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Public-images-osm logo.svg power = substation
Legacy National Grid Substation - geograph.org.uk - 39134.jpg
A place to step up and down voltage and transform power to suit transmission or distribution needs over a network Edit or translate this description.
Group: Power
Used on these elements
may be used on nodesshould not be used on waysmay be used on areasshould not be used on relations
Useful combination
Status: approvedPage for proposal

A substation is a place dedicated to step-up or step-down the voltage=* within an electrical power grid and is generally linked to the rest of the electrical network by one of more sets of power=lines and which may contains one or more power=transformers. Substations can vary in size from small buildings the size of a garden shed to much larger installations of the size of many football fields.

This tag should not be used for facilities where electrical power is produced, for which the power=plant or power=generator tag should be used. See wikipedia article for more information.

This tag is a refinement of power=station and power=sub_station and has replaced these tags. Do not try to automatically change these tags.

How to Map

Tag a node or a area as power=substation. Substations should in general be mapped as areas. Very small substations such as small "transformer" kiosks in residential areas may be mapped as nodes but such small facilities can also be mapped as power=transformer as this is what most people associate with small distribution substations.

Associated tags:

  • name=* The name of the facility.
  • operator=* The name of the company operating the substation.
  • voltage=* The highest voltage of operation within the facility.

Detailed mapping of substations

Note: This section describes an advanced tagging scheme for substations. It is particularly intended for mappers having some knowledge about power systems.

A substation performs switching of circuits, transforming of voltage
and several other important functions in a power system.

When should a facility be tagged as a substation and when should it be tagged as a transformer? Substations and transformers can be distinguished as follows:

  • power=substation represents an area that may contain transformers. It typically also comprises switchgear and other components.
  • power=transformer represents a transformer device, as a node. Power transformers are mostly found inside substations. However, a small distribution transformer located in a power pole is considered by most people to be a "transformer", not a "substation". According to this description, a pole mounted transformer should not be tagged as a substation. See power=transformer for more details.


A substation should be tagged as follows:

Key Value Comment Recommendation
power substation The substation should normally be mapped as an area. However, a small distribution substation may also be mapped as a node. mandatory
substation <substation type> The functional type or role of the substation. See below for possible values. recommended
location <location> The physical location of the substation, such as indoor. See below for possible values. The default value is outdoor recommended.
voltage <voltage>[;<voltage>..] The different voltages of the substation, ordered from highest to lowest (ex: 400000;225000;63000). It is recommended to tag at least the highest voltage of the substation. recommended
gas_insulated yes Use this tag for gas insulated substations using pressurized SF6 or SF6/nitrogen gas as insulation medium. Gas insulation is typically used in indoor high voltage substations. optional
name <name> The name by which the substation is known. recommended
operator <operator> Name of the company that operates the substation. optional
ref <reference> Abbreviation / number of the substation. optional

Substation values

List of possible substation=* values
Key Value Comment
transmission A transmission substation is a substation whose main function is to connect and switch transmission lines transmitting power between areas. It is suggested to use this value for substations handling voltages above 100 kV since transmission grids in most parts of the world have a voltage of 110 kV or higher. A transmission substation may also feed a medium voltage distribution grid (typically having a voltage of less than 100 kV). Substations collecting power from one or more generators of a power plant should also be considered to be of this type.
distribution A distribution substation is a substation coupled to a medium voltage distribution grid mostly having a voltage between 25 kV and 90 kV and that typically feeds a lower voltage distribution network (e.g. 10 kV) of an area. A distribution substation may be fed from the transmission grid via a transformer (see above) but provides no switching of transmission power lines (otherwise use substation=transmission). Unless fed from the transmission grid the highest voltage level will typically be 90 kV or lower. The lowest voltage is typically higher than 2.4 kV. A distribution substation does not directly supply households (see minor_distribution substation below).
minor_distribution This is a small substation at the lowest level of transforming in the distribution grid. This kind of substation directly supplies households and small businesses with low voltage power (e.g. 400V/230V in Europe). It is fed from the medium voltage distribution grid normally having a voltage between 3 kV and 30 kV. The substation is normally of the indoor type located in a small masonary building or prefabricated street cabinet.
industrial Electrical substations which may be found inside large industrial customers such as refineries and steel mills.
traction A traction substation (605-01-06) is a substation whose main function is to supply a traction system (railways, trams and/or trolleybuses). They are often located near a railway.
converter A converter substation ([1]) comprises an HVDC converter plant. It usually also performs the functions of a normal transmission substation.
compensation A compensation substation is used only for compensation of reactive power of a power line or underground cable. It usually does not comprise transformers or switchgear except possibly switches for disconnecting the compensation components such as reactors or series capacitors.
transition A transition station sometimes referred to as transition yard. This is not a real substation but a fenced-off area with cable terminals where an underground cable connects to an overhead power line. It comprises no active components such as switches or transformers. If the cable terminals are located in the tower itself (no fenced area on the ground) don't tag this as a substation. Use the attribute location:transition=yes on the tower instead.


List of possible location=* values.
Key Value Comment
location outdoor A substation substantially located outside in open air although some parts, such as lower voltage switchgear, may be indoor. This is the default value.
indoor A substation substantially located inside a building. Certain components, especially transformers, may be located outside the building.
underground A substation located underground.
platform A substation located on an offshore platform, for example associated with an offshore wind farm.
rooftop A substation located on top of a building that is used for something else.

The location=* tag may also be used together with power=transformer and other components of a substation when their location differs from that of the substation.
location=kiosk has been used to tag compact distribution substation located in small enclosures where technicians cannot enter to work. man_made=street_cabinet + street_cabinet=power is more suitable for such objects.

Substation components

A typical substation comprises at least the following components:

Substation-diagram.png Gray: Substation
Cyan: Power line
Blue: Bay
Green: Switches etc
Purple: Busbar assembly
Red: Transformer


Substation at Grafenrheinfeld Nuclear Power Plant

The switchgear assembly comprises one or more busbar assemblies and a number of bays each connecting a circuit to the busbar assembly. Normally the busbars and bays should be mapped individually, see below. However, sometimes the layout of the switchgear is not known, such as when the switchgear is inside a building or when no good aerial imagery is available. In such cases the switchgear may be mapped as an area. Only map switchgear in this way if it cannot be mapped in more details. If the entire substation is located indoor don't map the switchgear separately.

Key Value Comment Recommendation
power switchgear Defines this area as switchgear (only use this tag when more detailed mapping of the switchgear is not possible). mandatory
voltage <voltage> The voltage of the switchgear recommended
location <location> The location of the switchgear, for example indoor. See above for possible values. recommended
gas_insulated yes Use this tag for gas insulated switchgear using pressurized SF6 or SF6/nitrogen gas as insulation medium. optional


The busbar assembly makes connection to one or more circuits via the attached bays. The assembly comprises either rigid tubular conductors or flexible conductors. Strictly spoken, the term busbar refers to just one conductor but commonly an assembly of three busbars is also called a busbar [2]] which is the definition used here.

Key Value Comment Recommendation
power line Defines this way as a generic power line. mandatory
line busbar Identifies the line as a busbar assembly mandatory
cables <3,6,..> Number of individual conductors. It is recommended to map each three-phase busbar assembly individually. However, if double or triple busbars for some reasons are mapped as a single way the cables tag should be used to indicate this fact. recommended
voltage <voltage> The voltage of the busbar recommended


A bay connects an incoming circuit (power line, transformer, etc) to a busbar assembly. Each bay typically comprises circuit breakers, disconnectors, instrument transformers and surge arresters. It is suggested not to tag all these individual components. However, the circuit breaker may optionally be tagged as a switch.

Key Value Comment Recommendation
power line Defines this way as a generic power line. mandatory
line bay Identifies the line as a bay mandatory
cables <3,6,..> Normally bays should be mapped individually per circuit. However, if for some reasons the mapped way represents more than one circuit this should be indicated using the cables tag, e.g cables=6 for two bays. recommended
voltage <voltage> The voltage of the bay recommended


A switch normally comprises a circuit breaker and disconnector and is mostly found within bays but may also be used between busbar sections. See power=switch for other details, including switches outside substations.

A proposal currently aims to extend some kind of switches in OSM.


A power transformer is a static piece of apparatus with two or more windings which, by electromagnetic induction, transforms a system of alternating voltage and current into another system of voltage and current for the purpose of transmitting electrical power [3]

See power=transformer for more information and details about tagging.


Valve hall at Haywards in the New Zealand HVDC Inter-Island scheme

An HVDC converter converts electric power from high voltage alternating current (AC) to high-voltage direct current (HVDC), or vice-versa.

An HVDC converter plant comprises several components. The valve hall comprises the converter itself. Further components include a DC smoothing reactor, converter transformers, AC switch gear, harmonic filters and reactive power compensation. See below for compensation components. The converter itself may be tagged as follows:

Key Value Comment Recommendation
power converter Defines this node node or area area as an HVDC converter. Typically the converter building (valve hall) should get this tag mandatory
converter lcc A line commutated converter (LCC) uses thyristor based valves and is the most common type. This is the default value. recommended
vsc A newer type is the transistor-based voltage source converter (VSC). recommended
back-to-back A back-to-back converter couples two AC networks that are not synchronous or operate at different frequencies. There is no external DC power transmission link recommended
voltage <DC voltage> The voltage of the DC transmission in volt recommended
poles monopole / bipole The number of poles. recommended
rating <power> MW The power rating of the converter in MW (megawatt) recommended

General tags like name=* and operator=* may also be added.


Various components are used for controlling reactive power and voltage quality in a power grid.

See power=compensator for all details and examples

Map representation

  • area: The feature should be rendered as a gray area like the old power=sub_station tag.
  • node: Some sort of lightning symbol traditionally used to indicate high voltage.


Maperitive Mapnik Tagging Note
red:400kV, blue:132kV,
purple:converter,DC line/cable,
yellow:transformer, black:switch,
red circle:reactor, read area:filter
Standard Mapnik rendering
name=Bjæverskov HVDC Kontek

(valve hall)
name=HVDC Kontek
rating=600 MW
Bjæverskov HVDC substation in Denmark (northern terminal of Kontek HVDC connection).
Bing imagery of the substation.
Photo Tagging Mapnik Note
Bleiswijk-380kv-photo.jpg areapower=substation
name=380kV Bleiswijk
380kv-bleiswijk-mapnik.png 380 kV substation with three 380/150 kV transformers. Unusual for using outdoor gas insulated switchgear (GIS).
Indoor 25/10kV substation, Wateringen areapower=substation
25kv-substation-mapnik.png Indoor 25/10kV substation near The Hague. The entire fenced area should be mapped as a substation, not just the building.
Transformer cabinet, Netherlands nodeman_made=street_cabinet
An example of a small kiosk type substation.
Pole mounted transformer Uldum, Denmark nodepower=pole
Typical pole mounted 10 kV transformer.
Transformer house, Germany areapower=substation
Characteristic tower type transformer building functioning as an electricity pole.
Service building.png area power=substation


Typical minor distribution station located in a small masonry building.

Tools using this scheme

See also

Possible tagging mistakes

If you know places with this tag, verify if it could be tagged with another tag.
Automated edits are strongly discouraged unless you really know what you are doing!
If you know places with this tag, verify if it could be tagged with another tag.
Automated edits are strongly discouraged unless you really know what you are doing!