Dear all,
There is 2nos. 11kV, 2750kVA generator connected to a sync panel with 2 incomers and 6nos. outgoing VCBs, 1600kVA, 11kV/415V transformers. The generator incomers in the switchgear is provided with the siemens 7UM62 protection relay. While switching the transformer by the outgoing breaker, the protection relay of the incomer trips on over current and differential protection. We hope the reason is due to the inrush current drawn by the transformer for a short time. Please advise
1) how to prevent the tripping, the relay supplier is also investigating I hope there might be a provision of inrush blocking.
2) The generator is a back up for a hospital and supply must be restored withing 10seconds when there is power outage. So we are afraid that if we connect all 3 transformers which is already connected to the loads in 10seconds it may trip the generator also.
3) Presently there is not much load is available since the project is not yet commissioned, so we need to consider the possibility of the switching of the transformers which will be in fully loaded condition also. because nobody will switch off any loads in a power outage, will wait for the supply restoration. hence it will lead to the full loading of transformer in zero time which is inevitable
Please share your valuable knowledge in this subject, Thanks for spending your time and help.
Thanks
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