The plant capacity of a 3-phase generating station consists of two 8 MVA generators of reactance 14·5% each and one 4 MVA generator of reactance 9·5%. These are connected to a common bus-bar from which loads are taken through a number of 3 MVA step-up transformers each having 4% reactance. Determine the MVA rating of the circuit breakers on (i)

The plant capacity of a 3-phase generating station consists of two 8 MVA generators of reactance 14·5% each and one 4 MVA generator of reactance 9·5%. These are connected to a common bus-bar from which loads are taken through a number of 3 MVA step-up transformers each having 4% reactance. Determine the MVA rating of the circuit breakers on (i) L.V. side and (ii) H.V. side. Reactances given are based on the MVA of each piece of equipment. 

[(i) 15·24 MVA (ii) 50·25 MVA]

Expert Answer