Re: MOVs

[Terry Fritz <twftesla-at-uswest-dot-net>]

Hi Herwig,

	Really, no one knows the "best" current rating.  The bigger they are the
longer you can run them into overload before they short.  The 2500 amp ones
run for about 30 seconds into a pretty good overload before they short
which is long enough for you to turn the power down if you are going to
anyway :-)  They run a little over a buck each.  You can get 6500 amp for
about $4.

I think the 2500 amps will do fine.  They will easily stop any transeint
and should only die when you turn the variac up far too high unitl they
burn up.  With lots of transformers, the 6500 amp ones may give you a bit
more time to turn it down before the MOVs are damaged.  With like five
NSTs, the time to kill the MOVs may be rather short so the larger ones may
be worth the money in that case.  You can get really big ones like 25000
amp but that will run you about $60 each which is far too much...

Cheers,

	Terry

At 07:53 AM 7/18/00 +0200, you wrote:
>
>Hi, Terry,
>
>You wrote to Dave: "You may want to get higher current MOVs 
>although they get pricey at higher current levels."
>
>What's "higher current"?  Is there any ballpark figure you could  
>recommend? E.g. xformer output current / MOV peak current?
>
>Thank you for your rf-filter-design-advice.
>
>Herwig
>