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Re: NST Protection and Filters



Hi Ron,

At 07:36 AM 02/24/2000 -0800, you wrote:
>I am a bit confused on the recent thread of MOVs.  Do I have it correctly
>that they are a substitute for safety gaps on an NST?

I use them right up next to the NST.  I also have conventional safety gaps
if parrallel with the main gap.  MOVs will stop fast spikes and low current
(amps) easily.  However, I would depend on solid conventional safety gaps
to take a full hit from the primary cap (like trying to discharge full
voltage into a single leg of the NST).  The MOVs would stop that too but
only once ;-)

>
>If I have that right can tell me how to correctly set up a protection
>circuit using an MOV for a 15KV/60 NST?.  And maybe a supplier who sells
>them (part number would be great)?

DigiKey (www.digikey-dot-com)  part# P7215-ND  2500 amp 1800 volts.  I use 7 on
each leg of the NST.  See:

http://users.better-dot-org/tfritz/NSTFilt.jpg

>
>While I am on the subject of protection, can someone tell me how to
>properly filter for EMI?  Do you hook up a filter to the power lines
>leading to the RSG motor?  How are filters rated, in amps?  watts?  How
>do I properly match a filter to my coil?  Sources and part numbers?

DigiKey sells many (get their catalog).

I have one between the ac line and everything else.  I also have onle at
the input of the NST and at the input of the gap motor.  I also put 240
volt MOVs arcoss the line and from each line to ground at each line filter. 

>
>Thanks,
>Ron West
>