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Hit with 6kv yesterday... DON'T trust the Millen connectors!




 
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Author Topic: Hit with 6kv yesterday... DON'T trust the Millen connectors!  (Read 9980 times)
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W1RKW
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« Reply #50 on: December 22, 2018, 03:24:03 PM »

The conversation has been hams, their equipment and being safe.  What about prevention of potential "collateral damage"?

Do hams have the safety measures built into their shacks and/or equipment in an effort to eliminate or minimize the possibility of a family member or friend coming to aid the ham and getting killed themselves?  Things like emergency stop switches to de-energize the shack/rigs, built-in contactors to forcibly de-engergize or short out a power supply.  Do friends and family know what to do if that type of event happens?  Do they know how to kill power to the shack and equipment? Probably not to all of the above is my guess. 
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Bob
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« Reply #51 on: December 22, 2018, 04:03:23 PM »

In the context of the present discussion.....

https://www.w8ji.com/bias.htm

I believe the measured voltage 'soar' was appx 35 to 50 volts when the cathode is allowed to open with no snubber.

Definable, and would cause a little ouch....  And as stated could cause the vox to go full bore TX.   However, with the resistance of a human, I don't believe you would be subject to much more.

HOWEVER!  What we aren't taking into account is the sb220, etc. style of cut off.....  Appx 80 to 110 volts, depending in the amp...  In the case of the 220, taken from the fils xformer.

Non gg style amps have their own set of issues.  The cathode of my last 4cx style tetrode with handles was c 1300 volts negative as the screen was strapped to the chassis.

This style would be enough to make you push daisies.




Recovery is slow.  Hand hurts like all get out, and it hurts to type.....  But I am able to go to work and actually get things done.  My boss called Wed to check on me...  I said I had all the lights up, and was starting to wire them.... He replied, 'wait...  You're at work???' lol.  Yeah, I HATE sitting.

Have been back in the shop, that took a couple days.  PTSD is a bear!  Took some pics of the connector, etc....  The b+ wire is now pulled out of the connector.  It wasn't like that before the incident.....  But things did get pretty violent back there while I was trying to escape it!

There is now a large black mark on the top of the chassis as well....  It wasn't there before.  I had a thickish long sleeve work shirt (bright orange OSHA compliant THICK cotton) and a pendleton (flannel jacket for us w6 guys) on..  Neither show any marks, but I believe a lot of the energy was directed back at that spot...  There and the leg.  



Someone had mentioned how as the b+ goes up, things get more interesting.  Yes...  For sure!  I'd forgotten having built nothing but sub 7kv supplies the last few years....  The 8.5kv one I built was a whole new ball of wax.

Even the capacitor bank...  Using snap ins, I was forced to mill every non essential piece of copper off the board.  Otherwise, it would arc over. . Don't have that problem at sub 4kv.  Just mill copper pads out for the caps, with a half inch around them and your good. The 8.5 kv supply, nope.  Arc city!

The last 12kv supply was a lot of fun.  Everything mounts on glastic insulators, even the insulated equipment.


Anyway, off to bandage up the hand.  Thanks to everyone for the well wishes..  It does bring a smile to the face.

I'm also glad this has opened up a discussion about the safety of connectors, etc.   VERY glad I'm hear to be a part of said conversation!

--Shane
KD6VXI




Yes, that is my skin on the connector.  The arc grabbed me and pulled me in, just like they taught us in school.

I debated posting the pics, but I'd rather gross someone out and have saved their life by them treating hv with respect than not have posted the pics.  Sorry if it does gross anyone out, but it is truth.


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KD6VXI
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« Reply #52 on: December 22, 2018, 04:06:54 PM »

The conversation has been hams, their equipment and being safe.  What about prevention of potential "collateral damage"?

Do hams have the safety measures built into their shacks and/or equipment in an effort to eliminate or minimize the possibility of a family member or friend coming to aid the ham and getting killed themselves?  Things like emergency stop switches to de-energize the shack/rigs, built-in contactors to forcibly de-engergize or short out a power supply.  Do friends and family know what to do if that type of event happens?  Do they know how to kill power to the shack and equipment? Probably not to all of the above is my guess. 


My shop is entirely energized by a single breaker.

This incident brought to light:  Nobody else knew where it was or what to do.

I am installing a contactor (175 amp per pole) and the 'big red button' type disconnect at the door to do just what you describe.


I'd also add, an arc fault breaker in my panel could have been a tissue saver, although for something the size of the breaker feeding the big amps, it's cost prohibitive.

--Shane
KD6VXI
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K1JJ
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« Reply #53 on: December 22, 2018, 04:31:31 PM »

Bob,

OK, on the shack shut down advice.  Yes, I think with most of us - our ham activities are secret to the rest of the household.... :-)

My solution is that all HV supplies get keyed at the transformer primary with a step start.  Release the PTT and no HV in the shack. I never liked the sound of HV buzzing when I'm not talking.



Shane,

Yes, I can see your skin smudges.  Looks like your hand went across the aluminum panel and the point where the HV wire entered the plug. That PW HV connector assembly needs to go for sure.

T
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Frank / WA1GFZ says when he's working near high voltage, as a warning he sings this song by Jay and the Americans: "Come a little bit closer, you're my kind of man, so big and so strong, come a little bit closer, I'm all alone and the night is so long."
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« Reply #54 on: December 22, 2018, 05:04:54 PM »

Shane,

I edited your pictures to show Cause and Effect. I named the file "millens revenge". I think that's how the Millen HV Connector should remembered.

Don


* millens revenge.png (932.44 KB, 800x397 - viewed 173 times.)
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« Reply #55 on: December 22, 2018, 05:44:36 PM »

After getting belted as mentioned in my earlier post, I've thought long and hard about this but never implemented an emergency stop system in the shack.  I have the stuff to do it but just never got around to doing it.  Probably a good time to revisit.

My wife wouldn't know what to do without education and I have been remiss in doing that. And I know if I did educate her, she'd say get another hobby.

In my previous post, I didn't think about first responders either. Something to keep in mind.
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Bob
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His fear was when I turned it on for the first time life on earth would come to a stand still.
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« Reply #56 on: December 23, 2018, 09:37:21 AM »

"Risky Business"

Risk perception and risk tolerance are human psychological attributes. Counter-intuitively, installing a safety device doesn't necessarily make something safer. When we perceive something as being safer, we act more casually toward it. Our perception of risk is reduced.

Shane had 'all the covers on' so he perceived the risk of electrical shock as being very low. Still, I bet a little bell went off in his head when he reached behind the equipment to a place where he couldn't see. Had he been working on unguarded equipment where dangerous voltages where clearly present, he'd have perceived the danger of shock as being very high and wouldn't have reached into somewhere that he couldn't see.

In both instances the danger is there - an exposed high voltage conductor. What changed was his perception of the risk. This isn't to say that we shouldn't install safety devices. We should. The answer is in lowering our tolerance for risk. We must learn to listen carefully to that little bell in our head that says: "Risky Business".


Respectfully submitted,

Don
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K1JJ
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« Reply #57 on: December 23, 2018, 11:08:54 AM »

"Risky Business"
We must learn to listen carefully to that little bell in our head that says: "Risky Business".
KK4YY


Well said, Don.

The "little bell" in our heads is the key. No matter what we do, we need to use our lifetime of experience that has honed our intuition, pattern recognition and emotions.

"Hey, that car pulling out looks like trouble - it ain't gonna stop."  (pattern recognition warning)    

"The B+ is on and it feels scary  (emotional warning)  - I'd better use a fiberglass rod, not my hand," etc., etc.,

This is what keeps us alive for 95 years.

Frank / WA1GFZ, a man way ahead of his years, told me this story:  Whenever he turns the HV on and finds himself exposed, he sings that old cowboy song to himself... "Come a little bit closer, you're my kind of man so big and so strong.... come a little bit closer I'm all alone and the night is so long."   :-)

I find myself doing the same thing  - when close to live HV.

T

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Frank / WA1GFZ says when he's working near high voltage, as a warning he sings this song by Jay and the Americans: "Come a little bit closer, you're my kind of man, so big and so strong, come a little bit closer, I'm all alone and the night is so long."
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« Reply #58 on: December 23, 2018, 12:31:39 PM »


Not sure if anyone else noticed, but the center conductor of the HV wire going to
the Millen HV connector is BARE/exposed!!

and fwiw, Silicone Rubber is an effective HV insulator.
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« Reply #59 on: December 23, 2018, 01:29:31 PM »

The bare insulation area wasn't like that before, that ended up getting yanked out during the event.....  But, IL bet it wasn't in all the way.

As Don said, the risk was perceived as minimal, and that was almost my death wish, so to speak.

I've been researching connectors.  The 7 16 was promising, but I have people who use that for antenna connectors, so it was a no go.

I did find this one, and it's fairly cheap in ebay.  WAY less than Millen crap. 

https://www.amphenolrf.com/connectors/mhv.html

Still doesn't solve the problem of the center pin flying, but it makes a nice easy and FRIGGIN safe connection, with ground!




And to be clear, I was reaching way behind and to the side of this, to another seating area.....  Moving the wiring away from something else...  This is not being said as an excuse, reason, etc.....  But to underscore what's being stated:  you can't be too careful!


A contactor kill switch and some serious rewiring is under plans.  Already ordered a crimp kit to make the new jumpers, etc. 

Good to see you again, Don!

--Shane
KD6VXI


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« Reply #60 on: December 23, 2018, 01:48:52 PM »

   In my short time here on AMfone, this has probably been one of the most instructive threads I've followed; not because it imparts cool technical tips on designing and building better gear, but because it imparts tips on staying alive.  There are no cooler tips than that.  I've got a few pieces of older gear that I've picked up at hamfests, that use Millen connectors.  I'm thinking I'll change them out. Matter of fact, I bought a handful of Millens at recent hamfests; not saying I'll toss them, but I'll certainly apply them with greater discretion now. I'm looking into those 7/16 jobs - never heard of those before reading this thread.
   I think the takeaway here is that you can do - like the OP did - every thing right and according to the book, and still get nailed.  There's a cobra in the box, its bite is lethal, and sometimes it's not contained quite as well as we assume.
    Oddly enough, the very worst hit I ever took wasn't from HV, but only the humble 115 right from the power strip.  I was a technician at an aerospace company at the time - lots of rack mounted equipment - and I was reaching around behind a rack to pull out a power cord from a strip.  Left hand firmly planted on a bare aluminum enclosure for balance, right hand reaching for the plug.  Finger contacted the hot blade - WHOMP - up the right arm and out through the left, without pausing to enjoy the scenery as it passed through the heart.  Didn't wind up hospitalized or anything, but it shook the holy mucus out of me - had to sit down and breath slow for a few minutes - and both arms were sore for a while from the involuntary muscle contraction.  6KV or 115, it's like drowning in ten feet of water, or a hundred: dead is dead, either way.
   
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« Reply #61 on: December 23, 2018, 01:55:46 PM »


I did find this one, and it's fairly cheap in ebay.  WAY less than Millen crap. 

https://www.amphenolrf.com/connectors/mhv.html

--Shane
KD6VXI


I've got a couple of the old K2RIW/Arcos amps, and they use those same MHV connectors.  I like them.

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« Reply #62 on: December 23, 2018, 03:09:47 PM »

I just bought these.  Take rg-6 cable, rated to 5kv and for 5 pairs at 30 bucks, I just halved my cost for cabling amps!

Finding the wire capable of withstanding that voltage level was a bit hard when searching for RG6...  Then I remembered I have some already.

It's neon sign wire.  Get the stuff rated for 'no conduit necessary' and it will come with an outer shield.  We remove it when converting from neon to led.....  🤔😁😎👌

I couldn't figure out how to share the url, so I'll include 2 screen grabs so people can see what to search for.

They make this style up to 20kv.  They have a rating for both close circuit and open circuit.   Not that I'll ever want to test the open circuit voltage rating, but it is nice to know if you accidentally have it laying in the ground, the 20kv connector wouldn't arc to anything external (like your hand, grabbing the wrong kne) until after 10kv, I believe.  Even the SHV which I bought, rated at 5kv, tested to mated 12kv and open circuit 10kv.  5 bucks a set, half the cost of Millen!

Anyway, time to go christmas shopping for the kiddos.  

Ya know, I'm usually Mr Frugal at Christmas.....  But for some reason, this year.....  The kids are gonna do well!

--Shane
KD6VXI



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KK4YY
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« Reply #63 on: December 23, 2018, 06:19:50 PM »

Shane,

You beat me to it! I was about to post this:
https://en.wikipedia.org/wiki/SHV_connector
But my wife wanted us to go out for pizza. Roll Eyes
I think you got the real deal there.

Don
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« Reply #64 on: December 23, 2018, 08:27:20 PM »

Now if they could only figure out how to make a reversed gender connector like that...
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« Reply #65 on: December 23, 2018, 09:00:32 PM »



It's neon sign wire.  Get the stuff rated for 'no conduit necessary' and it will come with an outer shield.  We remove it when converting from neon to led.....  🤔😁😎👌

--Shane
KD6VXI



I missed the shielded neon sign wire. I use GTO-15, rated 15KV, but it has no shield. I would love it to have a shield!
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« Reply #66 on: December 24, 2018, 04:14:26 PM »

I have 10 and 15kv rated wire.  The 10 kv got brittle and started cracking....  The 15kv was more like spark plug wire externally....  No problems with cracking, etc.

I'll snap a couple pics when I'm out there next time.


--Shane
KD6VXI
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« Reply #67 on: December 26, 2018, 08:43:08 AM »

I've got some 50kv rated wire, it's about the size of RG-8 diameter-wise and made from silicone rubber...
never heard of sheilded neon sign wire, any links to that stuff?
Does it have a "nomenclature" to search for?
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« Reply #68 on: December 26, 2018, 11:03:34 AM »

I have a hunk of HV wire from an X-Ray machine....#14 stranded conductor and 1 inch outer insulation diameter...I have no idea what connector to use with it....No voltage markings.....
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« Reply #69 on: December 26, 2018, 12:53:04 PM »

Seems a little overdone. X-Ray machines work upto 100 keV or more, so the wire may be rated upto 100 kV
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« Reply #70 on: December 29, 2018, 09:50:03 PM »

Finally got out to the shop and grabbed a hank of the neon GTO wire I have.

It is definately coaxial, and is shielded and does not require a conduit.

It's made of two completely seperate insulators. Both are similar in feel:  The internal is like a teflon-ish material, the black one more like silicon.  Then the copper shield and then another layer of insulation.

15 kv rated.

I've not been able to find anymore online.....  Grr.

--Shane
KD6VXI


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« Reply #71 on: December 29, 2018, 09:53:56 PM »

Last two pics of the labeling.

I tried kne large pic, but it made a pretty big file.

--Shane
KD6VXI


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« Reply #72 on: December 29, 2018, 10:09:04 PM »

Not the same stuff, but found.

https://www.blackburnmarine.com/product/472/ancor-gto-white-high-voltage-coax-cable

Even has a pic of the braided end.

--Shane
KD6VXI
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Carl WA1KPD
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« Reply #73 on: December 29, 2018, 10:40:40 PM »

See this has been all very informative and has made me wonder if there are insulated gloves that are thick enough to provide protection, yet pliable enough to allow work on the larger elements.
Specifically I have a pair of long thick rubber gloves for use with paint stripper. Would they be helpful, or provide a sense of false security?
Shahhe, glad you are on the mend
Carl
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« Reply #74 on: December 30, 2018, 12:39:47 AM »

Carl,

At work we have suits that cover you to IIRC 50 kv.

A local electrician was subjected to an arc flash from 100kv the other day!  Wow!

I have 'linesmans' gloves.  Two piece, inner is about eighth inch thick rubber gloves and the outer gloves are more 'work glove' material.

Used or left to sit, they have an expiration date.  This is to prevent injuries due to cracking.

I don't remember the rating of mine, but I think they are rated to 1 or 1.5 kv.  I won't use them on anything over 480.  Anything higher, deenergize the cabinet.  Those guys that wear the Michelin man arc suits definitely earn their money!

Heres a link to what we use at work....

https://www.thinknsa.com/admin/document/document_download.aspx?UID=7eca635e-1b76-4e38-8dc2-fcad5c02d77f

And if anyone would like to get a pair, https://www.thinknsa.com/product-category/arc-flash-ppe/arc-flash-suits-kits/rubber-voltage-glove-kits

--Shane
KD6VXI
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