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25 Hz power stated as challenge to opening NYP tunnels

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25 Hz power stated as challenge to opening NYP tunnels
Posted by aegrotatio on Thursday, November 08, 2012 12:40 PM
Today's announcement from Amtrak of the Friday opening of all NYP tunnels, they state that the use of 25 Hz power is limiting capacity because the power needs to travel an excessively long distance in order to bypass the out-of-service Kearny substation.

Since all trains can use 60 Hz current, and Kearny is severely damaged, would it not be advantageous to replace this equipment with 60 Hz current to allow more opportunities for local power supplies? Or does it cost less to generate and transmit 25 Hz power from Safe Harbor dam?

More: http://www.amtrak.com/ccurl/10/874/Amtrak-to-Re-open-Three-NYC-Tunnels-ATK-12-104.pdf

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Posted by blue streak 1 on Thursday, November 08, 2012 2:21 PM

aegrotatio
Today's announcement from Amtrak of the Friday opening of all NYP tunnels, they state that the use of 25 Hz power is limiting capacity because the power needs to travel an excessively long distance in order to bypass the out-of-service Kearny substation.

Since all trains can use 60 Hz current, and Kearny is severely damaged, would it not be advantageous to replace this equipment with 60 Hz current to allow more opportunities for local power supplies? Or does it cost less to generate and transmit 25 Hz power from Safe Harbor dam?

More: http://www.amtrak.com/ccurl/10/874/Amtrak-to-Re-open-Three-NYC-Tunnels-ATK-12-104.pdf

 

The motors can use 12.0 kv 25 Hz, 25 kv 60 Hz,  and 12.5 kv 60 Hz interchangably either automatically when  coasting thru a phase break area (usually about 100 ft in case both pans on a motor are extended ) or by the engineer turning a rotary switch to switch what the power the loco is receiving.. However the NJ TRANSIT EMUs  with a few exceptions cannot switch frequencies on the fly without the operator going on the ground and manually switching frequencies &/or voltages.  (some NJT CAT is 25 kv 60 hz   So the EMUs from Trenton may not be able to take an on the fly change from 25 Hz to 60 Hz even though the voltage is  ~~  the same .. 

The real problem is all the land based equipment that uses the 25 Hz.  this formist does not know what station mechanicals are off the 25 Hz yet.  we do know that signal power uses frequency multipliers to convert the 25 Hz to 100 Hz signal power every 15 - 25 miles. there is an AMTRAK project to eventually have back up signal power at each signal location provided by a frequency converter that will use comercial 60 Hz 110. / 220v to provide 100 Hz power to  each signal bungalow. as far as known that project is not complete.  

Wha t would help is a conversion  to 12.5 from of the line from south of the NJT Morrisville yard to NYP BUT that will be a long term project.

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Posted by blue streak 1 on Thursday, November 08, 2012 2:46 PM

Safe Harbor  is a whole another question.  It actually generates both 25 Hz single phase and 60 Hz 3 phase commercial power current. I believe that there is a priority for the RR 25 Hz. Imagine that the 25 Hz is similar to the power going into your home transmitted as 69 Kv each leg to ground and 138 Kv leg to leg. That is steped down to 12 Kv CAT power  using auto transformers . If  you look at the transmission lines of AMTRAK you will notice that the25 Hz power lines are in multiples of 2 - 4 - 6. PRR did sell an easement to a commercial power line that is 3 phase 60 Hz above the 25 Hz. Sometime in the past the primary voltage was raised from 132 Kv to 138 Kv  and with out changing any transformers the CAT voltage went from 11.5 Kv to 12 Kv nominal voltages.

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Posted by aegrotatio on Thursday, November 08, 2012 6:40 PM
Yes and Amtrak retains ownership of an abandoned rail line just to keep the transmission lines in service, and I think that's the one that originates at Safe Harbor. My understanding is that they are renovating this line, too.

Another detail that I didn't mention that Blue Streak did is the 100 Hz signalling system. Evidently its clock is timed so it fits into the multiples of 25 Hz. There is another thread here that describes it in deep detail, too.

I guess it's not as easy as it looks. They want to restore service as soon as possible, too.

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Posted by MidlandMike on Thursday, November 08, 2012 9:22 PM

I get the impression Amtrak would like to upgrade the entire system to 60 Hz to avoid future problems like this emergency compatibility, but (according to another railfan forum) SEPTA is the final holdout.

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Posted by blue streak 1 on Thursday, November 08, 2012 10:15 PM

MidlandMike

I get the impression Amtrak would like to upgrade the entire system to 60 Hz to avoid future problems like this emergency compatibility, but (according to another railfan forum) SEPTA is the final holdout.

SEPTA may / should not be a big problem as the silverliner - 5s are being built to work on both 25 and 60 Hz. Power is taken directly from the  -- 5s  pan to a 25 / 60 Hz transformer, output to  rectifier(s), then those output( s ) to inverters to provide the various traction motors and auxlliaries.  Although not installed there is provision for SEPTA to add an automatic center tap on the transformer for future 25 Kv CAT transitions on the NEC or Harrisburg line or for thru operation on the AMTRAK New Haven  -- Boston line or even the line south to WASH.  No other provision for dual 25 / 60 Hz equipment on the  -- 5s as the 2 frequencies are essentially the same voltage.

Now the conditions of how the dual frequencies on silverliner  -  4s would operate are unknown to this formist. Remember the earlier silverliners have just recently been retired.

The dual frequency has some interesting characteristics.  A transformer originally built for 25 Hz will accept 60 Hz.  However a transformer built for 60 Hz will not operate very well on 25 Hz. A 25 Hz transformer is much more heavy for the same power output than a 60 Hz transformer of the same power.  Also a 25 hZ syncnorous motor is much bigger and heavier than a 60 Hz motor of the same horsepower. That is partially the result of the maximum speed of a 2 pole 60 Hz motor is 1800 RPM where as a 25 Hz motor is 750 RPM.  These same restrictions apply to the power generators at safe harbor requiring much bigger generators for the same power output.

If the USA had to build an electrical system from scratch today it probably would be 100 Hz + / - as the same scale ups would apply to the higher frequencies (max 3000 rpm) .  That may be why PRR signaling was made 100 Hz because they used a lot of motors originally in their signal systems.  

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Posted by erikem on Thursday, November 08, 2012 11:33 PM

blue streak 1

If the USA had to build an electrical system from scratch today it probably would be 100 Hz + / - as the same scale ups would apply to the higher frequencies (max 3000 rpm) .  That may be why PRR signaling was made 100 Hz because they used a lot of motors originally in their signal systems.  

I'd disagree - 50/60 Hz seems to a better compromise between the needs of long distance transmission and circuit breker operation versus the desires for smaller, lighter motors and transformers. The circuit breaker problem may be the most significant as 100 Hz would nearly halve the time around the current zero crossing point which is important for helping to extinguish the arc. 25 Hz is even better in that regards and that was brought in articles in such diverse rags as "Electric Lines" and "IEEE Spectrum" during early 90's discussion on converting the NEC to 60 Hz.

You are correct about 25 Hz motors and transformers being heavier than their 60 Hz counterparts.

- Erik

P.S. If we go to 3kVDC, we can run the traction inverters directly off the catenary voltage and thus get rid of the transformer.Mischief

P.P.S. The earliest AC distribution systems in the US ran on 133 Hz.

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Posted by henry6 on Friday, November 09, 2012 8:02 AM

My question is, then, that since the PRR system served so well with the ability to feed the whole system from Wilmington DE to Sunnyside Yards when needed with only a slight reduction in efficiency, stood and operated well for its entire life...lots still serving today in fact...then why does the whole system have to be thrown out and a completely new and different system have to replace it?  Ok..catenary has to change for higher speeds, but after that?

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Posted by John WR on Friday, November 09, 2012 6:12 PM

I'm not a technical expert about the theory and practice of electric traction motors, Henry.  I do know historically they have used different kinds of electricity.  Relatively low voltage DC (600 volts) was once common and my still be used on the New York subways.  The Delaware Lackawanna and Western used 3,000 volts DC but I do not know of any other systems that used DC at that high voltage.  The New Haven  used split phase AC motors at 25,000 volts I think.  I don't know why the Pennsylvania picked 25 hertz; perhaps one one who knows the theory can explain.  

But in the American electrical system 60 hertz is standard and you can get it pretty much any place you are.  I bet this has a lot to do with the decision.  

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Posted by MidlandMike on Friday, November 09, 2012 11:16 PM

Where the 25 Hz cat supply taps into the 60 Hz grid, there is the extra step of phase conversion.  PRR used rotary converters, an electro-mechanical device.  I believe some are still working, and some have been replaced by solid state devices, but either way it could be eliminated by adopting 60 Hz cat,  Also the voltage would be doubled, which could use lighter cat.  Basically the old system is obsolete.

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Posted by John WR on Saturday, November 10, 2012 9:54 AM

Thank you for the note about rotary converters, Mike.  What strikes me is not that 25Hz AC is obsolete today but that it was also obsolete in the 1930's when the PRR first electrified their lines.  60Hz was standard at that time.  So I wonder my the PRR used 25Hz in the first place.  

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Posted by blue streak 1 on Saturday, November 10, 2012 10:54 AM

MidlandMike

 PRR used rotary converters, an electro-mechanical device.  I believe some are still working, and some have been replaced by solid state devices, but either way it could be eliminated by adopting 60 Hz cat,  Also the voltage would be doubled, which could use lighter cat.  Basically the old system is obsolete.

well if the rotary converters are obsolete why is AMTRAK rebuilding the rotary converters ? You can find it on the monthly reports and the FY 2012 , 2011, 2010 budgets.  AMTRAK is adding new solid state converter devices as well. The rotaries are being rebuilt in place because they are so massive due to the low rpm they have to operate. Has to be a divisor of both 60 Hz and 25 Hz. (3600 & 1500 rpms).

The cat voltage cannot be easily doubled to 25 Kv until the cat is rebuilt with 25 Kv insulators. south of Newark to south of Trenton is the only place as  of now that the cat is scheduled for rebuilding and will not be completed until 2017 ? as well all circuit breakers and old PRR 25Hz transformers ( PCBs) will require replacing.  It may be the rebuilding  ( if necessary ? ) of the Kearney substation that was flooded will be of the dual frequency / voltage type.  Voltage cannot be increased in NYP & its tunnels, Newark, 30th St, ( wilmington ? ) Baltimore, WASH cannot be raised at this time due to clearance increases needed for the higher voltages.  The present CAT is too close to overhead structures. most stations except NYP, 30th st, BAL can eventually increase clearances but I would expect that is 10 - 20 years in the future.  However  

 

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Posted by timz on Saturday, November 10, 2012 3:58 PM

John WR
25Hz AC is obsolete today but that it was also obsolete in the 1930's when the PRR first electrified their lines.

What development made it obsolete? Was it obsolete when PRR first used it circa 1915? Can motors like GG1s and MP54s had use 60 Hz AC?

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Posted by MidlandMike on Saturday, November 10, 2012 5:08 PM

timz

John WR
25Hz AC is obsolete today but that it was also obsolete in the 1930's when the PRR first electrified their lines.

What development made it obsolete? Was it obsolete when PRR first used it circa 1915? Can motors like GG1s and MP54s had use 60 Hz AC?

When mainline electrification was being developed in the early 1900s, power companies were not really able to supply the needs of this scale, so RRs generally built their own power plants.  For the early AC motors, 25 Hz was optimal, so the RRs built as such.  By the mid century, rectifiers and DC motors made the  supply cycle rate unimportant.  Modern solid state electronics make the cycle rate irrelevant.  Nevertheless, until the system is converted to 60 Hz, the old rotary converters, of substitute electronics must be maintained. 

I had forgotten about the tunnel insulation clearance problems that would have to be resolved, as pointed out.  Rebuilding the cat for double the voltage would indeed need heavier insulators, but the wire could be lighter which allows faster speeds.  Also, while supply off the grid would be at the right Hz. it is 3 phase, and the cat would be single phase.  Some have said this would cause a phase imbalance in the grid, but others have said the problem is manageable.

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Posted by erikem on Saturday, November 10, 2012 5:13 PM

timz

John WR
25Hz AC is obsolete today but that it was also obsolete in the 1930's when the PRR first electrified their lines.

What development made it obsolete? Was it obsolete when PRR first used it circa 1915? Can motors like GG1s and MP54s had use 60 Hz AC?

Answering Tim's question to John...

The GG1's and MP54's used AC series (universal) motors, and were designed to run on 25 Hz. 60 Hz series motors top out at a few tens of HP, which is substantially less than the ratings for the motors used in either the GG1 or MP45.  Competing single phase AC electrification technologies in the 1930's were phase converter locomotives as used by the N&W and VGN (which operated at two fixed speeds), and motor generator locomotives as used by the GN. Neither approach was suitable for the MP54 and a motor generator "GG1" would have been heavier and much more expensive than the GG1 as built.

Some experimental rectifier locomotives were built prior to WW1, but on-board rectifiers weren't used in quantity in the US before the early 1950's - first on an order of NH MU's and then on the VGN EL-3 (E-33's).

My $0.02 worth,

- Erik

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Posted by blue streak 1 on Saturday, November 10, 2012 6:25 PM

timz

25Hz AC is obsolete today but that it was also obsolete in the 1930's when the PRR first electrified their lines. What development made it obsolete? Was it obsolete when PRR first used it circa 1915? Can motors like GG1s and MP54s had use 60 Hz AC?

the main reason it is obsolete today is the size of motors for the HP delivered.  ( for background aircraft use 110 / 220 V 400 Hz which enables very small motors).  There are manufacturing plants that even today still use 25 Hz that was installed when their buildings were built before WW-2 . another reason is that 25 Hz orders wouldl be special built whereas 60 Hz is off the shelf.  to further confuse the issues some of our more mature posters from the west may recall when there was a change from 50 Hz to 60 Hz after WW - 2.

my understanding is that there were special AC motors in GG-1s that could only use 25 Hz ? MP-54s ??

another confusing issue is that JAPAN has half of its country 50 Hz and the other 60 Hz. So all RR equipment is dual frequency capable.

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Posted by John WR on Saturday, November 10, 2012 6:43 PM

blue streak 1
well if the rotary converters are obsolete why is AMTRAK rebuilding the rotary converters ?

I am wondering why Amtrak is, as you say, rebuilding rotary converters rather than replacing worn out ones with solid state electronics. Perhaps they are still using rotary dial telephones.  Perhaps they are working on a 4-4-0 wood burner to pull a train.

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Posted by John WR on Saturday, November 10, 2012 6:57 PM

  Tim,  

My statement that 25 Hz was already obsolete in the 1930's is based on the fact that by that time most of the electricity generated and used in the US was 60 Hz.

However, Erik suggests that 60 Hz is insufficient to power the size motor needed on a locomotive but 25 Hz is or at least was in the 1930's.  I don't know the technology so I would defer to Erik's opinion.  

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Posted by MidlandMike on Saturday, November 10, 2012 10:29 PM

blue streak 1

MidlandMike

I get the impression Amtrak would like to upgrade the entire system to 60 Hz to avoid future problems like this emergency compatibility, but (according to another railfan forum) SEPTA is the final holdout.

SEPTA may / should not be a big problem as the silverliner - 5s are being built to work on both 25 and 60 Hz...

SEPTA might not object to ATK modernizing the lines they both run on, however, wouldn't SEPTA also have to modernize their own suburban lines as all the operations are integrated?

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Posted by erikem on Saturday, November 10, 2012 10:46 PM

John, Blue Streak,

CERA Bulletin B-118, Westinghouse Electric Railway Transportation has an article on the the development of the single phase system where it specifically mentions using a lower frequency to improve performance of AC series motors. 25 Hz was chosen as it was already a standard frequency first used in the Niagara Falls hydroelectric plant. The European standard was 16 2/3 Hz and the Visalia Electric used 15 Hz.

With the exception of the N&W and VGN phase converter locomotives (not to mention the PRR's Big Liz), the GN and VGN motor generator locomotives and a handful of experimental rectifier locomotives, all single phase electric railway equipment in the US prior to 1950 used AC series motors. As mentioned above, these motors required 25 Hz or lower to operate satisfactorily.

[Edit: Note that the GG1 used two traction motors per axle (not a big deal with geared quill drives) as two smaller AC series motors will be more efficient than a single larger motor. Another advantage was the smaller motor was was used elsewhere on the PRR.]

My uncle showed me a rectifier module for electric razors and demonstrated that the razor ran a bit faster on DC than AC.

FWIW, 25 Hz was widely used pre-WW2 for industrial processes that needed large quantities of DC power, e.g. aluminum smelters. This was because the rotary converters were typically more efficient running off of 25 Hz than 60 Hz. It was also widely used for feeding substations for trolleys, interurbans and third rail railway electrifications as well as the DC districts in many downtowns.  The last of the 25 Hz converters used on the Grand Central electrification were taken out of service ca 1990.

- Erik

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Posted by henry6 on Sunday, November 11, 2012 8:19 AM

MidlandMike

blue streak 1

MidlandMike

I get the impression Amtrak would like to upgrade the entire system to 60 Hz to avoid future problems like this emergency compatibility, but (according to another railfan forum) SEPTA is the final holdout.

SEPTA may / should not be a big problem as the silverliner - 5s are being built to work on both 25 and 60 Hz...

SEPTA might not object to ATK modernizing the lines they both run on, however, wouldn't SEPTA also have to modernize their own suburban lines as all the operations are integrated?

But SEPTA Rail  already has integrated their electric operations so all equipment seems to run on former PRR and former RDG tracks.

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Posted by John WR on Sunday, November 11, 2012 12:27 PM

Thanks for the detailed explanation of why the railroads stuck to 25 Hz for AC motors instead of just using  60 Hz.  However, no good deed shall go unpunished so please accept a couple of questions.  

1.  Why is a lower electric frequency (i.e. 25 Hz) more suited to powerful motors than a higher one?

2.  You say that 25 Hz was used up to the 50's.  Were new technologies developed at that time to allow the use of 60 Hz?

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Posted by schlimm on Sunday, November 11, 2012 12:57 PM

AFAIK, even now German Rail uses 15 kV, 16 2/3 Hz.  Seems to work fine for freight and high speed ICEs.

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Posted by erikem on Sunday, November 11, 2012 2:24 PM

John WR

Thanks for the detailed explanation of why the railroads stuck to 25 Hz for AC motors instead of just using  60 Hz.  However, no good deed shall go unpunished so please accept a couple of questions.  

1.  Why is a lower electric frequency (i.e. 25 Hz) more suited to powerful motors than a higher one?

2.  You say that 25 Hz was used up to the 50's.  Were new technologies developed at that time to allow the use of 60 Hz?

Answer to #1:

A couple of reasons. The inductive reactance of the field and armature windings becomes a significant part of the overall voltage drop across the motor - in an ideal series motor, the voltage drop is solely due to "back EMF". This is why my uncle's razor ran faster on DC than AC. The more serious reason has to do with commutation. On a DC series motor, the interpole compensates for armature reaction and thus allows the motor to be operated at a wide range of currents without having to adjust the brush position. An an AC series motor, the interpole does a poorer job of compensating for the combined effects of armature reaction and inductive reactance - where the inductive reactance increases with frequency.

Commutation problems increase with increasing terminal voltage, the motors on the GG1 were rated at 235 to 250 volts, where similar sized DC motors could be rated up to 1500 volts. The PCC's used two motors in series to allow use of 300 volt motors in the interest of better commutation. The downside of lower voltages is that the current increases - on the GG1, each motor was drawing over 2,000A when operated at its short time rating.

AC series motors need to be built with a laminated frame to reduce problems with eddy currents.

Answer to #2:

The mercury ignitron was developed to the point where it was practical to use in on-board RR service - mercury arc rectifiers where used on the South Shore Line in 1926 when it was converted to run on 1500VDC for compatibility with the Illinois Central commuter electrification - the rectifiers were in substations. Ignitrons work just as well at 60 Hz as they do at 25Hz. The use of ignitrons on locomotives and MU cars allowed those vehicles to be equipped with DC traction motors, which were smaller, lighter, more efficient and cheaper than AC series motors.

Silicon rectifiers became available about halfway through the E-44 production run, which made operation off of 60 Hz even more practical.

Further comments:

For a given power rating (actually volt ampere rating), the weight of a transformer is inversely proportional to the lowest design operating frequency. A 25 Hz transformer will need roughly 2.4 as much iron as a 60 Hz transformer (60/25 = 2.4). 400 Hz transformers will require 60 to 7 times less iron than a 60 Hz transformer, which is why aircraft power systems run on 400 Hz.

The size of an AC induction or synchronous motor is roughly proportional to its torque. Since the shaft power of a motor is the product of motor speed and torque, a high speed motor of a given size will almost invariably produce more power than a low speed motor. That's why a 400 Hz motor can produce more power for a given weight than a 60 Hz motor.

- Erik

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Posted by timz on Sunday, November 11, 2012 4:12 PM

So if you were building a new electric RR today, powered by AC catenary, and for some reason you wanted the locomotives and cars to use AC motors-- constant-frequency-AC motors, not variable-freq powered by inverters powered by DC-- you would still use 25 Hz or less?

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Posted by erikem on Sunday, November 11, 2012 4:50 PM

My first thought was "Why would anyone want to build a brand new locomotive or MU car with AC motors running solely at line frequency?". An AC series motor is inferior to a DC series motor and the rectifiers for the DC motor would be less than the costs differential between the AC and DC motors. A single phase induction motor doesn't make any sense as a traction motor with fixed speed and torque pulsations - it would make a bit more sense to us a phase converter to produce three phase for the traction motors. Fixed frequency synchronous motors don't make any sense - the wheel diameters would have to be kept within a small fraction of an inch - and this would apply to any locomotives running in MU. Using a variable voltage, variable frequency drive makes a lot more sense for an induction motor and is the only practical way of using a synchronous motor.

There are a few advantages to running at 25 Hz or less. One is that circuit breakers will work better as there is more time for the arc to clear around the zero crossing point for the current. Flashovers may be more likely to self-clear for similar reasons. Another advantage is that skin effect is less of an issue, which is particularly important for the track return as the skin effect is far more pronounced in the rails than in the catenary (rails are ferromagnetic). The final advantage is that phase loading on the grid will be better balanced.

There are a couple of corresponding advantages to using 50/60 Hz. The first is that the only conversion equipment needed is a transformer - just hook it up to the grid and go... The second is that the transformer will be smaller, lighter and cheaper compared to 16 2/3 or 25 Hz.

- Erik

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Posted by blue streak 1 on Sunday, November 11, 2012 6:48 PM

Eric;  reallly appreciate the primer.  It has been way too long  from my electrical courses to remember all of this and many of the advances and revelations that now are commonplace today were not even conceived. 

One item you may want to address as there is much confusion among our posters and myself is how phase balancing is accomplished from the 3 phase grid to a single phase CAT and return thru regeneration. That definitely was not covered in my courses as there seemed to be no need ?

also are there any power factor problems with large installations of electric traction? Power factor problems seem to have disappeared from residential areas in this country. 

 

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Posted by John WR on Sunday, November 11, 2012 7:20 PM

Thanks for your explanations, Erik.  If I understand you correctly the Pennsylvania choose 25 Hz because it was available at the time and needed only a step down transformer to directly power it traction motors.  At 60 Hz back emf is a real problem but at 25 Hz it is not.  DC was rejected because of the expense involved in converting AC to DC.  

But in the late 1990's (or early 2000's) when Amtrak electrified the line between New Haven and Boston solid state electronics made it much easer and cheaper to convert AC to DC.  In fact the conversion could be done on board the train itself.  And a 25 Hz motor may be run on DC.  At the same time 60 Hz uses much smaller transformers and is converted to DC as easily as 25 Hz is.  So Amtrak chose 60 Hz at high voltage and step it down and convert it to DC on the train to run DC motors.  

The reason Amtrak has not converted to 60 Hz and DC motors south of New Haven is because opponents in the Congress will not grant Amtrak the funds it needs to modernize.  

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Posted by erikem on Sunday, November 11, 2012 8:47 PM

Blue Streak,

Phase balancing is most definitely an issue with commercial frequency electrifications. A couple of things come to mind, the first having different sections of the track connected to different phases, and the second being that electrification loads would be a relatively small portion of the total utility load.

I would guess that power factor would be an issue as well, though switchable capacitors should be able to take care of reactive power problems. Most of the wiring diagrams for rectifier locomotives show use of a smoothing reactor (choke input filtering), so the line current will look more like square waves than the spiky current typical of capacitor input filtering. I wouldn't be surprised to see power factor correction applied to locomotives - note that this is to keep the line current a close approximation to a sine wave in phase with the voltage - might even be simplest using an IGBT H-bridge for for handling power transfer between the AC on the catenary and the DC bus on the locomotive.

It's getting uncomfortably close to 40 years since I took power systems, electrical machinery and power electronics courses at Cal and there have been a LOT of new devices that have come down the road since then (e.g. IGBT's, SiC diodes and SiC MOSFET's).

- Erik

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Posted by MidlandMike on Sunday, November 11, 2012 11:13 PM

John WR

...

But in the 1960's when Amtrak electrified the line between New Haven and Boston ...

I'm not sure if this was a typo, the line was converted in the late 1990s.  The following link has a review of early RR electrification supply systems, recent electric system conversions, and some thoughts for the future:

http://www.ltrc.lsu.edu/TRB_82/TRB2003-001318.pdf

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