Hi,
I have a bus which has a 25kA/1sec fault rating. Is this normally compared to IEC 60909-0 sub-transient, transient or steady state fault level? Any help is appreciated.
Hi, in IEEE 1584 equation (4) (page 11) it states "En is the incident energy (J/cm^2) normalised..."
Then in equation (6) E = 4.184*Cf*En(t/0.2)(610^x/D^x)
E is the incident energy (J/cm^2)
and in section E.3.1
Equation (E.1) E= Cf*En*(t/0.2)(610^x/D^x) in cal/cm^2
Is En from equation (4) in...
Hi, I was wondering what reason is behind IEC 60909's transformer impedance correction factor. Is this replace transformer impedance tolerance, or should they both be applied?
Hi, does anyone know what the instantaneous override current of an ABB Tmax T4S circuit breaker with PR222 trip unit is? I cannot seem to find an ABB document which has this.
Hi all,
I am currently using ABB circuit breakers, which has an uninterruptible current rating equal to their frame size. However the long time pickup of their associated trip devices has a tolerance of 1.05 to 1.20. Does the continuous current rating of the CB preclude me from using the...
Hi all,
In ETAP I have added LV circuit breaker opening times in the "Min. Delay" field under the Ratings Tab. However the opening times do not appear in the sequence of events or arc flash study results, and the arc flash fault clearing times appear to just use the trip device TCC time at the...
When attempting to validate IEC 60909 L-G fault calculations from ETAP, I find that the fault levels are higher than I calculated. It appears that ETAP is doing
Sqrt(3) c U / |2*Z1 + Z0|,
with Z0 taken directly from the R0 and X0 in the cable library entry, rather than using Z0 = Z0 phase...
