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Regarding a HV (6KV) PCB design there is a part of the circuitry related to reed relay connection.

I have chosen a HV relay (datasheet) with flying lead connection in order to separate physically LV board from HV lines circuit.

The full circuit is only a signal distributor based on relays for input multiplexing with output points. Hence, the HV PCB part could be very simple. I think it will only need connectors that receive the HV relay wires.

Full circuit consists of 8 points that:

  • Every point will be connected to B1 or B2 signal point towards Ai relay terminals.

  • But Every point (1..8) can't be connected (A1 and A2, A3 and A4, etc..) to B1 and B2 simultaneously. So it could fit well a DPST relay, but they do not exist for my electrical parameters. So we will use 2 relays per point: 1NO + 1NC or NO + NO. Hence we have Ai points, being i = 8 points x 2 relays.

  • Every one of the 8 points will have its connector interfacing the outside.

  • Important is that maximum current through these wires will be few mA.

enter image description here

This involves the two wires, A1 and A2 must be joined somewhere in the system before contacting external connector. Every wire would be like these red one:

enter image description here

So here is where I would like to know a professional even industrial way to join the two wires. I have never do it and I don't want to do sloppy job.

My first idea is:

  1. to create a simple PCB
  2. fit on PCB some special connectors that interconnect two signals internally (as a jumper) and
  3. put then 8 jumpers, with correct distances, clearances, creepages, whatever HV could need, and route them if needed to the external connectors (they are not defined yet).

A second idea is the same but using a kind of typical female connector with N pins -if it exists- instead connector couples being separated by clearance.

Questions:

  1. Is it possible that someone has ways/strategies for doing this?

  2. Any suggestion for the appropriate jumper connectors, considering HV?

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    \$\begingroup\$ Laser powersupplies make use of HV connectors that are rated to around 30kV. Cheap laser equipment also just twist wires together and slide sleeving over the joint with some hot melt glue or silicone sealant. Good advice is to minimise joints, use two thick layers of insulation over each joint. If you have HV on the PCB then pot or at least conformal coat the board to prevent creepage. \$\endgroup\$
    – KalleMP
    May 27, 2019 at 10:29
  • \$\begingroup\$ @kelleMP, thanks for this example. If I (conveniently) crimp 2 wires within a ferrulle in order to get one; then taking this wire directly to the output (at chassis case) connector, I could avoid the HV PCB creation. So, I'm considering shrouded banana jack. It' s said that they are better and non expensive. But it would be my first time designing with these components. So, I don't know the correct way for assambling the connectors within the chassis. I guess it will be professional ways of joinning all these elements: wires + ferrules + wire + chassis/interface HV connector (banana/shrouded). \$\endgroup\$
    – Suvi_Eu
    May 27, 2019 at 14:49
  • \$\begingroup\$ @kelleMP but on the other side you've said something that could be interesting for other module that I will need to have thought. I will have 2 connectors; 1 GND and 1VCC+ = 6KV. I will inevitably need 8 joints with every of these lines. Are you saying that doing every of these 8 signal junctions on separated layers will be good technique? Or am I misunderstanding your words? \$\endgroup\$
    – Suvi_Eu
    May 27, 2019 at 14:57
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    \$\begingroup\$ When I mentioned layers I was talking about insulation tubing. One heatshrink and another protective sleeve over that to give additional breakdown resistance and make sure there is no damage to the inner insulation. For PCB you must use large (massive) surface creep distances or use slots between HV nodes. Complete encapsulation is common to prevent future problems with dirt and moisture causing breakdown. When complete you should not be able to see any metal that is at high voltages and there should be generous insulation between any metal nodes with high voltage potential between them. \$\endgroup\$
    – KalleMP
    May 29, 2019 at 19:43
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    \$\begingroup\$ Take your tripped wire ends and solder them together. Take the complete joint and inset it in a plastic tub full of prepared silicone elastomer, let it cure. \$\endgroup\$
    – KalleMP
    Jun 4, 2019 at 16:11

2 Answers 2

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First try floating the cables using a bakelite or non-conductive stem in a single star joint then use a more robust AWG short single wire or two twisted enameled conductor straight to the ferrule. it's best to avoid soldering too. i'd do it that way.

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  • \$\begingroup\$ Thank you @Anil, regarding your words I have two questions. The first one is the case interface bananas that I have found for 6kV are having a soldable terminal. Do you think I could still avoiding solders? The second one is that I would like to know if you would be so kind of showing me some example of ferrules that you would use for this (i ex: sharing a link). No need to be so concrete. I have in mind something like this: spanish.alibaba.com/product-detail/… \$\endgroup\$
    – Suvi_Eu
    Jul 8, 2019 at 7:11
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Put the two relay leads into a single ferrule.

It's as simple as that. You aren't gonna find HV connectors which accept 0.6mm² ferrules easily anyway, so you have good use for that extra cross section.

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    \$\begingroup\$ With HV, your first concern should be not creating any additional nodes, as you will get into trouble isolating them properly. So, it's good practice to put both wire strands into one ferrule, and crimp them as one. Put that one into your HV connector clamp. \$\endgroup\$
    – Janka
    May 24, 2019 at 13:22
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    \$\begingroup\$ (To answer the question, why could you do that? Because a solder ending will never be safe to touch – it's uncontrolled. So it's required to be inside a properly grounded or isolated casing anyway. That silicone hose with two wires in it, and the unavoidable crotches is okay just because of this. It's more decoration that anything else. But then, you are at 6kV only, so, meh…) \$\endgroup\$
    – Janka
    May 27, 2019 at 10:05
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    \$\begingroup\$ My original idea was to use a single ferrule for both wires, crimp it, then clamp/screw it tight in the connector's backside. That way you don't create an additional mechanical node you had to support and isolate. \$\endgroup\$
    – Janka
    May 27, 2019 at 13:12
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    \$\begingroup\$ Oh, and banana plugs are okay if no one can touch that thing due to other measures, and the isolation distances are met by the mechanics of the assembly. \$\endgroup\$
    – Janka
    May 27, 2019 at 13:14
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    \$\begingroup\$ To the ferrule and crimping, it doesn't make a difference if the 400 strands come from 8 wires or from one. But you first have to find a connector in which such a big ferrule fits. \$\endgroup\$
    – Janka
    May 28, 2019 at 11:52

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