Fuse: fast blown vs slow blown

[Winston]

Tim Wescott wrote:

On 05/31/2011 10:16 AM, Winston wrote:

(...)

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

Uhhh...



D'oh!

The fuse for my Fluke 79 multimeter retails for $10.00.
(Ten U.S. Dollars)

http://www.flukeonlinestore.com/3478682.html

Guess what prompted that discovery.

Go ahead. Guess.

--Winston <-- It's better, now.

 

[Phil Allison]

"Winston"

The fuse for my Fluke 79 multimeter retails for $10.00.
(Ten U.S. Dollars)

http://www.flukeonlinestore.com/3478682.html

Guess what prompted that discovery.

Go ahead. Guess.

** That fuse is designed to protect the multi-meter, its leads ( and you )
from a worst case scenario.

That scenario is when you probe a 415 volt, 3 phase power outlet with the
meter accidentally set to the 10 amp range.

A standard glass fuse would simply arc from end to end, the probes and leads
would explode and cover you in hot metal and the meter would become a write
off.

The specified ( fast acting, high rupture current, high voltage fuse ) would
merely produce a loud pop.


..... Phil

 

[Winston]

Phil Allison wrote:

"Winston"

The fuse for my Fluke 79 multimeter retails for $10.00.
(Ten U.S. Dollars)

http://www.flukeonlinestore.com/3478682.html

Guess what prompted that discovery.

Go ahead. Guess.


** That fuse is designed to protect the multi-meter, its leads ( and you )
from a worst case scenario.

That scenario is when you probe a 415 volt, 3 phase power outlet with the
meter accidentally set to the 10 amp range.

A standard glass fuse would simply arc from end to end, the probes and leads
would explode and cover you in hot metal and the meter would become a write
off.

The specified ( fast acting, high rupture current, high voltage fuse ) would
merely produce a loud pop.

I didn't know that.

How about this one?
http://www.flukeonlinestore.com/3478747.html

--Winston

 

[Phil Allison]

"Winston"

Phil Allison wrote:
"Winston"

The fuse for my Fluke 79 multimeter retails for $10.00.
(Ten U.S. Dollars)

http://www.flukeonlinestore.com/3478682.html

** That fuse is designed to protect the multi-meter, its leads ( and
you )
from a worst case scenario.

That scenario is when you probe a 415 volt, 3 phase power outlet with the
meter accidentally set to the 10 amp range.

A standard glass fuse would simply arc from end to end, the probes and
leads
would explode and cover you in hot metal and the meter would become a
write
off.

The specified ( fast acting, high rupture current, high voltage fuse )
would
merely produce a loud pop.

I didn't know that.

** Cos you know fuck all about anything.

How about this one?
http://www.flukeonlinestore.com/3478747.html

** Standard glass (fast) fuse by the look of it.



..... Phil

 

[Winston]

Phil Allison wrote:

"Winston"

(...)

I didn't know that.

** Cos you know fuck all about anything.

It's a continuing problem.
Watta ya gonna do.

How about this one?
http://www.flukeonlinestore.com/3478747.html


** Standard glass (fast) fuse by the look of it.

It must be ~36 times safer than a commodity GMA
fuse in a multimeter application, yes?
http://www.amazon.com/125mA-250v-Fuses-0-125A-5x20mm/dp/B004HLZYVI

Fluke wouldn't overcharge for that part either,
surely.

--Winston

 

[Phil Allison]

"Winston"

Phil Allison wrote:

I didn't know that.

** Cos you know fuck all about anything.

It's a continuing problem.
Watta ya gonna do.

How about this one?
http://www.flukeonlinestore.com/3478747.html


** Standard glass (fast) fuse by the look of it.

It must be ~36 times safer than a commodity GMA
fuse in a multimeter application, yes?
http://www.amazon.com/125mA-250v-Fuses-0-125A-5x20mm/dp/B004HLZYVI

Fluke wouldn't overcharge for that part either,
surely.

** The price is very steep.

But I expect the fuse IS safe when used in the Fluke DMMs it is specified
for.

The scenario with a 0.125A fuse is nothing like the one with the 10A range
fuse.

Typical 0.125A rated fast fuses have resistances of 8 to 10 ohms - which
limits the fault current to a value the fuse can easily break.

A 10 amp fuse may well have a resistance of only a few milliohms, so the
fault current is only limited by the resistance of the DMM's leads.

A current of 40 amps is easy enough for a small fuse to break, while one of
over 4000 amps is not.

Capice?


..... Phil

 

[Winston]

Phil Allison wrote:

"Winston"

(...)

Fluke wouldn't overcharge for that part either,
surely.

** The price is very steep.

We agree.

But I expect the fuse IS safe when used in the Fluke DMMs it is specified
for.

Both the 'Fluke' brand and the commodity brand are safe, I suspect.

It wouldn't shock me to learn both kinds are sourced from the same
place.

The scenario with a 0.125A fuse is nothing like the one with the 10A range
fuse.

Typical 0.125A rated fast fuses have resistances of 8 to 10 ohms - which
limits the fault current to a value the fuse can easily break.

A 10 amp fuse may well have a resistance of only a few milliohms, so the
fault current is only limited by the resistance of the DMM's leads.

A current of 40 amps is easy enough for a small fuse to break, while one of
over 4000 amps is not.

We agree on that, too.

--Winston

 

[Phil Allison]

"Winston"

Phil Allison wrote:
"Winston"

** The price is very steep.

We agree.

** Yawnnnnnnnnnnnn....

But I expect the fuse IS safe when used in the Fluke DMMs it is specified
for.

Both the 'Fluke' brand and the commodity brand are safe, I suspect.

It wouldn't shock me to learn both kinds are sourced from the same
place.

** Nothing shocks a fuckwit like you.

The scenario with a 0.125A fuse is nothing like the one with the 10A
range
fuse.

Typical 0.125A rated fast fuses have resistances of 8 to 10 ohms -
which
limits the fault current to a value the fuse can easily break.

A 10 amp fuse may well have a resistance of only a few milliohms, so the
fault current is only limited by the resistance of the DMM's leads.

A current of 40 amps is easy enough for a small fuse to break, while one
of
over 4000 amps is not.

We agree on that, too.

** GIANT Yawwnnnnnnnnnnnnnnnnnnn

Piss off wanker.


.... Phil

 

[Man-wai Chang]

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

Coz you are in USA, not Hong Kong (ex-UK colony)!

--
@~@ 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
^ ^ 14:44:01 up 6 days 23:46 0 users load average: 1.00 1.01 1.05
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

 

[Phil Allison]

"Man-wai Chang"

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

Coz you are in USA, not Hong Kong (ex-UK colony)!

** Hey - rice muncher.

I am in Sydney, Australia.

BS1362 fuses are used in professional dimmers imported from the UK.



..... Phil

 

[Man-wai Chang]

** Hey - rice muncher.

Hello, wheat muncher!

I am in Sydney, Australia.
BS1362 fuses are used in professional dimmers imported from the UK.

How do you tell they were really BS1362 without any printing on the
fuse? So its look is unique among all fuses?

--
@~@ 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
^ ^ 17:59:01 up 7 days 3:01 0 users load average: 0.97 1.03 1.04
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

 

[Phil Allison]

"Man-wai Chang"

** Hey - rice muncher.

I am in Sydney, Australia.
BS1362 fuses are used in professional dimmers imported from the UK.

How do you tell they were really BS1362 without any printing on the fuse?

** Learn to fucking read - you stinking Chink moron.

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

They look much like this - fuckwit.

http://www.betterfuse.com/MyUploadFiles/image/2010-03/2010033110104827.jpg


Figured out what " The quick brown fox jumps over the lazy dog " means
??

Very deep.


..... Phil

 

[Jasen Betts]

On 2011-05-31, Man-wai Chang <toylet.toylet@gmail.com> wrote:

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

could be as dangerous as using a nail instead,

--
⚂⚃ 100% natural

 

[Man-wai Chang]

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

Sorry!

--
@~@ 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
^ ^ 20:09:01 up 7 days 5:11 0 users load average: 1.04 1.09 1.08
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

 

[Winston]

bud-- wrote:

(...)

Nice post a couple levels up.

Thanks!

Meters like the Flukes are "Category" rated - 1, 2, 3. When working on
high capacity services, like 1000A 480V, you really want a cat 1
meter. You won't wind up wearing it as in your previous post. The
problem is not just the meter. Arc in meter causes vaporized meter
leads that turns into an arc between busbars - very dangerous.

I learned about 'flashover' only very recently.
Once you know about it, it's obvious.

In addition to the nominal voltage you have the hazard of transients
that could start an arc which will then sustain at the nominal
voltage. In the US, OSHA may also take strong exception to using a
meter without the right cat rating.

One of the hazards in high capacity services is available fault
current, which can be 200,000A. Fuses have a rating for available
fault current. The fix is to use "current limiting" fuses. For high
currents they have a clearing time of under 1/4 cycle. You handle a
200,000A available location by the fuse clearing before the current
increases to anything near that value. The earlier Fluke fuse is
certainly current limiting. The fuse opens before the meter leads turn
to plasma.

So *that's* the '40,000 A' number in the 11A fuse ratings.
I always wondered about those stunningly huge numbers.

The fuse in the later link is a mere 250V - not likely a cat 1 meter.

I pointed to that fuse to show that Fluke were not
undercharging for replacement parts.
That fuse is in a 'hobby / light industrial' instrument.

But a glass 250V GMA fuse in a meter may exceed the fault current
rating for the fuse. One of the fuses in my Fluke is 0.44A and is
almost certainly current limiting.

That's the same package as the 11 A fuse I originally mentioned.

Ironically, I popped it measuring automotive electrical stuff.
(Note to self: Don't leave meters on the bench with the probes
connected to measure current!)

Lesson learned.

--Winston

 

[Winston]

Phil Allison wrote:

(...)

Piss off wanker.

You are so beautiful when you are angry, Phil.

--Winston

 

[Jamie]

Winston wrote:

Phil Allison wrote:

(...)

Piss off wanker.


You are so beautiful when you are angry, Phil.

--Winston
no, he's not angry, he's being Phil.

Jamie

 

[bud--]

On Jun 1, 12:09 am, "Phil Allison" <phi...@tpg.com.au> wrote:

"Winston"



Phil Allison wrote:

I didn't know that.

** Cos you know fuck all about anything.

It's a continuing problem.
Watta ya gonna do.  

How about this one?
http://www.flukeonlinestore.com/3478747.html

** Standard glass (fast) fuse by the look of it.

It must be ~36 times safer than a commodity GMA
fuse in a multimeter application, yes?
http://www.amazon.com/125mA-250v-Fuses-0-125A-5x20mm/dp/B004HLZYVI

Fluke wouldn't overcharge for that part either,
surely.

** The price is very steep.

But I expect the fuse IS safe when used in the Fluke DMMs it is specified
for.

The scenario with a 0.125A fuse is nothing like the one with the 10A range
fuse.

Typical 0.125A rated fast fuses have resistances of 8 to 10 ohms  -  which
limits the fault current to a value the fuse can easily break.

A 10 amp fuse may well have a resistance of only a few milliohms, so the
fault current is only limited by the resistance of the DMM's leads.

A current of 40 amps is easy enough for a small fuse to break, while one of
over 4000 amps is not.

Capice?

Nice post a couple levels up.

Meters like the Flukes are "Category" rated - 1, 2, 3. When working on
high capacity services, like 1000A 480V, you really want a cat 1
meter. You won't wind up wearing it as in your previous post. The
problem is not just the meter. Arc in meter causes vaporized meter
leads that turns into an arc between busbars - very dangerous.

In addition to the nominal voltage you have the hazard of transients
that could start an arc which will then sustain at the nominal
voltage. In the US, OSHA may also take strong exception to using a
meter without the right cat rating.

One of the hazards in high capacity services is available fault
current, which can be 200,000A. Fuses have a rating for available
fault current. The fix is to use "current limiting" fuses. For high
currents they have a clearing time of under 1/4 cycle. You handle a
200,000A available location by the fuse clearing before the current
increases to anything near that value. The earlier Fluke fuse is
certainly current limiting. The fuse opens before the meter leads turn
to plasma.

The fuse in the later link is a mere 250V - not likely a cat 1 meter.
But a glass 250V GMA fuse in a meter may exceed the fault current
rating for the fuse. One of the fuses in my Fluke is 0.44A and is
almost certainly current limiting.

--
bud--

 

[Winston]

Jamie wrote:

Winston wrote:

Phil Allison wrote:

(...)

Piss off wanker.


You are so beautiful when you are angry, Phil.

--Winston
no, he's not angry, he's being Phil.

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

I see.

--Winston

 

[Michael A. Terrell]

Man-wai Chang wrote:

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

Sorry!

Ignore Phil. He's mentally ill, and off his medication most of the
time.


--
It's easy to think outside the box, when you have a cutting torch.