Over-Head Electric Wire

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  • Member since
    February 2005
  • 1,987 posts
Posted by timz on Tuesday, April 13, 2021 10:06 AM

What's "HEP idle"? Think the U34 ran at 960 RPM in HEP-non-idle, hence 3430 hp or some such instead of 3600.

  • Member since
    April 2007
  • From: Palos Park, IL
  • 146 posts
Posted by bogie_engineer on Tuesday, April 13, 2021 10:51 AM

I don't know anything about U34's but the F40PH's were all built with a HEP standby mode where there was no traction power but delivering HEP from the traction alternator running at 720 rpm making 60Hz 3 phase power. Near the isolation switch on the back wall of the cab was a similar snap-action switch with positions for No HEP, HEP Standby Mode, and HEP from the HEP alternator with traction available, although I don't remember the exact labels.


  • Member since
    February 2005
  • 1,987 posts
Posted by timz on Tuesday, April 13, 2021 11:46 AM

So a minute or two before departure from the initial station, passengers would see the lights go out when the engineer switched from standby HEP to the regular mode. Think Caltrain still has a couple of F40s with 645-powered HEP? Dunno if engineers still bother with the standby HEP.

  • Member since
    March 2016
  • From: Burbank IL (near Clearing)
  • 12,382 posts
Posted by CSSHEGEWISCH on Tuesday, April 13, 2021 12:06 PM

As a regular Metra rider, I observed that the lights went out briefly in the switch from station power to locomotive HEP.

The daily commute is part of everyday life but I get two rides a day out of it. Paul

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