Solid Fuses: Visible Indicator If Blown?

Page 2 of 5  


Or if it's an industrial environment where equipment may need to be kept running unless absolutely necessary...

Zero volts DROP, you mean? In other words, that /all/ the voltage is going through the fuse, and /none/ through your DMM, which is supposed to have a higher impedance than the fuse has?
If the fuse was blown, then the DMM would present the lower-impedance path, and you'd see all the voltage traveling through the DMM?
--
Tegger

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Since we're splitting hairs, and using italics, I'll add a netpick. Voltage doesn't travel through wires, amperes do.
. Christopher A. Young Learn about Jesus www.lds.org .
On 9/22/2013 8:19 AM, Tegger wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I can netpick as well as anybody else here: Current travels ON wires, not THROUGH them.
(You'll notice I've avoided the use of italics in favor of upper case; I typed those words LOUDER than the others.)
--
Tegger

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/22/2013 7:41 AM, Tegger wrote:

RF voltage travels on the surface too. ^_^
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sunday, September 22, 2013 8:41:19 AM UTC-4, Tegger wrote:

You're trying to claim what exactly? That the current density inside a wire is zero? In my world, it's correct to say current travels through wires. Unless you're dealing with high frequencies, where the skin effect becomes of significance.
And Daring's statement was accurate as stated, at least with regard to what you're objecting to:
"First I check for voltage on either end of a fuse to ground then across the fuse, a good fuse should measure zero volts across it "
I can see raising issue with something that isn't clear or correct. But raising spurious issues that just confuse the correct answer is pointless. If there is anything that is wrong with the statement, it's that it should say a good fuse will measure "near zero volts" across it when it's in an energized circuit. A bad one will have typically have a large amount of voltage across it with the circuit powered. Example, take a 100W light bulb in a 120V circuit with a 5 amp fuse. Fuse OK, it will read very close to zero volts across the fuse. Fuse blown, it will read ~120V. The impedance of the meter, how the current splits between the meter and the circuit, etc is just noise, unless it's some very unusual circuit where the impedance of a typical VOM is going to matter because it's of significance compared to the circuit.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You stay out of this. I have him on the ropes; my next move will finish him off cleanly, and I alone will claim the Netpick Trophy..
--
Tegger

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'd be curious if you have any web sites that explain this. It seems counter intuitive.
Years ago, friends told me that microwave ovens heat food from the inside out, which is also counter intuitive. I'd ought have tested it by put in a box of frozen solid ice cream. Give it 60 seconds, and then slice the ice cream to see what is soft and hard.
. Christopher A. Young Learn about Jesus www.lds.org .
On 9/22/2013 8:41 AM, Tegger wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It is. That assertion I made about electricity traveling on the surface of wires is apparently wrong. In my searching for evidence to back up my claim, all I came up with was the opposite.
I lose the Netpick Tournament to you. Now I have to kill you.
--
Tegger

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
First, you stupid idiot, you can't apologize. Second, you have only but to beat me in a flame war, which will be impossible, considering what a numb brain you are. However, I await your victory, with eagerness. Give it all you got, twerp. :~)) Mashed nose, and double chins. That's me.
. Christopher A. Young Learn about Jesus www.lds.org .
On 9/24/2013 8:01 PM, Tegger wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Is there any other kind of idiot? Whoever heard of a smart idiot?

My barbecue is out of gas and I've been too lazy to get new cylinders.

My brain is NOT "numb". I poked it hard the other day and it really hurt. Or maybe that was my butt...

You mean "twerk", surely? Nobody says "twerp" anymore.
--
Tegger

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I surrender. I'm just no good at flaymin.
. Christopher A. Young Learn about Jesus www.lds.org .
On 9/25/2013 8:02 AM, Tegger wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wednesday, September 25, 2013 8:42:37 AM UTC-4, Stormin Mormon wrote:

Heh, give him a break. At least he admitted he got it wrong, which is something rare here. But he's kind of gotten it wrong a second time. He seems to be ignoring skin effect. With DC, the current density is uniform in a wire. As the frequency increases, the current distribution moves toward the surface. At very high frequencies, most of it is traveling at or near the surface. The wire could be mostly hollow and it would carry almost the same current.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/25/2013 8:31 AM, snipped-for-privacy@optonline.net wrote:

Let's not forget waveguides. ^_^
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Ah, I see. Would this be true regardless of voltage or amperage?
--
Tegger

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wednesday, September 25, 2013 9:52:30 AM UTC-4, Tegger wrote:

Yes.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

frequencies, and virtually non-existent at low frequencies and DC. A hollow conductor has 2 surfaces - not sure if the inner surface comes into play or not.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

For all reasonable values of voltage and current, yes. At the extremes strange things tend to crop up.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 9/25/2013 7:02 PM, snipped-for-privacy@attt.bizz wrote:

And as you get closer to Absolute Zero. ^_^
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

At high frequencies the current is mostly on the outer portion of the wire. At 60 Hz the skin depth is about .33 inches. That is for 67% of the current. The wire wold have to be larger than .66 inches to make much differance. Not too many are going to see that around the house. Even 4/0 wire is only .46 inches in diameter.
When the frequency gets to up 1 Mhz or more then the hollow tubes will start to carry almost as much current as the solid wire.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
We've been discussing this so often, it hertz. That's how frequently we're discussing.
. Christopher A. Young Learn about Jesus www.lds.org .
On 9/25/2013 10:00 AM, Ralph Mowery wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.