Nidec c200-021 VFD rotating at zero reference

Gene Bond said:

Just a closing thought....

I am betting that due to the low PF, the drive is not accounting for the total magnetizing current, and is *ASSUMING* some of the current is torque producing current.

Click to expand...

I'd be interested to know what the Rotating Autotune came up with for Power Factor...

0.69 pf. it is in the 0 menu pic that I posted earlier. First page, post 12, 00.0009. I'll default and re-autotune Monday and post the report.

Gene Bond said:

I'd be interested to know what the Rotating Autotune came up with for Power Factor...

Click to expand...

Autotune results.

Looks like it came up the same on the 2nd try, but considerably higher than the nameplate. I'd guess that means the Full Load RPM is actually higher than nameplate as well. Not easy to test for without a lab setup, but that'd be my bet.

Like I said earlier, I would cheat the RPM rating a little higher on 5.008 with 5.027 set back to 100% and see what it does. Regardless, unless you have a changing load, I wouldn't mess with Slip Comp, and just set RPM to 1800. No sense beating the motor up with all the gyrations of continuous changes in the speed regulator.

Interestingly, yesterday, I had a customer call with an issue on a blower (fairly high inertia) running on a CT C200. It was 'Hunting' and ultimately tripping on motor overload (It.AC). it was bouncing in speed a few Hz, and about 50% in current, trying to accel/decel the load.

Turns out, he set Pr7 (Motor Nameplate RPM) to 1725, when the actual was 1775. Setting it back to 1775 it ran smooth at about 80% load at full speed. Kinda sounds familiar to the issue you saw.

If I get a chance tomorrow, i will hook up to the older Commander SK 110v drive I have to test with. I have ran this motor on it many times on the desk with no motion, but i am not positive if i had the run forward command high with zero reference.

Hi Gene, it seems you know quite well the C200/C300.
I bought a few weeks ago a C200, 22 kw for multipurpose in our test center.
So I plug it on different machines depending on my needs.
Sometime, the frequency is very unstable, and you can't even turn it off (nothing stops when you push on the red stop button), I have to remove the plug...
I tried your trick to enter a slightly different rpm than the motor plates, and sometimes it works.
Most problems have been encountered on machines with high inertia (hammer mills or centrifugal mills) and 2 poles motor.
What is particularly unsafe for me is that it refuses to stop!
Have you already encountered that problem?
Many thanks

You can set it to coast to a stop, Pr 31 (00.031) for one thing.

By increasing the current loop gain, the drive will do a better job of regulating. Set 04.013 to 40-60 (from default of 20), and decrease the Integral, 04.014 from 40 to 20-10... This sometimes is enough to get the high inertia load under control.

Longer decel time, Pr 4 is called for when trying to decel a high inertia load. But, if you really want to get control, add a Dynamic Brake Resistor, and set Pr 30 to Fast to dump the energy.

The energy has to go somewhere, that's the issue. When you wind up a large inertial load, there is a lot of stored energy, and if there is little friction, there's nowhere for the energy to go, other than into the drive. It can only absorb so much, until it goes into bus-regulation mode, or trips on over-voltage. The Resistor can dump the excess into heat.

Thank you so much for your fast answer, I will try it

sharkyh2o said:

Lesson Motor 230VAC-1.2A-1700RPM-62.5PF

I am having trouble understanding this. My motor rotates at 0vdc reference with the run forward command. Even in pad. I can correct this by increasing the RPMs to 1800. it took me quite a bit of time to track down a remedy but i do not know what the relationship would be to cause this.Nidec service is unavailable right now so i was hoping for some explanation or advice on something I am missing. Thanks for any consideration.

Click to expand...

I've seen this happen with PF525's that are not properly Static Tuned.