I was looking through a book and noticed that some of the pictures showed a NYC P motor with both panographs up. Is there an advantage/reason to only have 1 or 2 panographs up at any given time?

Thanks!

I remember reading that the trailing one was usually used on the PRR GG1s in case of a problem. Debris from the forward one could take out the second.

Joshua

Two pantographs may be both up when a locomotive was changing ends (moving the control position from one cab to the opposite cab). The company may require that the lowered pantograph be raised before lowering the other; this would maintain electrical contact.

Sometimes going in and out of shops and certain parts of the yards have phase breaks or disconnects where there is a dead spot in the catenary, and you need both pans up to make it through without losing power.
Also they run 2 pans up when there is an ice storm to knock the ice off the catenary and save wear and tear on the carbon strips.

Having both pantographs up doubles the wear on the contact wire.

PRR did have both pans up in snow or ice storms to reduce arcing; also under high wire PRR used both pans as the pans were at the ends of their travel. When changing ends, you want to raise the new pan before you lower the old one so the motor stays alive and to prevent an arc when you lower the pan with the equipment still running.

You really don't want both pans up at a phase break as the other section may be out of phase and having both pans up could bridge the gap.

Phil Mulligan

A New York Central electric locomotive only uses its pantographs on the short lengths of overhead 3rd rail at complicated interlockings where there are long gaps in the ordinary 3rd rail. Having both pantographs up would slightly increase the distance that the locomotive could be powered. Or, did you mean a Cleveland Union Terminal electric locomotive, which did use catenary?

Jim,

Cleveland Union Terminal. I should have added that. My bad!

Same motors; they were built for Cleveland Union Terminal for 3000V DC using big pantographs, then in the 1950's as traffic to CUT was diesel-hauled, CUT discontinued the electrification and sold the motors to NYC for service in the third-rail zone out of Grand Central Terminal at 660V DC using third rail and those little pans (to reach an overhead third rail bridging complicated trackwork.)

I can see using both little pans to draw enough amps to move a heavy train at 660V but on CUT they didn't need both big pans at 3000V. MILW climbed mountains with their 5000 HP Joes at 3000V and one pan per motor.

Phil Mulligan

PRR class FF2 motors were required to run with both pantographs raised.

The former Great Northern locomotives were motor-generators.

Running with a single pan that momentarily lost contact with the trolley wire could cause the motor to get out of phase with the 25hz power supply which would trip to main breaker on the locomotive or shoot the line breaker.

EBL

I had heard something like that. They had rotary equipment to convert AC to DC and I understand the AC side was synchronous.

I have seen photos showing GN had installed Reading MU-type bus connectors on the 11kV side to ensure a set in MU would have continuous contact. I presume GN's power supply was such that they did not need phase breaks.

Phil Mulligan

My understanding is that for lower voltage DC systems, more than one pantograph was used due to the higher draw of traction current from the overhead wires.

The former 1500V DC line here in the UK between Manchester and Sheffield via Woodhead tunnel required both pantographs to be raised on locomotives, even when working in multiple.....(4 pantographs raised here)



Dutch Railways (also 1500V DC) also used both pantographs when starting trains away from stations........

Amtrak Sprinter in snow/ice conditions last April, northbound, approaching the Bowie MARC station, with both Pans up:



MOW equipment is stored on the number two track.

A review of my photos from that day show the Acela's were running the same way as well.

Bob

One day last month in Warsaw everything was covered in a thick layer of frost. Proved to be quite an interesting sight.