i need help from an electrical engineer.

I am an electrical engineer, but was into electronics, not power. My best guess with no further information is that the three wires represent 3 phase power. The only thing I will add, and hope I don't add confusion, is that in three phase power, each phase is 120 dergrees from it neighbors.

To run the catenary, with only one wire above and the track as ground, you need single phase power, where the overhead wire is the hot wire, and the track is the return. There is a transformer named a Scott-T transformer that can take 3 phase power in and yield 2 phase power. 2 phase power is what comes to your house (220v). Also like your house, the 2 phase can have a center tap, which is the return. This allows you to have 110v with respect to the return, and 180 degrees out of phase, another 110v with respect to return.

Again, guessing, one pair of your 8 wires could be 110v & return, the second pair a repeat of this, the third pair the 180 degree out of phase 110v & return, and the  fourth pair a repeat of this.

Again, please remember its just my guess. You know the old saying, a little bit of knowledge can be dangerous!

Could you provide a picture or perhaps coordinates of the substation in question?  I'm not a double-E, but I do have 25 years experience in high voltage electrical transmission.

You asked about 3 wires into a transformer becoming 8 wires out, which is why I would like to see the specific transformer.  On the system I work on, our distribution substations take transmission voltages into a delta-wye transformer.  Since the high voltage windings of the transformer (primary windings) are connected in a delta, there are only 3 wires needed - the 3 phases, connecting to the high voltage bushings on the transformer (H1, H2, & H3).  However, on the low voltage side of the transformer, the windings (secondary windings) are connected in a wye configuration, so there are four bushings (X0, X1, X2, & X3) and four wires out of the transformer - the 3 phases, plus a neutral wire.  However, in our substations, the neutral is usually bonded to the ground grid, so it usually doesn't come off the transformer like the phase wires do... but there isn't any reason it couldn't.  So, 3 wires in and 4 wires out make perfect sense on a distribution transformer, and it isn't a big leap for a transformer to have 8 wires.  Sometimes, bundled conductors are used on the low voltage side to handle the increased current.  Another possibility would be a transformer with more than two windings.  Our large transmission transformers typically have a 3rd winding (tertiary, or "tersh" in our slang) that is a delta winding.  It has 3 bushings, but one is typically grounded and one of the other bushings connected to a small station power transformer.

It may seem odd to use a delta configuration on the high voltage side and a wye configuration on the low voltage side, but it is important that it is connected in that manner.  The low voltage side needs to power both single phase and 3 phase load, and the wye configuration (with a neutral connection on each phase winding) is needed to supply single phase loads.  However, it is necessary to balance the loading on the phases for transmission level voltages, and the delta winding on the high side will redistribute phase imbalance current (ground current) among the 3 high voltage phases.  It also keeps ground faults on the low side from being detected by the high side protective relays.

Now, transmission level transformers are connected in a wye-wye configuration.  So, you will see 3 high voltage bushings, and 4 low voltage bushings... but one of the low voltage bushings is connected to the neutral of both the primary and secondary windings.  Therefore, you have the H1, H2, & H3 bushings on the high side, the X1, X2, & X3 bushings on the low side, plus the X0/H0 bushing.  Again, the X0/H0 bushing is typically bonded to the ground grid.

Also, there are "static" wires that are installed over the top of the lines and substations.  These wires may look like phases, but are at ground potential and aren't supported by insulators.  These are in place to provide lightening protection for the phase wires.  The can be confusing to look at from the air, as it may be hard to distinguish between the static wires and phase wires.

Hope that helps...

MED posted:

I am an electrical engineer, but was into electronics, not power. My best guess with no further information is that the three wires represent 3 phase power. The only thing I will add, and hope I don't add confusion, is that in three phase power, each phase is 120 dergrees from it neighbors.

To run the catenary, with only one wire above and the track as ground, you need single phase power, where the overhead wire is the hot wire, and the track is the return. There is a transformer named a Scott-T transformer that can take 3 phase power in and yield 2 phase power. 2 phase power is what comes to your house (220v). Also like your house, the 2 phase can have a center tap, which is the return. This allows you to have 110v with respect to the return, and 180 degrees out of phase, another 110v with respect to return.

Again, guessing, one pair of your 8 wires could be 110v & return, the second pair a repeat of this, the third pair the 180 degree out of phase 110v & return, and the  fourth pair a repeat of this.

Again, please remember its just my guess. You know the old saying, a little bit of knowledge can be dangerous!

I'm with you.  I have a little knowledge and enough to be really dangerous.  

thanks for help.  

prrtrainguy

WindupGuy posted:

Could you provide a picture or perhaps coordinates of the substation in question?  I'm not a double-E, but I do have 25 years experience in high voltage electrical transmission.

You asked about 3 wires into a transformer becoming 8 wires out, which is why I would like to see the specific transformer.  On the system I work on, our distribution substations take transmission voltages into a delta-wye transformer.  Since the high voltage windings of the transformer (primary windings) are connected in a delta, there are only 3 wires needed - the 3 phases, connecting to the high voltage bushings on the transformer (H1, H2, & H3).  However, on the low voltage side of the transformer, the windings (secondary windings) are connected in a wye configuration, so there are four bushings (X0, X1, X2, & X3) and four wires out of the transformer - the 3 phases, plus a neutral wire.  However, in our substations, the neutral is usually bonded to the ground grid, so it usually doesn't come off the transformer like the phase wires do... but there isn't any reason it couldn't.  So, 3 wires in and 4 wires out make perfect sense on a distribution transformer, and it isn't a big leap for a transformer to have 8 wires.  Sometimes, bundled conductors are used on the low voltage side to handle the increased current.  Another possibility would be a transformer with more than two windings.  Our large transmission transformers typically have a 3rd winding (tertiary, or "tersh" in our slang) that is a delta winding.  It has 3 bushings, but one is typically grounded and one of the other bushings connected to a small station power transformer.

It may seem odd to use a delta configuration on the high voltage side and a wye configuration on the low voltage side, but it is important that it is connected in that manner.  The low voltage side needs to power both single phase and 3 phase load, and the wye configuration (with a neutral connection on each phase winding) is needed to supply single phase loads.  However, it is necessary to balance the loading on the phases for transmission level voltages, and the delta winding on the high side will redistribute phase imbalance current (ground current) among the 3 high voltage phases.  It also keeps ground faults on the low side from being detected by the high side protective relays.

Now, transmission level transformers are connected in a wye-wye configuration.  So, you will see 3 high voltage bushings, and 4 low voltage bushings... but one of the low voltage bushings is connected to the neutral of both the primary and secondary windings.  Therefore, you have the H1, H2, & H3 bushings on the high side, the X1, X2, & X3 bushings on the low side, plus the X0/H0 bushing.  Again, the X0/H0 bushing is typically bonded to the ground grid.

Also, there are "static" wires that are installed over the top of the lines and substations.  These wires may look like phases, but are at ground potential and aren't supported by insulators.  These are in place to provide lightening protection for the phase wires.  The can be confusing to look at from the air, as it may be hard to distinguish between the static wires and phase wires.

Hope that helps...

the 8 wires I spoke of are high voltage wires from the high tension lines above the catenary.  there are usually 4 on each pole above the catenary.  sometimes more, many more and occasionally less.  

on the Princeton sub it almost looks like the are 8 wires coming in from each end and in between at least one or two are lost?

if you use google maps or better google earth and if you can find it google earth pro, you can easily find Morrisville sub just over the bridge from Trenton NJ (home town, looong ago) it is on west, northwest side of main line (PRR)  at junction of Trenton cutoff.  Princeton sub, just north about 10 miles at Princeton Junction also on maps.  

hope this help end some of the confusion.  

PRRtrainguy

Found this link on line that may help explain a lot.    The main grid the PRR put in was single phase 132kv 25 cycles while the catenary was stepped down to 11Kv 25 cycles.  There are  substations all over to drop to the 11kv. Not a EE either, but I suspect it is likely that on the transformer step down in voltage either bigger gage wire or more of the same size wire would be needed since, lower voltage dictates higher current and stepping down from 132kV to 11 kV would be a decent increase in amperage for the cables to carry.  I see a good bit of multiple cables to buss bars on gensets for this reason and this is what I suspect is going one with your 3 in and 8 out scenario.  That said, I'd be happy to learn what is going on there if it is different than I am speculating.

https://ipfs.io/ipfs/QmXoypizj...on_power_system.html

 PS, there is a ton of interesting info in this link btw  Lotso Juice used.

This should help you - link link clickety-click  See the photo of the Bryn Mawr sub-station built in 1915. A forum member had this modeled for his new layout.

Simply put - all of the wires going out to the catenary are reduced frequency - like model train track feeders - you need more for smooth operation

hi guys,

learned a lot and still have questions.  

all eight 132kv wires are all the same phase or are some multiphase or interchangeable?

where are circuit breakers and lightning arrestors?

was control manual or electrical or electronic?

is a bus bar a form of circuit breaker or am I totally wrong?

probably more but that's all I can think of at this time.

prrtrainguy

A bus bar is a form of a conductor!  Conductor is either wire (bare), cable (covered wire) or in Sub Station applications Bus Bar. Think of Bus Bar as super big wire. Bus Bar comes in flat/squarish shape or tubular shape. All conductor is either copper or aluminum. 

All electricity generated within the USA grids (there are 3 main grids ..Western west of the Rockies, Eastern ..east of the Rockies, and Texas. There are no interconnections between any of these 3 main USA grids) and Canadian grids is 60 cycle. ( The Eastern USA grid and the Canadian grid are interconnected) . All base 60. Modern  Generators usually turn at 3600RPM. Note the previous answers that the catenary power was/is in 25 cycles.That means the electricity was generated in that frequency (cycle) or was stepped down via a transformer from 60 cycle to 25 cycle. Many of the original trolley systems in the USA had their own generators probably at this 25 or so cycle type of power.

Transformers either step up voltage or step down voltage. 

PRRTrainguy posted:

 

hi guys,

learned a lot and still have questions.  

all eight 132kv wires are all the same phase or are some multiphase or interchangeable?

where are circuit breakers and lightning arrestors?

was control manual or electrical or electronic?

is a bus bar a form of circuit breaker or am I totally wrong?

probably more but that's all I can think of at this time.

prrtrainguy

 

 

The link that Dennis posted is very interesting.  Single phase electrical transmission and distribution has both similarities and significant differences to the polyphase electrical transmission that I work with.  

You asked, "All eight 132kv wires are all the same phase or are some multiphase or interchangeable?"  The page that Dennis linked states this: "All transmission lines within the 25 HZ system are two-wire, single-phase, 138 KV.  The center tap of each 138 KV/12 KV transformer is connected to ground, thus the two transmission lines are tied to +/- 69 KV with respect to ground and 138 KV relative to each other." 

So, the two wires of each circuit are 180 degrees out of phase with each other and not interchangeable. 

Presumably, if there are eight 138 KV wires, then that would consist of four circuits.  Even though four of those wires are one phase and the other four are 180 degrees opposite, that doesn't mean that any of the wires of the same phase should be interchanged or swapped at random.  I would need to see the one-line diagram to know how they have it arranged, but it is likely they have them arranged in dedicated pairs for maintenance, fault detection, and isolation... similar to the way the two hot wires on a 240 volt circuit in a house both go to the same circuit breaker, NOT one hot wire to one 240 volt breaker and the other hot wire to another 240 volt breaker.

You also asked, "Was control manual or electrical or electronic?"  The mechanism of the high voltage circuit breakers are usually operated by DC trip and close coils. On our system, those coils are operated on either 48 or 130 volt DC battery banks that are kept charged by battery chargers, but I don't know what voltage they use on the railroad's system.  Those coils are operated either by protective relays that are there to detect faults on the high voltage lines, or by remote control by a system operator if needed.  Local controls are also available on-site, and the mechanisms can also be operated manually at the breaker in the substation yard... sometimes the breaker manufacturer has dedicated mechanical open and close controls on the mechanism, other times a well-placed screwdriver can accomplish the same task.  Again, I'll stress that the system you are looking at has some significant differences from the equipment that I am familiar with, so I don't know exactly how their protection and control schemes work without seeing schematics - and in this day and age, those schematics won't be available for viewing by the general public.

Very interesting subject!

WindupGuy posted:

PRRTrainguy posted:

 

hi guys,

learned a lot and still have questions.  

all eight 132kv wires are all the same phase or are some multiphase or interchangeable?

where are circuit breakers and lightning arrestors?

was control manual or electrical or electronic?

is a bus bar a form of circuit breaker or am I totally wrong?

probably more but that's all I can think of at this time.

prrtrainguy

 

 

The link that Dennis posted is very interesting.  Single phase electrical transmission and distribution has both similarities and significant differences to the polyphase electrical transmission that I work with.  

You asked, "All eight 132kv wires are all the same phase or are some multiphase or interchangeable?"  The page that Dennis linked states this: "All transmission lines within the 25 HZ system are two-wire, single-phase, 138 KV.  The center tap of each 138 KV/12 KV transformer is connected to ground, thus the two transmission lines are tied to +/- 69 KV with respect to ground and 138 KV relative to each other." 

So, the two wires of each circuit are 180 degrees out of phase with each other and not interchangeable. 

Presumably, if there are eight 138 KV wires, then that would consist of four circuits.  Even though four of those wires are one phase and the other four are 180 degrees opposite, that doesn't mean that any of the wires of the same phase should be interchanged or swapped at random.  I would need to see the one-line diagram to know how they have it arranged, but it is likely they have them arranged in dedicated pairs for maintenance, fault detection, and isolation... similar to the way the two hot wires on a 240 volt circuit in a house both go to the same circuit breaker, NOT one hot wire to one 240 volt breaker and the other hot wire to another 240 volt breaker.

You also asked, "Was control manual or electrical or electronic?"  The mechanism of the high voltage circuit breakers are usually operated by DC trip and close coils. On our system, those coils are operated on either 48 or 130 volt DC battery banks that are kept charged by battery chargers, but I don't know what voltage they use on the railroad's system.  Those coils are operated either by protective relays that are there to detect faults on the high voltage lines, or by remote control by a system operator if needed.  Local controls are also available on-site, and the mechanisms can also be operated manually at the breaker in the substation yard... sometimes the breaker manufacturer has dedicated mechanical open and close controls on the mechanism, other times a well-placed screwdriver can accomplish the same task.  Again, I'll stress that the system you are looking at has some significant differences from the equipment that I am familiar with, so I don't know exactly how their protection and control schemes work without seeing schematics - and in this day and age, those schematics won't be available for viewing by the general public.

Very interesting subject!

 

thank you very much. it is a very complex and interesting subject.

your explanation was very informative for someone like me who doesn't but probably should read 132kv for dummies.  I really did learn a lot. 

my only question for now  is where are the breakers in subs? I have gone over Morris and Princeton jct. and the only thing I see that I cannot identify are multiple cream colored cannisters whose function I do not know and am a lousy guesser.

as an addendum if you have never used google earth or google earth pro, you have no idea what you are missing.  

thanks to all the replies it is and was enlightening experience.

Prrtrainguy

I've searched for high resolution pictures of 25 hz, single phase Amtrak substations... and not surprisingly, there is very little out there.  The images from Google and Google Earth Pro aren't clear enough to make out a lot of detail, at least for my purposes.  As a side note, this doesn't surprise me... in these times, details and pictures of critical infrastructure (such as substations) are usually only available on a need-to-know basis.  Anyway, I did take a screenshot of the Morrisville substation and this is my best guess as to the major devices in the yard - and again, I'll stress that this is my best guess, as the resolution and lack of blueprints make it impossible to be certain, and the single-phase system has significant differences from the three-phase system I am familiar with.

As best I can tell, the high voltage lines come in on the structures toward the top of the picture.  I believe the device circled in red is a step-down transformer that reduces the 138kv down to 12kv.  It looks like there are long bushings on the high voltage side, which is what I am basing this opinion on.  It looks like there are four transformers in the substation.  The device circled in yellow appears to be a 12kv breaker for the transformer next to it.  That takes us to the device circled in green, which I suspect is a feeder breaker.  Now, without seeing the one-line, I don't know how the feeds from the transformers are connected with the feeder breakers - are they all in parallel feeding one big bus, or does each transformer just feed the individual groups of feeder breakers?  Don't know.  And please, remember this isn't written in stone - I'm going off very limited information.  It is certainly possible that I might be mistaken on these items.

You asked about lightening arrestors - it would be very difficult to pinpoint them on this picture.  The ones we use basically look like insulators to the untrained eye; there are some subtle differences between a plain insulator and a lightening arrester in their appearance and how they are mounted/connected.  There would almost certainly be some instrument transformers in the substation as well - potential transformers to measure voltage, and current transformers to measure amperage.  It is common to have current transformers built in to breakers and transformers so external CT's aren't required.

It is interesting that utilities have their own preferences and philosophies when it comes to substations.  Much like railroads, different companies use different types of equipment, design, and configurations to accomplish the same basic task.  This makes it impossible to make a blanket statement about a substation always being designed in a certain way... much like steam locomotives, there are a lot of different designs out there.  

hi windup guy

I suspect you are right about the transformers.  they probably predate amtrack and 25kw catenary.  they are the only ones still on rails which was prrstandard so they could be easily moved and replaced  they are on rails at right angles to tracks.  I could find no other sub with these transformers on rails.  I presume the others are more modern, but this is speculation on my part.  

the 12kw breakers are also one for each transformer.   yellow.

green feed breaker to protect each separate feed line.  

I understand most of what you are saying and it makes sense to me.  

appreciate your input and all the others who have spoke to my electrical inadequacy.

great education for me and anyone else following the topic.  

I did not realize you could copy google earth etc and copy into topic. very interesting.

prrtrainguy

Why did different electrified railroads use different voltages, etc?

Steve

RideTheRails posted:

Why did different electrified railroads use different voltages, etc?

Steve

hi Steve,

I don't know most of the answers, but prr &NH used 11000 volts ac overhead.  nyc used660 volts dc via 3rd rail, good for short hauls but not for long hauls. Milwaukee if my memory serves me 3000 volts ac catenary.  Illinois central css&sb overhead but voltage unknown.  the only reason outside of ne was local access to power and all were isolated so no reason to standardize.  

hope this helps.

prrtrainguy

When selecting the high voltage, several things come to mind. One of the biggest, IMHO, is how much energy you need to transmit down the wires, and how far. The higher the voltage, the less current needs to go down the wire. As a trivial example, if you need to transmit 100watts, and you choose 1 volt, you then have to send 100 amps. But if you choose 1000 volts, you only have to send 0.1 amps. Loss in wire is predominantly resistance, so the less current being carried, the lower the loss.

This is mainly why Edison's DC lost, and Tesla's AC won.

Considering the range of responses I think you could model your power sub station any way you want and please most of the model RRers.  

I try to ask myself "How much of the rest of my life do I want to spend on perfection?"  Sometimes I lost a lot of layout production time when majoring on what was essentially nuances, scenery or style in the overall scope of things. 

Having contracted for the disassembly of many layouts over the years, I keep in mind most of what I am doing is headed for the dumpster.

I concentrate on getting as much of the RR functioning as possible so my goal is enjoyment of a running it.

Tom Tee posted:

Considering the range of responses I think you could model your power sub station any way you want and please most of the model RRers.  

I try to ask myself "How much of the rest of my life do I want to spend on perfection?"  Sometimes I lost a lot of layout production time when majoring on what was essentially nuances, scenery or style in the overall scope of things. 

Having contracted for the disassembly of many layouts over the years, I keep in mind most of what I am doing is headed for the dumpster.

I concentrate on getting as much of the RR functioning as possible so my goal is enjoyment of a running it.

Tom, to a great extent I agree. 

but I also am using this as a learning experience for me.  the amount of knowledge I previously had about what actually goes on in an electric sub station was minimal.  I now feel more knowledgeable about substations.  anyhow the next episode is figuring out how to apply.  I know  electrical parts are minimal to nonexistent in o gauge'  insulators, I cleaned out ed duddy.  transformers, circuit breakers, and other high voltage equipment have no idea, possibly walthers and fake it?  since the breakers are all in shinny boxes just use sheet plastic and model?  transformers? have vague ideas but... 

another member of forum has promised me a plan and price.  I will do nothing until I hear from him one way or another.  

actually it has been a great learning experience for me.

prrtrainguy