ATV310 Frequency fluctuation happening

[firdaus.alam]

Frequency fluctuation of @ATV310 drive – If I set 25 /30 Hz set point – output frequency is okay from drive and if I set above 30Hz, it give fluctuation in drive output frequency and it varies from setpoint value to maximum frequency. I has also been noted that many times it draws much higher current for same motor and Main voltage (from DC bus) (Modbus Register Address 16#0C87 = 03207) varies a lot. 

Please advise Solution for this - it's newly purchased VFD - 2 nos. and both are having this problem

Operation is 460Volts, 60 Hz, Location -KSA. 

[firdaus.alam]

The Device Status shows is (Obr)

[MatthewM]

I am not a drive expert, but will offer some things to consider.

Start by checking that your ramp settings are sensible.

It looks like your drive could be hunting the output frequency to try and control speed.  What motor control mode is it using?  My guess is it is uuC [SVC V].  Try using Std [Standard] V/F, or uF9 [V/F Quad] with an auto-tune.  I have been told by some experts that auto-tune should not be used, and yet in some circumstances this was the only way to make some loads settle down (I have not needed this on a pump before, though).

Obr is over-braking, indicating it is ramping down faster than the drive can dissipate heat.  This is probably a symptom of the output hunting rather than inertia or fluid flow causing it to be motored.

[MatthewM]

Opps sorry I was referencing ATV320.  ATV310 has different interface.  Check the Motor Control Type at menu 309.  Auto-tuning is under 318.

[firdaus.alam]

Hi Matthew,

Thanks for your guidance.

- 308 - is Maximum Frequency Set which I set 65 Hz whereas 301 (Standard Motor Frequency) I have set for 60 Hz)  - ---- Could this be a Problem?

- 318 is Auto Tuning which I have left as Factory Setting "00" which means "NO" ... Do I need to change this? Could this be the reason of this Frequency hunting?

[MatthewM]

308 and 301 should be fine.

I would be more interested in what 309 is set to.

[BJacqz]

A general comment on drive comissionning, we always advise to enter the motor name plate (with all information such as power, speed, current, ...) and after doing this, perform a motor autotune. This will allow the drive to "know" perfectly the motor. On you case, the OBr is due to motor unstability as it "brakes" when the frequency goes down. You could alos check that speed reference is stable (just to see if it is  a "drive issue", or if this is a "reference issue"). 

[firdaus.alam]

Thanks for your response, please provide the commissioning document link and in detail procedure for Auto Tuning please if possible.

[firdaus.alam]

Hi Mathew,

309 is set to 03 (Standard: 2 point V/F control without internal speed loop).

[BJacqz]

Here you are the user's manual on ATV310.

[MatthewM]

Hmm.  Not behaviour I would expect for 2pt V/F.

As per BJacqz reply, check all nameplate settings are correct, and then perform an auto-tune.  The procedure is described in the manual under 318 "Auto-tuning".

Check that the ramp settings are sensible.  I would suggest it should be 5s or more.