From: Paul
Date: Sat, 26 May 2001 14:37:20 +0100
Subject: Re: [TSSP] Loss due to ultrasonic mechanical vibration of secondary?
Metlicka Marc wrote: > i may be way out here, but here goes: could a laser be bounced off of > the secondary windings and the end of a fiber optic cable be mounted so > that the reflected beam entered it? would the jitter of the light be the > amount of movement or would it be the actual frequency of the coil? i > remembered reading of this setup used to measure vibrational movements > from earthquake echo's. Yup, that might work. Never mind the fibre optic, just bounce the laser onto a pinhole in front of a photodetector. Can the detector be far enough away that you can be sure its not picking up interference from the fields. If it detects movement, how will you know whether it's an ultrasonic vibration set in motion by the winding trying to expand, or whether the coil is just wobbling slightly due to a bulk electrostatic attraction to a nearby wall or something. You'd have to run at low power levels, and to do a control run with the secondary charged up with DC. Possibly better still - put DC through the secondary and look for a static expansion, but you'll need to measure both directions to allow for the earth's mag field pulling on the coil. How about attaching a microphone to the secondary, and listening carefully for any creaks and groans as the DC is ramped up? > these winding movements aren't strong enough to break the thin layer of > insulating enamel that i spray my coils with, no loose windings. I don't think any ultrasonic movement would be enough for damage or wear, we are perhaps talking of an amplitude similar to tapping on the coil with a screwdriver. One thing to measure or calculate the amplitude, but another ballgame to calculate the loss resulting. Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.