Author Topic: HRC Fuses  (Read 54997 times)

0 Members and 1 Guest are viewing this topic.

Offline mitpattersonTopic starter

  • Regular Contributor
  • *
  • Posts: 89
  • Country: us
HRC Fuses
« on: January 03, 2011, 03:50:57 am »
I hear Dave talking all the time about HRC Fuses in multimeters he reviews and I have a few questions:
  • I know HRC means High Rupture Capacity(or something similar), but what good is that in a meter? it not like the glass breaking on a normal meter is going to cut you until you take it apart, or am i missing something?
  • And if they are that much better, can you just replace the glass ones in a normal meter with HRC fuses of the same size and ratings? or is there something special there that would make this not possible?
This may be a bit "Noobish" but i appreciate you reading this and replying. Also if this should be in a different section(like the beginner one or the blog one) feel free to have a mod move it where it goes.

Thanks
 

Online Psi

  • Super Contributor
  • ***
  • Posts: 9889
  • Country: nz
Re: HRC Fuses
« Reply #1 on: January 03, 2011, 04:24:12 am »
As i understand it... when a normal glass fuse blows under extreme load. ie, you put your meter across something that can supply 1000's of amps at high voltage. The fuse wire inside instantly vaporizes creating massive pressure and heat which explodes outwards melting and breaking the glass case. You then have a shower of molten metal and glass moving out at high speed in all directions and cutting through the multimeter's plastic case as it goes, like a shaped charge cutting through the armour on a tank. So not the kind of thing you want to happen while you're holding the meter.  HRC fuses don't explode like that, they are designed to handle the pressure safely.

ok, that was probably a bit overly dramatic, it's pretty uncommon for them to actually do that but you get the idea, glass fuses break easier making a mess inside your meter that you have to clean up and which may damager other parts inside or hurt you throught the case. HRC fuses are designed to prevent flashover, the sand inside them melts into glass and because glass is an insulator they stop any arcs from trying to keep the connection.
« Last Edit: January 03, 2011, 04:42:33 am by Psi »
Greek letter 'Psi' (not Pounds per Square Inch)
 

Uncle Vernon

  • Guest
Re: HRC Fuses
« Reply #2 on: January 03, 2011, 04:30:14 am »
  • I know HRC means High Rupture Capacity(or something similar), but what good is that in a meter? it not like the glass breaking on a normal meter is going to cut you until you take it apart, or am i missing something?

Yes you are missing something, the other thread in this forum has gone off on quite a tangent about CAT ratings and life safety, these are far from the sole reason for selecting HRC fuses.  In general semiconductors and PCB tracks are an excellent means of protecting standard rated fuses in electronic devices. A HRC fuse is designed to interrupt current flow in as few cycles as possible. HRC applies as much to the ability to respond quickly as it does to the ability to ensure high fault current flow can be broken

Cheap meters use the audible THARWARPPP!!! indication of this error and are reset by substituting a replacement meter with its smoke still intact. Your Fluke or better meter can generally cope with the inadvertent resistance measurement across the mains at least for a few seconds while flashing their display to indicate PEBMAC error.
And of course there is the inevitable meter left on amps before a mains measurement. Try that with a standard fuse and the current shunt and PCB tracks will become a shiny patch on the back of the meter case. That is the primary reason for selection of HRC. As CAT rating increase so too do the specifications but what is stated above still applies.

Quote from: mitpatterson
  • And if they are that much better, can you just replace the glass ones in a normal meter with HRC fuses of the same size and ratings? or is there something special there that would make this not possible?
They are much better if the task is equipment protection, equally they are much worse if used in applications such as motor starting or capacitor charging.   Can you replace the glass fuses in a multimeter with HRC fuses of a similar voltage and current rating? Of course provided you can find ones of suitable dimensions. You can find 00 and 3AG sized HRC fuses, but don't forget to top up the credit on the Visa Card before purchase. But sure you can put a $20 fuse in a $35 Dollar meter.
« Last Edit: January 03, 2011, 04:43:41 am by Uncle Vernon »
 

Offline mitpattersonTopic starter

  • Regular Contributor
  • *
  • Posts: 89
  • Country: us
Re: HRC Fuses
« Reply #3 on: January 03, 2011, 04:43:37 am »
Can you replace the glass fuses in a multimeter with HRC fuses of a similar voltage and current rating? Of course provided you can find ones of suitable dimensions. You can find 00 and 3AG sized HRC fuses, but don't forget to top up the credit on the Visa Card before purchase. But sure you can put a $20 fuse in a $35 Dollar meter.

oh, wow, i didn't realize there where that much more expensive. Foe example if i wanted to find some at say, Mouser(http://www.mouser.com/Circuit-Protection/Fuses/_/N-5g3l/ ) what would i choose to find them? i don't see a HRC catagory, is there another name for them?

Oh and for the record, i got a $55 meter, lol
 

Uncle Vernon

  • Guest
Re: HRC Fuses
« Reply #4 on: January 03, 2011, 04:56:16 am »
Can you replace the glass fuses in a multimeter with HRC fuses of a similar voltage and current rating? Of course provided you can find ones of suitable dimensions. You can find 00 and 3AG sized HRC fuses, but don't forget to top up the credit on the Visa Card before purchase. But sure you can put a $20 fuse in a $35 Dollar meter.

oh, wow, i didn't realize there where that much more expensive. Foe example if i wanted to find some at say, Mouser(http://www.mouser.com/Circuit-Protection/Fuses/_/N-5g3l/ ) what would i choose to find them? i don't see a HRC catagory, is there another name for them?

Oh and for the record, i got a $55 meter, lol

They can be that expensive one off retail in AU anyway.  I'm not in the habit of stressing my meters so I don't see too much need for a bulk buy. You can often get fast acting glass fuses which are better than standard but not up to being classified as HRC.
Try a google search on 3AG HRC.
 

Offline NiHaoMike

  • Super Contributor
  • ***
  • Posts: 8972
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Re: HRC Fuses
« Reply #5 on: January 03, 2011, 05:03:28 am »
Another thing to consider is the series resistance. If it would significantly affect the circuit voltages while testing current, it would cause a significant inaccuracy.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline mitpattersonTopic starter

  • Regular Contributor
  • *
  • Posts: 89
  • Country: us
Re: HRC Fuses
« Reply #6 on: January 03, 2011, 05:10:32 am »
Another thing to consider is the series resistance. If it would significantly affect the circuit voltages while testing current, it would cause a significant inaccuracy.

Hmmmmm... Mouser doesn't seem to list the Series Resistance for the fuse i found. It seems that a Cermaic fuse would still be better than a glass one? am i right? even if its not HRC rated it would probaly be better than glass. Well anyways, tell me what you think of these fuses as drop in replacement's for my Extech EX330 meter(which only has glass fuses, i would probaly just get one or 2 on my next mouser order as replacements in case i ever blow the glass ones)

250V 500mA: http://www.mouser.com/ProductDetail/Schurter/00011001/?qs=sGAEpiMZZMseCiJT91fwIpCS8D8NVahFjqM5t9f0yKw%3d
250V 10Amp : http://www.mouser.com/ProductDetail/Schurter/00011014/?qs=sGAEpiMZZMseCiJT91fwIiiR5WGKbntkea7k9eh0bPE%3d

Now the 10 Amp one mouser list as glass, but the data sheet says is ceramic, so i generally believe the data sheet... but do those both look they could be drop in replacements?(same size, the fuses in the EX330 per my digital calipers are 5mm X 20mm, well a bit different, but thats the closest standard size)
 

Uncle Vernon

  • Guest
Re: HRC Fuses
« Reply #7 on: January 03, 2011, 05:27:23 am »
Another thing to consider is the series resistance. If it would significantly affect the circuit voltages while testing current, it would cause a significant inaccuracy.

Hmmmmm... Mouser doesn't seem to list the Series Resistance for the fuse i found. It seems that a Cermaic fuse would still be better than a glass one? am i right? even if its not HRC rated it would probaly be better than glass. Well anyways, tell me what you think of these fuses as drop in replacement's for my Extech EX330 meter(which only has glass fuses, i would probaly just get one or 2 on my next mouser order as replacements in case i ever blow the glass ones)

250V 500mA: http://www.mouser.com/ProductDetail/Schurter/00011001/?qs=sGAEpiMZZMseCiJT91fwIpCS8D8NVahFjqM5t9f0yKw%3d
250V 10Amp : http://www.mouser.com/ProductDetail/Schurter/00011014/?qs=sGAEpiMZZMseCiJT91fwIiiR5WGKbntkea7k9eh0bPE%3d

Now the 10 Amp one mouser list as glass, but the data sheet says is ceramic, so i generally believe the data sheet... but do those both look they could be drop in replacements?(same size, the fuses in the EX330 per my digital calipers are 5mm X 20mm, well a bit different, but thats the closest standard size)

Will it fit? Depends entirely upon the fit and quality of the fuse clips. In general the HRC cartridges are designed with a slightly smaller diameter. So in short you should be able to replace a standard cartridge fuse with a HRC one, (I did say should, not all clips are equal) but you should not be able to fit a cartridge fuse into a holder intended for a HRC fuse. (Application of sufficient force can disprove that theory too, usually with poor end results)
« Last Edit: January 03, 2011, 08:11:08 am by Uncle Vernon »
 

Offline mitpattersonTopic starter

  • Regular Contributor
  • *
  • Posts: 89
  • Country: us
Re: HRC Fuses
« Reply #8 on: January 03, 2011, 05:45:46 am »
Another thing to consider is the series resistance. If it would significantly affect the circuit voltages while testing current, it would cause a significant inaccuracy.

Hmmmmm... Mouser doesn't seem to list the Series Resistance for the fuse i found. It seems that a Cermaic fuse would still be better than a glass one? am i right? even if its not HRC rated it would probaly be better than glass. Well anyways, tell me what you think of these fuses as drop in replacement's for my Extech EX330 meter(which only has glass fuses, i would probaly just get one or 2 on my next mouser order as replacements in case i ever blow the glass ones)

250V 500mA: http://www.mouser.com/ProductDetail/Schurter/00011001/?qs=sGAEpiMZZMseCiJT91fwIpCS8D8NVahFjqM5t9f0yKw%3d
250V 10Amp : http://www.mouser.com/ProductDetail/Schurter/00011014/?qs=sGAEpiMZZMseCiJT91fwIiiR5WGKbntkea7k9eh0bPE%3d

Now the 10 Amp one mouser list as glass, but the data sheet says is ceramic, so i generally believe the data sheet... but do those both look they could be drop in replacements?(same size, the fuses in the EX330 per my digital calipers are 5mm X 20mm, well a bit different, but thats the closest standard size)

Will it fit? Depends entirely upon the fit and quality of the fuse clips. In general the HRC cartridges are designed with a slightly shorter diameter. So in short you should be able to replace a standard cartridge fuse with a HRC one, (I did say should, not all clips are equal) but you should not be able to fit a cartridge fuse into a holder intended for a HRC fuse. (Application of sufficient force can disprove that theory too, usually with poor end results)
so even with the same 5 X 20 mm dimensions it might not fit?
 

Offline Kiriakos-GR

  • Super Contributor
  • ***
  • !
  • Posts: 3525
  • Country: gr
  • User is banned.
    • Honda AX-1 rebuild
Re: HRC Fuses
« Reply #9 on: January 03, 2011, 10:23:50 am »
Forget all of you , the forum counter ranking , and say in simple words your answer to my question .

How worst are the Glass FAST blow fuses , from the HRC ?

Its an simple question !!

And before we get to High Voltage , I will just remind , that size in length does matters,
and so lets say that my glass fuse in my question its the long one .

Now you have only two things ( reasons ) so to debate about .

1) How fast is the " fast " ? (quick blow )
2) How safe its either type .

My view ..
About the No1  : there is an tremendous luck of information,
every one speculates that the Fuse testing , had be made by the companies that makes multimeters,
because they had to , so to pass the CAT certification , and so they know best ,
and their opinion must be accepted and respected .
Some people who are trying to find other answers , will get trapped in the physics rules,
by ignoring the chemistry ..
And some other people will turn to the manufacturers of fuses for additional info,
as I did , and I found an total chaos about the measuring standard of its electrical factor.
That makes impossible for my head at list, to make reliable comparisons of products among  just three manufacturers .

About the No2  ,  there many questions here too .
Does all Fuses explode ?
What will force one glass fuse to explode ?
Is it best the fuse to explode than just burn ?
In my opinion I believe that an small bang that will break some glass its no an major event at all.
Does the electricity loves the glass more than the porcelain ?
The burned material in the Fuse ( wire ) does it maters the chemical consistency after getting burned,
to make the exterior of the fuse , as important factor ?
Example if I make an fuse that uses as bridging material " toxic metal or elements "  I bet that I will use as exterior body on the fuse , something that does not break !!

Comparing Fuses , its an very confusing task , because every one speaks with out " Hard evidence " ,
at list at my eyes , its not called as  " Hard evidence "  some videos that show examples of what it will happens , in an very unique situation , regarding accidents in equipment that are used by highly trained personal ....  and I am saying all those , because its far from my understanding ,
how those examples will become advices that will have any value to the " home users " .. and will have any relation with what they do daily.

     
 
 
 

Online Zero999

  • Super Contributor
  • ***
  • Posts: 19342
  • Country: gb
  • 0999
Re: HRC Fuses
« Reply #10 on: January 03, 2011, 11:41:17 am »
Another thing to consider is the series resistance. If it would significantly affect the circuit voltages while testing current, it would cause a significant inaccuracy.

Hmmmmm... Mouser doesn't seem to list the Series Resistance for the fuse i found. I
It won't list the series resistance because it varies depending on the current and ambient temperature: the higher the current and temperature, the higher the resistance will be.

What is specified is the typical and maximum voltage drop at the rated current. Look at the data sheet and you'll notice that the higher the current rating, the lower the voltage drop which will only be an issue when a low current fuse is used near its rating at very low voltages. This means you won't be able to accurately measure the current drawn by a circuit connected to a couple of AA cells but it won't make a difference on a mains circuit or even one powered from a car battery.
http://www.schurterinc.com/var/schurter/storage/ilcatalogue/files/document/datasheet/en/pdf/typ_SP_5x20.pdf

every one speculates that the Fuse testing , had be made by the companies that makes multimeters,
because they had to , so to pass the CAT certification , and so they know best ,
and their opinion must be accepted and respected .
I don't see why anyone should think that.

I doubt multimeter manufacturers actually make fuses, the chances are they contract that out to someone who does.  All you need to do is replace the fuse with one with the correct current rating and a high enough voltage, breaking capacity and speed to protect the DVM and you. Of course, as you know, the problem is finding out the specification for the fuses supplied by the DVM manufacturer but I suspect any fuse designed to protect semiconductors with the correct rating and high enough voltage rating will do.

Quote
Comparing Fuses , its an very confusing task , because every one speaks with out " Hard evidence " ,
As far as I'm concerned, buying a fuse from a reputable supplier, with the appropriate approvals, is good enough evidence that it won't blow up.
« Last Edit: January 03, 2011, 11:43:12 am by Hero999 »
 

Offline cybergibbons

  • Frequent Contributor
  • **
  • Posts: 400
Re: HRC Fuses
« Reply #11 on: January 03, 2011, 11:48:13 am »
A HRC fuse is designed to interrupt current flow in as few cycles as possible. HRC applies as much to the ability to respond quickly as it does to the ability to ensure high fault current flow can be broken

And of course there is the inevitable meter left on amps before a mains measurement. Try that with a standard fuse and the current shunt and PCB tracks will become a shiny patch on the back of the meter case. That is the primary reason for selection of HRC.

Sorry - HRC has no relation to the speed of operation of the fuse. It just relates to the fact that the fuse will interrupt the circuit without rupturing or breaking even with very high (1.5kA+) fault currents. It's easy for 10kA to flow when you put a meter measuring current over a 1000V source.

It's quite likely that the HRC fuse in most high end meters will take longer to blow that a fast-acting glass fuse. But it isn't there to protect the meter - it's there to protect the use and stop them having their hand or face blown up if they make a mistake. This is entirely possible - just look for videos on youtube or read some arc flash accident reports. Some meters will have series protection - one set to blow quickly under normal fault conditions, and another to interrupt massive fault currents.

Kiriakos, in answer to your questions:
1. A fuse curve (I2t) will show how quickly a fuse blows in given conditions. They are widely available. In the UK at least there are standards for any fuse used in mains voltage distribution (BS88). These are easy to find but not always easy to compare - there is no single number to look at.
2. Again, this is just in spec sheets. HRC fuses tend to be 1.5kA+ breaking current, and 1" glass fuses 100A (at 250V). If you short a glass fuse across the mains it will not always break the circuit.

 

Online Zero999

  • Super Contributor
  • ***
  • Posts: 19342
  • Country: gb
  • 0999
Re: HRC Fuses
« Reply #12 on: January 03, 2011, 12:22:05 pm »
If you short a glass fuse across the mains it will not always break the circuit.
You also need to take into account of the impedance of the meter and the test leads.

For example, suppose the current setting and a cheap meter has a resistance of 1 Ohm, the resistance of the 500mA fuse is 0.5 Ohm and the mains voltage is 230V, the maximum current will be under 153.3A. Now a glass fuse might explode at that current and it might destroy the meter but it's unlikely it'll catch fire or kill you. A word of warning though: if it's the same or even a lower DC voltage it will from an arc which will cause it to catch fire.
 

Uncle Vernon

  • Guest
Re: HRC Fuses
« Reply #13 on: January 03, 2011, 01:08:55 pm »
It's quite likely that the HRC fuse in most high end meters will take longer to blow that a fast-acting glass fuse.

Bollocks! Much of the ability to not rupture in entailed in interrupting flow of fault current in the shortest possible time!!!  That fault current wont just be flowing in the fuse it'll be flowing through the leads, the shunt the sockets and PCB all of which will let go spectacularly with sustained fault current! Many of the larger HRC cartridges have a rating of maximum number of cycles before interruption.

Quote from: cybergibbons
But it isn't there to protect the meter - it's there to protect the use and stop them having their hand or face blown up if they make a mistake.

For sure! which is why interrupting fault current as quickly as possible is an essential parameter. 

If anyone is messing about with 1000V a high fault current capability on the bench they shouldn't be! 
And without wheeling out the flashing lights and the OH&S BS, some simple common sense should apply before working on LV or above. Don't work on mains alone, and if your going to work on mains on your bench invest in a RCB, the milliamps are going to kill you dead long before any fault currents based fuse explosion ever does.


Quote from: cybergibbons
Some meters will have series protection - one set to blow quickly under normal fault conditions, and another to interrupt massive fault currents.

For sure although we're yet to see this in anything but specialised equipment.


Quote from: cybergibbons
If you short a glass fuse across the mains it will not always break the circuit.

I'll bet you $1000 and a replacement box of glass fuses that those fuses will flame-out across 415V every time. But don't try this at home, such experiments are by convention only performed on-site by small groups of unsupervised third year electrical apprentices with way too much spare time on their hands. :)
« Last Edit: January 03, 2011, 01:25:31 pm by Uncle Vernon »
 

Offline Jimmy

  • Regular Contributor
  • *
  • Posts: 224
  • Country: au
Re: HRC Fuses
« Reply #14 on: January 03, 2011, 01:24:43 pm »
OP  (ad I didn't read all post's)

HRC fuses are the same as the glass ones. The current flows through a fillament once the current has exceeded the fuses rating it will blow. If it is over buy a large amount eg putting 4000amp on a 1 amp fuse the fuse blows creating an air gap that will arc like an arc welder, the granular "stuff" inside the fuse is there to extinguish the arc. This means that less electricity is passed onto the rest of the circuit.
 

Offline Chasm

  • Regular Contributor
  • *
  • Posts: 211
Re: HRC Fuses
« Reply #15 on: January 03, 2011, 02:16:54 pm »
Sorry - HRC has no relation to the speed of operation of the fuse. It just relates to the fact that the fuse will interrupt the circuit without rupturing or breaking even with very high (1.5kA+) fault currents. It's easy for 10kA to flow when you put a meter measuring current over a 1000V source.


It is also easy to get kA currents in industrial installations of the "normal" 230/400V net.

An real world accident from the nineties of the last century.

Part of the completion certificate is the input voltage of the machine. So the electrician grabbed the meter from his box and began measurements. 230/400V only. Nothing fancy, right?
The problem is that the certificate calls for a measurement at -but in front of- the input breakers. This machine drew current in excess of 1000A, so the substation was close.

Again, the electrician grabbed the meter from his box, switched it from off to voltage and took the first reading. The meter leads were in the Amps sockets. This is the "minor" mistake.
The fuse (or circuitry) did not break the current quickly. The leads got hot, very quickly. The electrician took quick look at his meter and knew what was happening. Now he made a second, the  "major" mistake. He panicked and drew the test leads back, in doing to he managed to draw a three phase arc.

It took a while until the closest fuse tripped, that it was on the other side of the substation in the 20kV net did not help too much. Not seconds, but long enough to turn most of the massive copper busbars into vapor phase copper and plasma, at literal arms distance from the electrican.

Since that accident the company only uses meters which have automatic socket covers like the Gossen Meters Dave has reviewed. Their job is not so much to prevent you from plugging the test leads into the wrong sockets, but to prevent you form turning it to the wrong range while the leads are plugged in, especially when taking it out of the tool box and turning it on.

The electrician survived badly burned. Wearing glasses helped his eyesight a lot.
 

Offline Kiriakos-GR

  • Super Contributor
  • ***
  • !
  • Posts: 3525
  • Country: gr
  • User is banned.
    • Honda AX-1 rebuild
Re: HRC Fuses
« Reply #16 on: January 03, 2011, 04:20:51 pm »
Nice story Chasm = interesting .

For four years, I had an contract working in the heavy industry as electrician,
in the factory that I was , yes we had  20KV transformers , fat bars and all .

Yes I had even see the remaining s , of an large power box with melted fat bars ...
The arc that caused the complete melting of this box ( explosion and all ),
caused by loose bolts and nuts , that the cables attaches at those bars ..
No one was even close when it happened that big bang.

Another Interesting reference of yours , are about the number one scenario that the fuses needs to engage.
That is ..... To protect some one if he try to measure volts , by having the selector to Amperes.

The Gossen Meters found the foolproof design , the FLUKE ones beep like crazy and the screen notify you too.
Plus the range switch is always at Zero , otherwise it does not turn on from  off  !!!
And so its not possible to have the selector forgotten at the wrong spot from the preview measurement ..  But even if it was on sleep mode , as soon you turn the range switch at the wrong setting it will beep and nag with visual indication again.

foolproof design  for fool electricians , its only the one part of the story.
foolproof design  for every one ??    Yes those meters of Gossen and Fluke at 400-500 dollars or Euro,
they do offer that.

But the story gets interesting , because the Fluke ones looks unable to stop you (mechanically ) of keep doing your own mistake , even if it beeps and having the notification on the screen.
And so at this point , Fluke looks to worry more about this matter (Fuses) than Gossen .
And if Fluke worry about that , explains why they promote those fuses with such passion.
Simply because those Fuses are capable to protect the user and the brand name it self from getting negative comments.

Lets go to the Gossen  camp , they have the foolproof design , why then they need HRC fuses ?
At every time that I had to do an direct amperes measurement , the multimeter leads was bolted on the live contact areas or I had the " crocodiles " crock clips engaged ..
Such in-line measurements never ever was risky , even if the measurement was made by old style analog instruments.       




         
 

Online Mechatrommer

  • Super Contributor
  • ***
  • Posts: 11534
  • Country: my
  • reassessing directives...
Re: HRC Fuses
« Reply #17 on: January 03, 2011, 04:38:57 pm »
the FLUKE ones beep like crazy
And so its not possible to have the selector forgotten at the wrong spot from the preview measurement ..  But even if it was on sleep mode , as soon you turn the range switch at the wrong setting it will beep.
foolproof design  for fool electricians , its only the one part of the story.
foolproof design  for every one ??    Yes those meters of Gossen and Fluke at 400-500 dollars or Euro,
they do offer that.
count uni-t in too! it does the same to fluke... beeps like crazy.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline mitpattersonTopic starter

  • Regular Contributor
  • *
  • Posts: 89
  • Country: us
Re: HRC Fuses
« Reply #18 on: January 03, 2011, 04:42:59 pm »
  • I know HRC means High Rupture Capacity(or something similar), but what good is that in a meter? it not like the glass breaking on a normal meter is going to cut you until you take it apart, or am i missing something?

Yes you are missing something, the other thread in this forum has gone off on quite a tangent about CAT ratings and life safety

Wow, i see what you mean, mine has gone of as well, lol, if some kind sole would just tell me if those fuses from mouser that i linked to should drop in and fit, they measure the same 5mm X 20mm, will they fit? someone mentioned they miight not. And do the ratings look good? Thanks
 

Offline Kiriakos-GR

  • Super Contributor
  • ***
  • !
  • Posts: 3525
  • Country: gr
  • User is banned.
    • Honda AX-1 rebuild
Re: HRC Fuses
« Reply #19 on: January 03, 2011, 05:37:07 pm »

Wow, i see what you mean, mine has gone of as well, lol, if some kind sole would just tell me if those fuses from mouser that i linked to should drop in and fit, they measure the same 5mm X 20mm, will they fit? someone mentioned they miight not. And do the ratings look good? Thanks

Post an link or a picture of the product that you own ...

Or post an picture of what you have at hand.

To all ..


Those are pictures of my own old in age Gossen ( Metrawatt) ... 80s

Should I worry that it has an 8A fuse for the 7.5 Amperes range,
an 4A Fuse for all the lower ranges , and the 25A range Not-fused.

Or should I worry about the fuse size and type.
No I am not trying to be ironical or fishy, I am trying to get some clear answers,
so to be able to share them in the future with my self , and any one who cares about.

If there is legal maters ( new electrical regulations)  that opposes the solution named B over the old solution named as A ,
I need to know about it .

If any manufacturer are able to use what ever he likes as fuses ...  I need to know about it .

If there is a better product , in comparison with the past ....  I need to know about it .
( But I need details that verify this superiority, and the theory of the Amperes arc in DC does not works as evidence, at list to me) .

But I can not hide one information that it came to me as an advice from other experienced technicians,
the fact that we always secure by Fuse the AC part of one device , and never the DC ...
One golden rule , that it does not stand at cars - motorcycles - Trucks, and vehicles in general.


(Click on the pictures for larger image )


  

« Last Edit: January 03, 2011, 05:42:54 pm by Kiriakos-GR »
 

Offline Neilm

  • Super Contributor
  • ***
  • Posts: 1545
  • Country: gb
Re: HRC Fuses
« Reply #20 on: January 03, 2011, 05:53:22 pm »
Wow, i see what you mean, mine has gone of as well, lol, if some kind sole would just tell me if those fuses from mouser that i linked to should drop in and fit, they measure the same 5mm X 20mm, will they fit? someone mentioned they miight not. And do the ratings look good? Thanks

Simply put - an HRC fuse is designed to quickly break a high current. They are superior to normal glass fuses as they tend to have better voltage ratings and contain something to douse the arc created when the fuse melts. A glass fuse does not have anything like this and so under extream conditions the metal in a glass fuse will vapourise and turn to plasma. This will continue to conduct and will essentally act as a short circuit and bypasses the protection the fuse should have offered.

HRC fuses are found in higher rated (more expensive) meters. I personally wouldn't trust a meter that didn't have HRC fuses. My view is that if they have skimpt with the fuse, what else have they missed? I have been involved in testing multimeters to see if they met the IEC61010 safety specifications. The best result was a cheap meter that claimed 300V CATIV. The test involved putting a high voltage spike superimposed on the 300V. The idea is that the high voltage (4kV?) causes an arc and the 300V continues it. The cheap meter exploded and marked the opposite wall of the test chamber, it also blew the 100A supply fuse.

In answer to your specific question you should be able to replace a glass fuse with an equivilent HRC fuse. Just check that you can get one the same shape / size and the same rating.

Yours

Neil
Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe. - Albert Einstein
Tesla referral code https://ts.la/neil53539
 

Offline ziq8tsi

  • Regular Contributor
  • *
  • Posts: 80
Re: HRC Fuses
« Reply #21 on: January 03, 2011, 06:01:01 pm »
Since that accident the company only uses meters which have automatic socket covers like the Gossen Meters Dave has reviewed.

I do not regard that as a particularly good safety feature.  Certainly not as useful as would be a working fuse.

Perhaps if someone makes the mistake of having both the leads and the switch set for current and then connecting a voltage, they will mandate meters with no current sockets at all?  Fused test probes are worth considering too for such obviously dangerous CAT IV live working.

Maybe if someone who does not wear prescription glasses makes a similar mistake, the company will consider providing proper face and eye protection as well.  And gloves, and flash-resistant overclothing.  If anybody dies, they might even like to consider how much it really matters which side of a circuit breaker you measure voltage at.

For an electronics engineering forum, the rare dangers of CAT IV arc blasts do seem to get a lot of press here, though, rather than the much more realistic CAT II/III dangers, such as electrocution.
 

Offline Neilm

  • Super Contributor
  • ***
  • Posts: 1545
  • Country: gb
Re: HRC Fuses
« Reply #22 on: January 03, 2011, 06:39:45 pm »

Those are pictures of my own old in age Gossen ( Metrawatt) ... 80s

Should I worry that it has an 8A fuse for the 7.5 Amperes range,
an 4A Fuse for all the lower ranges , and the 25A range Not-fused.

Or should I worry about the fuse size and type.

That appears to be quite an old meter. I believe that it predates the publication of IEC61010 which is the safety standard for test and measurement equipment. As such it would not be permitted to sell this (new) in the EU.

Quote
If there is legal maters ( new electrical regulations)  that opposes the solution named B over the old solution named as A ,
I need to know about it .
IEC61010 details the tests to be done on the meter prior to it going on sale. This includes reviews of the documentation, tests on the creepage / clearances on the terminals (corrected for altitude), mechanical construction (impacts, drops, extream temperatures), risks of fire and explosions, fluids (cleaning or used in the system), interlocks, and misuse (including trying to measure volts on amps range ect).

If someone is injured using a meter issued to them that has not been tested or does not pass the tests they may be able to claim compensation from their employer. I don't know for certain but it does seem vary likely.

IEC61010 was first published in the 90's. Issue 2 was published in 2001. Currently we are in a transition period between issue 2 and issue 3 which was published in June last year. This is the first version that includes ratings of solid insulation, for example multilayer PCBs.

Quote
If any manufacturer are able to use what ever he likes as fuses ...  I need to know about it .

If there is a better product , in comparison with the past ....  I need to know about it .
( But I need details that verify this superiority, and the theory of the Amperes arc in DC does not works as evidence, at list to me) .
The manufacturer can specify any fuse they want. After they have, they will test it to the requirements of IEC61010. I believe that one of these requirements is that glass fuses are not used in certain areas. I don't know if this is a general ban or if it is only in applications that might get high currents. To pass the requirements for markings and documentation, the fuse type and rating must appear in both the documentation and be marked on the instrument near the fuse.

Quote
But I can not hide one information that it came to me as an advice from other experienced technicians,
the fact that we always secure by Fuse the AC part of one device , and never the DC ...
One golden rule , that it does not stand at cars - motorcycles - Trucks, and vehicles in general.

Personally, working on a 600V DC system is as dangerous as working on a 420V AC system - possibly worse if the source of the 600v is a bank of batteries. If you short out the batteries with your meter on the (unfused) 25A setting something will get very hot.

I do not regard that as a particularly good safety feature.  Certainly not as useful as would be a working fuse.

Perhaps if someone makes the mistake of having both the leads and the switch set for current and then connecting a voltage, they will mandate meters with no current sockets at all?  Fused test probes are worth considering too for such obviously dangerous CAT IV live working.
The only advantage of that feature is that the test house does not have to do the failure test of switching range with the leads connected.
Quote
For an electronics engineering forum, the rare dangers of CAT IV arc blasts do seem to get a lot of press here, though, rather than the much more realistic CAT II/III dangers, such as electrocution.
You can still get arc and blast from a CAT III installation. (it is just a lot harder) Also the hobbyist is more at risk of poor meters bought cheap. Dispite the efforts of some of the international commuinity, there are still manufactures who fake labels and ratings, either deliberatly or by not correctly understanding the regulations. These meters are OK for low energy low voltage applications, but can be very dangerous in the wrong situation.

Yours

Neil
Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe. - Albert Einstein
Tesla referral code https://ts.la/neil53539
 

Offline Chasm

  • Regular Contributor
  • *
  • Posts: 211
Re: HRC Fuses
« Reply #23 on: January 03, 2011, 07:11:25 pm »
Since that accident the company only uses meters which have automatic socket covers like the Gossen Meters Dave has reviewed.
I do not regard that as a particularly good safety feature.  Certainly not as useful as would be a working fuse.

By itself? No, or course not!
But in conjunction with an actually working fuse.
The mechanism prevents single fault accidents. It will not prevent you from switching the meter to amps and then proceeding to measure voltages.

I can't check on it, but as far as I remember the DMM that failed to break the current in the accident was of the well yellow brand.


For an electronics engineering forum, the rare dangers of CAT IV arc blasts do seem to get a lot of press here, though, rather than the much more realistic CAT II/III dangers, such as electrocution.

Of course much of it is ...well I won't say the w word but it is overdone.
You don't need a CAT IV meter, but even my old CAT II meter uses a 32mm ceramic fuse.

Most people in this forum get told to keep their fingers of mains voltage. Especially when it comes to the modification of PC power supplies and similar stunts.


Still, high current accidents are quite possible at low voltages and not something you can simply disregard. Say the good old car battery. Brushless motors are also quite popular. LED lighting on larger scale may also involve high currents.
 

Offline mitpattersonTopic starter

  • Regular Contributor
  • *
  • Posts: 89
  • Country: us
Re: HRC Fuses
« Reply #24 on: January 03, 2011, 07:38:54 pm »

Wow, i see what you mean, mine has gone of as well, lol, if some kind sole would just tell me if those fuses from mouser that i linked to should drop in and fit, they measure the same 5mm X 20mm, will they fit? someone mentioned they miight not. And do the ratings look good? Thanks

Post an link or a picture of the product that you own ...

Or post an picture of what you have at hand.

I have the Extech EX330 meter that won Daves $50 multimeter shoot out(actually $54.95 most places) just has standard glass fuses in it, i measured a fuse that was in it, it measured 5mm X 20mm, here are the 2 fuses in Ceramic that i beilve might work(i just want to confirm with you guys) the meter has a 500ma and a 10amp fuse(both 250V):
500 ma: http://www.mouser.com/ProductDetail/Schurter/00011001/?qs=sGAEpiMZZMseCiJT91fwIpCS8D8NVahFjqM5t9f0yKw%3d
10 Amp(the mouser pages list it as glass, but the data sheet for the product number says ceramic): http://www.mouser.com/ProductDetail/Schurter/00011014/?qs=sGAEpiMZZMseCiJT91fwIiiR5WGKbntkea7k9eh0bPE%3d
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf