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What's Frying the Electrical Systems On BART Trains? (ieee.org)
Tekla Perry writes: Earlier this month, BART engineers shut down a substation in hopes that the closure would quiet the power surges that were frying the electrical propulsion equipment on BART cars -- a peak of 40 in just one day in February. The shutdown seemed to solve the problem, but BART officials weren't sure they'd really found the answer. Yesterday, the power surges popped up again, on an entirely different section of tracks, damaging 50 cars before BART closed off that section, rerouting passengers onto buses. Track inspections yesterday revealed nothing, and BART reports that it has reached out to experts around the country and asked them to fly in and help solve the mystery. Do you have a theory? Note: BART is the 5th-busiest heavy-rail rapid transit system in the U.S.
could there perhaps be enough inductance in the multi-motor systems that it is generating its own connect/disconnect/connect surges? try isolating those DC motor controllers from both the track and the motors with some diode stacks and snubber caps.
if this is supposed to be a new economy, how come they still want my old fashioned money?
Throw some power quality analyzers on various sections of the track and watch the system's transient voltage response with power sources in various configurations.
Have gnu, will travel.
So the A & B cars having inductions motors seem to be fine, while the problem seems to be confined to the C cars having the DC motor. That's one difference.
Also, what else has changed? Take a look at wunderground to see that the Bay Area is having a wet season.
Why would the C cars have been mostly fine all along and having trouble now?
So there's charge building up in the DC motors that they can't handle and that makes them blow out. The charge has nowhere to go. What controls the flow of charge? Grounding. What can go wrong with grounding? Good grounds can go bad when a lot of discharge causes the sand in the soil to vitrify (melt into glass) after discharges and lightning strikes have been shooting through it for decades. Better grounds can unexpectedly form when more highly conductive paths form up. The AC induction motors will suffer a power loss but can handle the charge jumping back & forth in unexpected ways, while the DC motors can't.
Add it all up. This has to be a grounding problem aggravated by the wet season, and an underlying assumption that once you sink a ground it's good forever. It isn't.
My "go to" excuse for any electronic problems is "sunspots, or stray cosmic rays". However.....
The Sun has been very quiet for the last several weeks, and Solar Cycle 24 is on a steep downward trend. I expect that we'll begin an extended Solar Minimum by the end of 2016 which may last 3-4 years (the "average" is 2 years, and the last Solar Min was nearly 3). I also expect that the next few solar cycles will be fairly quiet. Perhaps not Maunder Minimum quiet, but probably Dalton Minimum quiet, or nearly so.
You should visit www.spaceweather.com periodically to keep up to date on this.
Also; it's going to get somewhat chilly by and by.
Considering that it's aged - don't rule out aging wire insulation that no longer does its job.
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.