Proposed features/Transformer extension proposal
|Transformer extension proposal|
|Status:||Proposed (under way)|
|Definition:||Propose to add extra details about power transformers devices functionalities and specifications|
- 1 Rationale
- 2 Proposal
- 3 Tagging
- 4 Examples
- 5 Voting
- 6 See also
Power transformers are static devices designed to adapt electricity voltage or intensity in an alternating power network.
The amount of flowing energy through the whole network depends of transformers transfer capabilities.
Gather and know functions and figures about transformers can be a concern for consumers involved in power grid operation or environmental design.
As advanced technical knowledge, mappers may look for a consistent and well described model to guide them when adding such information to OSM.
Currently, the wiki doesn't describe enough tags to know well how each transformer work. They are considered as black boxes with input and output voltages but reality can be more complex actually.
Finally this proposal will help to improve data quality and completeness inside OSM and allow consumers to get a better information on how power infrastructure actually works.
Here is a list of common definitions useful to have in mind :
- Power Transformer (421-01-01) : A static device, with help of electrical induction between metallic windings, converts a given voltage and current to another voltage and current. The delivery is done at the same frequency.
- Winding (421-03-01) : An assembly of metallic wire turns forming a circuit associated with one of the voltages of a transformer. Note on a polyphase transformer, a winding is the combination of phase windings. Interfaces are use to be called primary, secondary, tertiary and so on, which will be useful to adapt tagging scheme in this proposal. The number of windings, nor voltage levels aren't limited in theory.
- Auxiliary transformer (605-02-46) : Transformer exclusively intended to supply the internal circuits of a power substation.
- Bank (151-12-11) : Set of devices connected and acting together.
It is proposed to add extra tags or values to get a better description of power transformer devices :
There is no point to replace or deprecate any reviewed key or value here.
Transformers have been tagged for years in OSM, most of the formal work regarding tags had already been done in the substation refinement proposal. This proposal only complete the existing stuff.
This proposal focus on tags to use if, and only if, data is available. It does not assume all data can be publicly known but provide a consistent model to add it to the map if possible, without any power grid operator help.
Where do I find such data ?
First of all, don't go inside power substations if you're not invited to do so please, it's dangerous and probably illegal.
Public information or aerial imagery will help to see outdoor transforming facilities safely.
On every transforming device found (not building, not fence), add a and put some tags described below like mandatory power=transformer.
Use location=* to give information about its position and transformer=* to let us know about its function.
High detailed information may be found on transformers themselves. A complete datasheet as exposed beside gives many figures on the machine capabilities and structure.
We basically need voltages, windings structure but manufacturer=* and start_date=* may also be completed.
Nevertheless, you may not be able to took picture of those plates and as a reminder : don't go inside restricted perimeters to get the one you couldn't. unless invited
It may be good to complete the transformer=* definition with following value :
|transformer||auxiliary||Auxiliary transformers intend to supply power to substation internal systems. They're not feeding any subscriber connected to power grid but act as a load on the substation architecture.|
Transformers are designed to adapt voltage between their windings connected to interfaces. We use to call them primary, secondary and so on.
Each interface is defined with its own voltage and transformers won't have a global voltage value. This proposal aims to discourage the use of voltage=* without suffix on transformers.
It's proposed to use voltage:primary=*, voltage:secondary=* instead according to the interface's name.
|voltage:primary||Primary interface's voltage||The operating voltage of a given transformer's primary interface.|
|voltage:secondary||Secondary interface's voltage||The operating voltage of a given transformer's secondary interface.|
|voltage:tertiary||Tertiary interface's voltage||The operating voltage of a given transformer's tertiary interface.|
Windings and interfaces description
Transformers are often composed of simple windings facing each other linked to identical primary and secondary interfaces which is pretty nice to tag with a few keys.
And sometimes, you may find 3-phases single primary winding but two 3-phases secondary windings or whatever arrangement you can imagine.
Those complex situations need extended keys to be accurately described in OSM. phases=* and windings=* may be suffixed with :primary, :secondary, :tertiary... to give as specific values as it needs for a specific interface. If no suffix is used, the values will be considered as common to all interfaces of the transformer.
Even if several windings can compose a single interface, they should operate at the same voltage. If voltage is different, then it's not the same winding/interface.
Let's introduce windings=* also to give the number of windings composing each interface of the transformer.
To describe all interfaces with a single bunch of keys
|phases||Phases number||For polyphase systems, like national, regional and local power grids, this key gives the number of phases connected to the transformer.|
|windings||Number of windings for the whole transformer||This key gives the amount of windings for the whole transformer whatever it's for primary, secondary...|
|rating||Global power rating||The power rating going through the transformer, mainly from primary to every other interfaces.|
To describe each interface separately, given with 3 interfaces but keys can be suffixed accordingly if more voltage levels needed :
|phases:primary||Number of phases composing the primary winding||-|
|phases:secondary||Number of phases composing the secondary winding||-|
|phases:tertiary||Number of phases composing the tertiary winding||-|
|windings:primary||Number of primary windings||Amount of polyphase windings connected to the primary interface of the transformer|
|windings:secondary||Number of secondary windings||Amount of polyphase windings connected to the secondary interface of the transformer|
|windings:tertiary||Number of tertiary windings||Amount of polyphase windings connected to the tertiary interface of the transformer|
|rating:primary||Rating of primary winding||Rating of the primary winding only|
|rating:secondary||Rating of secondary winding||Rating of the secondary winding only|
|rating:tertiary||Rating of tertiary winding||Rating of the tertiary winding only|
In some situations and countries, polyphase transformers may not be contained in a single box. It's not unusual to find several mono phase transformers boxes assumed as an equivalent to a single polyphase transformer.
This proposal would introduce devices=*, defaults to 1, to indicate how many different boxes you see, sharing the same figures and functions.
It won't be useful to add a transformer: prefix since such a key can be used in many other situations far beyond power field of knowledge.
Such a key will factorise as many features as possible on a same node. Thus, all keys giving figures or functions will have to be valued for a single device.
More example are available below, here the principle : 2 similar three-phase 50Hz transformers may be factorised as this on the same node : devices=2 + phases=3 + frequency=50.
Please note that, according to IEC 151-12-11, such disposal of transformers can't be properly called a bank since transformers aren't connected together but each one connected to a different live cable (or even different power circuit). A set would be more appropriate.
Values to be replaced
Some pretty used tags should be carefully replaced like suggested below.
It's recommended to check the values of such tags and to not mass edit.
|Obsolete tag||Usage volumetry||Used for ?||New tag(s) to use|
|voltage=*||~10 500 on 2017-07-30||Give a list of used voltages on a power=transformer||voltage:primary=* + voltage:secondary=* + ...|
|voltage-high=*||6 128 on 2017-07-30||Voltage used on a transformer's primary interface||voltage:primary=*|
|voltage-low=*||3 996 on 2017-07-30||Voltage used on a transformer's secondary interface||voltage:secondary=*|
|--|| This transformer intends to stup up 6kV power output from a 2 units hydraulic power plant to the 63kV local power grid.
|--|| This transformer has 3 windings operating at 3 different voltages. 225kV side is on the foreground while 63kV is hidden at the back
|--||Tranformers can directly be hosted on poles to save ground place and prevent complex infrastructure building when not needed.|
|--||Multiple mono phase transformers used on a 3-phase network|
|--|| Such transformer are used in France to feed legacy 15kV distribution zones from current 20kV infrastructures.
|--||High speed rail lines are fed from transmission power grid with such biphase transformers.|
On one of each transformer inside of the substation
|Due to pretty long distances, high speed rail 25kV catenaries have to be regularly fed by auto-transformers which take power from a -25kV feeder line going along railways.|
Voting has not started yet.