Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!rutgers!sunybcs!kitty!larry From: larry@kitty.UUCP (Larry Lippman) Newsgroups: sci.electronics Subject: Re: UPS's that aren't Message-ID: <1947@kitty.UUCP> Date: Wed, 19-Aug-87 21:34:52 EDT Article-I.D.: kitty.1947 Posted: Wed Aug 19 21:34:52 1987 Date-Received: Sat, 22-Aug-87 06:00:02 EDT References: <161@tmsoft.UUCP> <1924@kitty.UUCP> <654@neoucom.UUCP> <845@gt-stratus.UUCP> Distribution: na Organization: Recognition Research Corp., Clarence, NY Lines: 75 Summary: "mystery" transformer - use caution... In article <845@gt-stratus.UUCP>, chen@gt-stratus.UUCP (Ray Chen) writes: > A friend of mine found me what seems to be a 2500 watt isolation > transformer. > > It's black, *heavy*, and made by Freed Transformers of Brooklyn, NY. > Dimensions are 10" long X 6" wide X 7" high (or so). The thing weighs > a ton. We managed to put it inside an industrial strength milk crate. > So now 2 people can lift it and not get hernias if they're careful. > There are 2 sides with terminals. One side says "Input 115 V/50 60 Hz". > The other side says "Output 25KVA". We think that's a misprint that > should read "Output 2.5KVA" as the concept of a 1 cubic foot > 25,000 watt transformer boggles the mind. > > There are some numbers on the top that read "5950-856-1800" and > "37076". The "5950-856-1800" is a universal military stock number, indicating that this was built for the government. I don't have any NSN directories, so I can't offer any help. The "37076" is probably a date code of sorts, since normal Freed part numbers for transformers are all alphanumeric. An example Freed p/n for an isolation transformer is IT4, and for a ferroresonant transformer is MCV61000LC. According to a Freed catalog, they don't manufacture isolation transformers greater than 500 va, and they don't manufacture ferroresonant transformers greater than 1.0 kva. Since this is a military transformer, Freed could have made almost anything under these circumstances. Bear in mind that ferroresonant transformers ALL require capacitors; if this is a ferroresonant device then you are either going to find a removable plate which will reveal capacitors, or you will find additional terminals for external capcitors (military ferroresonant transformers made by Freed all have external capacitors, according to their catalog). I have a funny feeling that this is NEITHER an isolation transformer NOR a ferroresonant transformer. I don't know what it is - it may even be a high-voltage transformer which puts out 25 kilovolts. My advice is to forget it, since you don't know what you are getting into. If you are bound and determined to power it up, use extreme CAUTION in case it is 25 kilovolts on the secondary! > Output Xformer Wall > + ---------- +|+ -------- + > GND -- | -- GND > - ---------- -|- -------- - > > Is this the right way to do it? That's a conventional method of connection, but the +/- business bothers me. Turns direction on AC transformers are usually designated by a "dot" on the "start" of winding, or by "S" and "F" to indicate start and finish terminals. > Third, anyone got any idea on how much E&M (RFI, whatever) this > thing will put out? Plain 'ole transformers generate no RFI, but do generate a weak magnetic field. I certainly wouldn't be concerned about anything at least 2 feet away. Ferroresonant transformers do generate some RFI, but it is rather low frequency, and limited to powerline harmonics (<< 1 KHz). > Fourth, any ideas on heat output? A very rough guess is a 5% energy loss to heat on a conventional transformers. UNloaded ferroresonant transformers can get quite warm. > Sixth (just for fun), how bad do you think the noise might be? Probably less noise than the fans on your PC, unless the transformer is a real pig with loose laminations. <> 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|seismo|utzoo}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"