Fuse failures

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T.M.Haja Sahib

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I'm well aware of BS88 fuse characteristics.
Then do you agree at least for the British fuses this?

Two simple tests to ascertain the health of a fuse in a given batch.First test.The fuse should not blow for current up to 140% of its rated current within one hour.Second test.The fuse should blow for current beyond 160% of its rated current within one hour.Of course the second test can not be performed on all fuses in the batch but only on a select few.
 

Besoeker

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Then do you agree at least for the British fuses this?
I see. Moving the goalposts yet again because your previous contention has been demonstrated to be invalid?
But, to answer your question, no I don't agree that it holds true for British fuses.
Get a copy of BS7671 and check Appendix 3.
 
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T.M.Haja Sahib

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no I don't agree that it holds true for British fuses.
Get a copy of BS7671 and check Appendix 3.
Some more specific information from Appendix 3 of BS7671 narrated here is beneficial to this forum as a whole.
 

Besoeker

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Besoeker

Senior Member
Location
UK
These curves from 16th edition of BS 7671 - http://www.tlc-direct.co.uk/Book/3.6.3.htm .You mean major changes in appendix3 in the current 17th edition?
Compared to what?
The earliest version of BS7671 I have is the 2001 Sixteenth Edition and even that's quite difference in appearance to the curves you provided.

BTW, you might to look at, say, the 20A fuse in your 3.14b. Do you think that would pass your tests of post #84?
 
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T.M.Haja Sahib

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Compared to what?
Compared to the 16 th edition.

The earliest version of BS7671 I have is the 2001 Sixteenth Edition and even that's quite difference in appearance to the curves you provided.
Then I can not help you.:happyno:

look at, say, the 20A fuse in your 3.14b. Do you think that would pass your tests of post #84?
Surely,yes.The 140% of 20A fuse is 28A only and it is not shown the curve is passing it.

Now time has come to show why the two tests can not be shown conclusively to be false in all cases and why they are valid ones for checking the health of a fuse.

But you finish first.
 
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T.M.Haja Sahib

Guest
The two tests about which so much contoversy was raised were actually for verifying particular
specs of a fuse.Time period and overload percentages are specified for a fuse at two points.If 140% and 160% percentages and 1 hour period as mentioned earlier are not suitable per one manufacturer's fuse specifications but his own fuse specifications such as 135% and 200% for a definite time are also suitable to the circuit protection under consideration,the same may be adopted.The important thing not to miss is the statistical checking of fuses in a lot using test-1 and test-2 using different parameters other than 140% and 160%,if so required.
 

Besoeker

Senior Member
Location
UK
The two tests about which so much contoversy was raised were actually for verifying particular specs of a fuse.Time period and overload percentages are specified for a fuse at two points.If 140% and 160% percentages and 1 hour period as mentioned earlier are not suitable per one manufacturer's fuse specifications but his own fuse specifications such as 135% and 200% for a definite time are also suitable to the circuit protection under consideration,the same may be adopted.The important thing not to miss is the statistical checking of fuses in a lot using test-1 and test-2 using different parameters other than 140% and 160%,if so required.
In post #86 you were asked what type of fuse your tests referred to.
All types was your response. ALL types.
Now, after I have pointed out two specific cases which one fail one or other of the tests you proposed in post #84, you now change it from all types to "particular specs".

You haven't just moved the goalposts. You've removed them...........
 
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