Arc Flash - Current required to sustain an arcing current
Arc Flash - Current required to sustain an arcing current
(OP)
I am using PTW's Arc Flash software which has a default parameter "Cleared Fault Threshold" which is the percentage of initial arcing current which when interrupted results in arc being extinguished.
The default setting for the "Cleared Fault Threshold" current is 80%. ie. the assumption is that the remaining 20% of arcing current can not sustain the arc. Using Warrington's empirical formula for arc resistance, an arcing current of 1.74kA across a 'Gap' ( arc length ) of 25mm has a resistance of only 0.0208 Ohm. I am therefore reluctant to assume that the arc can not be supported after the 'Cleared Fault Threshold" current is interrupted.
Does anyone with arc experience know what magnitude of current will sustain an arc in a system where the 'Gap' is approx. 25mm and the phase to phase voltage is 415V, 50Hz ?
The default setting for the "Cleared Fault Threshold" current is 80%. ie. the assumption is that the remaining 20% of arcing current can not sustain the arc. Using Warrington's empirical formula for arc resistance, an arcing current of 1.74kA across a 'Gap' ( arc length ) of 25mm has a resistance of only 0.0208 Ohm. I am therefore reluctant to assume that the arc can not be supported after the 'Cleared Fault Threshold" current is interrupted.
Does anyone with arc experience know what magnitude of current will sustain an arc in a system where the 'Gap' is approx. 25mm and the phase to phase voltage is 415V, 50Hz ?





