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Author Topic: Testing MOV surge protectors Joules of energy absorption  (Read 1897 times)

Jerome Malsack

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Re: Testing MOV surge protectors Joules of energy absorption
« Reply #30 on: April 23, 2018, 10:00:20 am »

Another consideration would be flash burns.  if the arc would flash burn your eyes, welding glasses ??? 
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Mike Sokol

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Re: Testing MOV surge protectors Joules of energy absorption
« Reply #31 on: April 23, 2018, 10:21:59 am »

Another consideration would be flash burns.  if the arc would flash burn your eyes, welding glasses ???

I have a 6-ft tall lead-lined gobo on wheels with a lead-glass window that came out of a 1950's doctor's office when they had their own X-ray machines. No kidding. That will be my last line of defense along with a welding face shield and ear plugs. Since the idea is to keep raising the power level until something breaks, I have to assume it will be north of the product's rated 5,000 joules of spike protection which is nothing to take lightly. I'll design this thing for up to a 10,000 joule  discharge, start low, and take it up a bit at a time.   
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Mike Sokol
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Stephen Swaffer

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Re: Testing MOV surge protectors Joules of energy absorption
« Reply #32 on: April 23, 2018, 12:21:15 pm »

I should have made the distinction in my earlier post-the "faceshield" I mentioned was intended to be one made for arc flash-they have UV protection as well as being designed not to melt  in the event of an arc flash.  Presumaby this is a paying job-charge enough to cover the cost for the correct PPE.  It's cheaper than an ER visit.
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Steve Swaffer

Mike Sokol

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Re: Testing MOV surge protectors Joules of energy absorption
« Reply #33 on: April 23, 2018, 01:49:24 pm »

I should have made the distinction in my earlier post-the "faceshield" I mentioned was intended to be one made for arc flash-they have UV protection as well as being designed not to melt  in the event of an arc flash.  Presumaby this is a paying job-charge enough to cover the cost for the correct PPE.  It's cheaper than an ER visit.

Yes, this would be a well paying job, so I'll get the correct PPE and be super safe. I've had a few serious burns in my youth and saw a few arc-flashes from a distance, so I'm very respectful of what can go wrong with this type of experiment. Kids, don't try this at home....
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Mike Sokol
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Mike Sokol

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Re: Testing MOV surge protectors Joules of energy absorption
« Reply #34 on: May 27, 2018, 08:16:39 pm »

I now have a second client asking about a test that could use my big bug zapper. Let's see: 5,000 volts, 10,000 joules and a few thousand peak amperes. Oh baby!
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Michael Ardai, N1IST

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Re: Testing MOV surge protectors Joules of energy absorption
« Reply #35 on: May 28, 2018, 08:16:41 pm »

We use an ECAT line transient tester at work (made by Thermo Fisher Scientific).  It's more than just a big cap; there's some form of LC pulse-shaping network in there.  There's a specific test sequence that we use (if I recall, 3 pulses 30 seconds apart at +/-6kV 200A  every multiple of 30 degrees from zero crossing of the AC line).  That's for indoor stuff; when we did a device that mounts to street lighting poles, we had to send it out to a site that could do much higher power.

As for failure modes, MOVs tend to fail shorted, and since they are across the AC line, then tend to go bang...  So yes, the blast shield is needed :-)
« Last Edit: May 28, 2018, 08:21:51 pm by Michael Ardai, N1IST »
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