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Nov 11, 2009 10:50:23 GMT
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I'm gathering parts for an electric window conversion for my jetta. I'm trying to sort out a relay and fuse. Origionaly they would use a thermal fuse like this  Is there any reason why i cant use a normal fuse? I just looked up thermal fuses and they don't re-set, they just blow like a normal fuse, so can i just use a normal 30a blade fuse? What are thermal fuses all about? Why are they used instead of normal fuses anyway? Thanks  |
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Nov 11, 2009 12:19:21 GMT
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I'm not sure, but I suspect it's a surge rating thing. A standard car blade fuse is a quick-blow, and will blow with even a momentary current above the rating. A thermal fuse will take much longer to blow, as it has to heat up first.
I suspect, given that electric windows don't run for long, and have short-term surge currents when starting the motor or at the end of travel, that a standard fuse would blow repeatedly, while a thermal fuse would only blow in extremis - from a jammed switch or a proper short circuit.
I'd try a normal fuse, but be prepared to replace it if it blows at the end of travel of the window.
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Nov 11, 2009 13:06:52 GMT
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that makes sense, maybe ill just get a proper fuse from the breakers.
Thanks.
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stinkwheel
Posted a lot
Doctor Of Gonzo Journalism - One of gods own proptypes, never even considered for mass production.
Posts: 2,280
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Nov 11, 2009 13:18:16 GMT
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Some 70's american cars had a system of thermal blow circuit breaker things. My 78 camaro certianly did, but my 79 olds didnt........anyway, i digress............ these things were fitted instead of normal fuses to some circuits, so you had to actually go buy a new trip and fit it if it blew, weird set-up. Why did they do that?
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1973 Citroen Dyane 6 1980 Citroen Acadiane
1992 Citroen AX 1990 Citroen BX
1997 Citroen XM 1993 Citroen BX
1997 Citroen Xantia 1977 Citroen Ami 8
1996 Ford Escort 1989 Citroen BX
1997 Suzuki RF900 1988 Yamaha TDR250
1979 Honda CB400.
'I need less vehicles'
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Nov 11, 2009 14:28:54 GMT
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On high current stuff like this, don't use a normal blade fuse, get one of the "maxi" blade fuses instead. The risk with normal fuses is that at high currents, if there is a short circuit, the power wil arc across the blown contacts, but the maxi fuses contacts are much further apart once its blown so arcing is impossible. Raid a scrappy for cheap/free ones. Most modern stuff have a few, often in a seperate fusebox under the bonnet. maxi on the left, normal in the middle and mini on the right.....  |
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1986 Panda 4x4.
1990 Metro Sport.
1999 Ford Escort estate.
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ezzysi
Posted a lot
Posts: 1,189
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Nov 11, 2009 23:27:40 GMT
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Thermal fuses are just that, a fuse that blows at a pre-determined temperature. We use them in copiers and printers etc.
You can get them from maplins for not much money if you want to put one back in the circuit.
Si
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1991 Mk2 Golf Gti 8v
2005 Passat tdi (daily)
1971 Mk1 Escort
2004 Touran (her's)
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Nov 12, 2009 14:00:50 GMT
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Some cars have thermal cutouts that automatically reset, Datsun Skyline for instance. Only time they'd trip is if you acidentlly held the switch down for a long period perhaps by some cargo (or your dog) standing on it.
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69 Plymouth Fury Convertible 75 Range Rover 2 door 82 Range Rover 4 door
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04 Berlingo Multispace petrol 07 Land Rover 130 15 Nissan E-NV200 15 Fiat Ducato
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Nov 12, 2009 14:06:05 GMT
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Thermal fuses are just that, a fuse that blows at a pre-determined temperature. We use them in copiers and printers etc. You can get them from maplins for not much money if you want to put one back in the circuit. Si I don't think that they are the same ting as used in a car window circuit. You're referring to what I've always heard called thermal cutouts (rather than fuses), used to stop something (usually something with a heating element) from overheating. The fuses referred to by VW have a current rating, and appear to replace a standard blade fuse in the circuit. I stand by what I said earlier about them being a time-delayed cutout in case of surge currents. |
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Nov 12, 2009 14:06:08 GMT
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thats good to know.
Might look for a re-seting one then.
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