Electric Propulsion Questions

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Electric Propulsion Questions

Postby EuroStar » Fri Jul 21, 2017 7:11 am

I think I know the answers to these questions, but I would like confirmation/additional information.
1. Does phase gap between 25Hz and 60Hz catenary require lowering of the pantograph or slowing down? Assume same voltage to ground.
1a. Can transformers made for 25Hz handle 60Hz without modifications (on-the-fly while in motion or in the shop)? Again, assume same voltage.
2. How long is the section of catenary that is unpowered in a phase gap? Does it matter if the wire is constant tension or not?
3. Are the Arrows the only equipment that cannot change traverse a voltage gap 25kV to 12.5kV?
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Re: Electric Propulsion Questions

Postby DutchRailnut » Fri Jul 21, 2017 12:24 pm

a phase gap normally does not require dropping pantographs on newer equipment, the circuit breaker drops out and will not reset till it senses correct voltage.
a transformer made for lower frequency has no problem handling higher frequency , as core is just bigger.

the dead section can never be smaller than distance between pantographs feeding same source, so on NEC it would be length of longest locomotive. on MN length of M-4/6 cars as they had two pantographs feeding same source.

can't answer that.
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Re: Electric Propulsion Questions

Postby Sirsonic » Sun Jul 23, 2017 10:29 pm

EuroStar wrote:I think I know the answers to these questions, but I would like confirmation/additional information.
1. Does phase gap between 25Hz and 60Hz catenary require lowering of the pantograph or slowing down? Assume same voltage to ground.
1a. Can transformers made for 25Hz handle 60Hz without modifications (on-the-fly while in motion or in the shop)? Again, assume same voltage.
2. How long is the section of catenary that is unpowered in a phase gap? Does it matter if the wire is constant tension or not?
3. Are the Arrows the only equipment that cannot change traverse a voltage gap 25kV to 12.5kV?


1. No, neither lowering the pantograph nor slowing down is required to negotiate a phase gap.
1a. Yes, and ALP-44, ALP-46, ALP46A, and ALP-45DP locomotives all are so equipped.
2. The grounded wire section is roughly 5-10 feet long. If you include the insulated rod section on either side of the grounded wire the entire section is no longer than 20 feet. Specifically, the entire section is shorter than the distance between the two pantographs on an ALP-44
3. On NJT right now, yes.
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Re: Electric Propulsion Questions

Postby EuroStar » Mon Jul 24, 2017 9:01 am

Thank you both. This is information is very useful to me.
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