Re: [CAD_CAM_EDM_DRO] Fast Blow Fuses

Jarrett & Heidi Johnson wrote:

>I've read many places that "fast blow" fuses are recommended. Can anyone tell me the difference between these and the regular "Barrel" fuses used in the older model cars [ and else where]. Are the new style block fuses used in car's concidered fast blow?
>If no to both of these questions, how do you tell what is and isn't a fast blow fuse?
>
>

You tell the difference by the code number. 3AG is a fast-blow (really
standard non-delay)
fuse. MDL is a delay fuse, but there are dozens of different types with
different delay
characteristics.

Note that these fuses (3AG and MDL) are rated for AC only. Different
fuses are
required for interrupting DC. I had an "interesting" situation come up
a while ago
in my servo amps. A guy was pushing the ratings a bit and was running
them at
160 V even though I hadn't tested them at that voltage. Fast current
transients
turned on both transistors in a half bridge at the same time,
effectively shorting
out the power supply. The 15 A standard-blow fuse just sat there while
the current
sensing resistor exploded like a bomb!

Jon