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Old 01-23-2010, 08:36 PM   #1
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Default NYC Subways..
Why do they use 600V DC to operate trains..

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Old 01-23-2010, 08:49 PM   #2
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Dunno.. They use 1kV DC here for the local train we have.

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Old 01-23-2010, 08:51 PM   #3
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I belive they use 550v dc here for the light rail. I think.
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Old 01-23-2010, 08:52 PM   #4
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From that info, I suppose there is no other reason to use 600V over 550 or 1000 than that is what the train car was designed for.

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Old 01-23-2010, 08:52 PM   #5
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Easier to control speed with DC. The level 600, 750 or 1000 is system dependent. Large dump trucks in mines use DC motors precludes having a transmission.

I heard BUT NOT SURE, that flash over is less common with DC than AC, thus smaller insulators. This has to due with the peak of the sine wave with AC? 1000 VDC is 1414 VAC at the peak of the sine wave.
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Old 01-23-2010, 08:56 PM   #6
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From that info, I suppose there is no other reason to use 600V over 550 or 1000 than that is what the train car was designed for.

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I was curious why the different voltages also.
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Old 01-23-2010, 09:01 PM   #7
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Alot of answers can be found here
http://citytransport.info/Electtrn.htm
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Old 01-23-2010, 09:01 PM   #8
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I was curious why the different voltages also.
It is likely that the voltages are a relic of the ancient past. They probably used the highest voltage possible (for voltage drop and low current) in the 1890's or whatever, and over time as more equipment is accumulated from different eras you are pretty much stuck with it.
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Old 01-23-2010, 09:02 PM   #9
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We were all taught transmission of AC was much more efficient than transmission of DC power

That is what I am wondering about...
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Old 01-23-2010, 09:06 PM   #10
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I think the dc motors have more controllable torque than the ac counterpart. Also the dc can charge the batteries during breaking. Just a few things ive read. Cant beleive everything you read though except the code.
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Old 01-23-2010, 09:10 PM   #11
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Alot of answers can be found here
http://citytransport.info/Electtrn.htm
Nice link. Thanks.
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Old 01-23-2010, 09:38 PM   #12
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Most diesel electric locomotives used DC motors until recently. GE and EMD offers both AC and DC versions. DC is cheaper; AC can pull at slower speeds without burning out the motors.
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Old 02-04-2010, 05:15 PM   #13
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I thought it was because when a train has 12 cars and 24 contact pads on the 600v DC 3rd rail energizing a common interconnected feeder, it won't matter to the train when it passes over onto a new rail fed from a different source and is being fed from both sources simultaniously until the crossover is complete.
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Old 02-04-2010, 05:33 PM   #14
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every time i eat there i get gas. real bad.
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Old 02-04-2010, 05:38 PM   #15
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We were all taught transmission of AC was much more efficient than transmission of DC power

That is what I am wondering about...

I was taught "converting" ac to dc was more efficient.
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Old 02-04-2010, 05:39 PM   #16
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I think the dc motors have more controllable torque than the ac counterpart. Also the dc can charge the batteries during breaking. Just a few things ive read. Cant beleive everything you read though except the code.
Your always full of helpful info codeone thanks
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Old 02-04-2010, 07:42 PM   #17
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They use 600 v.d.c.to power the trolley as far as the d.c. can be sent without voltage drop,then handing off to the next d.c .station,isolated from the previous power station.
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Old 02-04-2010, 07:53 PM   #18
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The transit trolley system around Pittsburgh,uses overhead copperweld lines under high tension ,countered by a weight system to counteract the temp changes,ect.A few snacthers got whipped when they cut the conductor under 15k lbs. of tension. Too bad.
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