Littlefuse Spec Error

Summary

The specification for " i^2 t " has units of Amps squared times seconds. There is a spec to test fuse blowing performance which uses i squared t. In the spec, that "iit" uses a current i in a fuse for a time t of 8ms. The error is that Littlefuse calls (i^2 t) energy. But it is not Joules, it is Joule seconds.

iit = Joule Seconds, not energy as Littlefuse claims.

Details

Joules = distance*force = meters*kilogram*meters/second^2

Ampere = Coulomb/second

Ampere^2 = Coulomb^2 / second^2

iit = Coulomb^2 / second

The ERROR is there. The denominator has second, but energy has second^2 in the denominator. I call upon Littlefuse to notify all of its distribution corporations to correct their documentation. It is not energy, Joule Seconds is Action.

Joule Seconds = angular momentum, and was called Action by Planck.

Joule = energy = meters*kilogram*meters/second^2

iit = Coulomb^2 / second

Reference Specs:

Littlefuse Error Spec: "This energy is described as nominal melting I^2 t and is expressed as “Ampere Squared Seconds” (A^2 Sec.). A pulse of current is applied to the fuse, and a time measurement is taken for melting to occur."

http://www.littelfuse.com/technical-resources/~/media/files/littelfuse/technical%20resources/documents/reference%20documents/elec_fuse_temp_derating.pdf

Mersen: "AMPERE SQUARED SECONDS, I^2 t It is the measure of heat energy developed within a circuit during the fuse's clearing. It can be expressed as "melting I^2 t", "arcing I^2 t" or the sum of them as "Clearing I^2 t ". "I" stands for effective let-through current(RMS), which is squared, and "t" stands for time of opening, in seconds. The use of I^2 t values to determine proper fuse typing/ rating is only valid under adiabatic conditions, where there is no external heat transfer."

http://ep-us.mersen.com/fileadmin/catalog/Literature/Application-Guidelines/electronic_fuse_facts_and_numbering_system.pdf

Alan Folmsbee, MSEE

 

[Phil Allison]

omni...@gmail.com wrote:

Summary

The specification for " i^2 t " has units of Amps squared times seconds.
There is a spec to test fuse blowing performance which uses i squared t.
In the spec, that "iit" uses a current i in a fuse for a time t of 8ms.
The error is that Littlefuse calls (i^2 t) energy. But it is not Joules,
it is Joule seconds.

** "I squared T" is an engineering term that characterises a particular fuse type. It is proportional to energy, NOT a direct measure of energy like Joules.

The resistance of the fuse and how it changes with temperature must be taken into account to know the *energy* required to melt the metal link.

I squared R times T gives Joules, but R varying with T makes computation messy.

Using "I squared T" instead solves that problem, in the case of fuse links.



..... Phil

 

[John Larkin]

On Thu, 2 Jun 2016 20:02:09 -0700 (PDT), omnilobe@gmail.com wrote:

Summary

The specification for " i^2 t " has units of Amps squared times seconds. There is a spec to test fuse blowing performance which uses i squared t. In the spec, that "iit" uses a current i in a fuse for a time t of 8ms. The error is that Littlefuse calls (i^2 t) energy. But it is not Joules, it is Joule seconds.

iit = Joule Seconds, not energy as Littlefuse claims.

No, iit = I^2 * T is not joule seconds.

I^2 * R * T is joules.

The fuse has some implicit resistance R, and some amount of
quickly-delivered joules will melt the element.


Relax. This is electronics, not physics.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Bob Engelhardt]

On 6/2/2016 11:02 PM, omnilobe@gmail.com wrote:
> ... Littlefuse calls (i^2 t) energy. But it is not Joules, it is Joule seconds. ...

i^2 t is Joule seconds? I think not. If i^2 t were Joule seconds then
i^2 would be Joules. Joules is energy; i^2 r is power; i^2 r t is
energy (Joules)

> Alan Folmsbee, MSEE

"MSEE"? What school was that?

 

On Friday, June 3, 2016 at 11:57:00 AM UTC-10, Bob Engelhardt wrote:
"

i^2 t is Joule seconds? I think not. If i^2 t were Joule seconds then
i^2 would be Joules. Joules is energy; i^2 r is power; i^2 r t is
energy (Joules)"

Thank you Bob for confirming that

i^2 r t is energy (Joules)

i^2 t is not energy

Amps squared t is not energy, as Bob has confirmed

i^2 t is not energy, it is energy per ohm.

That indicates that an ohm is the inverse second.

V = IR

V = Coulomb per square second

In the Periodic Table of Units of Measure, that is put in context.

http://fcgravity.blogspot.com/p/first-law-of-difffusion-of-herenowium.html#elec

This insight is provided by the gravity volume theory.

Alan Folmsbee, Master of Science Degree, 1989