Hi all.
I have been reading conflicting arguments when it comes to fuse sizing for transformers. Especially when it comes to smaller transformers say <25VA.
To complicate things further some manufactures include a thermal fuse in the windings.
Reading some of Rod Elliotts articles suggests that smaller transformers can’t be made safer with the use of external fuses. I still can’t understand why he says so. Maybe someone can explain?
I have opened up many wall wart type packs only to find no fuses and sometimes only thermal fuses. What if i find a replacement transformer that has no thermal fuse?
I do mainly repairs and want to give my clients the assurance when having to replace a transformer in their gear.
Thank you in advance all!!
I have been reading conflicting arguments when it comes to fuse sizing for transformers. Especially when it comes to smaller transformers say <25VA.
To complicate things further some manufactures include a thermal fuse in the windings.
Reading some of Rod Elliotts articles suggests that smaller transformers can’t be made safer with the use of external fuses. I still can’t understand why he says so. Maybe someone can explain?
I have opened up many wall wart type packs only to find no fuses and sometimes only thermal fuses. What if i find a replacement transformer that has no thermal fuse?
I do mainly repairs and want to give my clients the assurance when having to replace a transformer in their gear.
Thank you in advance all!!
One practical problem is that it is hard to find very low rated fuses.
I guess that 25VA limit comes from having minimum 0.1A fuses (in a 220-240V Country)
I also guess, and not too comfortable with that, manufacturers "think" the very thin primary winding wire will act as a fuse ..... what could go wrong? 🙄
If you want to protect the load, use a fuse on the secondary which makes the task easier.
The so called thermal "fuse" is not "a FUSE" in the normal meaning, it does not react to current but temperature.
I guess that 25VA limit comes from having minimum 0.1A fuses (in a 220-240V Country)
I also guess, and not too comfortable with that, manufacturers "think" the very thin primary winding wire will act as a fuse ..... what could go wrong? 🙄
If you want to protect the load, use a fuse on the secondary which makes the task easier.
The so called thermal "fuse" is not "a FUSE" in the normal meaning, it does not react to current but temperature.
