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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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#1
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Power supply
On Wed, 29 Sep 2010 11:55:59 -0500, 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. Is the part labeled 1 an isolation transformer? If so, should DC- 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" The purple stud mount things are definitely not diodes; they're either SCRs or triacs. Label 1 is a three-phase trsnsformer; "DC-" should only be grounded if it is grounded in the original design. Item Label 2 is a current transformer; the wires you've cut were used in the control circuitry. In pic 2, it looks like label 1 _could_ be a 3-phase common mode choke, to keep the switching transients of the SCRs/triacs out of the power lines. But, as others have said, without the control electronics, you have a pile of probably not very valuable spare parts. Sorry! Rich |
#2
Posted to rec.crafts.metalworking
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Power supply
In pic 2, it looks like label 1 _could_ be a 3-phase common mode choke, to keep the switching transients of the SCRs/triacs out of the power lines. Tim suggested checking for continuity. Theres 0 ohms accross leads, so its not an isolation transformer. Any use for a chocke, or just toss it? But, as others have said, without the control electronics, you have a pile of probably not very valuable spare parts. Sorry! Rich Looks like i spent the morning making a large hunk 'o junk into a pile 'o junk parts. But at least I learned a little bit. Thanks everybody. I've got a very old VFD I'll tear down next. I know it has electrolytic caps and I'll look for diodes. Karl |
#3
Posted to rec.crafts.metalworking
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Power supply
On 2010-09-29, Karl Townsend wrote:
In pic 2, it looks like label 1 _could_ be a 3-phase common mode choke, to keep the switching transients of the SCRs/triacs out of the power lines. Tim suggested checking for continuity. Theres 0 ohms accross leads, so its not an isolation transformer. 0 Ohms from side to side along one coil, or 0 Ohms between terminals on the same side of the transformer? If the former, then yes, it is a choke. If the latter -- and high resistance between sides, it could still be a transformer. Any use for a chocke, or just toss it? Keep it. You'll reduce the hash which you put into the power line (especially if you brew your own circuitry to turn on the SCRs), and it will help keep the circuit from blowing away in a hurricane. :-) But, as others have said, without the control electronics, you have a pile of probably not very valuable spare parts. [ ... ] Looks like i spent the morning making a large hunk 'o junk into a pile 'o junk parts. But at least I learned a little bit. Thanks everybody. If you have the manuals -- maybe you can restore the control board to the SCRs and wind up with a nicely regulated power supply to drive the servo amps. If not -- you could perhaps hook up some wall warts to power the gates of the SCRs to turn them on full time and at least use them as rectifiers. The wall warts will probably be cheaper than that many high current rectifiers would be. The main trick is determining how many of those you can wire to a single wall wart (through current limiting resistors to each gate). I suspect that you can get away with three wall warts -- one per bank of SCRs. Are you going to be running this from true three phase? If not, you can probably get away with fewer wall warts. Hmm ... I wonder about those banks of SCRs. If all are the same part number, then you have three rows of common cathode ones and three wall warts for three phase. However, this does not sound right for a proper three phase bridge -- so you either have half of them with a different part number (anode to case instead of cathode to case) in which case the number of needed wall warts increases, or some strange setup. A lot better if you can get the original control board working, and each set of terminals connected to the right SCR's terminals. (Proably coupled pulses through small transformers on the logic board, so you get proper isolation between SCRs. I've got a very old VFD I'll tear down next. I know it has electrolytic caps and I'll look for diodes. Does the VFD still work? What kind of horsepower is is supposed to drive? If it still works, I would be tempted to keep it intact. And if it doesn't, it is likely that the rectifiers were what failed -- or the failure of the output MOSFETs took out the rectifiers too. The diodes in that are likely to be combined in fewer packages, one package being three rectifiers in a single package with common cathode, and the other three rectifiers in a single package with common anode instead. The real question is whether they will handle enough current for your needs. Based on the looks of that original supply, it was to drive some hefty motors. (Hmm ... could it be that big supply was purely to drive the spindle servo motor and the axis motors were some other supply? 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 --- |
#4
Posted to rec.crafts.metalworking
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Power supply
"Karl Townsend" wrote in message ... In pic 2, it looks like label 1 _could_ be a 3-phase common mode choke, to keep the switching transients of the SCRs/triacs out of the power lines. Tim suggested checking for continuity. Theres 0 ohms accross leads, so its not an isolation transformer. Any use for a chocke, or just toss it? But, as others have said, without the control electronics, you have a pile of probably not very valuable spare parts. Sorry! Rich Looks like i spent the morning making a large hunk 'o junk into a pile 'o junk parts. But at least I learned a little bit. Thanks everybody. I've got a very old VFD I'll tear down next. I know it has electrolytic caps and I'll look for diodes. Karl Don't give up yet, it doesn't take much to use an SCR as a diode. Probably just connecting the 2 control lead wires together or maybe connected through a resistor. A SCR is a silicon controlled RECTIFIER, it is a rectifier that can be turned ON and OFF. To use as a diode rectifier you just have to wire it to be turned ON all the time. I haven't messed with SCR's much and don't know how you connect it without looking it up but find out, make a simple connection, and use what you have if possible, they are already mounted on a heat sink and everything. I worked 13 hours today so I'm not going to be of much help today but I'll try to look up a little info on SCR's maybe tomorrow. RogerN |
#5
Posted to rec.crafts.metalworking
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Power supply
"DoN. Nichols" wrote in message ... On 2010-09-29, Karl Townsend wrote: In pic 2, it looks like label 1 _could_ be a 3-phase common mode choke, to keep the switching transients of the SCRs/triacs out of the power lines. Tim suggested checking for continuity. Theres 0 ohms accross leads, so its not an isolation transformer. 0 Ohms from side to side along one coil, or 0 Ohms between terminals on the same side of the transformer? If the former, then yes, it is a choke. If the latter -- and high resistance between sides, it could still be a transformer. Any use for a chocke, or just toss it? Keep it. You'll reduce the hash which you put into the power line (especially if you brew your own circuitry to turn on the SCRs), and it will help keep the circuit from blowing away in a hurricane. :-) But, as others have said, without the control electronics, you have a pile of probably not very valuable spare parts. [ ... ] Looks like i spent the morning making a large hunk 'o junk into a pile 'o junk parts. But at least I learned a little bit. Thanks everybody. If you have the manuals -- maybe you can restore the control board to the SCRs and wind up with a nicely regulated power supply to drive the servo amps. If not -- you could perhaps hook up some wall warts to power the gates of the SCRs to turn them on full time and at least use them as rectifiers. The wall warts will probably be cheaper than that many high current rectifiers would be. The main trick is determining how many of those you can wire to a single wall wart (through current limiting resistors to each gate). I suspect that you can get away with three wall warts -- one per bank of SCRs. Are you going to be running this from true three phase? If not, you can probably get away with fewer wall warts. Hmm ... I wonder about those banks of SCRs. If all are the same part number, then you have three rows of common cathode ones and three wall warts for three phase. However, this does not sound right for a proper three phase bridge -- so you either have half of them with a different part number (anode to case instead of cathode to case) in which case the number of needed wall warts increases, or some strange setup. A lot better if you can get the original control board working, and each set of terminals connected to the right SCR's terminals. (Proably coupled pulses through small transformers on the logic board, so you get proper isolation between SCRs. I've got a very old VFD I'll tear down next. I know it has electrolytic caps and I'll look for diodes. Does the VFD still work? What kind of horsepower is is supposed to drive? If it still works, I would be tempted to keep it intact. And if it doesn't, it is likely that the rectifiers were what failed -- or the failure of the output MOSFETs took out the rectifiers too. The diodes in that are likely to be combined in fewer packages, one package being three rectifiers in a single package with common cathode, and the other three rectifiers in a single package with common anode instead. The real question is whether they will handle enough current for your needs. Based on the looks of that original supply, it was to drive some hefty motors. (Hmm ... could it be that big supply was purely to drive the spindle servo motor and the axis motors were some other supply? Good Luck, DoN. -- DoN, I don't remember SCR's all that great but I remember once the gate voltage goes high the SCR turns on and latches on until current goes below some threshold. A person gave me some small hockey puck SCR's to use to make a rectifier for my welder. I didn't get the details but I thought he said you could connect the gate to the (?anode or cathode) and the SCR would turn ON and operate as a rectifier. I'll have to experiment before I recommend to Karl but as soon as the SCR turns on it prevents the gate voltage from going any higher than the (I think Anode ?) voltage. I could try hooking up one using a resistor to connect the gate to the anode (?) and seeing if there are any voltage or current spikes showing up at the resistor. What I do remember of SCR's is that you can turn them on in the rising part of the sin wave with a simple voltage divider, and you can use a resistor and capacitor to get a phase shift to be able to turn the SCR on almost anywhere during the sin wave. RogerN |
#6
Posted to rec.crafts.metalworking
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Power supply
On Wed, 29 Sep 2010 22:52:58 -0500, "RogerN"
wrote: "Karl Townsend" wrote in message .. . In pic 2, it looks like label 1 _could_ be a 3-phase common mode choke, to keep the switching transients of the SCRs/triacs out of the power lines. Tim suggested checking for continuity. Theres 0 ohms accross leads, so its not an isolation transformer. Any use for a chocke, or just toss it? But, as others have said, without the control electronics, you have a pile of probably not very valuable spare parts. Sorry! Rich Looks like i spent the morning making a large hunk 'o junk into a pile 'o junk parts. But at least I learned a little bit. Thanks everybody. I've got a very old VFD I'll tear down next. I know it has electrolytic caps and I'll look for diodes. Karl Don't give up yet, it doesn't take much to use an SCR as a diode. Probably just connecting the 2 control lead wires together or maybe connected through a resistor. A SCR is a silicon controlled RECTIFIER, it is a rectifier that can be turned ON and OFF. To use as a diode rectifier you just have to wire it to be turned ON all the time. I haven't messed with SCR's much and don't know how you connect it without looking it up but find out, make a simple connection, and use what you have if possible, they are already mounted on a heat sink and everything. I worked 13 hours today so I'm not going to be of much help today but I'll try to look up a little info on SCR's maybe tomorrow. RogerN I'd really appreciate the help Roger. This unit was built for this machine, it has to be designed and sized for it. Karl |
#7
Posted to rec.crafts.metalworking
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Power supply
On Sep 30, 6:55*am, "RogerN" wrote:
"DoN. Nichols" wrote in message ... On 2010-09-29, Karl Townsend wrote: In pic 2, it looks like label 1 _could_ be a 3-phase common mode choke, to keep the switching transients of the SCRs/triacs out of the power lines. Tim suggested checking for continuity. Theres 0 ohms accross leads, so its not an isolation transformer. 0 Ohms from side to side along one coil, or 0 Ohms between terminals on the same side of the transformer? If the former, then yes, it is a choke. If the latter -- and high resistance between sides, it could still be a transformer. * * * * * * * * * * * * * * * * * Any use for a chocke, or just toss it? Keep it. *You'll reduce the hash which you put into the power line (especially if you brew your own circuitry to turn on the SCRs), and it will help keep the circuit from blowing away in a hurricane. :-) But, as others have said, without the control electronics, you have a pile of probably not very valuable spare parts. [ ... ] Looks like i spent the morning making a large hunk 'o junk into a pile 'o junk parts. But at least I learned a little bit. Thanks everybody. If you have the manuals -- maybe you can restore the control board to the SCRs and wind up with a nicely regulated power supply to drive the servo amps. If not -- you could perhaps hook up some wall warts to power the gates of the SCRs to turn them on full time and at least use them as rectifiers. *The wall warts will probably be cheaper than that many high current rectifiers would be. *The main trick is determining how many of those you can wire to a single wall wart (through current limiting resistors to each gate). *I suspect that you can get away with three wall warts -- one per bank of SCRs. Are you going to be running this from true three phase? *If not, you can probably get away with fewer wall warts. Hmm ... I wonder about those banks of SCRs. *If all are the same part number, then you have three rows of common cathode ones and three wall warts for three phase. *However, this does not sound right for a proper three phase bridge -- so you either have half of them with a different part number (anode to case instead of cathode to case) in which case the number of needed wall warts increases, or some strange setup. A lot better if you can get the original control board working, and each set of terminals connected to the right SCR's terminals. (Proably coupled pulses through small transformers on the logic board, so you get proper isolation between SCRs. I've got a very old VFD I'll tear down next. I know it has electrolytic caps and I'll look for diodes. Does the VFD still work? *What kind of horsepower is is supposed to drive? *If it still works, I would be tempted to keep it intact. *And if it doesn't, it is likely that the rectifiers were what failed -- or the failure of the output MOSFETs took out the rectifiers too. The diodes in that are likely to be combined in fewer packages, one package being three rectifiers in a single package with common cathode, and the other three rectifiers in a single package with common anode instead. The real question is whether they will handle enough current for your needs. *Based on the looks of that original supply, it was to drive some hefty motors. *(Hmm ... could it be that big supply was purely to drive the spindle servo motor and the axis motors were some other supply? Good Luck, DoN. -- DoN, I don't remember SCR's all that great but I remember once the gate voltage goes high the SCR turns on and latches on until current goes below some threshold. *A person gave me some small hockey puck SCR's to use to make a rectifier for my welder. *I didn't get the details but I thought he said you could connect the gate to the (?anode or cathode) and the SCR would turn ON and operate as a rectifier. *I'll have to experiment before I recommend to Karl but as soon as the SCR turns on it prevents the gate voltage from going any higher than the (I think Anode ?) voltage. *I could try hooking up one using a resistor to connect the gate to the anode (?) and seeing if there are any voltage or current spikes showing up at the resistor. What I do remember of SCR's is that you can turn them on in the rising part of the sin wave with a simple voltage divider, and you can use a resistor and capacitor to get a phase shift to be able to turn the SCR on almost anywhere during the sin wave. RogerN SCR tutorial: http://www.allaboutcircuits.com/vol_3/chpt_7/5.html The gate may have a maximum current rating and should be protected with a series resistor. jsw |
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