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Attempting to identify some nice HV capacitors.

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LAN_403

GrantX

Mon Sept 21 2015, 05:34PM

Registered Member #4074 Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335

I found some new-old-stock HV capacitors (a little dusty, but they look pretty much untouched) and decided to pick them up for a bit of fun, because they were quite cheap. They all measure the correct capacitance, and don't seem to have any internal bleeder resistors or shorts (tested up to 325VDC).
Here's a photo showing the total bounty:

Now I just need to find the datasheets, or at least what dielectrics and internal construction they use.

First up are four capacitors made by TPC, part number K9HFMAB420506. They're rated at 4,200VDC (4,700V pk), 50uF +/-5% and have "prototype" on the label. After a bit of searching the only data I can find is they're hermetically sealed oil-filled construction, designed for motor run applications. From this, I assume the dielectric is just paper-in-oil.
-Photos:
-Closeup of label:

-Overview/scale:

-Closeup of terminals:

Next is a pair of very heavy-duty capacitors made by NWL, part number EX9520. They're rated at 8,000VDC (9,000V pk), 300nF and 20A RMS. These are a bit more enigmatic, I haven't been able to find any additional information other than the label. They don't feel like they contain any liquid (although the label mentions "no PCBs"). They seem to be wonderfully over-engineered, with thick TIG-welded stainless steel cases and huge contacts that dwarf any of the monster electrolytics I own. I can't see an EX capacitor series on the NWL site, but they look similar to some of their film/foil capacitors. If they happen to be polypropylene pulse-rated I'd be extremely happy, but one can dream.
-Photos:
-Closeup of label:

-Overview/scale:

-Closeup of terminals:

If the TPC caps turn out to be simple motor run capacitors I might abuse them with some pulsed-power nonsense. I could use them in series for smoothing/filtering a large DC supply I'm working on, but that's a lot stored energy once we get up to a few kilovolts. The NWL pair are the wildcards, they could turn out to be amazing high current PP film capacitors (doubtful), or garden variety oil pulse units. Either way, a rather good score for the low price.

If anyone has any info about the dielectrics in these caps I'd be very grateful. I might be able to get the datasheets by emailing the companies, these appear to be discontinued items but there's still hope.

Hydron

Tue Sept 22 2015, 07:55PM

Registered Member #30656 Joined: Tue Jul 30 2013, 02:40AM
Location: UK
Posts: 208

Maybe try and measure the dielectric loss vs frequency?
Can be tricky with big caps unfortunately, as I found out trying to measure PP snubbers (never got realistic values).

Signification

Wed Sept 23 2015, 04:24AM

Registered Member #54278 Joined: Sat Jan 17 2015, 04:42AM
Location: Amite, La.
Posts: 367

The 50uF units bring to mind YAG pulse.

macona

Wed Sept 23 2015, 05:26PM

Registered Member #3272 Joined: Mon Oct 04 2010, 11:40PM
Location: Beaverton, OR
Posts: 101

Way too high voltage for YAG, flash lamps never run in that voltage range.

4160v is high voltage utility so they may have been intended as PFC caps or something like that.

GrantX

Thu Sept 24 2015, 07:48AM

Registered Member #4074 Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335

macona wrote ...

Way too high voltage for YAG, flash lamps never run in that voltage range.

4160v is high voltage utility so they may have been intended as PFC caps or something like that.

That makes sense, I suppose they're just meant for generic use up to 4.16kV max at line frequency, as I did see mention of motor run applications. I've used a 450VAC motor run cap for mild pulse duty, and it seemed to hold up okay with no noticeable degradation after almost a hundred shots. I didn't have to pay much for these caps, but it would be a shame to damage them unnecessarily, so I think I'll email the manufacturer before blowing them up :)

Would it be practical to try and determine the dielectric loss with some kind of improvised test rig? I was thinking that the large metal structure, epoxy potting and plastic insulators on the NWL units could drastically skew the results. Again, I guess emailing the manufacturer is probably the easiest option.

The last batch of random stuff I found was much easier to identify, a pair of 180J Sangamo laser pulse capacitors and some General Atomics defibrillator caps. They looked shiny, and the Sangamo caps make great bookends for my engineering textbooks!

Signification

Thu Sept 24 2015, 09:53AM

Registered Member #54278 Joined: Sat Jan 17 2015, 04:42AM
Location: Amite, La.
Posts: 367

macona wrote ...

Way too high voltage for YAG, flash lamps never run in that voltage range.

4160v is high voltage utility so they may have been intended as PFC caps or something like that.

I was speaking of the 50uF, definitely NOT the kV rating.

radiotech

Tue Oct 06 2015, 12:13AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

The 440 Joule cans might have been used in a defibrillator .

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