hi. i am working with a packaging company at daman in india. we have one multilayer blown pe-film extruder. my concern is about the parkers ssd drives connected to 3 extruder motors (55kw,55kw and 75 kw) and fixed in the electrical panel of the same m/c.

after commissioning, the m/c ran very wellfor 3-4 months without any problem. but from march onward we have been facing igbt blown off problem for all 3 drives. we have rectified each drive for 3 times from parker chennai. but unfortunately after every 2days of continuous operation igbt of one or two drives use to blow off along with 125 amps fuses connected prior to drives.

all the factors like earth-bits, input supply fluctuation, power trips, magnetic noise etc. were checked several times, shielded and found to be ok.

now my request is that if any expertise from maintenance field could give me some tips on what else could be the possible reasons behind disaster and what precautions we should absorb to avoid them.

warmest thanks,
abhijit saha
uniglobe packaging pvt. ltd.

 

Abhijit Saha, to start, please provide the following:

1) Supply voltage to your drives.
2) Size of supply transformer.
3) Is neutral of supply xfmr earthed?

Regards, Phil Corso ([email protected])

 

Abhijit, further to my 11-May-09 (11:48), response to your query, please provide the following measurements to and from each drive:

4) Line-to-Line Voltages.
5) Line-to-earth Voltages.
6) Line Amperes.

Please make sure you use a "true" rms reading meter!

Regards, Phil Corso ([email protected])

 

abhijit saha

We have had similar problems in our plant but with servo drives. We found the supply transformer had an ungrounded Y (star) point. Since we grounded it our failure rate has dropped by 90%.

With an ungrounded star, a ground fault anywhere in the system will produce unbalanced voltages to ground. (we saw 600+v to ground on our 480 system)

 

My guess is the thing that has change in India in 3-4 months is the weather. my guess is it is fairly warm there and my guess is that like most blown film plants your plant is not climate controlled. my guess is that like most OEM's they have undersized the cooling in this extruder cabinet or the cooling is no longer functioning properly. I would check A/C and or Fan units. I would check the drive temp to see what it is running at vs. the specs Parker says it can run at.

 

one last thought, since extruder drives are generally large and field repaired vs. sent back for repair. if that is the case, are you sure the IGBT's were torqued correctly when they were replaced and was the proper heatsink compound used when they were replaced. if they were replaced by a Parker service Tech or sent to the factory this is probably not an issue, but end users usually do not realize the importance of installation of an IGBT or SCR on a Drive.

 

Yes, it is critical to get the heat out of the semiconductors. I worked with a 9MW inverter for an iron melter. If you didn't get the mounting and heatsinking right, it was really, really, exciting to turn the inverter on.

Regards
cww

 

I'll second that grounded wyes are very important. I like isolation transformers and line reactors as well. again they have to be sized and installed properly.