|Voltage of a transformer interface which delivers power to consumers|
|Used on these elements|
|Tools for this tag|
A transformer is a power device and it has got different interfaces that can be documented separately.
See dedicated documentation about those interfaces.
Some configurations may be complex, see windings=* also for more information.
The secondary voltage (421-03-07) is the voltage bound to the secondary interface of a power transformer, that outputs the power (to consumers).
It's a constant design convention we intend to describe here. As of today, power can actually flow in every direction connected to a power transformer depending on power grid operational status OSM isn't aware of and then won't change secondary side established during mapping.
How to find the value
In the general case (transformer=* except generator)
secondary voltage is the voltage lower than voltage:primary=* and possibly higher than voltage:tertiary=* if applicable.
For a two interfaces transformer, it's the lower voltage.
Beware with some transformers having tertiary (and further) with yet lower voltages.
generator transformer, in power plants
They are intended to step-up voltage coming from a power generator, the secondary voltage is higher than voltage:primary=* since the power outputs on the high voltage side.
It is understood that in special circumstances, for maintenance operations purpose for instance, power plants can actually consume power from the network through their step-up transformers. It doesn't change the chosen convention for OSM as those transformers are first of all designed to transmit power from generators.