Re: [PSES] Fuse designations

[Bill Owsley]

 An aside related to delayed fuses.
Two issues with the subject came up when I was an intern a few decades ago.
The fuses were used in ELV circuits so could be touched in application.  In 
use, they got too hot to touch, so said the safety folks.  Tasked with finding 
a lower touch temp fuse to use.  Samples from every vendor and some never heard 
of.  Found one, half the resistance, and temp.  But unknown source so lots of 
testing to evaluate performance.
Then found that the in-rush current at each turn-on affected the delay 
mechanics.  The fuse used a little solder cup and spring to make connects, and 
each in-rush caused a slight slip.  5-10 turn on's and it would open.  Power 
supply engineers found a way to limit in-rush current to avoid the condition.
Saw this in-rush issue over and over in the following decades.

Bill Owsley
EMC First LLC


On Wednesday, March 2, 2022, 05:44:09 PM EST, Douglas E Powell 
 wrote:  
 
 Very nice, thanks.
Now I may need to convince my client to stop using Slow Blow on international 
shipments.
-Doug

Laporte, Colorado USA
LinkedIn

(UTC -07:00) Mountain Time (US-MST)



On Wed, Mar 2, 2022 at 3:34 PM Scott Aldous 
<0220f70c299a-dmarc-requ...@listserv.ieee.org> wrote:

Hi Doug,
As the link Rich provided from Littelfuse indicates, the international symbols 
come from IEC 60127-1. See the last page of this preview, section 6.1.
On Wed, Mar 2, 2022 at 2:22 PM Richard Nute  wrote:


 

 

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  
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  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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-- 
Scott Aldous | Regulatory Compliance Manager | scottald...@google.com | 
650-253-1994
-


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discussion list. To post a message to the list, send your e-mail to 
emc-p...@ieee.org

All emc-pstc postings are archived and searchable on the web 
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formats), large files, etc.

Website: http://www.ieee-pses.org/
Instructions: htt

Re: [PSES] Fuse designations

[Douglas E Powell]

Very nice, thanks.

Now I may need to convince my client to stop using Slow Blow on
international shipments.

-Doug


Laporte, Colorado USA
LinkedIn <https://www.linkedin.com/in/coloradocomplianceguy/>

(UTC -07:00) Mountain Time (US-MST)




On Wed, Mar 2, 2022 at 3:34 PM Scott Aldous <
0220f70c299a-dmarc-requ...@listserv.ieee.org> wrote:

> Hi Doug,
>
> As the link Rich provided from Littelfuse indicates, the international
> symbols come from IEC 60127-1. See the last page of this preview
> <https://www.sis.se/api/document/preview/568043/>, section 6.1.
>
> On Wed, Mar 2, 2022 at 2:22 PM Richard Nute  wrote:
>
>>
>>
>>
>>
>> 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 
>> *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 
>> 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)
>>
>>
>>
>>
>>
>> -
>> 
>>
>> This message is from the IEEE Product Safety Engineering Society emc-pstc
>> discussion list. To post a message to the list, send your e-mail to 
>> emc-p...@ieee.org
>>
>> All emc-pstc postings are archived and searchable on the web at:
>> http://www.ieee-pses.org/emc-pstc.html
>>
>> Attachments are not permitted but the IEEE PSES Online Communities site
>> at http://product-compliance.oc.ieee.org/ can be used for graphics (in
>> well-used formats), large files, etc.
>>
>> Website: http://www.ieee-pses.org/
>> Instructions: http://www.ieee-pses.org/list.html (including how to
>> unsubscribe) <http://www.ieee-pses.org/list.html>
>> List rules: http://www.ieee-pses.org/listrules.html
>>
>> For help, send mail to the list administrators:
>> Scott Douglas sdoug...@ieee.org
>> Mike Cantwell mcantw...@ieee.org
>>
>> For policy questions, send mail to:
>> Jim Bacher j.bac...@ieee.org
>> David Heald dhe...@gmail.com
>>
>
>
> --
> Scott Aldous | Regulatory Compliance Manager | scottald...@google.com |
>  650-253-1994
>
> -
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a

Re: [PSES] Fuse designations

[Douglas E Powell]

Thanks Brian,

I knew about the prefixes Fs & Ts but not the M. I tried looking for source
information in the past and at the time I was certifying to a VDE standard
through LGA Nuremberg. I was also told the acronyms used different German
terms, but fortunately the first letters were the same as for English
words.

A quick check again today and I found:

[image: image.png]

Thanks

-Doug

Laporte, Colorado USA
doug...@gmail.com

(UTC -07:00) Mountain Time (US-MST)





On Wed, Mar 2, 2022 at 2:07 PM Brian Kunde  wrote:

> 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  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)
>>
>>
>>
>>
>> -
>> 
>>
>> This message is from the IEEE Product Safety Engineering Society emc-pstc
>> discussion list. To post a message to the list, send your e-mail to 
>> emc-p...@ieee.org
>>
>> All emc-pstc postings are archived and searchable on the web at:
>> http://www.ieee-pses.org/emc-pstc.html
>>
>> Attachments are not permitted but the IEEE PSES Online Communities site
>> at http://product-compliance.oc.ieee.org/ can be used for graphics (in
>> well-used formats), large files, etc.
>>
>> Website: http://www.ieee-pses.org/
>> Instructions: http://www.ieee-pses.org/list.html (including how to
>> unsubscribe) 
>> List rules: http://www.ieee-pses.org/listrules.html
>>
>> For help, send mail to the list administrators:
>> Scott Douglas sdoug...@ieee.org
>> Mike Cantwell mcantw...@ieee.org
>>
>> For policy questions, send mail to:
>> Jim Bacher j.bac...@ieee.org
>> David Heald dhe...@gmail.com
>>
>

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
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Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
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For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Fuse designations

[Scott Aldous]

Hi Doug,

As the link Rich provided from Littelfuse indicates, the international
symbols come from IEC 60127-1. See the last page of this preview
<https://www.sis.se/api/document/preview/568043/>, section 6.1.

On Wed, Mar 2, 2022 at 2:22 PM Richard Nute  wrote:

>
>
>
>
> 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 
> *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  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)
>
>
>
>
>
> -
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to 
> emc-p...@ieee.org
>
> All emc-pstc postings are archived and searchable on the web at:
> http://www.ieee-pses.org/emc-pstc.html
>
> Attachments are not permitted but the IEEE PSES Online Communities site at
> http://product-compliance.oc.ieee.org/ can be used for graphics (in
> well-used formats), large files, etc.
>
> Website: http://www.ieee-pses.org/
> Instructions: http://www.ieee-pses.org/list.html (including how to
> unsubscribe) <http://www.ieee-pses.org/list.html>
> List rules: http://www.ieee-pses.org/listrules.html
>
> For help, send mail to the list administrators:
> Scott Douglas sdoug...@ieee.org
> Mike Cantwell mcantw...@ieee.org
>
> For policy questions, send mail to:
> Jim Bacher j.bac...@ieee.org
> David Heald dhe...@gmail.com
>


-- 
Scott Aldous | Regulatory Compliance Manager | scottald...@google.com |
 650-253-1994

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
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For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Fuse designations

[Richard Nute]

 

 

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  
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 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)

 






-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
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Attachments are not permitted but the IEEE PSES Online Communities site at 
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formats), large files, etc.

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List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Fuse designations

[Brian Kunde]

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  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)
>
>
>
>
> -
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to 
> emc-p...@ieee.org
>
> All emc-pstc postings are archived and searchable on the web at:
> http://www.ieee-pses.org/emc-pstc.html
>
> Attachments are not permitted but the IEEE PSES Online Communities site at
> http://product-compliance.oc.ieee.org/ can be used for graphics (in
> well-used formats), large files, etc.
>
> Website: http://www.ieee-pses.org/
> Instructions: http://www.ieee-pses.org/list.html (including how to
> unsubscribe) 
> List rules: http://www.ieee-pses.org/listrules.html
>
> For help, send mail to the list administrators:
> Scott Douglas sdoug...@ieee.org
> Mike Cantwell mcantw...@ieee.org
>
> For policy questions, send mail to:
> Jim Bacher j.bac...@ieee.org
> David Heald dhe...@gmail.com
>

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: