kiely@lownlab.harvard.edu (James P. Kiely) (04/30/88)
Given that toroid power transformers are lighter, more efficient, and generate a smaller spurious magnetic field than the more traditional stacked pole transformers, why doesn't everyone use toroids? ============================================================================= NAME: James P. Kiely USPS: Kiely Laboratories USENET: ...!harvard!lownlab!kiely P.O. Box 624 DOMAIN: kiely@lownlab.harvard.edu Allston, MA 02134-0624 PHONE: +1 617 782 4136 USA
sfs@panda.UUCP (Stephen F. Santarelli) (04/30/88)
In article <4496@husc6.harvard.edu>, kiely@lownlab.harvard.edu (James P. Kiely) writes: > > Given that toroid power transformers are lighter, more efficient, > and generate a smaller spurious magnetic field than the more > traditional stacked pole transformers, why doesn't everyone use > toroids? Ever try winding one? How about 1,000,000?
larry@kitty.UUCP (Larry Lippman) (04/30/88)
In article <4496@husc6.harvard.edu>, kiely@lownlab.harvard.edu (James P. Kiely) writes: > Given that toroid power transformers are lighter, more efficient, > and generate a smaller spurious magnetic field than the more > traditional stacked pole transformers, why doesn't everyone use toroids? In general, two reasons: 1. Toroids cost much more to manufacture than comventional transformers with E-type or U-type laminations. 2. Toroids become quite impracticable to use for power ratings (at 60 Hz) beyond, say about 1 KVA. The diameter becomes large, along with the concurrent difficulties in winding long lengths of heavier gauge wire. To get some idea of the problems in manufacturing "larger" transformers, take a look at a toroidal coil winder some day. <> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {hplabs|ihnp4|mtune|utzoo|uunet}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"
noise@eneevax.UUCP (Johnson Noise) (05/02/88)
>In article <4496@husc6.harvard.edu>, kiely@lownlab.harvard.edu (James P. Kiely) writes: > Given that toroid power transformers are lighter, more efficient, > and generate a smaller spurious magnetic field than the more > traditional stacked pole transformers, why doesn't everyone use toroids? > One other point worth mentioning is that the efficiency gained is simply not necessary (read not always with respect to manufacturing cost). Conventional transformers can be very efficient (> 90%), suggesting that other components may be the limiting factor in overall efficiency. Consider a dc-dc converter which uses some type of semiconductor switching element (bipolar, thyristor, VMOS etc). There is some voltage drop across the element when the device is on, this turns into heat and wasted power. This can be very significant at low voltages. Diodes also.