hey guys as you may see I'm in my pickup
today because my van is in the shop so I'm very limited in what it can do and I thought I
would do a video I've been planning for some time about Transformers and
fuses the VA ratings on them and it's been a while since I've done a tech
tips video so here we go with one okay guys let's assume you're shopping for a Transformer you may
have found one that's blown you'll notice on these Transformers they all have a VA rating so what
does the VA rating mean that is basically volts times amps which is the same thing as wattage
that's how many watts a Transformer can handle and I'm gonna try to show a screen here that was
a 40 that's a 40 VA Transformer so that means 40 watts is what it can handle so you take
that 40 and you divide it by 24 we're assuming 24 is going to be your secondary
voltage and that tells you how many watts that Transformer can handle all right
so here it is is 40 VA divided by 24 volts that tells you that Transformer
can only handle 1.67 amps so it's not meant for high amperage of any kind
and in fact we often put a three amp fuse on these that means between 1.67 amps and three there
is space where that Transformer can burn up but not blow the fuse in those instances you
need a bigger Transformer like a 50 VA or a 75 VA I have run across this where people have tried to
run a zone system off the same Transformer that's in the air handler and it don't work out it burns
up the Transformer now a 50 VA divided by 24.
Can handle 2.08 amps and I'm going to show a picture
here of a 50 VA that has a 2.5 amp breaker on it once again there's a little bit of room right
there where it could burn up the Transformer and not trip that little bit that little breaker
so the lower the fuse the better I have actually seen some of them fused on the high voltage
side which is something you should never do you can fuse on the high voltage side but the
fuse would have to be up to 10 times smaller than the one that you need on a low voltage
so always fuse on low voltage inside now in more commercial equipment you might see a
Transformer that reduces down to what's control voltage it might be 120 volts you have 120 volt
contactors and stuff like that on the equipment it's the same thing they come in VA ratings
in the actually the wattage rating on those is for both the high side and the low side
either side no matter how you hook it up the VA rating is the same all right guys so
I hope that was a little bit helpful and helping you decide what size Transformer
to get explaining what the VA rating means and um maybe selecting the right size fuse
for example if you're using 40 or 50 VA you need to use the smallest one possible even
a 2.5 is just a little bit too big for 50 VA so if you up the fuse size from three to
five that gives it more room to burn up that Transformer before it blows the fuse
alright guys I hope you enjoyed that little video and I hope it was informative to some of
the new guys if you like these kinds of videos how about like And subscribe it really
does help out I'll catch you on the next
