Constant-tension catenary as used on the NEC

Trains Magazine General Discussion
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What does the NEC use to tension the catenary on the NEC north of New Haven, is it weights or a hydraulic system?

Does anyone know of good photographs of the tensioning system? (There is a picture here in the forums that is supposed to be it’s a tensioner but I couldn’t identify anything in the structure that looked like a tensioner.)

Here’s a tensioner in Germany. http://en.wikipedia.org/wiki/Overhead_lines#Tensioning

Thanks.

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I live a couple miles from the NEC in the Providence, RI area and see the Catenary on an almost daily basis. It uses a system of weights and pulleys to maintain tension.

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I thought I had a better pic but this picture was taken about the Acela Express arriving at South Station in Boston.

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Below is a close up of the same photo at South Station.

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Below is a picture of a catenary arm photographed at Ruggles Station in Boston just west of Back Bay Station.

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Below is a view of the Southwest Corridor looking east towards Back Bay Station from the Ruggles Station platform. A Regional train is slowing down for the Back Bay Station stop.

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[quote user=“aegrotatio”]

What does the NEC use to tension the catenary on the NEC north of New Haven, is it weights or a hydraulic system?

The NH-BOS, NJ Transit’s new 25 KV systems, and the airport extension of SEPTA to PHL airport all use weights. I am not aware of what is installed New Rochelle - NH and Harold - New Rochelle. Weights are a passive system and will require no additional work except maybe some maintenance to repair any tensioning problems by adding or subtracting weights. However there are some considerations in the placing and amount of weights.

1. Constant tensioning (in Kilo Newtons) will be set depending on the ultimate speed of the trains under that section. The more the tension the faster the oscillating wave created by the pan will move. The wave needs to move faster than the speed of the pans to prevent harmonic waves causing pan snags. Therefore more weights on an ACELA 150 MPH line vs 60 MPH freight line. Then you would want to design for as much weight as any possible future speed upgrades even though the weights might not be needed at first. Imagine the NJ straightaway north of Trenton eventually going to 200+MPH.

2. distance between the CAT horizontal holders also affect the wave and modern CAT design has the cat holders (arms) on a shorter spacing than the present PRR designed variable tension system. So to install constant tensioning on the PRR sections will require a holder between each present PRR holder. Also the anchor poles to hold the weights will probably need to be new to provide sufficiently robust anchoring.

3. On tangent track weights at each end will have the CAT, Auxillary, and Contact wire anchored at the mid point to allow strech of the wire. That distance will be where the wire will not streach more than some value (about 18 - 20 inches) at the encountered temperature extremes .

4. Th

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Wow, thanks, say for north of New Haven, how far apart are the tensioners?

Does the pulling affect the zig-zag profile of the wire, and if so does that affect the longevity of a pantograph’s carbon strip?

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May have not explained the mile post numbers on the poles. Look at the pole numer in the close-up. It is MP228.181 (228.181 miles more or less from GCT). So any 2 tensioners connected to a single wire subtract the 2 values. 5 ft is close enough for govenmit work.