|
Tech Square Technical and speculative discussion of amps, cables and other topics. |
|
|
|
Tech Square Technical and speculative discussion of amps, cables and other topics. |
|
In Reply to: Isolation Transformers? posted by dalcorn on February 9, 2005 at 19:44:00:
Ten year ago, I had to test for EMI our airborne predictive maintenance computer. I used Topaz 1000W ultraisolation transformer between the mains and the testbench.
Another time, I made EMI conducted susceptibility testsfrom the mains, and I had the habit to set an ultraisolation Topaz transformer between the mains and the LISN (Line Impedance Simulation Network). My main goal was to get rid of any external source common mode perturbation, in order to make correct measurements from the standardized CM signals I injected, but not the neighbor...
Ultraisolation transformers are built this way:
primary and secondary are split in several sections, and completely separated. Primary cores are surrounded by an insulated copper foil (which does not short itself thanks to covering insulation. This primary shield is connected to the ground inlet. Then, another non-self-shorting insulated copper foil separates the primary/ secondary coils pairs. This shield is connec ted to the transformer chassis. Then, a third set of non-self-shorting insulated copper foil surrounds the secondary coils. This shield is connected to the ground outlet.
A heavy-gauge small coil links the ground inlet to the transformer chassis, and another heavy-gauge small coil links the ground outlet to the transformer chassis.
A non-insulated copper foil is used as a magnetic shield/short around the transformer.
A sheet of steel separates the primary and secondary case.
The result : superb common mode insulation, up to 140dB (!) at 1MHz. Why?
Because, done as it is, the capacitive coupling between the primary and secondary coils is quite zero (<0.00001pF, yes!), and furthermore, the symetric construction avoids that some CM noise be changed into differential noise.(BTW, I was unable to google out the Topaz site. Does the company still exist? Somebody knows?)
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Isolation Transformers: how it works - Jacques 08:49:39 02/13/05 (1)
- Re: Isolation Transformers: how it works - N-set 05:23:35 05/12/05 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
