Fault Code 09 Power Flex 753

[Saturn_Europa]

The VFD is for a large Reverse Osmosis pump. The motor was replace about 3 months ago. The pump has about 2 weeks of run time on the new motor. The new motor is the same name plate amps and hp. Rotation has been confirmed.

The drive has faulted 3 times on start up with the error code Fault F9 Trnsistr OvrTemp. Power cycling the drive and starting it after a few minutes has allowed the unit to operate. I tried using the reset button on the drive panel and but it would immediately fault.

None of the drive parameters have been changed since commissioning. Parameter 35 [Motor Control Mode] is set to 1 – Induction SV.


Rockwell Automation Knowledge base recommends doing an autotune among other things:
Rockwell Automation Knowledgebase

The instructions in the manual for Auto Tune are a little unclear to me. Uncoupling the motor from the pump is not an option.


Auto Tune is on Page 61 of the manual: PF 750 Manual

Is autotune the right path to go down? The drive does not fault during operation. It faults immediately on start up.

Its a critical piece of equipment and right now we are discussing just leaving it running and letting the extra water go over the side when demand drops.

 

[Joethemechanic]

This is a 755 service bulletin. So I'm not sure it will help but it's worth reading

PowerFlex® 755, Series A, Firmware Release 1.00X and F9 Faults Issue For firmware versions 1.009 and less, fault F9 (transistor overtemp) may occur when starting into large torques from zero speed in Sensorless Vector mode. Sensorless Vector ("Induction SV") is the default setting for P35 [Motor Cntl Mode], offering good performance and simple setup for many applications. Corrective Action If the F9 fault occurs at start: • Ensure that Motor Nameplate settings (parameters 25…31) are correct • Drive has been autotuned • Value of current limit (see parameters 421…423) is at its maximum If the problem still occurs, increase P64 [SVC Boost Filter] from the default value of 0.1 to 0.4. Important:This change is not recommended when the problem is not present because it can decrease responsiveness and starting torque on some power ratings. If the change to P64 does not resolve the problem, change P35 [Motor Cntl Mode] to Flux Vector ("Induction FV"), and rerun the autotune routine, including the inertia test

 

[Jraef]

When you change the motor, you MUST do an autotune again, even if the nameplate says it is the same. Every motor is slightly different, so a drive tuned for a different motor may act erratically when connected to another one. It used to be that if you were using V/Hz control that didn’t matter, but the latest generation of transistors now turn on so much faster than previous generations that they need to be tuned even for that.

If you are using basic SVC (or V/Hz) control, you can do a static autotune, meaning the motor doesn’t move so you don’t need to uncouple it.

 

[Saturn_Europa]

Thanks, Jraef.

We left port on a Friday and have been having a heck of a trip ever since.

Is it just as simple as setting parameter 70 to 2 then letting it do its thing?

 

[petersonra]

I have found that using sensorless vector mode can create all kinds of problems with some Allen Bradley drives. Most of the time there's no real advantage to using it as best I can tell so if I have trouble getting it working in sensorless vector mode I usually just turn it to volts per Hertz and tune it that way. I agree with the guy who said you should tune it regardless of what the motor nameplate says. I don't think it makes that much difference most of the time but Best to cover all your bases.

 

[Jraef]

Thanks, Jraef.

We left port on a Friday and have been having a heck of a trip ever since.

Is it just as simple as setting parameter 70 to 2 then letting it do its thing?

Yes, that’s all it takes.

Well, that followed by a Start command… which in some applications may require switching to keypad control and/or disabling interlocks that may shut it down before it finishes due to it not actually turning, for example if you have no-flow detection on a pump.