heated rear screen

Post by **Cam** » Thu Dec 18, 2003 8:15 am

Yes, this is why you can buy slow blow and quick blow glass fuses. The quick blow are the ordinary type, but the slow blow has a small in-line low value resistor. These are normally used for 'spikey' appliances as the wire can handle short bursts at high current, so the slow blow fuse stops the fuse blowing all the time.

I have only seen these fuses for electronic applications and never for automotive, but I suppose anything is possible!

Post by **Gareth** » Thu Dec 18, 2003 11:12 am

I guess you may have passed GCSE science

Yup, but I appear to have forgotten most of it... However, ask me about Yr6 Materials and Properties, and I'm up there with the best of them, 'cos I was teaching it up until last week!

Post by **Kevin** » Thu Dec 18, 2003 11:47 am

However, ask me about Yr1906 Materials and Properties, and I'm up there with the best of them,

OK Gareth how much was a 3 Bed detached house in Halesowen in 1906 worth (that was the sort of question you meant wasnt it

)

Post by **Cam** » Thu Dec 18, 2003 11:49 am

There's always one...................................... and it's always you!!

Post by **Kevin** » Thu Dec 18, 2003 11:56 am

What do you expect at my age

Post by **Gareth** » Thu Dec 18, 2003 12:23 pm

About the same price as a Four Door Minor in 1962...

;)

Post by **lowedb** » Thu Dec 18, 2003 1:23 pm

Yes, this is why you can buy slow blow and quick blow glass fuses. The quick blow are the ordinary type, but the slow blow has a small in-line low value resistor. These are normally used for 'spikey' appliances as the wire can handle short bursts at high current, so the slow blow fuse stops the fuse blowing all the time.

You are right, there are different kinds of fuse. I'm not sure I've ever seen a fuse with a resistor in it, only ones with springs. There is a blob of material like solder (I don't know what the material is) that melts and the spring pulls the contact away. The metal takes a time to heat up and melt so they stand surges better.

Any fuse has a certain time delay, and it depends how far over the rated current you are. A 'standard' fuse can take minutes to go at just over rated current. For example, a fuse carrying 110% of it's rated current will last at least 4 hrs, and has to blow in less than 1hr at 135% according to one specification. The specification about time delay or normal fuses is considered at 1000% of rated current. This is why you have to consider the resistance of the wire to make sure it doesn't get hot before the fuse has time to blow. You need to get into the 1000% current region to make sure.

Post by **Cam** » Thu Dec 18, 2003 1:28 pm

I'm not sure I've ever seen a fuse with a resistor in it, only ones with springs.

I used to sell them when I worked in an electronics shop in 1992/3 - Worthington Bros, Newcastle-Under-Lyme.