MHRestorations:
I'm definitely with Andy Jewsbury here... the fault has to be substantial to physically throw cables around, but to simply make an audible noise, especially as arcing tends to be high frequency.. steel trunking tends to sound tinny (pun not intended), inasmuch it accentuates higher frequency noises.
I can imagine that a significant series arc could cause current fluctuations enough to cause a crackling or arcing noise a long way away from the actual fault.
Morning,
Where's the high frequency coming from? A 230V arc might be caused twice every cycle, i.e. once per half cycle, and that's about it (the arc current itself will follow the sine wave, where there is current flowing). So the crackling or buzzing should have a 50Hz sound to it.
Also, a series arc will limit the current drawn as it is inline with the load and as far as impedance goes, it is additive. I.e. if the cable doesn't move under load, I don't see why it would be moving (due to magnetic effects) under series arc conditions.
A parallel arc would be different and could cause higher currents (low impedance from phase/phase, phase/earth) but that would imply cable damage, which has not been shown up by the IR testing.
MHRestorations:
I'm definitely with Andy Jewsbury here... the fault has to be substantial to physically throw cables around, but to simply make an audible noise, especially as arcing tends to be high frequency.. steel trunking tends to sound tinny (pun not intended), inasmuch it accentuates higher frequency noises.
I can imagine that a significant series arc could cause current fluctuations enough to cause a crackling or arcing noise a long way away from the actual fault.
Morning,
Where's the high frequency coming from? A 230V arc might be caused twice every cycle, i.e. once per half cycle, and that's about it (the arc current itself will follow the sine wave, where there is current flowing). So the crackling or buzzing should have a 50Hz sound to it.
Also, a series arc will limit the current drawn as it is inline with the load and as far as impedance goes, it is additive. I.e. if the cable doesn't move under load, I don't see why it would be moving (due to magnetic effects) under series arc conditions.
A parallel arc would be different and could cause higher currents (low impedance from phase/phase, phase/earth) but that would imply cable damage, which has not been shown up by the IR testing.
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