19-04-2011, 01:42 PM
Just to add a helpful comment.
When you do install it, make sure you fit an adequately rated anti-surge fuse in series with the primary (at least): it's easy to overlook this during the excitement of installation. A "Variac" has the most hardest time when the ratio between Vin and Vout is large, since under those conditions it is the common part of the winding that is doing most of the work. Consequently, when inspecting a "Variac" for intended purchase, check for smoothness of operation at the ends of the rotation. Since "Variacs" are most commonly used to provide 110v / 115v from 230v / 240v, it is also the approximate centre of the windings where overload damage is most likely also; usually manifest by darkened areas of enamel on the copper windings.
Finally, and just as an aside, the name "Variac" is a registered name of the Zenith Corp. A bit like the word "Hoover", where one name has become synonymous with all makes of a given product.
Al.
When you do install it, make sure you fit an adequately rated anti-surge fuse in series with the primary (at least): it's easy to overlook this during the excitement of installation. A "Variac" has the most hardest time when the ratio between Vin and Vout is large, since under those conditions it is the common part of the winding that is doing most of the work. Consequently, when inspecting a "Variac" for intended purchase, check for smoothness of operation at the ends of the rotation. Since "Variacs" are most commonly used to provide 110v / 115v from 230v / 240v, it is also the approximate centre of the windings where overload damage is most likely also; usually manifest by darkened areas of enamel on the copper windings.
Finally, and just as an aside, the name "Variac" is a registered name of the Zenith Corp. A bit like the word "Hoover", where one name has become synonymous with all makes of a given product.
Al.
