Something is taking out our 250hp DC drives

Good afternoon everyone-

I apologize if I leave anything out, but I'll try to paint the best picture I can of our situation.

We just lost a control board on our NEW ABB DCS 800 DC drive. I installed it about 5 days ago.

We replaced it because we were unable to communicate any longer on our previous (Ebay used) drive from the HIM to either port on our AB 1736.

Both of those conclusions were reached with their respective tech support and doing the "required" troubleshooting. Happy to go into either one of those failures more, just wanted to make sure to get the important info.

There is no line reactor installed. After trying to order one at the same time as the drive, since the last one didn't have one either, the filter was 1.5-2 weeks out, so against everyones advice, they decided to run it "Temporarily"

They're looking for a different answer of why we lost this new drive than "We should have gotten a line reactor". They're thinking is that the last used AB drive from circa '95 I believe, lasted 6 months, and the new one only lasted about 5 days.

What I'm hoping to get is more possibilities to look into of what could have taken out the drive, and also, other ideas or best practices for better protecting this drive in the future. currently there is no Line Reactor, Line contactor, or armature fusing, which I hope to change. This is my first DC drive of this size, and although I've done alot of AC drives, I thought I might ask the professionals. Depending on who I get on the phone, Tech Support hasn't been the most helpful

I'll also add that the fault on the new drive was a "Low Mains Voltage", which was reading 2v on the drive, but measuring normal with my meter. I'll also add that it faulted out another drive on the same extrusion line with a 0v fault, but that one reset.

Thanks to everyone for taking the time out of your day to read this, and I look forward to any responses/questions.

Work safe everyone-

I have little experience with drives in general, but I've had people tell me that ABB drives are built to fail. They're cheap so that they can make money off the service.

Good luck though.

On that drive, you really cannot operate it unless you have a minimum amount of line impedance (I think 1% relative to the unit), otherwise it shuts down when it attempts to power up. With insufficient relative impedance, the rectification causes ringing transients and their firing board will shut down if any one of those transients lasts more than 15 milliseconds.

Not knowing anything about that particular DC drive, but knowing DC drives in general, I have a couple questions/comments.

Does the Control Card have a high voltage interface, or do all the high voltage (Mains, Armature and Field) go through a separate high voltage card first? Most drives I've seen have all the higher voltages isolated from the control card. On some I've seen the Armature and/or field, but never the mains.

Assuming the mains don't go directly to the control card, I don't really see where not having a line reactor would kill the card. I can see where it might see a 0v main from the high voltage interface, but I would be surprised if it locked up... I'd think it would fault, and then read the proper voltage when the transient was gone.

Does the ABB drive lock the monitor parameters (such as mains voltage) while it's tripped? This is a common practice, with some drives, so you can troubleshoot. The parameters go back to 'live' when reset.

Generally, the ABB DCS800 drive is rock solid reliable but two installation issues come to mind right away. First, as mentioned above, an input line reactor is essential. Second, check your 480V power source for floating delta. If it is floating delta, forget the line reactor and install a drive isolation transformer with a grounded wye secondary instead.

Drives with a CE label are not designed to operate on floating delta three phase power. It doesn't matter which brand. This is pretty much an across-the-board statement on DC drives.

DickDV said:

(snip)
Drives with a CE label are not designed to operate on floating delta three phase power. It doesn't matter which brand. This is pretty much an across-the-board statement on DC drives.

Click to expand...

Forgot that one... and here I am in the center of corner-grounded-delta-land

That's ANY drive, AC or DC. Delta power should be illegal!

why not just change the whole thing out with a VFD you get better performance and lower maintaince costs and fay less problems

DickDV said:

Generally, the ABB DCS800 drive is rock solid reliable but two installation issues come to mind right away. First, as mentioned above, an input line reactor is essential. Second, check your 480V power source for floating delta. If it is floating delta, forget the line reactor and install a drive isolation transformer with a grounded wye secondary instead.

Drives with a CE label are not designed to operate on floating delta three phase power. It doesn't matter which brand. This is pretty much an across-the-board statement on DC drives.

Click to expand...

And AC drives really. Some can be modified to disconnect the ground reference for the MOVs protecting the front-end, but that just lowers the risk, not eliminate it.

Corner grounded delta!!!! Good grief. Run, don't walk to the drive isolation transformer store and install it with grounded wye secondary. You will be most pleased by the sudden increase in reliability.

Wye, oh wye...?!

Thanks to everyone for taking the time to respond. Thought I would post an update.

it did have a grounded secondary on the transformer.

After replacing the power board and thyristor control board once, they decided AGAIN to try to run without the line reactor. Low and behold, they fried another power board and thyristor control module. After finally receiving our line reactor, I reinstalled everything, and the drive has been running like a champ.

Lesson of the day.. Don't give them an option to gamble. Because at the end of it I was told I "didn't stress enough the importance of the line reactor".. I'm not sure what more I could have said.

Thanks again everyone.

Because at the end of it I was told I "didn't stress enough the importance of the line reactor"

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The classic excuse of those who ignore good advice when confronted with the fact that the advice was in fact good.

Someone's signature here says "you can lead a horse to water, but if its got its head up its a$$ it will die of thirst anyway".

I think what needs to be stressed to your superiors is the importance of listening to expert advice. I mean, it probably won't do your career any good, but I'd feel better about myself afterward

Maybe you can at least use it as ammunition next time they want to ignore your advice

The facts can always be twisted and steered into 'it's your fault'