What's "HEP idle"? Think the U34 ran at 960 RPM in HEP-non-idle, hence 3430 hp or some such instead of 3600.
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.
Dave
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.
As a regular Metra rider, I observed that the lights went out briefly in the switch from station power to locomotive HEP.
Our community is FREE to join. To participate you must either login or register for an account.