Abb Ac Drive Failure

rajendrad

Member
Join Date
May 2003
Location
Pune, India
Posts
19
Hi DickDV & All,

First of all sorry as I couldn't able to give you the details of motors in time as you asked.I was out for commissioning and could not got all these details from plant engineer.I had got chance to visit the plant again and I was able to collect the details of the same.The configuration now has been changed, instead of 48 motors on one drive, they had used two drives and then also They had one more failure on the drives..............The incoming voltage to AC drives measured was 455V however drive is rated of 415V.....

I am giving brief description of the problem for those who might not aware about this.

ABB AC drives are used for roller table application in wire & rod mill ( steel rolling application).These drives were running since last four years. They had five failures in recent two years.Everything including cable, motors, distrubution board has been checked and found no any problem but still drive is failing.

I feel that some body might be playing with parameters.

I had attached herewith Motor, drive details and parameter list for referance. This is a big challange infront me and need your help..

I am sure that we are going to win........................

- Rajendra.
 
Rajendra, I want to say this kindly and don't mean any personal offense here but, honesty demands that I say plainly that there are massive problems with the application and programming of these systems.

I could likely solve most of these problems for you but, people deserve to be paid for this work. I strongly recommend that you make contact with an ABB drive certified startup technician in your country and use his or her services to straighten out the problems.

For informational purposes only, let me list a few problem areas that jump out at me.

1. ABB drives with model numbers -0XXX-3-XXX are rated for 380/400/415VAC input plus 10%. That would be 456VAC which is right where you are measuring input voltage. This is too dangerous since there are surely voltage excursions higher than that occasionally. You need drives with a -4- in the model number. These are rated from 380V thru 500V plus 10%.

2. The motor data clearly indicates that they are 415VAC rated. The higher drive input voltage means that these motors are being subjected to chopped DC drive output pulses of approx. 650V where, on 415VAC input, the pulses would be around 590VDC. It is possible that you have good inverter rated motors capable of pulses of this magnitude but it should be checked. Using a higher voltage rated drive will not change the pulse output voltages either way--they are a function of the input AC voltage.

3. The motor data in your Excel file seems to indicate that these are six pole motors wound for an 80Hz base speed of 1600rpm. This is a rather expensive choice of motor being special wound but are OK from an application standpoint. Being six-pole, they make multiple motor starting current worse from a drive standpoint as compared to a four pole motor. If they are not six pole, you should check with the motor manufacturer to determine just how the nameplates should be interpreted.

4. The motor data entered in Group 99 of the parameters does not match the totals of the motors on each drive. Neither does the base frequency and resulting speed. There is no way the drive can properly configure a V/Hz profile with the Group 99 data you listed.

5. In Group 11, the reference is limited to 50Hz on two of the systems even tho the motors seem to be specially wound for 80Hz. I have to wonder if these aren't really 50Hz motors with confusing labels.

6. In Group 30, the motor thermal protection is turned OFF as it should be for multiple motors but I see no provision for an external fault loop and individual overload blocks for each motor. You may well have one or two motors out there with failed or failing windings and the drive has no recourse but to fault on Short Circuit without any indication of which motor is in trouble. I would suggest overload blocks in each motor feed with manual reset capabilities so you can see where problems are.

Finally, Rajendra, please go back to my last post in your earlier thread on this subject. I mention some essential items there for operation on multiple motor systems that don't seem to be incorporated into your drives.

Again, please consider hiring a qualified drive tech to straighten out your problems here. It is clear that the drive programmer doesn't understand the complexities of multiple motor applications and you need a higher skill level to get this done.

Good Luck.
 
I concur with DickV especially regarding point 2.

May I ask a question as to what lengths of cable are being used from the drive to the motors? Longer lengths will create all sorts of harmonics problems at the motors which again will add to the higher voltages on the windings.

Good luck with this one and as Dick says try to find an expert, it sounds like you will need one.
 
Thanks DickDV and all.

I know that somebody has figured out these drives and I need to fix it.I am trying to get commissioning docuement of these drives to see that what parameters were set during commissioning. While examining I also realised that group99 is not matching with motor data nor some of the parameters.

I will try to get help of ABB engineer.

Thanks once again for your prompt support.

Rajendra.
 

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