In the past, it was discussed very often in several panels to
what extend IR currents are a jeopardy for the transformer windings.
As it is well known, the value of these IR currents occurring
when energizing unloaded transformers can be in the same
order of magnitude as a fault current [1], thus producing significant
electromagnetic forces. The difference to SC is that the IR
may last for several tens of seconds, whereas a fault normally is
cleared within tens of milliseconds. In addition, an IR situation
is much more frequently as this can be considered as normal
service operation.