# VDF failure ABB ACS800



## Wardenclyffe (Jan 11, 2019)

https://www.electriciantalk.com/f28/abb-acs800-104-inverter-em-stop-263168/#post5043088


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## Absulen (Jun 11, 2020)

Thank you very much, I have read that information and I am going to verify some of the observations.

But the VDF 2 days ago was working normal without any failure and now it is presenting (EM STOP f081) that is why I am making the query.

Is it possible that the control cards are showing a fault?


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## Absulen (Jun 11, 2020)

I meant, is it possible that the RDCU-12 or DSSB-01C has problems?


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## JRaef (Mar 23, 2009)

From what I have heard, the ACS800 was plagued with problems from the outset and is what lead ABB to pull it so quickly and release the ACS880


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## paulengr (Oct 8, 2017)

What is your line voltage?

DC voltage from a free wheeling 6 pulse DC rectifier (basically open circuit) is 145% of Vline to line yet you are reporting over 1000 VDC. That doesn’t make any sense for any low voltage drive. How are you getting your DC bus reading? Something doesn’t sound right here.


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## Absulen (Jun 11, 2020)

paulengr said:


> What is your line voltage?
> 
> DC voltage from a free wheeling 6 pulse DC rectifier (basically open circuit) is 145% of Vline to line yet you are reporting over 1000 VDC. That doesn’t make any sense for any low voltage drive. How are you getting your DC bus reading? Something doesn’t sound right here.



The input voltage is 720 VAC and the voltage after the rectifier is 1000 VDC.
The VDF is ACS800-07-0750-7


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## paulengr (Oct 8, 2017)

Ok so the 1000 V makes sense and the picture helps. It’s obvious now.

Find the precharge circuit. There’s a very good chance (95%) that the current limiting resistor or inductor is burned up and shorted turns, or the timer/voltage sensor failed. Might even have a welded contactor. This is all pretty common. I don’t know why but the bigger the drive, the more poorly constructed the precharge circuit. That will be your problem. There is usually no electronics in the precharge...it’s just discrete electronics.


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## Absulen (Jun 11, 2020)

I was checking and found in the rectifier a diode-thyristor with a fault. The measurement tells me that the thyristor is open in one direction between anode and cathode.

Already request authorized ABB personnel for repair and commissioning.

Here I show you a picture of the diode-thyristor


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## paulengr (Oct 8, 2017)

Wow that’s hilarious. ABB used to make their own. Semikron makes good stuff and sells to anyone.


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## MOA (Mar 12, 2008)

You just have to report back what the issue was. I'll lose all faith in VFD manufactures if they attribute a blown thyristor, scr in the back-end to read "EM STOP (f081}" on the display. Thought they were more sophisticated than that. A shot in the dark. Parameter: 10.03 DO1 encompasses some of Your symptoms. re: EM STOP and 3-4 sec. time-out. Good luck


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## Absulen (Jun 11, 2020)

Today will be the authorized personnel of ABB, I will be commenting on the complete solution to the problem.


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## PSmitty (Aug 19, 2019)

*Just a thought.*



Absulen said:


> Good afternoon, first of all excuse my basic English.
> I need your help to solve a fault that I have in a VDF ABB ACS800 which does not allow me to start the rectifier. When the VDF is energized, the 1000VDC reaches the DC bus and after approximately 3 seconds, the "EM STOP (f081)" appears on the display (HMI).
> 
> The connection of the existing emergency stop has already been verified and it has no problem.
> ...


Verifying the Estop was a good check. one more step > Try pulling estop of terminal strip then jump it out right at terminal strip. (make sure everything is safe, Machine ect).

Also the estop is probably an opto coupler to circuit. (Could be blown?)
Can scroll to a screen that that shows inputs? Then push estop in and out and see bit change?


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