I am designing a 3000A main-tie-main system from (2) 2500kva, 25kV to 480V utility transformers for a hospital. Our typical design is to control CBs manually with kirk key and tie breaker normally open.
But in this project, the CBs are controlled automatically. Now the owner?s facility engineer is asking if we can close tie breaker before we open the one of the mains when we restore the system to normal after a single source failure. This will be automatic transfer and the main will be often without any delay right after tie breaker is closed so two source will be paralleled very short period of time.
The 2500kva utility transformers are identical and supplied from the different substations so, they might be supplied from the different sources.
I know I have to consider the higher AIC rating of the CBs and switchgear but considering the transformers are supplied from the different sources, can I make a closed transition?
But in this project, the CBs are controlled automatically. Now the owner?s facility engineer is asking if we can close tie breaker before we open the one of the mains when we restore the system to normal after a single source failure. This will be automatic transfer and the main will be often without any delay right after tie breaker is closed so two source will be paralleled very short period of time.
The 2500kva utility transformers are identical and supplied from the different substations so, they might be supplied from the different sources.
I know I have to consider the higher AIC rating of the CBs and switchgear but considering the transformers are supplied from the different sources, can I make a closed transition?