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Old September 27th, 2003, 12:15 AM   #1
mrdegold
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Question AC Drive Question

I know this is a little off topic but
I have a 200 hp ABB ACS 600 Drive. I am getting a Supply Phase Fault. All input legs appear to be good. I am only getting the Fault when the motor is under a load and then only above 800 to 1000 RPM (The production guys told me 800 but they had more of a motor load)
I’m seeing a fluctuation on the DC bus of about 675 vdc to 590 vdc.
Now my question is could a bad thyristor module cause this or what else should I look at.
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Old September 27th, 2003, 09:19 AM   #2
mrdegold
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Continued 9hrs later

Ok I replaced all 3 of the Thyristor modules. Then I button it up and took it for a spin. This is a batch process so we ran some batches the first 2 were fine at the end of the third batch lost all power to the equipment. Turns out we blew apart an IGBT (output control component).
While cleaning up the silicon and plastic casing mess I used a vacuum cleaner dust from the exhaust set off the smoke detector. Lucky for me I stopped the fire suppression system before discharging. After meeting with the Police and Fire Chief and explaining the situation. I went back to work. Finished replacing the parts as well as 2 of Amp Traps. Power up the cabinet and reset the e stop at which point more raw material discharge spoiling the batch.
Time to test AGAIN but all down stream equipment was full of material and needed time to be started. After watching a few batches and all seems fine it was time to go home.
Then to top off a wonderful all night call in when I went to pull in the driveway there was dog dodo blocking my way so I’m parked in the street.
Good night

Last edited by mrdegold; September 27th, 2003 at 09:21 AM.
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Old September 27th, 2003, 10:31 AM   #3
DickDV
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I know when you're having a bad night, everything seems to go wrong but, mercy, that must have been some pile in your driveway to keep your car from entering!! (snicker!)

No, seriously, in eight years of dealing with 100's of ACS600's, I've never needed to replace a power circuit component so that leaves me a bit inexperienced in that area. However, as long as your input power was good on all legs and reasonably balanced to neutral (definitely not running one leg deliberately grounded), they you probably did the right thing by replacing the input rectifiers. The fact that the fault didn't show up until the drive was loaded pretty much indicates either the rectifiers or bad bus capacitors. And bad caps generally fail in a most conspicuous way by rupturing and spraying metal foil all over.

The failure of the output IGBT seems odd though. I don't see any connection between that and the original fault. Maybe (please don't take offense here), somehow in the process of replacing the rectifiers, something was disturbed in a way to fail the IGBT.

Hope this is the end of your problems with this drive. I'd be interested to know what your overall experience with ABB drives has been. I'm a rep for ABB in Michigan and its always good to get the facts from outside my normal territory. Incidently, the ACS600 is, just now, rolling over to an ACS800--pretty much the same drive but with newer components, smaller size, a few new bells and whistles, but otherwise, about the same.
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Old September 27th, 2003, 02:29 PM   #4
rsdoran
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Just wondering for future reference

Quote:
Incidently, the ACS600 is, just now, rolling over to an ACS800--pretty much the same drive but with newer components, smaller size, a few new bells and whistles, but otherwise, about the same
Dick my new job has LOTS and LOTS of the ABB ACS600, to me they seem overkill for the app but its what is being used.

Except for mounting is the ACS800 a drop in replacement? Wiring, modules etc the same?

Or will the 600 still be available for awhile?
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Old September 27th, 2003, 04:02 PM   #5
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Just some more info for you to chew on. The DC buss voltage should be the input (RMS) voltage times 1.414 or input divided by .707. If this is high typical drive fault would be bus overvoltage. The IGBT or insulated gate bipolor transister is not a common failure point. DC bus capacitors should be changed out every three to five years along with the coolant axis fan.
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Old September 27th, 2003, 10:21 PM   #6
mrdegold
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After waking up

I would like to try to answer some of the questions now that I feel a bit more rested (about 4 hours of sleep)
1st The pile of dog dodo wasn’t overly large just well placed. (laughing)
We are a plastic compounder and do quite allot of batch processing. We use ABB drive exclusively roughly about 5 – 200hp or larger ACS 600 drives about 3 ACS 500 drives of about the same size and quite a few smaller drives mixed mostly between the 500 and 600 series.
The drive that failed is used on a high intensity turbo mixer. We have experience a lot of IGBT failures in these drives. So many in fact that myself (plant automation and electrical control) and the Maintenance Manager have become very good at replacing these components. In fact it takes us just around 2 hrs to complete the repair under “normal” circumstances.
I have been working with both my ABB dealer and Service Tech. Since these failure started to occur. At some point along the time line ABB themselves started looking into the problems. I have 3 identical machines (Same hard ware, same motors, and same drives) and this recurring IGBT failure occurs on all 3. The other ACS drives of the same basic size are used in a different application and perform wonderfully.
This of course leads us to an application problem. Well these drive modules are run hard I will not deny that. We take them over current for a short time during almost every batch cycle. I have done trends and am told that although we are working these drives pretty hard that the life of the failing components would be shorted to only about 10 years. Well to tell the truth at this point I would be happy with 2 to 3 years even a year would be kind of nice.
I have to say it does appear like everyone involved is tiring to resolve this continuing problem although after nights like last night I think it is taking a bit too long.
I would like to thank everyone who replied or just read this post. I am the only “controls” person at my company and it’s great to have a place to go where someone speaks my language.
Thanks again
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Old September 28th, 2003, 08:06 PM   #7
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Ron, for many applications, the full capabilities of the ACS600 are overkill but, over 50hp, it doesn't really cost anything extra to include them. At that point and up, the ACS600 has always been a pretty competitive drive even on fans and pumps. Plus, with DTC's superior torque producing cabilities, I'm often able to do the same job with a one-size-smaller drive which makes it even more competitive.

The 600 will still be available until about the end of the year. After that, service parts will continue on for many years. Even now, the prices of the 600 are gradually rising to push new applications toward the new 550 and the 800.

The 800 is, for all practical purposes, a 600 in a smaller package. The software looks very much the same and the control terminals look the same too. The only real change in IO is the addition of a Digital Input 7 at the bottom of the X2 strip. It is permanently assigned as a Run Enable or "safety loop" function. Several industries, especially automotive require either contactor release on an E-stop or a programmed input that is NOT software accessible. The new input is in response to that need.

The only substantial changes in my opinion are: integral brake chopper included in all units under 20hp, startup and tuning wizards for just about everything (I never use these), and PLC-type logic modules that can be used to create all kinds of unusual timing, boolean, and comparative operations on internal drive functions as well as the ability to use any spare drive inputs and outputs for process control unrelated to drive operation. This is called Adaptive Programming and will be a big deal with the systems people but, for us ordinary blokes, I don't think it will be used very often.

For bells and whistles, there are: space inside even the smallest drive for two option modules and a fieldbus communication module, a larger LCD display, and, on the digital inputs, the option of setting up Run Forward, Run Reverse inputs. This was not available on the 600. There are also some new choices to make the creation of a nice crisp jog a lot easier to set up.

And, for those simple jobs, you might want to look at the new ACS550. It replaces the 400 but extends all the way to 400hp. I expect a lot of the higher hp 600 applications to go to the 550 rather than the 800.

And, for mrdegold, I would sure like to hear about any conclusions that are reached on the IGBT failures. I routinely use 600's well into overload and don't recall even having a failed IGBT. Something peculiar must be going on there. (I seem to gravitate to stamping press and forging hammer drive applications and these drives usually go to 160-180% overload for a short time on every cycle!)
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Old September 29th, 2003, 01:39 AM   #8
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Hello !
Had some problems with "exploding" IGBT:s not ABB but siemens micromaster drives. Turned out that when the conditions for the drive are hot (plant was in south korea) the IGBT:s would brake when driving at slow speed for some times.
The "cure" to stop that from happening was to change the IGBT update frequenzy to slower. Apperently the high refresh frequenzy heated the IGBT so it broke?

Don't know if it could be the same with ABB `?
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Old September 29th, 2003, 07:09 AM   #9
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nif makes a good point about higher carrier frequencies putting additional stress on IGBT's. However, on the ABB ACS600 and 800, there is no carrier when running in DTC. The IGBT firing is not software selectable. The output pulses are based on the motor model and the control algorithms with the result being output pulses which appear to be random. In fact, they are placed and timed to provide exactly what the motor needs to produce the torque and speed consistent with the drive control input commands.

I'm told that the pulses average somewhere around 3KHZ but that is only a loose estimate.

The bottom line is that nif's suggestion about using the lowest possible carrier frequency is good for drives generally but not applicable to the ACS600 or 800.
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