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Reactance and impedance of 300 mm2 Aluminium 4-core cable
Former Community Member
I am doing 6.3.4 example in the IET Electrical installation design guide: calculations for electricians and designers. in part 2: three-phase to earth fault current at C, it says a 100m of 300 mm2 cable aluminium SWA thermosetting (Table F7A). but the table does not have x value, only r value. where and how to find these values to help in calculating the prospective fault current ?
The question the OP is answering does not concern voltage drops, it is a fault current calculation based on an LV network given in the book mentioned.
As I stated above - Table F.7A is (partly) based on BS 6346 (Table H2).
The BS 6346 table only gives resistance values, in this case for PVC armoured cables with aluminium conductors. Table F.7A extends the BS 6346 table to included reactances values for the conductors and for the armour. The reactance values quoted come from other sources (look at The IEE Commentary on the IEE Wiring Regulations - take the x voltage drop from BS 7671 table 4H2B and divide by root 3).
The OP has correctly identified the parameters needed to answer the question in the "IET Electrical installation design guide: calculations for electricians and designers".
The similar book I have is the IEE - Electrical Installation Design Guide - ISBN 978-0-86341-550-0
The question the OP is answering does not concern voltage drops, it is a fault current calculation based on an LV network given in the book mentioned.
As I stated above - Table F.7A is (partly) based on BS 6346 (Table H2).
The BS 6346 table only gives resistance values, in this case for PVC armoured cables with aluminium conductors. Table F.7A extends the BS 6346 table to included reactances values for the conductors and for the armour. The reactance values quoted come from other sources (look at The IEE Commentary on the IEE Wiring Regulations - take the x voltage drop from BS 7671 table 4H2B and divide by root 3).
The OP has correctly identified the parameters needed to answer the question in the "IET Electrical installation design guide: calculations for electricians and designers".
The similar book I have is the IEE - Electrical Installation Design Guide - ISBN 978-0-86341-550-0
