RCCB burn out
RCCB burn out
(OP)
hello, can anyone tell me most probable reason for this kind of RCCB(4P, 400V, 63A, 100mA, 3kA) burn out. there was isolator in the system before this RCCB.
can this happen due to a lightening strike? then why isolator didnt burn out first?







RE: RCCB burn out
RE: RCCB burn out
can heat from a overload current melt the tightening screws also?
RE: RCCB burn out
No2 would be water getting into the box and allowing a soggy short getting tracking and corrosion on the fast track leading to arcing.
No3 lightning. It could be just the leader that sets up main current arcing. This would not necessarily cause problems with nearby equipment.
No4 the overload protection has failed or is incorrect and an overload like a stalled motor runs thru that RCCB for an extended time. I'd expect the load to show some overheating signs.
No5 something that causes the supply voltage to more than double briefly. This would cause other things in the immediate vicinity to be toasted also. This could be a tree branch connecting the HV to LV.
Keith Cress
kcress - http://www.flaminsystems.com
RE: RCCB burn out
RE: RCCB burn out
RE: RCCB burn out
This leads me to the thought that whatever did this, it was most likely a short-duration high-intensity event. Possibly a lightning strike?
A few years back, I saw something similar where a 3-phase MCB-type isolator was similarly destroyed.
The cause was determined to be the set of tin-plated busbars which were fed by direct connection to the isolator, these separated by a ~8mm air gap.
Tin-plated copper grows metal whiskers out of the plated surface. When you get a forest of these whiskers growing between busbars, eventually something will allow them to touch, and when they do, you get something like photoflash going off. The enclosure got its insides liberally coated with black soot, the isolator got blown apart, but the upstream MCCB protecting the circuit was not fast enough to react and stayed untripped.