The relationship between FUSE and voltage

Hey!
I want to know that is there any relationship of FUSE with voltage.
According to my view FUSE is independent of voltage am I right?
On some Fuses it is written 5A, 125V & on some other Fuses it is written 5A, 250V.
Is there any difference in between them?

how to tell if a 125v 5a fuse is blown

Hi,

heres the idea behind fuse ratings, try to think of the fuse as a wire, wires are conductors with different characteristics such as resistivity, etc..., now fuse ratings also depends on the equation:

I=V/R but R=ρL/A, where ρ is the resistivity constant of the material, L is the length of fusible conductor, and A is the area of the cross-section of the fusible conductor. The I here defines the current rating of the fuse(now fuses also depends on current ratings depending on how much current will flow on it not solely on the voltage rating)

am I clear or something?:|

fuse ratings

Another factor in the voltage rating is that enough of the fuse wire has to melt so that the gap left is large enough to not break down at the rated voltage. You may notice some fuses have springs in them to pull the wire ends further apart.

1a fuse rating

When voltage and current, both the parameters , are written on fuse, which tells that the written current is the maximum current, which will be allowed by the fuse at specified voltage. The current above than specified value, will blow the fuse by melting it.
Melting of the fuse is due to power dissipatiion.
P=V×I
V=I×R WHERE R is the resistance of the fuse
For example if specification of the fuse are 1Amp. and 250V. So, the resistance of fuse is R=V÷I=250Ω
So, max. power P=1×250=250W
Now, if current exceeds due to increase in voltage by relation . If the voltage exceeds to 300 VOLTS, the current will increse to
I=V÷R=300÷250=1.2 Amp
So, the power dissipation increses to
P=V×I=300×1.2=360W
This dissipation is more than specified diissipation of 250 W , and the fuse will be blown.

So, Voltage is also important for Fuse Ratings.

Re: FUSE rating

@ Hamdrad
(Considering the Fuse specifications 1A, 250v)

if u r treating Fuse as a resistance of 250 Ω then it means that u can replace a Fuse of 250v,1A by a resistor of 250 Ω . Strange ?

you have said that
R=V/I = 250 Ω (Resistance of the fuse)
P=VxI = 250w (power dissipation in the form of heat responsible for melting the Fuse or if it exceeds this limit the fuse will melt)
Or
P=I2R = 250w
Ur statement
“Now, if current exceeds due to increase in voltage by relation . If the voltage exceeds to 300 VOLTS, the current will increase to
I=V÷R=300÷250=1.2 Amp
So, the power dissipation increases to
P=V×I=300×1.2=360W
This dissipation is more than specified dissipation of 250 W , and the fuse will be blown.

So, Voltage is also important for Fuse Ratings. “

According to my own way of thought,
Suppose this Fuse is connected to a load (27.7 Ω) in series with a supply of 250v.
if the resistance of the Fuse is 250Ω (as u said) then the voltage drop across the fuse is 225v if we r applying a supply voltage of 250v & the current flowing through it is 0.9A

V = IR = 0.9A x 250 Ω = 225v (voltage drop across the fuse)
V = IR = 0.9A x 27.7 Ω = 25v (voltage drop across the load)
As these results clarify that most of the volts (225v) r dropping across the fuse, which is practically impossible.
Secondly if u put this fuse 250V,1A in a circuit where the supply voltage is only 10v then according to ur concept the power dissipation required to melt this fuse is 250w
P = VxI = 10v x 25A = 250w (power dissipation)
Oooh now see in this way we need more then 25A to melt the Fuse, does is make any logic?????
In an actual case the resistance of 250v, 0.5A Fuse is app 0.1Ω (Digital meter Reading) & the resistance value for 125v, 0.5A Fuse is approximate the same

@ flatulent
“You may notice some fuses have springs in them to pull the wire ends further apart” the spring is used to create a tension in the wire the purpose behind this is make the fuse very sensitive .These type of Fuse are used in sensitive equipments to protect the equipment with out any serious damages.

FUSE rating

So basically if a fuse has a 1amp rating, any voltage source that produce a current over 1amp will blow the fuse? Assuming the voltage doesn't go above the maximum printed on the fuse.

What's the different between AC and DC fuse? Why is it not safe to interchange them?