Today we spent some time characterizing the motor for a mid-size grinder. Specifically, a 5/8 HP DEWALT DW756 6-Inch Bench Grinder. I've been working with the eval board for the Microchip MCP39F511A Energy Monitor IC and finally tweaked my code enough to run it via an Arduino at an overall read-rate of about 50hz. I then use MegunoLink (which I highly recommend) for basic GUI and visualization. This is the test setup:

I was able to plot the startup and run characteristics of the motor and shared the plots below. Of note is the impact of mechanical load on the electrical characteristics. That's just one of the many things we need to characterize. Pretty cool plots. One thing doesn't look right though - can anybody spot it?