Hello all. I've done some programming but I'm new to Arduino. So I apologize in advance for what I'm sure will be dumb questions. That said; I'm working on a var feed system for a something like a planer. It's more elaborate than that, other activities involved. Nonetheless, what I would like to do is monitor the amp draw on the machine. Then use that to control the feed speed. That is as the load gets higher the amp draw will raise and, via my imagined system/board, will decrease the speed. What I have so far is a Minarik mm23000 drive running a 90vdc motor. The drive has, among other things, a speed pot. What I imagine is a board, similar to a breakout board, that will monitor the amperage and output something that that my Arduino can interpret. Then drive a servo which will physically turn the pot. Since I already have a working setup I'd rather not convert to a VFD since I don't think it would be much different that what I have anyway. So my first question is what is out there that I can use to monitor the amperage and send a usable signal to my Arduino? Second Do I need something else to convert it to, I'm thinking, 4-20ma. I think Adruino can interpret that.
Thanks for any tips, tricks or ideas you care to share.
In general it's doable how you described. A pitfall may be the current monitoring, depending on the current waveform generated by the speed control. But a strong low pass filter should provide a useful current signal.
Hi,
What is the planer motor that you want to monitor the current from?
I understand you want to use the feed motor speed to keep the planer motor under constant load, am I right.
Will changing the feed speed have any effect on the quality of the planed surface?
The manual for the feeder drive does show a voltage level speed input.
Can you tell us your electronics, programming, arduino, hardware experience?
Tom... 
earthworx:
Hello all. I've done some programming but I'm new to Arduino. So I apologize in advance for what I'm sure will be dumb questions. That said; I'm working on a var feed system for a something like a planer. It's more elaborate than that, other activities involved. Nonetheless, what I would like to do is monitor the amp draw on the machine. Then use that to control the feed speed. That is as the load gets higher the amp draw will raise and, via my imagined system/board, will decrease the speed. What I have so far is a Minarik mm23000 drive running a 90vdc motor. The drive has, among other things, a speed pot. What I imagine is a board, similar to a breakout board, that will monitor the amperage and output something that that my Arduino can interpret. Then drive a servo which will physically turn the pot. Since I already have a working setup I'd rather not convert to a VFD since I don't think it would be much different that what I have anyway. So my first question is what is out there that I can use to monitor the amperage and send a usable signal to my Arduino? Second Do I need something else to convert it to, I'm thinking, 4-20ma. I think Adruino can interpret that.
Thanks for any tips, tricks or ideas you care to share.
AC series motors can do speed regulation under load/no load conditions automatically via phase control and simple feedback.
No need for Arduino, servos etc.etc.