Hello.
We are developing an off-line powered processor-based piece of
equipment for the international industrial control market. The
selected universal input off-line switching power supply (100-240VAC
input; +5V, +12V, -12V DC output, 45W) has a single fuse, which is
presumably rated for safety protection, rather than component
protection. This soldered-in fuse is placed before the VDE/FCC level
'B' input filter. The cabinet in which the device is to be housed
will be closed with screws, and is not INTENDED to be opened by the
user. Small ventilation holes are present.
I wonder if I need to provide user-accessible fuses on the unit at the
IEC power entry module. I would rather use a module incorporating
only IEC connector and DPST switch (voltage selection isn't needed
with this supply), and I understand that the EC is moving away from
traditional fusing anyway.
I realise that fusing for safety is never really wrong, and would
protect against failure between the power entry site and the supply's
fuse. However, I find that most off-line equipment, including yer
average personal computer, does NOT have a user-accessible fusing
scheme, and I suspect that it would be unnecessary I'd be interested
in your opinion, but will certainly check with UL, CSA, and a European
certification agent before finalising this.
Thanks for your comments.
Jonathan Malton
S-S Technologies, Inc.
Kitchener, Ontario, Canada.
[email protected]
