Well, as I thought, the values are simple to change. Unfortunately, the upper RPM is programmed as a maximum in the VFD controller (an Emerson Commander SK, which is an interesting little box). I didn't take too long snooping around it, but it looked to me like the maximum frequency programmed is 170 Hz, but the controller only hits 144.2 Hz tops (on its little display) wide open. It does that before you get to 5140 on the Mach display, by the way. It's more like 4900 to Mach, but I measured it again at an actual 5260 RPM or so. I think I'll calibrate that out, now that I know more about the calibration parameters.
Anyway, I'm not really interested in voiding my warranty, so I put it all back how I found it. The difference between 144.2 and that "maximum" 170 Hz is curious, however. Had it actually gone to 170 Hz, it would have peaked right at 6200 RPM...
Regards,
- Just Gary |