliable indicator of which railroad it is.

The railroads maintain a potential across the tracks in sections. When a train enters that section, the axles complete a circuit that turns the signal light from green to red, warning any trains ahead or behind it not to enter that section. Is it possible this is what you were seeing? If not, is it possible the potential you're seeing could be changing the lights?
 
I am measuring across the isolated section of track with a fluke 187 volt meter. I am using a jumper across the isolated section and using a clamp on amp probe to check current flow. The voltage and amps are on both tracks and only in the isolated section of the signal area. Checking to ground drops the voltage approximately 2 volts. I have contacted the RR and we have deenergized all of their equipment and the voltage and amps do not go away. The RR uses some kind of coupler hooked across at the isolated points of each track to handle the voltage difference, but they are only designed to handle miilivolts. With the amount of voltage, they fail.
 
I'm glad you're working with the railroad. It's amazing you get that much power coupling to the tracks. For how far are the transmission lines parallel to the tracks?
 
Would having a better impedance matching of your power lines to the load make a difference in the coupling to the rails? I'm not an expert here and would refer you to one of our members, m.s.j , who seems to have knowledge of power line problems. You could PM (personal message) him and see if he might have experienced such a problem. Here's his member profile page: https://www.physicsforums.com/member.php?u=84682"

Welcome to PF
 
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They run parallel for about 5 miles or so...

skeptic2 said:
I'm glad you're working with the railroad. It's amazing you get that much power coupling to the tracks. For how far are the transmission lines parallel to the tracks?
 
We use capacitor banks for our impedance matching and we have a power factor of .98 lagging to 1.00 unity between the 3 phases of 12 KV. Hard to get much closer...
dlgoff said:
Would having a better impedance matching of your power lines to the load make a difference in the coupling to the rails? I'm not an expert here and would refer you to one of our members, m.s.j , who seems to have knowledge of power line problems. You could PM (personal message) him and see if he might have experienced such a problem. Here's his member profile page: https://www.physicsforums.com/member.php?u=84682"

Welcome to PF
 
Last edited by a moderator:

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