AB Powerflex 525 Adjustable Frequency AC Drive

[jleif81]

I getting an unbalance voltage out from this Freq Drive. The output should be around 480V. From time to time I'm getting 380 on one leg, 290 on another leg and 440 on the 3rd leg. After I cycle power it will work for a period of time. Has anyone ever experienced anything like this?

 

[robertmee]

How are you determining the output voltage?

 

[jraef]

The 525 does not report individual output phase voltages, only averaged for all three. So you must be reading it with a meter. I would not trust those values too much, most reasonably affordable hand held meters don't do a good job of reading output voltage of VFDs, especially those using 4th gen IIGBTs like the 520 series. Some meters do a good job of reading current, so if your currents are balanced I would not concern myself with voltage. Is there something else you are concerned with that cause you to take the readings?

 

[jleif81]

I was just using my Fluke 179 multimeter. The reason I checked voltage was because motor was not running correctly. Almost as if it was single phasing.

After I cycled power on the machine the problem hasn't came back.

 

[robertmee]

You can't check it with an RMS meter....you'd need a scope.

 

[jraef]

A common issue that looks kind of like this is if you have not done an Autotune procedure.

 

[jleif81]

Ok. Thanks for the feedback. The problem hasn't occurred again so it has been pushed down the priority list...

 

[jraef]

Ok. Thanks for the feedback. The problem hasn't occurred again so it has been pushed down the priority list...

But was the Autotune performed? If not, you really should do it.

 

[JaxGTO]

But was the Autotune performed? If not, you really should do it.

For sure a must on the PF5xx drives. The PF70 and PF700 usually didn't need it, but these new one really do.

 

[spence144db]

But was the Autotune performed? If not, you really should do it.

At a bare minimum, a static tune needs to be performed. Both static and rotate is the preferred method. Is the drive running V/Htz, SVC...ect? Depending on the setting you may need a inertia tune also.