Electromagnetic Fields in Locomotive Cabs

[mononrr]

Can anyone tell me how strong the electromagnetic field (EMF) is in the cab of older diesel locomotives?

 

I have a “pacemaker” and wanted to find an excursion / tourist line that sold tickets for cab rides.

 

I figured that riding in front of a generator and electrical panels plus sitting above traction motors that the EMF may be too strong and affect the pacemaker’s operation.

 

If anyone can provide the data, I can contact my doctor &/or pacemaker manufacture to see if the levels are too high.

 

Thanks!!

[erikem]

When seeing the title my first thought that this was going to be a crackpot post, but the reality is that you do have a very legitimate question. The two things you would be concerned about is "DC" magnetic fields in excess of 5 gauss (this resets many pacemakers/ICD's), and high dB/dt situations (such as the fields generated by spark plug wiring), which interferes with .

I would guess that the steel in the locomotive frame would do a pretty good job of shielding stray fields from the motors and generators. It's possible that the pacemaker manufacturer may have data with respect to train crew members, so contacting the manufacturer would be my first choice.

- Erik

P.S. Dealing with pacemakers and ICD's has been a concern at where I work.

[redwingz]

That's a difficult thing to predict without actually measuring the field with a gaussmeter which measures the flux lines per square centimeter.  There are many factors to consider such as:.

1)  An electrical conductor produces a magnetic field which surrounds the conductor whenever electrical current flows through it.  This is true for ANY wire including the wiring in your house, iPod, TV, doorbell, washing machine, etc.

2)  The strength of a magnetic field created by electromagnetic force is dependent upon the amount of electrical current flowing through the wires.

3) Any ferromagnetic material, such as iron or steel, will shunt the majority of flux lines through itself.  This is due to the fact that the flux lines find it easier to flow through ferromagnetic materials than through air. It essentially acts as a shield.

4) The magnetic field produced around the wires of a DC source is static, or at some fixed level for a given current.  The magnetic field from an AC source is constantly changing its strength and polarity. 

5) The magnetic field in electrical conductors laid side by side with current flowing in opposite directions will cancel out each other, leaving very little flux leakage.

6) The magnetic field produced by any source, including permanent magnets, follows the inverse-square law from physics.  The intensity of the field decreases by a factor of 4 for as the distance (r) from the source is doubled.  

The bottom line is that with all the ferromagnetic material in the frame and cab of a locomotive and the distance you are from the source of the fields means the chance of your pacemaker malfuctioning is minimal.  I find it odd that airlines require you to turn off all electrical devices on takeoff and landing.  If the amount of electromotive force emitted from these devices can interfere with navigational equipment, why doesn't it interfere with them during the rest of the flight.  Why only takoff and landing?  I think they say that they say that to insure they don't have laptops flying around the cabin in case of an emergency. 

 

 

[selector]

I would guess that insurance and safety requirement loom largely in the matter as well.  The cabin crew want your attention while they are performing the safety briefing, for example, and they may be concerned about 'tweaked' electronics with a lot more oomph to them in terms of radio/freq intrusion.  But, it is a good question...is it still a serious matter, and if so, why?

Crandell

[klahm]

There was an extensive article in IEEE Spectrum a few years ago on the electromagnetic spectra emitted by laptop computers and such when activated aboard aircraft.  The researchers (Carnegie Mellon, IIRC) recorded spectra onboard during all flight segments and found some evidence of potential interference to aeronautical radionavigation from malfunctioning or poor-quality consumer devices.  This is most critical during takeoff and landing.