[Jim Dawson]

Interesting readings. And a very cool graph. What Fluke meter do you have? Mine have no provision for data recording, a 87V and a 32 Clamp Meter. I'll get some readings from my lathe tomorrow morning.

Do you have any power factor correction caps across L1-L2? Those really reduced my input current.

Here is my as built schematic



And the panel meters under idle load with the hydraulics running, spindle off. These meters agree with my Fluke meters. Not bad for $14 each.

[torinwalker]

Mine is a Fluke 289. I operated with a Radio Shack Multimeter for nearly 30 years, and had many models including the three (of ten) benchtop meters I photographed earlier. I also had this Fluke 100Khz to 2.1GHz signal generator sitting in my basement from my old ham-radio days, but I just never really used it. One day, I saw the Fluke 289 on Kijiji (Canada's craigslist) and the guy accepted a trade. He got the better deal, I thought, until I made that graph :-)

Yes, I saw your schematic before - the one with the switches. I actually have some ideas for how one could make those switches of yours programmatic (during operation that is), but I won't share here. Not just yet. Possibly patent-able IP :-)

What values are you using for those caps? And if you were to double your RPC capacity from 15HP to 30HP, what would you do to modify it? I have to do that with mine. I'm at 20HP now, and must boost to 30HP. I don't know if it's a simple linear equation (i.e. just double the capacitors.) Many RPC manufacturers are unwilling to share the inner details of their units.

No, I don't have a power-correction capacitor across L1-L2. The guy at WNY warned me to be careful (not to add too many lest the voltage get too high for my machine), but I don't exactly know how to add them proportionally. Any advice? WNY actually sells a "gold" version of their RPC which Jacques claims better balances for CNC and it has three groups of caps rather than two. I tried calling him and leaving a message, but no call back.

The meters you have on your RPC are incredible. I don't think I saw them before. They are exactly what I need. Where did you get them? What ebay vendor?

I am pretty impressed with the Fluke for showing me that data, and I'm eager to perform more of these tests but I want to write a program first. One that incrementally adds more load to the system representative of what I might actually encounter during a program that cuts my products. My plan is to write the program, trigger the fluke to start recording using threshold value (so it always starts at the same place), then use the meter to record Current on mains (L1-L2), then voltage on each of the phases (T1-T2, T2-T1, T1-T3), and perhaps I'll also monitor my hydraulic motor since it's the big pain in the ass in this scenario. When I'm all done, I will take all of the data and overlay them onto the same graph giving me a readout of current consumption, voltage drop, and balance effect on the hydraulic motor.

On a completely different note, I was able to get wiring details from Baldor on their gen-purpose 20, 30, and 40HP motors figuring that if I could somehow relate the baldor 20HP motor's winding resistance with the voltage drop I'm seeing, I could somehow translate that to a proportionally lower drop on the 30 and 40 HP motors because of the larger motor's lowered resistances. Unfortunately, I haven't figured out the relationship (math) to give me the ratio I'm looking for. I need to measure the current through each of T1, T2, T3 during the imbalance to figure out why the generated leg is so saggy. Otherwise, I will have trouble deciding on which of the 30HP or 40HP motors to buy.

Sorry... too many questions and topics in one thread. I do tend to go on :-) Gotta go and find me those meters.


Torin...