When building any kind of ultra high voltage boost circuit or transformer, the high voltage will often arc between components if the voltage is high enough and the distance between them is short enough. In many cases, it’s easy to fix this by increasing the air gap or coating with insulation, but not always.

In applications where resistors are employed in systems over a few hundred kilovolts, the resistor may offer a greater resistance than the insulator and the breakdown voltage of air over the length of the resistor may be far below the circuit operating voltages. In that case the insulator will fail and the current will arc around the resistor.

What’s the best way to fix that? In high power applications you can often use wire wound resistors. When doing that, the current could just arc between the windings if the insulation isn’t thick enough, or between the connector and the resistor housing. This is definitely a problem because bushings are often used in conductors in high voltage applications, but is there a way of fixing this for resistors?

  • 4
    \$\begingroup\$ Better voltage rating on said resistors? \$\endgroup\$
    – winny
    Jan 29, 2021 at 18:04
  • 5
    \$\begingroup\$ Use multiple resistors in series to increase the distance? \$\endgroup\$
    – The Photon
    Jan 29, 2021 at 18:06
  • 3
    \$\begingroup\$ Any resistor worth its salt that is rated for X tens of kilovolts will have (or should have) a data sheet that explains how they should be used and how they are interfaced with. So, choose a resistor that has a suitable rating and leave a link to the data sheet. At the moment your question is too open ended and should be closed IMHO. \$\endgroup\$
    – Andy aka
    Jan 29, 2021 at 18:11
  • \$\begingroup\$ In a wire-wound resistor, with 100V across the whole resistor, the voltage between individual coils will be much much less. If there are 100 turns of wire, there'd only be 1 volt between them. \$\endgroup\$
    – Kyle B
    Jan 29, 2021 at 19:34
  • 1
    \$\begingroup\$ Transformer oil! \$\endgroup\$
    – K H
    Jan 30, 2021 at 9:16


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