Gallery, Projects and General > How do I??
poorly seig c3
PekkaNF:
Time-current characteristics
http://www.littelfuse.com/~/media/automotive/catalogs/littelfuse_fuseology.pdf
Looks like 3,15A fuse blows about 10A in 0,1 sec, would that card withstand 30A for 0,01s?
http://www.farnell.com/datasheets/1447843.pdf
Generally those fuses are fine when they are chosen to blow out on wire short circuit and prevent wires. To dimension these glass tube fuses to protect electronic circuit on small over current or surge load is not easy.
Another issue is selectivity. The mill fuse should blow before plug fuse and plug fuse should blow before mains fuse. Two fuses near same melting current is a bad idea.
Pekka
John Rudd:
--- Quote from: PekkaNF on June 08, 2017, 11:21:23 AM ---
Generally those fuses are fine when they are chosen to blow out on wire short circuit and prevent wires. To dimension these glass tube fuses to protect electronic circuit on small over current or surge load is not easy.
Another issue is selectivity. The mill fuse should blow before plug fuse and plug fuse should blow before mains fuse. Two fuses near same melting current is a bad idea.
Pekka
--- End quote ---
Pekka,
I was merely suggesting that to prolong the life of the machine, the the op change the fuses to a value lower than those originally fitted.
It is cheaper to replace a blown fuse in the event of a fault than have to buy a new motor or pcb.
The manufacturers of these machines will fit protective fuses, albeit with values that are far too high...the number of machines that have come my way for repair have fuses that are far in excess and have not afforded any protection to the motor or electronics....
I did not make my recommendations on a whim, there is evidence from other forums, that members there have had the same recommendation from a major machine tool supplier....
At the end of the day, its no skin off my nose if the op does nothing..however, if I carry out repairs to a machine, I ensure that the equipment fuses are adequate and fit for purpose in order tomoffer any guarantee of repair.
Rant over....
PekkaNF:
Something lost in translation :wave:
My intention was not to criticize your choice of fuse on this particular instant. Merely to point out some points to greater public that there is some logic on fuse selection.
I have noticed the same thing about fuse size, maybe they rather sell new card/motor than listen rap about burnt fuses. Also the mill might not reach rated power with smaller fuse, but there is risk of burning something under other circumstances.
Cheers,
pekka
tom osselton:
That happened to me on my Craftex mill the doughnut wire wrapped thing (choke?) unsoldered itself and dropped onto wires below! They gave me a different board but the tack has not worked since.
bpud:
I've only just caught up on this thread. My Sieg C3 had a very similar problem. A short time after getting the lathe about 11 or 12 years ago the plastic chuck guard was removed, it got in the way all the time. The switch and metal guard mounting rod were left in place. Sometimes the rod needed a bit of a tweak to ensure that the switch was open and the motor would run. The chuck guard microswitch was a bit hair trigger, so it was removed and a small wire link applied to the PCB. End of problem!!
cheers
Bill
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