HRC Fuse failures
Posted 20 June 2005 - 06:48 PM
I have recently been asked to look at a situation where there is reported failure of the HRC fuses in that the fuses supply a motor driving a high inertia load and started by a soft starter.
I believe that the fuses may be a little on the light side for the starting current and time of the machine.
The report is that the fuses are failing at times during start, and that the fuses are then physically ruptureing, allowing ionized gas into the surrounding area and causing an insulation breakdown between two phases on the fuse holder.
The argument put forward is that because the current is limited by the soft starter, the arc is being sustained for a long time and the energy build up inside the cartridge is causing the gas to leak. If the current was higher, the arc would extinguish quicker and the gas would not leak.
The fuses are a blade type fuse in the correct holder and rated at 120KA.
Any comment or experiences? ;p;
Mark Empson | administrator
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Posted 15 November 2006 - 11:27 AM
Sounds interesting that the rupturing of a fuse, can possibly cause ionization of the surrounding air. I can understand the circuit trying to maintain the current – due to a collapsing field, but then explode and ionize the surrounding area sounds a bit strange, maybe it’s carbonizing the surrounding area causing “tracking”.
Posted 16 November 2006 - 01:51 AM
Who is the fuse manufacturer? What is the part number of the fuse? Although these questions have a commercial bent, the fact is that fuses should not explode. In fact, there has been a recent recall made by one manufacturer where the cited reason for the recall was the possibility of explosion.
Posted 16 November 2006 - 05:17 AM
Posted 16 November 2006 - 05:29 AM
This actually came from a patent aplications for an HRC fuse, here is the link.
Posted 16 November 2006 - 05:31 AM
Was posting this at the same time as you jraef. I read that as being more concerned with High Voltage so perhaps not an issue with this case?
Posted 17 November 2006 - 08:31 PM
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