Replacement of Inverter Skid transformer with different vector configuration

[adityalagudu3291]

This is related to the Operating Solar plant. Our contractor has replaced an Inverter skid unit transformer with ungrounded Yd1 with the similar KVA rating of ungrounded Dy11 Transformer. It worked for few months and failed recently. We came to know about this vector configuration change recently and working on RCA. What are the consequences of this vector configuration change and affects on the Inverters as well as substation protection? All the remaining electrical parameters of both the transformers are same. Please see the attached nameplate details of both units. The RCA might be something else also, we are trying to analyze whether we can do this replacement again with Dy11 as we don't have any Yd1 Transformers available immediately?

Original configuration: Yd1 Ungrounded
Replacement configuration: Dy11 Ungrounded

 

[adityalagudu3291]

Attached is the original nameplate

 

[ron]

Is the HV side connected to the Y in the original transformer and the D in the replacement? If the transformers are running in parallel with other solar transformers or the utility, you need to be sure the paralleled connection is synchronized.

"Yd1" and "Dy11" are transformer vector groups, indicating the phase shift between the high-voltage (HV) and low-voltage (LV) windings. Yd1 signifies a star (wye) connected HV winding and a delta-connected LV winding with the LV winding lagging the HV by 30 degrees. Dy11 indicates a delta-connected HV winding and a star (wye) connected LV winding with the LV winding leading the HV by 30 degrees. These vector groups are crucial for ensuring proper parallel operation and phase relationships in electrical power systems.