What's the "AC motor stop" sign for?
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I remember this image from long ago - one of my favorites from you which inspired many trips afterwards to that location, now long fenced off. I believe the "AC Motor Stop" designates where the overhead power is off or non-existent. Electric trains would either stop or coast to a stop and if necessary to move further, a diesel would be brought out for the move.
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| Posted by Dana M. on August 13, 2014 | |
To answer Alexandria's question: "What's the AC MOTOR STOP sign for"? In the 30th Street Station Passenger "Yard" tracks limit where this train is currently about to leave, to slow momentum of the trains entering and exiting the yard limits of the station, there was a switch in the locomotive that would reduce the amount of electrical power from the overhead cantenary to put power to the traction motors that was drawn from an AC current generator that works similar to a diesel locomotive. There is a "backup" power supply in the locomotive. It supplies emergency and independent power to the locomotive as a backup should the overhead power through the cantenary lines fail. The AC motor supplies emergency and yard operational power. Hence, as the trains leave the yard limit - the sign is there to remind the crews to turn this AC motor off and return the locomotive to full operating power off the overhead lines.
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That's a siding and the wire stops a few feet behind me.
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