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#1 2019-07-27 21:44:53

Jonathan Masur
Member
Registered: 2016-04-23
Posts: 98

Why are frequency= and voltage= a tag of OSM ?

Dear OSM fellow contributors,

In my understanding, OSM is supposed to collect data about the physical world, not the electrical world. In an overhead-line, or in a high-voltage power line, the frequency of the current is not part of the infrastructure. We could connect the conductors to a power source of any frequency, and it'll work (*). Nevertheless, there's a frequency tag in OSM.

Voltage and current are more tricky. They are not themselves part of the infrastructure, even though it is true a fixed voltage and variable current is often used. For example when the simply shut off a power line for maintenance, the voltage=0 and as such the data in OSM becomes "wrong" even though the infrastructure hasn't changed !

The infrastructure allows for a maximum voltage and maximum current. If the maximum voltage is exceed, it will become dangerous and electrical arcs could appear. If maximum current is exceeded, the conductors could overheat. So maximum voltage and maximum current are part of the infrastructure (mappable of OSM), but voltage and current are electrical properties that can vary and should not be mappable on OSM.

Some high-voltages lines where I live use a mixing of different voltages frequencies. For instance this one. Some conductors in the line are used to power trains (16.67 Hz) and some to power civilians (50 Hz). As such the taging is confusing. Even the "maximum" voltage, which is part of the infrastructure, would be different depending on the conductors.

I'm sorry if it sounds like I'm complaining about tiny details.

(*) Ok this is false, a too high frequency will very quickly create RF emissions and related problems, but my point is that the wires doesn't by themselves a frequency - yet a frequency is tagged on OSM.

Last edited by Jonathan Masur (2019-07-27 21:49:07)

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#2 2019-07-27 21:49:05

wambacher
Member
From: Schlangenbad/Wambach, Germany
Registered: 2009-12-16
Posts: 16,227
Website

Re: Why are frequency= and voltage= a tag of OSM ?

Jonathan Masur wrote:

I'm sorry if it sounds like I'm complaining about tiny details.

Yes, we do tag frequency and voltage:

see https://wiki.openstreetmap.org/wiki/Power_lines

Regards
walter

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#3 2019-07-27 21:52:18

Jonathan Masur
Member
Registered: 2016-04-23
Posts: 98

Re: Why are frequency= and voltage= a tag of OSM ?

I know but that wasn't my point. My point is that frequency and voltages are not observable on the ground, and as such, should not be part of OSM database according to OSM "on the ground" philosophy. Or you could just answer me that it's an exception and that I'm a moron - and I already know that.

Last edited by Jonathan Masur (2019-07-31 19:36:45)

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#4 2019-07-27 21:55:30

Colin Smale
Member
From: Maarssen, NL
Registered: 2010-08-25
Posts: 185

Re: Why are frequency= and voltage= a tag of OSM ?

Jonathan Masur wrote:

Dear OSM fellow contributors,

In my understanding, OSM is supposed to collect data about the physical world, not the electrical world. In an overhead-line, or in a high-voltage power line, the frequency of the current is not part of the infrastructure. We could connect the conductors to a power source of any frequency, and it'll work.

Voltage and current are more tricky. They are not themselves part of the infrastructure, even though it is true a fixed voltage and variable current is often used. For example when the simply shut off a power line for maintenance, the voltage=0 and as such the data in OSM becomes "wrong" even though the infrastructure hasn't changed !

The infrastructure allows for a maximum voltage and maximum current. If the maximum voltage is exceed, it will become dangerous and electrical arcs could appear. If maximum current is exceeded, the conductors could overheat. So maximum voltage and maximum current are part of the infrastructure (mappable of OSM), but voltage and current are electrical properties that can vary and should not be mappable on OSM.

Some high-voltages lines where I live use a mixing of different voltages frequencies. For instance this one. Some conductors in the line are used to power trains (16.67 Hz) and some to power civilians (50 Hz). As such the taging is confusing. Even the "maximum" voltage, which is part of the infrastructure, would be different depending on the conductors.

I'm sorry if it sounds like I'm complaining about tiny details.

In practice though a given power line (or other component) will be used to carry a fixed nominal voltage and frequency, with the current varying according to demand. Just like maxspeed on roads will vary according to the conditions (traffic, roadworks, weather etc).

The example you quote, is what it is. Actually it would be two sets of wires, sharing pylons I guess, and never connecting in any way. How would you suggest mapping this otherwise?

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#5 2019-07-28 09:30:49

Jonathan Masur
Member
Registered: 2016-04-23
Posts: 98

Re: Why are frequency= and voltage= a tag of OSM ?

Colin Smale wrote:

In practice though a given power line (or other component) will be used to carry a fixed nominal voltage and frequency, with the current varying according to demand. Just like maxspeed on roads will vary according to the conditions (traffic, roadworks, weather etc).

Maxspeed is very observable from the field, also it is tagged "maxspeed=" and not "speed=" which is correct. OSM seems to be mapping "voltage=" for what is either maximum or nominal voltage, but it's definitely not always what you'd measure if you had a giant voltmeter and measured the voltage here. Doing so is similar to if a road would be tagged "speed=" instead of "maxspeed=".

The example you quote, is what it is. Actually it would be two sets of wires, sharing pylons I guess, and never connecting in any way. How would you suggest mapping this otherwise?

It was just an example of shortcomings. The wires just carry current from point A to point B and don't have intrinsic voltages nor frequency. They could decide to modify the connexions at substations and uses wires used for trains for civilians or the other way arround, and the frequency would change, but the infrastructure would be the same. Similairly, for whatever reason they could decide to change the voltage anytime, including to shut off the line (that is, voltage=0).

Similarly, the overhead catenary of a train line could change voltage or frequency to accommodate for a different rolling material - but the infrastructure would stay the same.

If I had to suggest something, voltage= and frequency= tags should be used on substations only, not on power lines themselves which does not have any intrinsic voltage or frequency.

Last edited by Jonathan Masur (2019-07-28 09:34:45)

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#6 2019-07-28 15:09:55

goedegazelle
Member
Registered: 2017-07-19
Posts: 374

Re: Why are frequency= and voltage= a tag of OSM ?

Jonathan Masur wrote:

My point is that frequency and voltages are not observable on the ground, and as such, should not be part of OSM database according to OSM "on the ground" philosophy.

That will not become easier when maximum values are demanded.

Although the idea is in itself not strange you're actually asking people to remove all frequency and voltage tags because nobody knows their maximum values.

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#7 2019-07-28 16:38:02

OverThere
Member
Registered: 2017-02-28
Posts: 74

Re: Why are frequency= and voltage= a tag of OSM ?

1. Occasionally, power lines are not powered for one reason or another for periods of time.  Should the lines' tags be changed to frequency=undefined and voltage=0 during those periods. I, for one, would neither expect nor desire that such changes be made.

2. The presence of power, frequency of alternating current and good estimates of the operating voltage can all be done "from the ground" by measuring the electric and magnetic field characteristics. Power companies often have such equipment. Such equipment are quite legal for private individuals to own and some do. Distance from the ground and sizes of insulators are clues to the operating voltages. The effective diameter (see skin effect; there is a discussion of this issue for power lines in the Wikipedia article) of the power lines provides clues to the operating frequency--the higher the frequency; the larger the diameter.  See Hall effect for measurement of magnetic fields. See electrical field measurement techniques. Commercial electrical field meters do exist.

3. Lay people can learn easily to identify visually the general (e. g., the power of 10) designed or nominal operating voltages and currents of power lines. This knowledge then can be used for identifying such a feature on a map, if present, for orientation purposes.

4. I would not be surprised that OSM data included the locations of subterranean features such as subways, vehicle and pedestrian tunnels, water mains and sewers, power and communication cables, etc. I would not be surprised that OSM data included the locations of near surface features and airways as well.

5. OSM allows, permits and encourages users to select which data is desired. If you do not desire or see a use for certain data, then do not enter it yourself (perhaps, someone else will enter it later and you should not then remove it and do not extract it from the OSM database. Remember that someone else may be using data for which you see no use. Only remove data that is wrong.

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#8 2019-07-28 20:44:11

Jonathan Masur
Member
Registered: 2016-04-23
Posts: 98

Re: Why are frequency= and voltage= a tag of OSM ?

Argh it seems no matter I say people misunderstand me 100%. I do not speak good english so please be nice. I never had the intention to remove the data, or to alter it temporary when a line is shut down. I wanted to point out that his data shouldn't have been part of OSM and discuss the concept of why those tags exist in the 1st place.

But in all cases this is pointless and I should just accept things as they are, no matter whether this makes sense or not - and I regret making this thread in the 1st place.

Last edited by Jonathan Masur (2019-07-28 20:48:15)

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#9 2019-07-28 23:29:01

OverThere
Member
Registered: 2017-02-28
Posts: 74

Re: Why are frequency= and voltage= a tag of OSM ?

1. I do not believe that I completely misunderstood you.

2. Your largest error is contained in "...that [t]his data shouldn't have been part of OSM...."  That is wrong. That is why you received such as strong response.

3. This discussion is not pointless. People tried to inform you of some of the reasons that those data were there..

4. Yes, "I[You] should just accept things as they are, no matter whether this makes sense or not to you.

5. I am sorry that you regret making this thread in the first place. I hope that you learned sometime useful from this thread.

6. English not my first language. I lost my first language as a very young child when my great-grandmother died. That language was German.

7. I spent the last quarter century working in a heavily multi-lingual environment. Eighty-seven languages were known to be used on site.  Your English is fine. I understood you to mean that you wanted an explanation of why those data were in the OSM database.

8. Power transmission facilities are part of the physical world and many of their characteristics are determined by the voltage, amperage, frequency and phasing of the power they transmit. I have power lines in the maps I make for my older car GPS receivers and at times, I can place where I am at by seeing a high-voltage transmission facility. I assure you that a 130KV, a 650KV and a 1.5MV facility look quite different.

9. OSM has had problems in the past by new editors whom did not understand why certain data were present and set up facilities to remove those data in mass causing many problems.  This is not welcome. I am not saying that you would do this.

Last edited by OverThere (2019-07-28 23:30:32)

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#10 2019-07-29 06:42:47

Maarten Deen
Member
Registered: 2010-05-20
Posts: 232

Re: Why are frequency= and voltage= a tag of OSM ?

Jonathan Masur wrote:

I know but that wasn't my point. My point is that frequency and voltages are not observable on the ground,

That's not true. Many powerlines have the voltage on a warning sign, and most transformers have a specifications sign fixed to it.

OSM tags many things that are not observable on the ground, like boundaries.

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#11 2019-07-29 20:51:25

Tordanik
Moderator
From: Germany
Registered: 2008-06-17
Posts: 2,409
Website

Re: Why are frequency= and voltage= a tag of OSM ?

Some people have offered good arguments that frequency and voltage can, in fact, be observed. But more fundamentally, there isn't any strict rule requiring on-the-ground visibility in the first place.

We do have a "map what's on the ground" section as part of our "Good practice", but that only says that on-the-ground observation trumps other sources (imports, imagery, ...) if there is a contradiction.

We also have the goal of Verifiability, which excludes subjective features. But it doesn't necessarily demand verifiability on the ground, which would be a much stricter standard.

Mapping objects that can be observed on the ground is certainly what OSM does best. But at the moment, there is no rule only such objects are allowed in OSM (even though quite a few people might support such a rule).

In the absence of a conflict with any rules, all that's required for people to add frequency and voltage attributes is that they find them useful or interesting.


OverThere wrote:

4. Yes, "I[You] should just accept things as they are, no matter whether this makes sense or not to you.

I'd rather encourage people to ask questions. When things make no sense, they should absolutely be questioned, and possibly changed. Not unilaterally, of course.

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#12 2019-07-31 19:27:37

Jonathan Masur
Member
Registered: 2016-04-23
Posts: 98

Re: Why are frequency= and voltage= a tag of OSM ?

OK I guess I spoke wrongly again. It effectively does not matter whether it is observable on the ground or not, because the "on the ground rule" is applicable to whether there's ambiguity. Here it's not the case so I shouldn't even have mentioned that. Let's forget I ever mentioned that, ok ?

What I meant however, is that pylons and wires does not have an intrinsic voltage nor frequency. They just carry the voltage and frequency they are powered with. Companies could and did change the voltage and/or frequency without changing the infrastructure. This was definitely done for railway electrification - where the power had been altered but not the infrastructure. The infrastructure could even be built with that in mind from the start.

I do not have any "plan", "suggestion" or anything in mind when it comes to those tags. I just wanted to mention I found this funny that voltage and frequency are tagged on the wires when they should really be tagged maybe at the substation or transformer that powers the wires. Now I agree there's not much we could do even if anybody agreed with me in the first place.

I agree that in the case of aerial high-voltages lines, the "voltage" tag could be useful in order to have a global idea of the size of the pylons, that could reveal how important the line is and play a major role in cartography and potential 3D representation of the area for instance. However, that is actually using a "voltage" tag to map what in reality is pylon's size. A true tag specifying size directly would be better suited - even if I fully understand measuring each pylon's size is extremely impractical. When it comes to railways' catenary, I don't even think the pylon's size changes that much anyway, and those are more prone to voltage changes as high-voltage supply lines.

Last edited by Jonathan Masur (2019-07-31 19:35:26)

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#13 2019-07-31 19:46:19

alester
Member
Registered: 2011-09-21
Posts: 238

Re: Why are frequency= and voltage= a tag of OSM ?

I think most of us understand what you're asking, but I think the problem is that the answer to:

Why are frequency= and voltage= a tag of OSM ?

...is basically, "because they are". At some point, someone thought it would be useful to tag the frequency and voltage that are typically found on particular lines, and nobody objected strongly enough that the data was removed.

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#14 2019-08-01 04:50:10

escada
Moderator
Registered: 2011-08-13
Posts: 1,546

Re: Why are frequency= and voltage= a tag of OSM ?

I agree that the voltage can change, but isn't the same true for a maxspeed value? A group of people decided that the current maxspeed on a certain street is X today. Next year it can be something else. The same is true for voltage, I do not see a lot of difference between the two tags. We map the value at this moment and will modify it when it changes.

P.S. I never map the voltage of lines, as I don't know them, but I do map the voltage of substations, which is always indicated on their door. Of course, I do not check whether the sign values is actually used.

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#15 2019-08-01 10:41:55

Maarten Deen
Member
Registered: 2010-05-20
Posts: 232

Re: Why are frequency= and voltage= a tag of OSM ?

Jonathan Masur wrote:

What I meant however, is that pylons and wires does not have an intrinsic voltage nor frequency. They just carry the voltage and frequency they are powered with. Companies could and did change the voltage and/or frequency without changing the infrastructure. This was definitely done for railway electrification - where the power had been altered but not the infrastructure. The infrastructure could even be built with that in mind from the start.

Then we change the tags in OSM. It's the same as when opening hours of a store change. Something changes in the real world, we change it in OSM.
I also do not see the point in this argument.

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#16 2019-08-06 16:46:01

Jonathan Masur
Member
Registered: 2016-04-23
Posts: 98

Re: Why are frequency= and voltage= a tag of OSM ?

escada wrote:

I agree that the voltage can change, but isn't the same true for a maxspeed value? A group of people decided that the current maxspeed on a certain street is X today. Next year it can be something else. The same is true for voltage, I do not see a lot of difference between the two tags. We map the value at this moment and will modify it when it changes.

It's not the same. If you're talking about traditional, maxspeed indicators(*), changing max speed requires changing the infrastructure, an employee should go there and actually change the signals so that a different maxspeed is displayed for drivers.

(*) There exist indicators which can change dynamically/electronically. This is another story.

Voltages and/or frequency can however be switched without changing the infrastructure. There's actually a train line which does this near Geneva.

but I do map the voltage of substations, which is always indicated on their door.

In my opinion, this is a better approach than mapping voltage on the line themselves. However I doubt every substation in the world has voltage written on it's door.

Then we change the tags in OSM. It's the same as when opening hours of a store change. Something changes in the real world, we change it in OSM.

That's exactly my point - it's possible to change voltage or frequency without changing the infrastructure - i.e. nothing "changes in the real world".

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#17 2019-08-06 18:32:04

muralito
Member
Registered: 2012-09-04
Posts: 1,751

Re: Why are frequency= and voltage= a tag of OSM ?

I have seen that a lot of power lines have the voltage indicated on them, mostly used as a warning on towers or poles, or in concrete plates in case of an underground line. The same information/warning is indicated on outdoor transformers.
Maybe your ideas to improve the database could be discussed in the context of the Project Power networks, which suggests to discuss them in IRC.

Last edited by muralito (2019-08-06 18:42:18)

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#18 2019-08-07 05:28:49

escada
Moderator
Registered: 2011-08-13
Posts: 1,546

Re: Why are frequency= and voltage= a tag of OSM ?

Jonathan Masur wrote:

It's not the same. If you're talking about traditional, maxspeed indicators(*), changing max speed requires changing the infrastructure, an employee should go there and actually change the signals so that a different maxspeed is displayed for drivers.

I was talking about implicit speed limits like on motorways and within city limits. They are rarely sign posted (although they might be posted on borders)

Last edited by kocio (2019-08-08 03:02:31)

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#19 2019-08-08 09:09:24

Maarten Deen
Member
Registered: 2010-05-20
Posts: 232

Re: Why are frequency= and voltage= a tag of OSM ?

Jonathan Masur wrote:

Voltages and/or frequency can however be switched without changing the infrastructure. There's actually a train line which does this near Geneva.

And that is mapped as well, like https://www.openstreetmap.org/way/54815 … 40/6.17309

Then we change the tags in OSM. It's the same as when opening hours of a store change. Something changes in the real world, we change it in OSM.

That's exactly my point - it's possible to change voltage or frequency without changing the infrastructure - i.e. nothing "changes in the real world".

That also happens with speed limits. There are lots of roads that have a different speed limit depending on the hour of day or on the weather conditions.
No changing of infrastructure is needed there.

I still see no argument why setting voltage or frequency would not have a place in OSM.

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#20 2019-08-08 12:37:14

Jonathan Masur
Member
Registered: 2016-04-23
Posts: 98

Re: Why are frequency= and voltage= a tag of OSM ?

escada wrote:

I was talking about implicit speed limits like on motorways and within city limits. They are rarely sign posted (although they might be posted on borders)

In this case you're totally right, France recently brought the global limit down from 90 to 80 km/h outside of villages, and this was done without (significantly) changing the infrastructure.

And @Maarten, you're totally right too.

Last edited by Jonathan Masur (2019-08-08 12:37:23)

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#21 2019-08-09 08:37:21

Pedja
Member
From: Užice, Serbia
Registered: 2012-03-22
Posts: 359
Website

Re: Why are frequency= and voltage= a tag of OSM ?

Jonatahan, maybe that information is insignificant for you but someone else might find it quite useful.

For example, imagine one wants to render map of power lines. Voltage and current information for such map could be important information.

In other words, if some data in OSM is not important for you, just ignore it. Pretend it is not there. But leave it be as someone else might need it.

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#22 2019-08-09 19:57:02

Jonathan Masur
Member
Registered: 2016-04-23
Posts: 98

Re: Why are frequency= and voltage= a tag of OSM ?

Pedja wrote:

Jonatahan, maybe that information is insignificant for you but someone else might find it quite useful.

Hello,
The information is significant and I never said otherwise. I just found it was on the wrong data - on the lines rather on the substations which connects to them, which are what gives the lines a voltage/frequency. The lines does only transmits the voltage/frequency they're connected with.

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