Fuse: fast blown vs slow blown

M

Man-wai Chang

Guest
How dangerous is it to replace a 500mA fast-brown fuse with a 500mA
slow-brown one?

--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
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"Man-wai Chang"
How dangerous is it to replace a 500mA fast-brown fuse with a 500mA
slow-brown one?
Click to expand...

** Confucius once say:

" The quick brown fox jumps over the lazy dog "

Think about it ...........



..... Phil
 
"Globemaker"


The danger, on a scale from 1 to 10 is 8. Some equipment can be
damaged in a millisecond, so a slow-blown fuse can result in a ruined
piece of equipment. For example, an integrated circuit could need 12
volts, but you plug in the wrong wall wart that has no labels on it.
It has 18 volts instead of 12 volts, but it uses the same diameter
coaxial connector. A fast fuse protects in 400 microseconds, but the
slow blow does not blow that fast so the 45 nanometer digital device
gets melted in 1000 microseconds.


** Globemaker is one of those personages who sincerely believes that " Star
Trek " is a documentary.

And he has pointy ears too.

Beam me up Scotty ........



.... Phil
 
On May 31, 7:41 am, Man-wai Chang <toylet.toy...@gmail.com> wrote:
How dangerous is it to replace a 500mA fast-brown fuse with a 500mA
slow-brown one?

--
   @~@   Might, Courage, Vision, SINCERITY.
  / v \  Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (x86_64 Ubuntu 9.10)  Linux 2.6.39
   ^ ^   19:36:01 up 6 days 4:38 0 users load average: 1.22 1.09 1.06
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa
Click to expand...
The danger, on a scale from 1 to 10 is 8. Some equipment can be
damaged in a millisecond, so a slow-blown fuse can result in a ruined
piece of equipment. For example, an integrated circuit could need 12
volts, but you plug in the wrong wall wart that has no labels on it.
It has 18 volts instead of 12 volts, but it uses the same diameter
coaxial connector. A fast fuse protects in 400 microseconds, but the
slow blow does not blow that fast so the 45 nanometer digital device
gets melted in 1000 microseconds.
 
On 05/31/2011 04:41 AM, Man-wai Chang wrote:
How dangerous is it to replace a 500mA fast-brown fuse with a 500mA
slow-brown one?
Click to expand...
It depends entirely on the equipment. Slow-blow fuses used to be more
expensive than fast-blow fuses, and tend to be less available. So a
designer's knee-jerk reaction may be to specify a fast-blow fuse
'because it's there'.

So there's a good chance that you can drop your slow-blow fuse in there
and everything will be fine, but if you do and burn something up, don't
come crying to me. I would hesitate to do so myself unless I knew what
was in the product, and felt that a slow-blow would work OK. I would
also hesitate to replace the fuse unless I knew why the original had
blown -- fuses blow for reasons, and if the equipment is dorked and
blowing fuses, then putting in more fuses will just make it more dorked.

Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.
Click to expand...
For a multimeter, is it always better to use a fast blow fuse?

--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.39
^ ^ 23:56:02 up 6 days 8:58 0 users load average: 1.05 1.09 1.06
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa
 
It has 18 volts instead of 12 volts, but it uses the same diameter
coaxial connector. A fast fuse protects in 400 microseconds, but the
slow blow does not blow that fast so the 45 nanometer digital device
gets melted in 1000 microseconds.
Click to expand...
Is the 13A BS1362 fuse a fast blow one?

--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.39
^ ^ 23:56:02 up 6 days 8:58 0 users load average: 1.05 1.09 1.06
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa
 
On 05/31/2011 08:57 AM, Man-wai Chang wrote:
Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.

For a multimeter, is it always better to use a fast blow fuse?
Click to expand...
It depends on the multimeter. I'd stick with the fast blow fuse and
stop putting it in 'voltage' mode when you've got it connected to
measure current.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
On 05/31/2011 08:57 AM, Man-wai Chang wrote:
Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.

For a multimeter, is it always better to use a fast blow fuse?

Check to make sure that the fuse isn't being used as the current shunt
Click to expand...
-- if it is, then you don't just need the right current rating, you need
a matched fuse.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
It depends on the multimeter. I'd stick with the fast blow fuse and stop
putting it in 'voltage' mode when you've got it connected to measure
current.
Click to expand...
It's a glass one, 500mA fast blow according to the manual.

--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.39
^ ^ 00:36:01 up 6 days 9:38 0 users load average: 1.12 1.09 1.12
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa
 
On Tue, 31 May 2011 09:02:08 -0700, Tim Wescott <tim@seemywebsite.com>
wrote:

On 05/31/2011 08:57 AM, Man-wai Chang wrote:
Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.

For a multimeter, is it always better to use a fast blow fuse?

Check to make sure that the fuse isn't being used as the current shunt
-- if it is, then you don't just need the right current rating, you need
a matched fuse.
Click to expand...
Chuckle. If a fuse were used as a current shunt, then when the fuse
blows, instead of a few millivolts across the fuse, the meter now gets
the full voltage of whatever is being measured. The fuse holder
contact resistance will probably be larger than the wire resistance in
the fuse (fast blow). I don't think anyone uses a fuse as a current
shunt.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
On Tue, 31 May 2011 23:57:58 +0800, Man-wai Chang
<toylet.toylet@gmail.com> wrote:

It has 18 volts instead of 12 volts, but it uses the same diameter
coaxial connector. A fast fuse protects in 400 microseconds, but the
slow blow does not blow that fast so the 45 nanometer digital device
gets melted in 1000 microseconds.

Is the 13A BS1362 fuse a fast blow one?
Click to expand...
That's the number of the plug, not the fuse:
<http://en.wikipedia.org/wiki/BS_1363>
It does have a fuse inside, but I don't know the value or type.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
Tim Wescott wrote:
On 05/31/2011 08:57 AM, Man-wai Chang wrote:
Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.

For a multimeter, is it always better to use a fast blow fuse?

It depends on the multimeter. I'd stick with the fast blow fuse and stop
putting it in 'voltage' mode when you've got it connected to measure
current.
Click to expand...
That's 'current' mode when you've got it connected to measure
voltage, yes?

--Winston
 
On 05/31/2011 10:16 AM, Winston wrote:
Tim Wescott wrote:
On 05/31/2011 08:57 AM, Man-wai Chang wrote:
Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.

For a multimeter, is it always better to use a fast blow fuse?

It depends on the multimeter. I'd stick with the fast blow fuse and stop
putting it in 'voltage' mode when you've got it connected to measure
current.

That's 'current' mode when you've got it connected to measure
voltage, yes?
Click to expand...
Uhhh...



D'oh!

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
Man-wai Chang wrote:

Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.


For a multimeter, is it always better to use a fast blow fuse?

yes
Click to expand...
 
Jeff Liebermann wrote:

On Tue, 31 May 2011 09:02:08 -0700, Tim Wescott <tim@seemywebsite.com
wrote:


On 05/31/2011 08:57 AM, Man-wai Chang wrote:

Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.

For a multimeter, is it always better to use a fast blow fuse?


Check to make sure that the fuse isn't being used as the current shunt
-- if it is, then you don't just need the right current rating, you need
a matched fuse.


Chuckle. If a fuse were used as a current shunt, then when the fuse
blows, instead of a few millivolts across the fuse, the meter now gets
the full voltage of whatever is being measured. The fuse holder
contact resistance will probably be larger than the wire resistance in
the fuse (fast blow). I don't think anyone uses a fuse as a current
shunt.

Hush, you wasn't suppose to notice that! Built in obsolescence.
Click to expand...

Jamie
 
Jeff Liebermann wrote:
On Tue, 31 May 2011 09:02:08 -0700, Tim Wescott <tim@seemywebsite.com
wrote:

On 05/31/2011 08:57 AM, Man-wai Chang wrote:
Your best bet is to get the right fuse, and at least try to fix the
fault before you turn the equipment on with your shiny new fuse.

For a multimeter, is it always better to use a fast blow fuse?

Check to make sure that the fuse isn't being used as the current shunt
-- if it is, then you don't just need the right current rating, you need
a matched fuse.

Chuckle. If a fuse were used as a current shunt, then when the fuse
blows, instead of a few millivolts across the fuse, the meter now gets
the full voltage of whatever is being measured. The fuse holder
contact resistance will probably be larger than the wire resistance in
the fuse (fast blow). I don't think anyone uses a fuse as a current
shunt.
Click to expand...

Too hard to calibrate. :)

I used some test fixtures on the PRC-77 QA line for module
interchangability that had to be returned to the cal lab if a module
blew a fuse. !@#$%^&*( RCA/NATO design. @#$%^&*


--
It's easy to think outside the box, when you have a cutting torch.
 
Man-wai Chang wrote:
How dangerous is it to replace a 500mA fast-brown fuse with a 500mA
slow-brown one?
Click to expand...
Hope this helps answer your question!

http://flippers.com/fuses.html

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
 
Man-wai Chang Inscribed thus:

It has 18 volts instead of 12 volts, but it uses the same diameter
coaxial connector. A fast fuse protects in 400 microseconds, but the
slow blow does not blow that fast so the 45 nanometer digital device
gets melted in 1000 microseconds.

Is the 13A BS1362 fuse a fast blow one?
Click to expand...
No !

--
Best Regards:
Baron.
 
"Jeff Liebermann"

Is the 13A BS1362 fuse a fast blow one?

That's the number of the plug, not the fuse:
Click to expand...

** Funny, I have any number of fuses in my bins with "BS 1362" printed on
them.

http://en.wikipedia.org/wiki/BS_1363

It does have a fuse inside, but I don't know the value or type.
Click to expand...
**From the very same Wiki:

http://en.wikipedia.org/wiki/BS_1363#Fuses

A 13A, BS 1362 fuse is very much a Slow Blow !




..... Phil
 
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