Married pair of M-8s being tested on Amtrak east of New Haven. Note yard switcher being pulled by M-8s. That is probably due to verifying that the M-8s have no problem transitioning from 12.5Kv to 25 Kv in case they should fail ?.
https://www.youtube.com/watch?v=oJCdin6_nTE
Were those M-8's modified to handle 25 kV, or do they come that way?
MidlandMike Were those M-8's modified to handle 25 kV, or do they come that way?
Note that this does not mean that they can also operate on 25 Hz from Sunnyside into Penn Station. Larger transformers would be required. But eventually that will aslo be 60Hz.
Shore Line East is eventually to be mu electric, replacing diesel operation.
The M-8's were build to run both on 12.5 Kv 60 hz or 25 Kv 60hz, the yard switcher was not being pulled by M-8 but was shoving the M-8 past the voltage change near Mill River, once under 25Kv the pantograph was raised and some testing performed. running M-8's in service is a long way off, as ACSES testing etc still has to be done plus doing voltage change on the fly with multiple cars. the single pair in video is assigned to Amtrak for while for testing.
Any one know if this first time for any M-8 to operate under 25 Kv? Imagine MNRR will want to know results as well. That will be for M-8s running to Springfield when that line gets 25 Kv CAT. Is the voltage change location in New Haven on level track ? That would enable lead EMU to pull rest of train thru voltage change.
The Amtrak Hell Gate line was converted some time back from 25 Hz to 12.5 Kv 60 Hz from Gate CP ( near Sunnyside ) to New Rochelle for several reasons.
1. CAT needed rebuilding ( constant tension ? )
2. 60 Hz to 25 Hz transition moved away from New Rochelle preventing any chance of a stall fouling that intersection.
3. With the new ACS-64s coming on property the possibility of 4 ACS-64s and a couple of Acela trains all on that segment might have severly overtaxed the 25 Hz Sunnyside frequency converter substation.
4. In reference to #3 gave Sunnyside yard and NYP a more reliable and less demand 25 Hz system. As well Sunnyside could power North river tunnels and beyond in a pinch. However we are aware of the problems with the CAT feeders in the North tunnels. Have not heard of problems in East Rivier tunnels.
The transformer situation of M-8s on 25 Hz has not had any solution disclosed. 25 Hz transformer would be much larger and heavier but completely useable on 60 Hz. Probably would have a center tap transformer for 25 Kv. Some where it was posted that the power drain on the present 60 Hz transformer could be limited when on 25 Hz. A problem that might occurr is if train is stopped at bottom of East river tunnel and has to climb out. That might be a big problem if Amtrak's 12 Kv 25 Hz line voltage decreases to the lower limit of 10.2 Kv (?). It does happen.
Would imagine that before a M-8 train left New Haven that the under running 3rd rail shoe is verified retracted.
Question arises why not convert Sunnyside = Newark Penn to 60 Hz. Money and time. The old PRR electrical equipment has many components not 60 Hz capable. As well Amtrak in its early years did not buy dual frequency equipment. Now all new equipment is dual frequency capable but have no idea when that started. As well there may be items in the present North river tunnels that cannot be replaced until the major closings for rebuilding after Gateway bores are in service. Would look to 2030 - 2035 for even any attempt to change frequency. 12.5 Kv will be final voltage as higher not possible due to clearances in the present NYP and tunnel bores.
yes it was first time for M-8 to be powered by 25kv.
the 25 Hz transpormer has been discussed ad nausuem and is way to heavy plus if used to NYP they be powered by LIRR third rail, not catenary.
One pair could not pull train trough phase or power gap as power switchover and pantographs are not able to be controlled by engineer on individual pairs.
no the third rail shoes do not retract, they have fixed possistion. with a sping controlling tension on LIRR or MN third rail.
DutchrailnutThe 25 Hz transformer has been discussed ad nauseam and is way too heavy ...
For once, and hopefully for all, THERE IS NO PROBLEM WITH A MODERN 60Hz TRANSFORMER RUNNING ON 25Hz POWER. The problem is the 'other way'; an older transformer built for 25Hz power (like the ones in GG1s) can't handle the higher frequency. But there aren't any M-8s with that problem, are there?
... plus if used to NYP they be powered by LIRR third rail, not catenary.
Why in God's name would an M-8 coming from 'east of Stamford' need to switch over to DC third rail at any point coming into NYP? SURELY it is simpler and easier to switch AC power keeping the pans up?
I have a technical question, which perhaps has been answered and I haven't seen it or read it properly. "Springs" won't be enough to assure correct switching from overrunning to underrunning contact on third-rail shoes. There would have to be something else, and I don't think that 'something' would be a mandated by-hand switchover of every shoe on every train before a train goes from one 'system' to another. So isn't there aome other system, perhaps air-operated, that switches the shoe on a car from overrunning position to underrunning, with the spring then providing the necessary action in the 'correct' direction thereafter?
New Haven's FL9's were initially fitted with air-operated shoes that could be set either way or folded up. In later years they were set one way or another until replaced by fixed shoes in the 1970s. Amtrak operated Turbos, FL9s and P32s were supposed to work either way, but dual capability was dropped completely after 1991. Today's P32s are required to operate with shoes folded in MNRR territory.
Wizlish For once, and hopefully for all, THERE IS NO PROBLEM WITH A MODERN 60Hz TRANSFORMER RUNNING ON 25Hz POWER. The problem is the 'other way'; an older transformer built for 25Hz power (like the ones in GG1s) can't handle the higher frequency. But there aren't any M-8s with that problem, are there?
While a student at MIT, and I have both SB and SM degress in EE, I designed transformers of all types at Mystic Transformers, while also an unpaid employee of Boston and Maine Transportation while working on my SB thesis on Diesel Locomotive Load Regulator Controls, solving my Cambridge - Winchester transportation problem. rather neatly. A transformer at 50 or 60 Hz can be smaller than one for 25 Hz, because during each half cycle, flux build-up in the magnetic structure is half or less. You can use a 60-Hz transformer at 25 Hz, but only at one-half the current, meaning one-quarter the total power. The other way around is also a problem, and in that you are correct. A normal 25 Hz transformer will be much larger than the equivalent 60 Hz transformer, and capacitive coupling short-circuiting between coils and hysterises magentic losses will start to reduce effiency, the power lost will create heat, and the danger of insulation burning or charring with the best of materials is possible. Multi-frequency transformers are possible. Indeed classic tube-type audio power amplifiers have wonderful examples, with reasonable efficiency, say 75-90%. over the hearing range 20-15,000Hz, typical. But the iron is far more expensive (Alnico or better), and often a tiny air-gap is introduced to linearize the response while sacrificing a bit of efficiency. (Think the famouse Williamson Amplifier transformer, and its interpretation in a Heathhkit.) An efficient dual-frequency power transformer that works well at both 60Hz and 25Hz can be designed using regular iron, and indeed Amtrak's electric locomotive fleet and Acela trains would not work without them, but they are much larger and more expensive than regular 60Hz transformers.
I was unaware that the new M-8 has a shoe similar to the original EMD-FL9 dual-sprung third rail shoes, that with good shoe and rail maintenance, can work well on both overrunning LIRR and underruning MN third rail. I thought they still had the standard MN shoe which works only on underruning third rail. But I understand there is still a section of 25Hz bertween LIRR third rail and the start of 60Hz on Amtrak. Possibly LIRR third rail can be extended over this short section, and a mile further to provide some necesary overlap with the 60Hz catenary.
Although my memory may be incorrect, what I remember from frequent contact witih FL-9's while at MIT and at BBN, (1949-1954) 1956-1967, is that the orginal FL-9 shoe was double-spring, with the horizontal rest position both lower that the top of the overruning LIRR (and NYCTA and PATH) third rail and also higher than the bottom of the MN underruning third rail. This was different than certain NYNH&H electrics, including EP-5 GE`rectifier "Jets," which did have air-operated cam adjustable third rail shoes. Possibly someone has access to drawings?
But then, at least most, if not all, the NH electrics with adjustable shoes by power, simply retracted them, not using the LIRR 3rd rail. Indeed, I have learned from these forums that before the Trenton - Sunnnyside electrification, New Haven Electrics would be exchanged for DD-1's at Harold, and these of course would run through to Manhattan Transfer.
In general, the FL-9s were used to Penn only when a Jet was not available. After the great EF-3's had been sidelined and Van Ness closed and the freight dieselized until the advent of the Ex-Virginia EF-4's.
A power transformer that operates at both 60 and 25 Hz would be designed with the same size and number of coils as a pure 25 Hz. But it would have twice the number of iron laminations, each half the width, approximately,,with superthin insiulation between laminations, and it would have a segmented coils rather than straight coils. It would perorm even better, marginially, at 25 Hz than the lower-cost regular 25 Hz transformer, and it would be efficient at 60Hz. In any power transformer, more expensive and better iron, and the use of expensive square wire instead of round wire are measures to reduce size and weight.
Dave, I had not known of flat wire, but after seeing your reference to it I understand how it reduces the size. I think of how difficult it is to lay an ordinary cord flat when winding it on a reel.
Johnny
Dave thanks for the transformer primer.
A very memorial moment in college was when a electrical engineering professor said to our class that electrical engineering was a mature profession and to only expect minor improvements.
So now we have much more efficient transformers, IGBTs, variable frequency AC motors, fiber optics, solid state electronics, all the information now on just plain telephone wires, etc. Allways laugh at those who make never or always statements especially pols.
daveklepperWhile a student at MIT, and I have both SB and SM degress in EE,
Dave, Did you mean BS and MS as in Bachelor of Science and Master of Science or did MIT have dislexia?
daveklepperBut I understand there is still a section of 25Hz bertween LIRR third rail and the start of 60Hz on Amtrak. Possibly LIRR third rail can be extended over this short section, and a mile further to provide some necesary overlap with the 60Hz catenary.
You have me confused here. I presume youmean the catenary AC voltage & frequency and not the third rail which is DC. I think the Hell Gate Cat is still 25 Hz as is Sunnyside's .
An earlier poster noted that the Hell Gate tracks owned by Amtrak have been converted to 60 HZ, and I assumed that was correct. But there is still some LIRR track not converted and without third rail between the end of Amtrak ownership and the LIRR third rail. I am unsure whether the Hell GAte and Bronx Amtack tracks are 12,500 or 25,000 volts, but I think the former.
I am the one with Dislexia, not MIT. The degrees are correct as you state.
Thank you both.
Mr. Klepper,what is that about "alnico" in audio transformer iron? I am only familiar with that alloy in permanent magnets which I would NOT think good for limiting hysteresis at AF! So I am missing something again. Do you mean "Armco iron" or something like mu metal?
(I found a historical review reference on transformer iron here (PDF download) for those who may be interested...
blue streak 1A very memorial moment in college was when a electrical engineering professor said to our class that electrical engineering was a mature profession and to only expect minor improvements.
There's a famous similar comment about physics, around the time "Hertzian waves" were recognized. Just more decimal-place improvements... there do seem to have been some changes since then.
With respect to 'never or always', I think Gilbert and Sullivan had the best observation...
Dave: Below is link to Amtak's 25 Hz system that has a graphic showing the 12.5 Kv 60 Hz of Hell Gate. New Rochelle to Hell gate now is same voltage and freq the trains only pass thru a phase break.
25 Hz begins at Gate CP which is just south of Sunnyside junction ( freight line to LIRR ) but before Harold intersection. Your spectulation is probably correct of no 3rd rail Gate - Harold. Adding 3rd rail would require changing signal system to different frequency see article.
Article does have a few errors. PRR raised 25 HZ CAT from 11Kv to 11.5 KV in 1948. Amtrak then further raised voltage to 12 Kv at some later date unknown. These raises were accomplished by simply raising the High voltage feeds. CAT Transformers did not require changing only changing Safe Harbor, rotary converters, and solid state converters to higher outputs. Since the raises were within normal voltage ( see article ) +/- not a real problem.
https://en.wikipedia.org/wiki/Amtrak%27s_25_Hz_traction_power_system
The third rail is there only for the LIRR trains, and as far as I know, the only "foreign" power that ever used it were the Hew Haven FL-9s. If I remember, the eastbound flyover is used by both Port Washington LIRR trains and NEC trains, and has third rail. Just east of that flyover is the switch taking NEC trains off the LIRR, and the 25Hz cat continiues until the track is off LIRR property, where the break to 60Hz occurs. Westbound is similar, but without a flyover. So, to get 60Hz-only M8s into Penn, about 1-1/2 miles of double-trackthird rail would be required. Note the thru NH-NJT thru service for Meadowlands events used NJT locomotive-push-pull trains. NJT locomotives, like Amtrak's, can swith from 25 to 60 Hz and back at speed.
Again the M-8 can not handle 25 hz, to go to nyp it will run on LIRR third rail, the pantograph can not be raised if any of 8 shoes on a pair touches third rail, all Lincoln, nebr M-8's except for first cars made in Japan have new dual purpose third rail mechanisms.
There is something about the 25Kv system not mentioned. The feeders on the Amtrak New Haven - BOS system uses the same system as your house. Your house has 110 V / 220 V system where it is 2 - 110 V to ground and 220 V feed to feed. Amtrak and probably NJT uses two feeders that are 25 Kv to ground and 50 Kv feeder to feeder. Remember doubling voltage increases power capability 4 times. V sq / Resistance.
Just as an aside if you put an voltmeter on your house wire you will find the indicated voltage higher. NEC standards have gradually increase allowable voltage from the pre WW-2 110 V to ~130 V although still referred to as 110 V. For those of you that have electric motors check their plates. Have a pre war listed as 110 V and motor bought last year stating 110 - 130 V / 220 - 260 V My line voltage here is reading 127 V.
Note Amtrak HEP is listed as 480 V - 3 phase. so dividing twice give 120 V.
Back to Amtrak. An auto transformer is connected to lineside feeder to feeder and then has a center tap to ground and outside taps giving 25 Kv to the CAT.
The feeders get their power from the commercial grid by way of an auto transformer connected to 2 phases of the grid. There is a balancing circuit to the 3rd phase.
How MNRR does it is unknown . It may be 12.5 / grd / 12.5 giving 25 Kv feeders . Have read that New Haven RR used straight 11Kv 25 Hz but have no confirming information. If so that may have been the reason NYG - New Haven had so many power problems. The rebuilding of Hell gate line probably is the 12.5 - grd - 12.5 60 Hz feeders.
The Amtrak 25 Hz system is similar as each high voltage feeder is 69 Kv with feeder to feeder 138 Kv.
Amtrak HEP is the industry-standard utility 277/480 "Y" configuration. This allows the use of 480V 3 phase motors (for A/C) and 277v single phase fluorescent bulbs, as well as easy setup of shore power in servicing areas. A standard transformer set makes 120v available for things like laptop chargers and vacuum cleaners, in a 120/208v "Y".
What Daveklepper is describing is a high voltage "Delta" configuration with a center tap on one phase for an intermediate voltage. In a low voltage (120/240) commercial setup a large center-tap 120/240 transformer will be accompanied by a smaller 240v transformer on a second leg of the delta. No actual transformer is required for the third leg, where a "shadow" 240v phase is formed.
blue streak 1 NEC standards have gradually increase allowable voltage from the pre WW-2 110 V to ~130 V although still referred to as 110 V. For those of you that have electric motors check their plates. Have a pre war listed as 110 V and motor bought last year stating 110 - 130 V / 220 - 260 V My line voltage here is reading 127 V.
Where I worked, the substation transformer voltage regulators were set to provide 127 V leaving the sub, this allowed the first customer to be within the voltage limits and with additional switched capacitors on the line to maintain a voltage to the meters at 113 V or above to meet the 120 V ± 7 volts service requirements. At least that was the plan.
Blue Streak, do you know how close you are to your utility's feeder source? The 127 V looks like you are close to it or perhaps they have a regulator near you.
daveklepper While a student at MIT, and I have both SB and SM degress in EE, I designed transformers of all types at Mystic Transformers, while also an unpaid employee of Boston and Maine Transportation while working on my SB thesis on Diesel Locomotive Load Regulator Controls, solving my Cambridge - Winchester transportation problem. rather neatly. A transformer at 50 or 60 Hz can be smaller than one for 25 Hz, because during each half cycle, flux build-up in the magnetic structure is half or less. You can use a 60-Hz transformer at 25 Hz, but only at one-half the current, meaning one-quarter the total power. The other way around is also a problem, and in that you are correct. A normal 25 Hz transformer will be much larger than the equivalent 60 Hz transformer, and capacitive coupling short-circuiting between coils and hysterises magentic losses will start to reduce effiency, the power lost will create heat, and the danger of insulation burning or charring with the best of materials is possible. Multi-frequency transformers are possible. Indeed classic tube-type audio power amplifiers have wonderful examples, with reasonable efficiency, say 75-90%. over the hearing range 20-15,000Hz, typical. But the iron is far more expensive (Alnico or better), and often a tiny air-gap is introduced to linearize the response while sacrificing a bit of efficiency. (Think the famouse Williamson Amplifier transformer, and its interpretation in a Heathhkit.) An efficient dual-frequency power transformer that works well at both 60Hz and 25Hz can be designed using regular iron, and indeed Amtrak's electric locomotive fleet and Acela trains would not work without them, but they are much larger and more expensive than regular 60Hz transformers.
A transformer with a 25KV/60Hz primary should just about work at 11KV/25Hz, the required Phi_max (flux) is about the same provided that the number of primary turns stays the same (the unit for Phi (Flux) is the Weber, not to be confused with B, which is flux density measured in Tesla (Webers/sq meter)). Available flux is limited by the saturation flux density in steel and may be limited by core loss). The bad news is that the secondary windings would have have the change-over taps to maintain the same output voltage. The increase in copper losses would only be partially offset by reduction in core losses.
The rule of thumb for power transformers is that the copper loss should equal the core loss. Since this relationship varies with frequency, a multiple frequency transformer will end up being a compromise. Compromise is sort of relative here, it may mean 98% efficient versus 99% efficient and heavier than something designed solely for operating at the highest frequency.
- Erik
P.S. The cgs unit for flux is the Maxwell, also known as a "line" of force. The cgs flux density is the Gauss, equal to one Maxwell per sq cm. Engineering flux density was lines per sq inch.
P.P.S. I'm currently working on a unique transformer, hence the familiarity with transformer design rules - had thoughts about Dave when working on it over the last year.
If you are clever in handling the design and balancing the losses, you should not need to change taps when changing between the two frequencies, only when changing input voltage. In the case of 25Hz, the resistive losses would be highter, and in the case of 60Hz the core losses would be higher, but the total losses would be equal at the two frequencies. Otherwise, your analyis is correct.
You and I are in agreement on not needing to change turns ratio if the primary voltage remains the same. My point was that for a constant maximum flux density, a transformer would need the same number of primary turns when running 10KV/25Hz and 24KV/60Hz - which is darn close to 11KV/25Hz & 25KV/60Hz.
I did have to edit my prevous posting to reflect constant Phi_max, not constant dPhi/dt (the latter gives constant voltage).
It would be interesting to compare the weight of say NJT or Septa's 25/60 Hz EMU transformers to the M-8's 60 Hz only transformers.
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