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Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
I was walking along and I came across three 12kV surge arresters on the ground under a utility pole. The plastic cover on the top was damaged, but otherwise they looked like they were in good condition. They must have been recently replaced because they still had wire attached to them. I took them home and now I'm wondering what I can do with them. Could I test their clamping capabilities with a flyback transformer, measuring the voltage across it with a voltage divider? According to the datasheets they are just a bunch of MOVs in series with lots of insulation.
The only thing I can think of is using it as protection for a NST in TC operation.
Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
All I have is a 12kV NST but I can overdrive it with a variac for a short bit, I suppose. I tried to look at the top of the pole today while passing by but there were trees in the way. I'll keep an eye out. They were all just lying under it with the wires cut off and metal brackets unbolted, so I'm guessing they were replaced. I hope it was for some silly regulatory reason and not because they are busted...
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
Don't forget that the 12kv rating is RMS voltage, so the peak will be 17kv without any overdriving.
In any case, hopefully they work, but my understanding is that they are usually 'disposable' in the sense that they can only absorb so many joules of energy before they fail short. Looking at the literature at cooper power it appears that there should be a 'fuse' of sorts on the bottom that will go open when the they have failed short and need to be replaced.
One word of warning, there is a pretty beefy spring (its my understanding that MOV disks need about as much force as would a puck SCR) so if you feel like dismantling one be aware that it under tension internally.
Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
Well, I'll check the waveform for clipping with my NST without overdriving then. I thought that the arrester's rating was RMS, too, though. I'll check with overdriving if I don't see clipping, just to make sure. I'm sure all three can't be bad! *knocks on wood*
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12KV VariSTAR Surge Arresters
