1
\$\begingroup\$

I was thinking of a design for bringing VCC+ and GND to a board through a PCB connector. VCC = 6 kV. It comes from external source towards a banana jack within a metal case. The first idea was to fit the PCB design into this case.

I don't find any PCB connector with 6 kV capable to support the 6 kV voltage difference from other connector with 0 V at the same PCB side. I have found some of them, Wurth, with 3.5 kV dielectric strength. This is the maximum I have found.

enter image description here

In this situation I thought that the material offered by my manufacturer could be a good insulator with 1.6mm --> 40 kV > 6 kV. So, if I put VCC on top side and GND on bottom side (I think of doing it this way) the connector dielectric will never fail.

But now my problem is that someone asks for me to put all the connectors at the TOP of the PCB: VCC+ and GND, in order to access both them by the same side. The connectors have only 3.5 kV of dielectric strength.

Is it possible to place the 2 connectors at top side of a PCB with these features: 6 kV between VCC+ connector and GND connector, being two connectors having a maximum voltage = 3.5kV according the manufacturer datasheet?

I need PCB connectors for supporting this 6 kV between them. I can't find any. I have looked for connectors at typical and non-typical distributors, without success. Is there a way to do this? How can I put connectors with this voltage difference between one connector and the other?

enter image description here

Clearance calculation does not take into account connector dielectric. I don't think it could be solved applying clearance or creepage calculations without taking into account the 3.5 kV connector dielectric strength.

\$\endgroup\$
3
  • \$\begingroup\$ Have you considered screw terminals? You can place them at whatever distance you need. media.digikey.com/Photos/Keystone%20Elect%20Photos/8730_sml.jpg \$\endgroup\$
    – scorpdaddy
    Commented Jun 19, 2019 at 18:38
  • \$\begingroup\$ Eugenia,you asked this question many times and it is a very difficult problem with a simple solution. Choose the right tools for the job. Look at any old car distributor and copper cable made with rubber and design around this interface. It needs a rubber boot for dust and moisture. One connection per wire unless using chassis ground which I would not suggest unless like in a car or Hipot tester or furnace igniter, it is OK. Choose hardwire to board or socket with boot on banana plug or whatever offers a rubber boot and cable insulation. Nothing less will do if you need safety certification. \$\endgroup\$
    – D.A.S.
    Commented Jun 19, 2019 at 19:57
  • \$\begingroup\$ @SunnyskyguyEE75 I have found a solution, but now here they ask me to put all the connectors at PCB top. I have not found enough information that clarify if to put pcb connectors on a printed circuit board is often used in high voltage. In low voltage seems to be a common thing. But I don't know whether to put pcb connectors carring V = nKV is a very rare and difficult thing or not. So is it the thing that are you telling, is it? I would solve this with bananas, they support 7kV. But here are trying to put terminal blocks or similar. Thanks. \$\endgroup\$
    – Suvi_Eu
    Commented Jun 20, 2019 at 6:46

1 Answer 1

Reset to default
6
\$\begingroup\$

It's not only the dielectric strength that you must worry about, but also the spacing between connectors. As you know, high voltage tends to arc. Because of this, you won't find connectors that are closely spaced in high voltage parts, even with high dielectric strength materials, per IPC spec, there is a minimun distance even if there is insulation.

If you want to find addtional distances that are not on the table, then use the calculator. At 6kV, the minimum distance is 30mm if you have bare conductors, and 18 for coated/insulated conductors.

For example: At 40kV this distance increases to 200mm and 121mm (coated). For this reason it would probably be rare to see connectors with two conductors as the conductors need to be placed 121mm apart per IPC spec. The traces on the board would need to be 100mm apart.

The clearance calculation does not account for the dielectric because the IPC spec only considers coated vs uncoated conductors. The spacing needs to be the same no matter what the dielectric breakdown is. In addition to that, the terminals pictured above have bare conductors, and this needs to be taken into account in the clearance calculations.

enter image description here
Source: http://www.smpspowersupply.com/ipc2221pcbclearance.html

How can I do this? How can I put connectors with this voltage of difference between one connector and the other one?

After determining the max voltage, then deterimine how far apart the connectors need to be and get connectors that are single terminal, not multi terminal and space them the required distance apart.

\$\endgroup\$
1
  • \$\begingroup\$ thanks very much! 8 wires must go connected until 6KV voltage level. Other 8 wires must go until 0V voltage level. This is why I think in a multiterminal connector. So I think I will only need to space the VCC+ group connector from GND group connector. But I don' t know If the space I must have into account (from the table) is the 3.5KV (connector strength) or 6KV (max V between the two connectors) in order to determine the appropiate distance. \$\endgroup\$
    – Suvi_Eu
    Commented Jun 20, 2019 at 6:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.