Here is some info:
https://www.swe-check.com.au/pages/learn_fuse_markings.php
https://www.littelfuse.com/~/media/files/littelfuse/technical-resources/documents/reference-documents/littelfuse_5x20mm-iec-fuse-cap-marking_guide.pdf
Rich
From: Brian Kunde <bkundew...@gmail.com>
Sent: Wednesday, March 2, 2022 1:08 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Fuse designations
I do not know where the information I have originally came from, but I got this
and have been using this for over 30 years:
FF = Very Fast Acting
F = Fast Acting (Common)
M = Medium Time Lag
T = Time Lag (Common)
TT = Long Time Lag
I got this from Bud Lang who was our Safety Guru at Heath Kit many years ago.
The Other Brian
On Tue, Mar 1, 2022 at 5:33 PM Douglas E Powell <doug...@gmail.com
<mailto:doug...@gmail.com> > wrote:
All,
Over the years, I've seen various ways people include a caution or warning, in
their user documents or product labels, for replacement fuses. Similar to:
"replace only with same type and rating of fuse"; followed by a code:
T1.6AH250V. And for those who may not understand the code, they may sometimes
add in parentheses some variant of "(1.6 Amp time-lag, ~250V, high breaking
capacity)".
So now to my question, US manufacturers sometimes use the phrase "SLO-BLO" or
"Slow Blow" instead of Time-Lag or Time-Delay. Are these terms commonly used
internationally and if so, are they clearly understood?
I took some time to look up SLO-BLO and found it's a registered trademark for
Littelfuse going back to 1957, and it has been continuously renewed since that
time.
Incidentally, a German Engineer once told me the way he would designate a fuse
type for a variety of tripping characteristics was in this order from very slow
to very fast: TT1.0A250V, T1.0A250V, 1.0A250V, F1.0A250V, FF1.0A250V.
Thanks, -Doug
Douglas E Powell
Laporte, Colorado USA
(UTC -07:00) Mountain Time (US-MST)
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