On Sun, Apr 26, 2009 at 01:23:08PM -0400, Gene Heskett wrote, on another thread which I'd rather not hijack:
> That UPS is about to hit the yard sale table, its > a Belkin, monster sized 1500WA rated, eats its batteries in a year a $225 set. > > I'll have to go reboot it I suppose. Ok, its attached. The UPS? I had to > bypass it, toast. Gene, If the transformer's OK, then you may still have more than a boat anchor. I've just eviscerated a similar sized UPS, to start to make my first EMC box. The transformer may be able to remain, to provide power to the drives. There were no batteries to confirm the voltage, but the H-bridge uses 100v IRF3710s, and the electrolytics on the bridge are 80v, so my first guess is 48v. That should be fine to feed drives for some 300W 24v motors I have. My beginner's understanding is that so long as the current is limited, and the motor insulation takes it, modest overvoltage will give better acceleration without harm. If I had to go to higher voltage motors, voltage doubling would require twice as many capacitors, but I could use 80v types in the two 48v halves, which might make them easier to find. Admittedly, there'd only be half-wave rectification in each leg, so I'd need twice the capacitance x twice as many capacitors. Don't want to go there. Low ESR capacitors [1] are what I have to seriously look for now, after confirming the transformer voltage. Since there are two primaries I can't just connect them in series and apply 240v. If I chance to connect them in antiphase, the circuit breaker would be seriously tested. I'll feed low voltage AC into the secondary, to measure the turns ratio. Your enclosure and transformer might still be able to earn their keep, too. [1] I'll heed your admonition about catastrophic capacitor failure. :-) Erik ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensign option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
