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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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Power supply
On 2010-09-29, Karl Townsend wrote:
Turns out I have a power supply for my Matsurra bedmill. After stripping everything not needed away I ended up with this: http://www.metalworking.com/dropbox/supply1.jpg http://www.metalworking.com/dropbox/supply2.jpg A few questions. Each of the twelve diodes has a pair of wires, 24 connections on the terminal strip. I don't know the function here and if anything needs to be connected. I *think* those are SCRs (Silicon Controlled Rectifiers), and one of each pair is the gate, while the other is likely the cathode (which the gate signal is applied relative to. Try a resistance measurement between the black and the white to the high-current lead from the top of the rectifier -- and to the end bolted to the heat sink. Whichever one reads zero should be a low-current duplicate connection to the cathode, and the other needs to go positive relative to the other lead to turn on the SCR. It may be that you should have kept the board which was connected to those leads to regulate the output voltage by turning those on at the right time. To double check -- look for part numbers stamped on the sides of the rectifiers. Is the part labeled 1 an isolation transformer? If so, should DC- be grounded? What is certain is that it is a high current three-phase transformer.. It is likely to be an isolation transformer. Check with an ohmmeter between the terminals on the heast sink side and the terminals connecting to the contactor. If it isolation, you should get an "infinity" reading for resistance -- except with certain rare meters which can measure very tiny leakages. And yes -- DC- should be grounded. Can the part labeled 2 be used to read current? There are four leads, how would they be connected. The part says "Nana Electronics NNC-05AF" It *looks* like a current transformer -- though why there are four leads remains to be seen. Normally, you hook a known (fairly low) resistance across the *two* terminals, and measure the voltage developed. This, with the turns ratio of the current transformer (you've got two turns on the primary -- and the number or a ratio should be somewhere on the label of the CT.) will let you turn the voltage to a current reading. Or -- you use a current meter on the secondary, which provides its own low resistance. Look for something like 250:1 (or some other ratio) on the label. I wonder whether it includes some kind of alarm sensor to account for the extra terminals. Good Luck, DoN. -- Remove oil spill source from e-mail Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
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