Surge protector that uses no MOVS at all.

[AlanR]

I bought a surge protector made by some company called Zero Surge. Apparently, it works by first putting the surge energy through a huge inductor to slow it down and then the surge energy after is rectified (wired parallel to the means of course) to DC and then this DC voltage level triggers SCR's that dump the energy into a bank of capacitors that the SCR's connect to. Over time the energy stored in the capacitors is drained away with resistors. I just wonder why this is not more common compared to MOV based surge protectors. I don't see any flaw in this design compared to MOVs.

Must still be under patent protection I guess as to why this topology is not widespread in usage:
http://www.zerosurge.com/wp-content/uploads/US4870528.pdf


Here are some pictures:










I have not tore it down yet because the screws are #0 Philips and they are VERY tightly bound in place to where they will strip out if turned.

[BradC]

I have heard/read some pretty good things about their products actually. There was a teardown done somewhere but after a cursory look I lost the link. Interesting technology with a higher design life due to the lack of sacrificial components, but you'd have to burn off a lot of MOV's to justify the extra expense.

[amyk]

Looks more complicated than a ferroresonant transformer, which might be the basic principle they're relying on.

[T3sl4co1l]

Nah, it's not that.  I see reference to the inductor being wound on an iron rod core, which is already a little disturbing as that will saturate quite easily under transient conditions.  So the inductance value will change, but not by orders of magnitude, maybe only 1/2 to 1/4, still leaving a lot of inductance left to drop the transient voltage across.

Now, if it were made on a conventional transformer core, the saturation ratio would be huge, and it wouldn't work very well at all!

You could put a saturable core in parallel with the mains, so that when a huge gulp of flux is delivered (such as from lightning!), it saturates the core.  The leading edge is still let through, but that can perhaps be filtered away without too much trouble.  You still need the series inductors, which increase the transient impedance of the mains supply.  Maximum clamping ratio is simply an inductor divider: series inductor over saturated inductor.  So it's still not all that great.

Just a plain old conventional transformer, does a pretty good job at this, actually.  The poor leakage of a bank-wound transformer is an advantage here, because the leakage acts as the series inductor, and the secondary is more effectively shorted out by the saturated core.

Tim

[AlanR]

Found a video where they show the insides at 1:14   You can see the capacitor bank that stores the surge energy and the large inductor.












***UPDATE***


I was able to get inside the surge suppressor. 

Here are some pics and a schematic I made when I traced all the components on the board.