Transformer behaviour feeding a fault from a DC supply

[e_bettio]

I am trying to understand the behaviour of a transformer under a fault condition.
The transformer feeds a fault (three-phase bolted short for example). The supply to the transformer is an inverter. the inverter may fail in such a way that the inverter DC circuit effectively connects across two phases of the transformer.

So a DC supply is connected to the transformer primary with a fault on the secondary. What happens next?

I expect the fault will reflect across the transformer to the inverter DC circuit initially, but as the fault current rises the transformer will saturate (or will it? saturation is driven by the voltage across the transformer). The DC voltage collapses. Once the transformer has saturated, then I expect the fault will no longer reflect across the transformer to the DC circuit supplying it. So I expect the fault current will disappear at the fault, but may continue into the saturated transformer.

So I have a hunch how it will work. But I am not sure, and very sketchy on details.

Does anyone know how this really works?


thanks,

 

[godfreyl]

So a DC supply is connected to the transformer primary with a fault on the secondary. What happens next?

With only DC on the primary, there is no voltage induced in the secondary, and the secondary current will quickly drop to nothing.

OTOH, current through the primary will rise until either the transformer burns out, or something else breaks the circuit or limits the current.