adiabatic equation

[andydj99]

Can someone please explain where to get the time (t) in the adiabatic equation

i can work out the rest just need the (t)

the MCB is a BS 60898 63A

my PFC is 940A

Thanks

 

[telectrix]

kook in ntime/current graphs. determine the time taken for your MCB to trip with a given fault current, that is t.

 

[Guest123]

Appendix 3, page 301 of BS 7671 current edition.

 

[ackbarthestar]

You can use the maximum time of 0.4s, regs give a minimum time of 0.1s but in reality most manufactures quote 0.01 s as the minimum time, which of course will make a difference to the size of cpc. The only limiting factor will be the speed of the mechanical operation og the protective device.

However in most situations the maximum time would service since there are few sizes of conductor available .

 

[andydj99]

Thanks Everyone for your help