Key:voltage

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voltage
Description
For describing the voltage of power lines, cables, and substations. Show/edit corresponding data item.
Group: power
Used on these elements
may be used on nodesmay be used on waysmay be used on areas (and multipolygon relations)should not be used on relations (except multipolygon relations)
Useful combination
Status: de facto
More details at taginfo
Tools for this tag

The nominal voltage (601-01-21) of a power line, cable, circuit, or substation. The voltage tag is also used on rails to denote the railway electrification voltage.

Values should be entered in volts without the unit or thousand delimiter. For example, for a 15 kV line, the value should be voltage=15000, not "15 kV", nor "15,000".

This tag should not be used for transformers - the voltage:primary=* and voltage:secondary=* tags should be used instead.

Power

Voltage of power lines can sometimes be safely determined from signage on the support structures (or signs on sites where underground cables run). Alternatively, they can be deduced from the length of insulators, conductor spacing, or other characteristics, in combination with some general knowledge of the power system.

When multiple voltages are in use, for example on a power line carrying two circuits, or a substation converting between two voltages, the voltages should be separated by semicolons with the highest voltage listed first: voltage=275000;132000.

For AC lines, the voltage tagged should be the highest voltage present. For three-phase or two-phase power lines, this is the phase-to-phase voltage. For single-phase lines, it's the phase-to-ground voltage.

For DC lines, the convention in OSM is to use the pole-to-ground voltage, so a bipolar ±800 kV HVDC line will be tagged voltage=800000, circuits=2. This is inconsistent with the AC usage (as our ±800 kV line will have a pole-to-pole voltage of 1.6 MV), but this convention is well-established and we don't want to change it at this point.

Tools

  • Open Infrastructure Map shows power lines colour coded by voltage range and its exact value, allowing for quick analysis of the OSM data.
  • The Power Network Tools JOSM plugin can be used to estimate the voltage of substation busbars from aerial imagery.

Nominal, rated, and maximum voltages

There is some disagreement between system operators about "nominal" line voltages. A line which is classified 400 kV in the UK and a one which is classified as 420 kV in continental Europe may be carrying very similar levels of voltage in practice - it is only the nominal voltage designation which is different.

In some areas the "nominal" voltage published may actually be the maximum continuous rated voltage, especially as methods for regulating voltage improve so lines can be run closer to their theoretical maximum.

There's no easy way of finding out the actual levels of voltage, so the system operator's designation should be used, but it should be noted that these "nominal" voltages aren't directly comparable between countries.

IEC 60038 on Wikipedia defines a number of voltage ranges, which may be useful for voltage classification.

List of min./max. AC voltages as defined by IEC 60038, and typical values used by country (kV)
Series 1 Series 2 Belgium Canada Great
Britain 		India Indonesia Ireland Japan Korea Norway Philippines Taiwan United States
Nom. Max. Nom. Max.
3 3.6
4.16 4.40 4.16 4.16 4.16
6 7.2 6
6.3
6.6 		6.6 6.6 6.9
10 12 10
11
12
12.4 		11 11 10 11
12.47 13.20 12.47 12.47
13.20 13.97 13.2
13.80 14.52 13.8 13.8 13.8
15 17.5 15
15.6
20 24 20
22 		22 20 20 22 22.9 22 23
24.94 26.47 25 25
30 36 36 33 33 33
34.50 36.50 34.5 34.5
35 40.5 38
45 52 45
50 		46
66 72 70 66 (Manitoba), 69 (Alberta, British Columbia, New Brunswick, Newfoundland and Labrador, Nova Scotia, Prince Edward Island)
72 (Alberta on ATCO Electric and EPCOR, Saskatchewan) 		66 70 66 66 69 69 69
110 123 115 (southern Manitoba, Northwest Territories, Ontario)
120 (Quebec) 		110 110 110 110 115 115
132 145 138 (Alberta on AltaLink and ENMAX, British Columbia, northern Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, Prince Edward Island, Saskatchewan)
144 (ATCO Electric) 		132 132 138 138
150 170 150 161 (Quebec only) 150 154 154 161 161
220 245 220 230 (British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, Ontario, Quebec, Saskatchewan)
240 (Alberta) 		220 220 230 230
275 300 300 287 (British Columbia only) 275 275 275 275 300 287
330 362 345 (New Brunswick, Nova Scotia) 345 345 345
380 420 380 400 400 400 420
500 550 500 (Alberta, British Columbia, Manitoba, Ontario) 500 500 500 500
735 765 735 (Quebec)
765
765 800 765 765 765

HVDC systems

Most HVDC systems use the earth as a return conductor. This is used all the time in monopolar systems -- bipolar systems may use it if one of the poles fails.

The grounding conductor (known as the "electrode line") is installed with insulators on the support structures, because ground currents can lead to electrochemical corrosion and other undesirable effects. The electrode line can be carried on the same towers as the HVDC line, or on separate towers, and is connected to grounding electrodes at a dedicated grounding site, which may be quite far away from the converter station.

If the towers of an HVDC line also carry an electrode line, the voltage should be described with "HVDC voltage ; 0". For AC-lines carrying a grounded return conductor of an HVDC scheme, set as voltage "AC voltage(s) ; 0" and as frequency "AC frequencies ; 0". Ground return conductors of HVDC schemes should be included in the cables=* count.

The voltage value 0 for such lines is strictly not correct, as it will exhibit a voltage against ground equal to the product of the line current and the sum of ground resistance and resistance of line to grounding point, but we choose to use 0 for simplicity.

Examples

A high-voltage transmission line carrying two circuits with a voltage of 110 kV would use the following keys and values:

A transmission line carrying two circuits at 110 kV and one at 66 kV:

An electrified railway track in Germany with overhead power supply:

Nearly the same for a subway with separate rail for power supply:

A street with overhead wires for trolley buses:

A distribution substation, stepping down the voltage from 11 kV to 400 V for use by houses:

See also

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