My 890SD/5/0016 has 720VDC buss but no low voltage on control card or HMI display

That's bad news considering drives are not readily available.  I really need to fix this drive.  I'll try the external 24v supply as you suggest.  This is not an AFE.  Just an 890SD connected to 480VAC with a small motor connected.

Since the drive isn't working correctly its easy to foresee the buss regulator not working properly either.

Thanks for the info.

Hi Daniel,

With external 24VDC applied I get back to the original error message that displays when trying to run from the drive HMI.

"Key inactive-DC Precharge"

I have 715VDC on the Bus terminals but 0V DC Link displayed on the HMI.

Can I get a service/repair manual with enough detail to really troubleshoot this issue?

Thanks,

Dave

There is no bus regulator in this drive (only a small buck converter that makes low voltage from the bus).  If this is a standard 890SD connected via its L1/L2/L3 terminals to a 480 VAC 3 PH mains, you should be getting 650-680 VDC on the bus.  The drive's input stage simply rectifies the incoming AC -- it does not regulate.  Bus voltage on this drive will always be 1.414 * Line Voltage (1.414 being the square root of 2).

The reason I thought this might be an AFE (or part of a system fed by an AFE) is because AFE's boost the DC bus to 720 VDC by using a line reactor as a boost converter.  In that case, the voltage is under active control.

What's your incoming mains voltage?  If you're physically reading 715 VDC, your AC should be around 505 VAC, which is beyond the rating for this drive.

There is no repair manual for this product, which is true of most of our drives.  Larger drives can often be serviced by replacing certain assemblies.  This is really not the case with the frame B 890s.  The part that is damaged is most likely the power board.  Getting a power board takes about the same amount of time as a new drive at this point.

Hi Daniel,

High lines is a common problem. My test bench is 495VAC right now but it can drift higher.

Factory voltages are all over the place and routinely go higher than 500VAC.

What is the 890SD max line voltage anyway?

The manual shows

but the 8900CS lists 500+/-10%

Is it correct that the CS can operate as high as 550VAC but the SD is limited to 500VAC?

Hmm.  I agree there is some ambiguity there.  The 890CD says its nominal rating is up to 705 VDC, but of course 550 VAC on an 890CS module would produce 777 VDC on the 890CD.  So unless there was a surge, I suppose it is unlikely overvoltage damaged the unit.