orm8426 said:
Rick Christopherson said:
As long as it is a conventional transformer, it shouldn't cause the vacuum to continually run. Yes, the vacuum will auto-start when the transformer is first plugged in because there is some inrush current to "charge the windings". Once that inrush current has settled down, the vacuum should turn back off.
Other vacuums may have a lower trigger threshold, but the Festool vacs are high enough that they don't.
This is interesting. My Bosch extractor runs indefinitely when my 3.3kva transformer is plugged into it. Have you actually tried this on a festool extractor, if so which one?
Yes, I have tried it with a Festool CT extractor. They have a reasonably high trigger threshold. As a matter of fact, they have been known to not auto-start right away with a small sander set at low speed. The CT vac will fire momentarily from the transformer inrush current, but then it shuts back off.
I was recently doing some testing with CT vacs, and I wanted to use the smallest load possible to trigger them. So I grabbed a 40 watt desk lamp, thinking that surely it would be big enough to trigger the vac, but small enough to not interfere with my measurements. Nope! It wouldn't trigger the vac. I ended up using a small dremel tool that drew 1-amp at idle.
Transformers are one of the most efficient inventions the human race has created, in that the real-life device behaves very close to the theoretical-ideal equations. Without a load on the secondary winding, there is very little current flowing through the primary. The infinite resistance of an open circuit on the secondary reflects back to the primary as almost infinite resistance. However, many of these transformers have tiny light bulbs that could trigger a vacuum with a very low threshold.
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