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This tag should also be used for a transformer feed trolleybus overhead contact line, shouldn't it? A trolleybus is not the rail transport, so current comment excluded it.

+1 Fanfouer (talk) 23:21, 26 April 2014 (UTC)
In principle no problems with that. But I believe that such contact lines are fed by dc which requires more than just a transformer. You probably need a power=substation + substation=traction for that. --polderrunner (talk) 07:20, 27 April 2014 (UTC)

phases=* when tagging transformer banks, (with 2 to 3 transformers)

While the phases=* tag applies to the number of phases the transformer converts, but I am not certain if that tag can apply to the number of transformers in a transformer bank, which is composed on two or three single-phase transformers, whether they are mounted on a pole, on a platform between poles, or on a substation? Three-phase transformers are usually a single transformer with three primary windings, or either three secondary windings (in the case of large transformers in substations) or four secondary windings (in the case of distribution transformers to provide three-phase electricity in a wye configuration, but in countries primarily using single-phase transformers, like the US, Canada, Japan, South Korea, and the Philippines, three-phase pole-mounted distribution transformers are rather three single-phase transformers forming a "transformer bank", that are used to provide wye configuration three-phase electricity with either a voltage of 120/208 V 60 Hz (US, Canada), 100/173 V 50/60 HZ (Japan, depending on region in that country), or 220/380 V (South Korea, Philippines); however, three-phase transformers in substations in those countries can be a single unit or three single-phase transformers. Also, two-phase transformer banks, composed of two single-phase transformers (one with two secondaries with center tap, and the another, that may be larger, with two secondaries, having one connected to one secondary of the other transformer, but without a center tap) exist, and are used to provide "high leg" delta power with voltages that can be 120/208/240 V, 100/200/173 V, or 220/380/440 volts, usually for larger users, usually larger businesses, for example, a bank, where three-phase is used for ATM's and single-phase is used for lights, air conditioning, and most appliances, or a fast-food restaurant, where three-phase is used for larger kitchen appliances, and single-phase for lights, air conditioning, and single-phase appliances.

Below is a table providing possible tagging for certai:

Description Image Tags
37.5 kVA three-phase pole-mounted transformer bank. Example pictured in Illinois, United States 37.5kVA three phase utility stepdown.jpg

power=pole transformer=distribution rating=* phases=3 voltage=[primary voltage];208

Two-phase pole-mounted transformer bank, used to provide "high leg" delta. Example pictured in Bulacan, Philippines. 0815jfCamias Poblacion Supermarket San Jose San Miguel Bulacan Bulacanfvf 10.jpg power=pole

transformer=distribution rating=rating (in kVA) of each transformer, separated by bars. Not necessary when transformers have the same rating operator=Meralco phases=2

Can phases=* be used to tag the number of transformers in a transformer banmk?--TagaSanPedroAko (talk) 15:24, 23 December 2016 (UTC)

I don't think so, because you won't be able to make the difference from 1 trafo with 3 phases and 3 trafo with 1 phase each.
It is important to keep phases=*, cables=* to one single feature.
The picture showing 3 different transformers at top of a pole should be mapped with 3 independent Node with phases=1 on each around the node's Node.
It may be the same with many radio antennas on a single support. Fanfouer (talk) 16:34, 23 December 2016 (UTC)
If transformers on a pole-mounted transformer bank should be mapped as three nodes, that wouldn't be a good idea, as it will mean unnecessary repetition of the feature. One possible idea is to map the transformers on one node along with the pole, then tag the phases and ratings of each transformer, separated by bars (|), so when tagging a three-phase pole mounted transformer bank composed of 50 kVA single-phase transformers, the tags would be phases=1 and rating=50 kVA. I tried to tag a three-phase transformer bank, composed of three 333 kVA single-phase transformers placed on a platform between two poles and serving an industrial customer, using three nodes, but seeing it as repetitive, I reduced it to one node.
But, a two-phase or three-phase transformer bank in a pole or platform will rather function as one transformer, instead of two or three transformers, as each single-phase transformer secondary there is connected to each other, so, considering two or three transformers in a pole as one transformer unit, they will be in one node, either along with the node for pole (in case of a pole-mounted transformer bank), or on a node between poles (in the case of a three-phase transformer bsnk in a platform between two poles), then tag each transformer with phases=2 or 3 and the rating of each transformer with rating=*, having the ratings (in kVA or MVA) of each transformer separated by bars (e.g. 37.5 kVA|37.5 kVA|37.5 kVA, for a three-phase transformer bank with three 37.5 kVA single-phase transformer, or 25 kVA|50 kVA for a two-phase transformer bank with one single-phase transformer rated 25 kVA and the other 50 kVA), however, for the case of a transformer bank in a substation, it may be based on the distance between the phase conductors in a bay connected to it, so, it can be mapped as one node, if each cable is too close to each other, like in a line with voltages below the approximate limit of 300 kV, or as three nodes, when the bays connected to the transformer bank are far enough, like in a 400 kV or 500 kV line.
I respect your opinion about mapping transformer banks, but, it is best to map transformer banks on a pole as one node (the same node as the pole); however, mapping a transformer bank in a substation should be considered in a case-by-case basis.--TagaSanPedroAko (talk) 18:30, 23 December 2016 (UTC)
Multivalues keys actually exists on OSM with ; separated lists. But these are not convenient to work with in automated processes.
We currently got the case with power=switch : several chambers can be electrically linked and operate as a single switch. It is recommended to map them with a single node.
No problem to do so with transformer banks as well, but they must share the same properties. If not, several nodes should be preferred as for ensuring data usability.
Which key do you propose to get the number of transformer in a consistent bank? Fanfouer (talk) 19:04, 23 December 2016 (UTC)
One possible solution is proposing this tag: transformer_bank=*, which will have the values two, for two single-phase transformers, and three.
But, I still have problems tagging a single-phase transformer with two bushings, which are prevalent in the provincial areas in the Philippines. These are called "phase-to-phase" transformers, which are used where a neutral is not used, like in long distribution lines, but these not always connect to another phase wire in the primary windings. See this images.
Power Transformer.jpg

240v transformer - - 1062014.jpg
The first image shows a phase-to-phase transformer in the United States. Notice the second bushing is not connected to another phase in the primary lines, but with the grounded/earthed side of the transformer. This will be have phases=1 instead of phases=2.
But for the second image, showing a phase-to-phase transformer in the United Kingdom, tagging is challenging, because the transformer is connected to two primary wires. While it serves as a single-phase transformer, the two primary wires will call for phases=2, but its function as a single-phase transformer will call for phases=1.
While the first example above can be easily tagged, because the second primary wire is connected to the grounded side of the transformer instead of another phase of the primary line, the second example, is however, confusing, because it is a single-phase transformer with two primary phase wires connected instead of one. I encountered phase-to-phase pole-mounted transformers in the Philippines, used to step down 34.5 kV or 13.8 kV into 220/440 volt split-phase power for residential and small commercial customers, and I tagged them with phases=2, like the tagging of two single-phase pole-mounted transformers forming a transformer bank and are used to provide 220/380/440 volt "high leg" delta service for commercial users. What will be the best tagging for a phase-to-phase transformer, which has two primary wires connected and two or three secondary wires, providing either split-phase (hot-neutral-hot) or single-phase (hot-neutral)?--TagaSanPedroAko (talk) 08:33, 24 December 2016 (UTC)


This type of transformer is used to measure current on high voltage substations or meters of large customers, either single-phase or three-phase. And I came up with this tag when those I mapped as SVCs have a connection to a box containing a meter and are actually transformers used for metering large customers with high current usage (200 amperes and above). Should the tag transformer=current be introduced, that such kind of transformer be mapped? TagaSanPedroAko (talk) 00:27, 7 April 2017 (UTC)