I was thinking about the need for a high voltage feed through in IEC devices and I was wondering if the need for such a high voltage rated feed through is necessary if you are running an IEC at a much lower amperage rating than the ceramic feed through is rated for.
In other words if you have a 20kv feed through rated for 3 amps can you run it at 40kv at .60 amps.
Also is the rating of the feed through important for the airside or for the vacuum side, or both? The reason I ask is, because the deeper the vacuum the higher the dielectric break down rating will be on the vacuum side and I can’t believe that the high voltage cable that came with my high voltage power supply would be rated for a higher rating than these much larger ceramic feed through that some IEC devices are using.
As a note I have a Spellman SL 130 high voltage power supply rated for 130kv at 1200watts, its high voltage line is only a half-inch thick.
Sincerely,
Hector
High Voltage Feedthroughs
Re: High Voltage Feedthroughs
The Spellman SL series are excellent supplies. And the RG8 cable they use for HV is okay at 130 kv, but that's getting close to its operating limits.
I have used the Spellman Supplies rather extensively and they are quite well designed. The inherent voltage grading of the multiplier itself is used to good advantage as the high voltage feedthrough goes right alongside the multiplier. The problem you will have is with the other end of the cable...
Surface flashover occurs at only a few percent of the puncture stress levels. Even in a hard vacuum, surfaces are typically very much weaker that the bulk dielectric breakdown. ... because of contamination, outgassing, impact ionization and secondary emission. So one needs fairly generous creepage distances to avoid flashover inside or on the outside.
This makes a robust high voltage feedthrough fairly large.
The current rating , incidentally, is governed entirely by the cross sectional area of the conductor. You cant trade off amps for increased HV withstand.
Dave Cooper
I have used the Spellman Supplies rather extensively and they are quite well designed. The inherent voltage grading of the multiplier itself is used to good advantage as the high voltage feedthrough goes right alongside the multiplier. The problem you will have is with the other end of the cable...
Surface flashover occurs at only a few percent of the puncture stress levels. Even in a hard vacuum, surfaces are typically very much weaker that the bulk dielectric breakdown. ... because of contamination, outgassing, impact ionization and secondary emission. So one needs fairly generous creepage distances to avoid flashover inside or on the outside.
This makes a robust high voltage feedthrough fairly large.
The current rating , incidentally, is governed entirely by the cross sectional area of the conductor. You cant trade off amps for increased HV withstand.
Dave Cooper