[Premium-Rx] Surges and spikes

[Steve Stutman]

Hi All,

Ferro-resonant conditioners operate as George states; usually with 
saturated cores. Because of this they run warm, but are designed to do 
so and are very durable and long-lasting. They will also cruise through 
a brown-out, no problem. I used a couple rated at about 2 kVA for almost 
a decade in a place where I needed a clean line.  Did not notice any 
RFI; big dumb reactances all around. They are quite heavy, of course, 
but a better soln, I think, than more digital glop.

Because they are resonant at line freq, they hum a lot, but can be 
remoted. Most common brand in North America is SOLA; very good product, 
in my experience.

See:

http://www.solaheviduty.com/support/faq.html#Q5 for some basic comments.

They are usually reasonably priced on the used market, but cost a lot to 
ship. The ones I used weighed well over 8 stone. Are also some UPSs 
which are ferro-resonant, usually on output, as I recall. One brand 
is/was FerrUPS. Nice box, complicated controller. I think I still have 
one; if I can find it, it's free for pickup and rework; same fun as 
restoring old rusty bandsaw boilers, though.

I'd buy another SOLA; and no connection.

73,
Steve




George Georgevits wrote:

>Rick,
>
>  
>
>>A very good option is to get a sine tracking filter which clips
>>spikes that
>>are instantaneously a few volts greater or less than the value of the sine
>>wave at that time. I can't say how they work,
>>    
>>
>
>As I understand it, one form consists of a tuned circuit at the mains
>frequency, hence the need for large inductors. They can store energy and
>exhibit a "flywheel" effect when power is removed. That is they can provide
>very brief periods of power at the mains frequency during voltage sags.
>Also, they filter out spikes because they are tuned to the mains frequency.
>
>Hope that helps.
>
>George Georgevits
>VK2KGG
>
>
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