Semi conductor fuses

[YachtJem]

I'm trying to find a replacement for the fuse that lies between the voltage regulator and the batteries. The installation is a 25 year old perkins diesel with Cobb alt and CAV regulator (24V)

It is a big cyclindrical one, 240 volt semi conductor with 75 LET written on the side. Electrical suppliers have looked blankly at me when presented with it.

Anyone know what this might be called these days?

 

[bobgosling]

Is it one of these ?

click here

 

[Evadne]

Semiconductor fuses are often listed as resettable, polyfuse or multifuse fuses, if that helps. Farnell ones are here but none look big enough for your needs (6A max). I presume you're sure it is a fuse and not an inrush preventer (another thermister).

 

[allangray3]

It could be a FET used to control overcharging.

 

[William_H]

We need a photo. Semiconductor fuses are not common but are aften used to protect loud speakers in high fi systems. They have a low resistance when cool but increase rapidly in resistance when heated (overloaded) So in a fault condition they willl still tend to pass enogh current to keep themselves hot and so high in resistance.

I am probably way off the mark but older 24 volt aircraft generator systems used a carbon pile regulator. These may be described as large cylindrical. They have a magnet coil and armature which crushes together or releases pressure on a pile of carbon discs. The pressure reduces the resistance which increases the current to the field coil of the generator. What you think is the regulaor could be in fact a cut out coil. This is a relay which diconnects the gen from the battery at low revs or stop.

So what made you call it a semiconductor fuse? PM me for more searching the dark recesses of olewill's skull