Considering the Lexel has a direct input autotransformer, you could get away with the VFD, provided you lock it at 60 Hz and have the duty cycle set correctly. Its going to get a little warmer from harmonics, and the tap settings may change. I know one fellow who bought a 25 horse VFD and is very happy.
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The autotransformer usually will hum/moan quite loudly if its unhappy with its input power. Some lamination singing is normal when unloaded, but if it really starts to hum/scream/radiate loudly when loaded, stop.
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If it blows up, which I really, really doubt it will, I have one spare 95 input transformer in my barn. Whatever you do, DO NOT attempt to regulate the laser power by constantly tweeking the VFD. You will have to check the cathodes with an amp clamp and voltmeter. Your "ABC" switch ranges will be a bit different. Depending on which cathode is installed, they are either 75 watt or 125 watt cathodes.
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Other psus, expecially Innova 70 and Innova 90, and newer SP products, will not be so forgiving. Most other systems use a phase fired SCR rectifier bank and really are set up for sine wave.
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So Lexel, probably, depends on the quality of the VFD's output.
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HGM/ALC three phase supplies are basically the same for three phase and single phase, and they are switchers. The first thing after the contactor is a bunch of water cooled rectifiers, the only difference being a few extra diodes for the three phase models. So for HGM, just make sure you rewire the cathode transformer, magnet supply rectifier and low voltage transformers, and interlocks for single phase operation. HGM checks for two phases connected by placing the low voltage transformer on a different phase, that's it. They then run just fine off a single phase line once you make all the standard adjustments on the control board. Then ensure you're not sagging the power line down low enough that the cathode gets too cold. The difference between a 9 series and 20 series is the amount of filter capacitance and passbank transistors HGM used. I've done this with HGM systems.
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The one thing to NEVER do, is run a Lexel off a single or three phase SOLA transformer /power line filter that is designed to regulate its output voltage using Ferro resonance. I had a client do that, and the PSU was a mess inside. I repaired it on site, and tried it again, and again, the harmonic currents started to rip the PSU apart. . Customer refused to pay me for the service call, however, because the local surplus place told him the Sola step down regulator would be one third the cost of the 480 to 220 transformer I specified. He bought it, could not return it, and got burned. Club owners can be so stubborn and stingy some times, well all the time.. Since those only exist in computer centers and nuclear bunkers, I'm not too worried about it happening again.
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Sir Steven
Last edited by mixedgas; 05-18-2017 at 06:26.
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