Fuse confused

[S'mise]

Can someone give me some basic info on the different types of fuses and their usual applications?
For instance a FRS type fuse is generally used for motors.
But, how would its response curve compare to say a FLS or LPS or TRS , or other of the same amperage?

When is it warranted to use a time delay instead of just going to a larger size (when allowed)?

I'm hoping there is a short cross reference that can steer me in the right direction, as opposed to reading a hundred of pages of specs.

Thanks, John

 

[kwired]

Most of what you mentioned is manufacturers designations more so then industry standards.

The FRS, FLS and TRS that you mentioned are all class RK-5 fuses, each from different manufacturer, they should all have very similar trip curves because they are all RK-5.

 

[S'mise]

Most of what you mentioned is manufacturers designations more so then industry standards.

The FRS, FLS and TRS that you mentioned are all class RK-5 fuses, each from different manufacturer, they should all have very similar trip curves because they are all RK-5.

Thanks Kwired, I will have to look into RK ratings also.
I believe the L designates: limiting (let through current) and T designates: time delay. Wish letters were more standardized. FRS is time delay also but had no T.
I had a LP (low peak) fuse blow on me to today and I wondered how it compared to a FRS. Is it faster, or just better at limiting let through current?
I obviously need to read up on fuses. I just don't have to time to read a book on it.
Thanks, John

 

[kwired]

Thanks Kwired, I will have to look into RK ratings also.
I believe the L designates: limiting (let through current) and T designates: time delay. Wish letters were more standardized. FRS is time delay also but had no T.
I had a LP (low peak) fuse blow on me to today and I wondered how it compared to a FRS. Is it faster, or just better at limiting let through current?
I obviously need to read up on fuses. I just don't have to time to read a book on it.
Thanks, John

Not sure you quite understood what I was trying to say.

FRS is Bussman 600 volt RK5
FLS is Littelfuse 600 volt RK5
TRS is Ferraz 600 volt RK5

They are all the same thing just different manufacturer's versions of it. The RK5 is the standard that matters, pick your favorite manufacturer if you wish.

 

[S'mise]

...all the same thing just different manufacturer's versions of it. The RK5 is the standard that matters, pick your favorite manufacturer if you wish.

Not sure you quite understood what I was trying to say....
They are all the same thing just different manufacturer's versions of it.

Got it, thank you. I'm comparing a Ford to a Chevy.

Would it be safe to say; RK-5 class fuses are slower, better suited for inductive type loads, while a RK-1 class would be better suited for sensitive loads where a quicker response is desired?
I'm trying to avoid nuisance fuse failure on inductive loads.

 

[kwired]

Got it, thank you. I'm comparing a Ford to a Chevy.

Would it be safe to say; RK-5 class fuses are slower, better suited for inductive type loads, while a RK-1 class would be better suited for sensitive loads where a quicker response is desired?
I'm trying to avoid nuisance fuse failure on inductive loads.

RK1 being quicker - not sure how trip curve compares but RK1 is considered a current limiting fuse.

An FAQ page on littelfuse site mentions that RK1, RK5 and class J all have same listing requirement for minimum time delay of 10 seconds at 500% of fuse rating.

 

[Jraef]

LPS = "Low Peak" Class RK-1, FRS = "Current Limiting" Class RK-5.

The time delay characteristics of Class RK-1 and RK-5 are identical. Class RK-5 is less expensive, but although both are considered as "current limiting" fuses, RK-1 is more current limiting (lower peak let-through) than Class RK-5 in the case of a high energy fault. So if you (or someone before you) relied upon the current limiting characteristics of the fuses for coordination with other protective devices, you have to pay attention to that detail.

 

[S'mise]

Thank you both. Your comments lend needed incite.

 

[Jraef]

Thank you both. Your comments lend needed incite.

I know I'm being picky, but "incite" is to cause angst, as in "Incite to riot".

I think you meant "insight" as in clarity of thought.

Forgive me, but my older sister is an English teacher and I was subject to her constant barrages of grammar correction for so long that I internalized them...

 

[S'mise]

I know I'm being picky, but "incite" is to cause angst, as in "Incite to riot".

I think you meant "insight" as in clarity of thought.

Forgive me, but my older sister is an English teacher and I was subject to her constant barrages of grammar correction for so long that I internalized them...

Thank you for the correction.
I nearly put "insite". Lol