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55v - 110v centre tap transformer short circuit calculations

Anthony Sullivan

hello

i have been trying to work out how to work short circuit calculations for 110v systems. do i use 55V with c max or do use 110v or even use a 3phase calculation. i am trying to work out if a circuit will trip on 16A c type mcb for short circuit as i am putting a rcbo in to cover the fault current. 

110v 55v 

0.85ohms line to line tested

4mm 2 core cable 

 

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    Both!

    The prospective fault current for a line-to-line fault will be twice that for a line to cpc ("earth") fault.

    Cmax (or possibly Cmin if you are using circuit-breakers, dependent on the I2t curves) applies to both. The difference comes with the adiabatic criterion, although which will be worse could depend on whether you are using circuit-breakers or fuses.

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  • 0

    Both!

    The prospective fault current for a line-to-line fault will be twice that for a line to cpc ("earth") fault.

    Cmax (or possibly Cmin if you are using circuit-breakers, dependent on the I2t curves) applies to both. The difference comes with the adiabatic criterion, although which will be worse could depend on whether you are using circuit-breakers or fuses.

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