Inspection & Testing

[Fifer46]

Describe a situation where the L-E prospective fault current could be higher than the L-N Needing help with this question, was unsure if it was to do with earthing systems used. it must be single phase as well i guess and the PSCC is doubled in 3 phase so must be under some fault condition on a single phase system, any help

 

[pc1966]

Draw a basic diagram of a TN-S supply and label the various cable impedances, for now assuming the supply has zero impedance and you can use R1, R2, Rn as simply resistive.

Now write out the equations for PSCC and PFC.

What is different and what is common? What difference would be needed for PFC > PSCC?

From those that are different, then ask how you might lower an impedance but connecting something.