TallMike Posted July 10, 2008 Share Posted July 10, 2008 I have a couple of AlphaPacks which drive 1k PAR cans, one per channel so an easy 1amp clear of the fuse rating. The problem is, fuses keep blowing on the packs, at random times. On a gig, I can expect a couple to go - it's at the point where they no longer are available for hire. They blow at random times as well, I'll repatch a lamp only to find that the channel fuse has gone. I've got fast-blow 6.3a fuses in there at the moment. I've assumed they're correct - but are they? Any help would be appreciated guys. MikeLSH Link to comment Share on other sites More sharing options...
timmeh Posted July 11, 2008 Share Posted July 11, 2008 Hi You'll probably find that the ramp current for a 1K will exceed 6.3A, especially if you factor voltage drop-down over fairly long bits of 1.5mm cable. Try swopping them out for slow-blow T6.3A fuses and see what happens. All the bestTimmeh Link to comment Share on other sites More sharing options...
Brian Posted July 11, 2008 Share Posted July 11, 2008 ....especially if you factor voltage drop-down over fairly long bits of 1.5mm cable.??????????????????????????????? Link to comment Share on other sites More sharing options...
TallMike Posted July 11, 2008 Author Share Posted July 11, 2008 erm, I'll be honest, it's something I didn't factor. But the cable length is about 2m - the packs sit at the bottom of the stands, that's the beauty of them! Mike Link to comment Share on other sites More sharing options...
Trunker Posted July 11, 2008 Share Posted July 11, 2008 Hi You'll probably find that the ramp current for a 1K will exceed 6.3A, especially if you factor voltage drop-down over fairly long bits of 1.5mm cable. Try swopping them out for slow-blow T6.3A fuses and see what happens. All the bestTimmeh A 1K Par-can is roughly 4.17 amps. How would you loose over 2 amps running doen a lead that will take nearly 16 amps? You will loose a bit, but nothing to shout about. 3000 watts on an Alpha pack @ 100% is fine and at 13amps you still have 120 watts 'headroom'. Link to comment Share on other sites More sharing options...
Colin Posted July 11, 2008 Share Posted July 11, 2008 Vague thought but do you use the parcans elsewhere? could be an issue with them when they get hot with one of them slowly burning out). Is it the same alpha pack that the fuse goes in or vary between packs? indictating a potential issue internally to a specific pack. When the fuses blow were they on the same channel? i.e. channel 2 on all the packs Regarding the fuse blowing due to load fairly unlikely if the above suggested as I quite often use alpha pack 2s with 5A fuses and dont have many issues. However a potential issue may exist with the batch of fuses that you have so might be worth trying to rule that out as well. Link to comment Share on other sites More sharing options...
boatman Posted July 11, 2008 Share Posted July 11, 2008 Hi You'll probably find that the ramp current for a 1K will exceed 6.3A, especially if you factor voltage drop-down over fairly long bits of 1.5mm cable. Try swopping them out for slow-blow T6.3A fuses and see what happens. All the bestTimmeh A 1K Par-can is roughly 4.17 amps. How would you loose over 2 amps running doen a lead that will take nearly 16 amps? You will loose a bit, but nothing to shout about. 3000 watts on an Alpha pack @ 100% is fine and at 13amps you still have 120 watts 'headroom'. Please stop this nonsense. It is impossible to lose any current down a cable, however long it is. You may lose voltage but that is a different thing entirely. The longer the cable the higher is the resistance and therefore, for a given voltage, the current from the dimmer pack is less. A longer cable on a lantern can not be the reason for fuses blowing, provided that the cable itself does not have any shorts. Link to comment Share on other sites More sharing options...
adam2 Posted July 12, 2008 Share Posted July 12, 2008 Please stop this nonsense. It is impossible to lose any current down a cable, however long it is. You may lose voltage but that is a different thing entirely. The longer the cable the higher is the resistance and therefore, for a given voltage, the current from the dimmer pack is less. A longer cable on a lantern can not be the reason for fuses blowing, provided that the cable itself does not have any shorts. True, an excessivly long cable will cause voltage drop, and result in a dimmer light, and the lamp will draw less current, and REDUCE the chances of blowing fuses. It is widely believed that if the voltage supplied to an incandescent lamp is reduced, that the current will increase.It will not, a lower supplied voltage will result in less current, not more.This is not simply my opinion, but an observed physical fact which may be easily confirmed by some very simple tests. As regards the original question, fast blow fuses are liable to fail due to the inrush current of a cold lamp, or due to the internal arcing that may occur at end of lamp life. Slow blow or antisurge fuses would be far less liable to fail under such conditions, BUT such fuses would give less protection to the triacs in the dimmers, which may fail before the fuse in some conditions. If the fuseholders are in poor condition, then the fuses may get warm or hot which increases the risk of failure. (edited for typo) Link to comment Share on other sites More sharing options...
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