We are currently facing an issue with multiple SINAMICS DCM 6RA80 drives that have been stored for approximately 1.5 years. Upon unboxing and attempting initial power-up, we observed the following:

• A brown, sticky liquid is visible around the capacitors on the power board. This is consistently present in all five drives.

• For testing, we supplied 230 V AC to terminals 5U1 and 5N1 (with 5U1 and 5UW shorted), but there was no response — no indication on the Control Unit (CU) or the Basic Operator Panel (BOP).

• We also attempted to power the drive with 440 V AC via the line input, along with the fan supply, but still received no response.

We would appreciate your clarification on the following points:

1. Is the brown substance on the capacitors considered normal (e.g., from manufacturing), or does it indicate potential damage due to moisture or storage conditions?

2. For initial power-up (just to activate the CU and BOP), is it sufficient to supply 230 V AC to terminals 5U1 and 5N1, or is additional wiring or a specific startup sequence required?

Photos of the drive’s internal components — including the capacitors — are attached for your reference.

Those capacitors with the brown liquid appear swelled at the top as well as opposed to flat like the capacitors with the still shiny tops.

That usually means the dielectric is leaking which can cause serious harm to surrounding components should they explode.

How long had the drive been in storage?

There is a procedure to reform capacitors after long-term storage for Sinamics drives.

If you cannot locate the correct procedure for your drives (either as an FAQ, or system manual or repair manual for your drives), contact Siemens Support, share the same pictures you posted here, and ask what to do first, and also, where to locate the reforming procedure.

On at least one of the uploaded images, I noticed considerable amounts of dust.

I recommend with power feed into each drive locked out to use clean pressurized plant air and approved nozzle (as well as protective eye wear - safety glasses/goggles/face shield) and blow all the drive boards, connections, terminals, and such.  Repeat until no more dust flies out of the drives when blowing everything off.

Siemens Support may recommend sending the drives or boards back for repair.

You may also locate a local or regional circuit board or drive repair facility that will accept bare circuit boards and replace all suspect and matching capacitors banks (like the DC bus capacitors).

You don't replace just 1 out of a bank of capacitors.  Best to replace them all from the same lot manufactured at the same time.

Once the system is back together with good capacitors, you then need to perform the capacitor reforming procedure - according to Siemens Support guidance - based on which capacitors were replaced.

For example, capacitors exposed to 24VDC do not typically need reforming.  Just those capacitors that are exposed to full system AC / DC voltages (but again, follow your drive's reforming procedures which may differ from my own experiences).

Please post back your results and what Siemens Support recommends.

ANIL02573

We are currently facing an issue with multiple SINAMICS DCM 6RA80 drives that have been stored for approximately 1.5 years. Upon unboxing and attempting initial power-up, we observed the following:

• A brown, sticky liquid is visible around the capacitors on the power board. This is consistently present in all five drives.

• For testing, we supplied 230 V AC to terminals 5U1 and 5N1 (with 5U1 and 5UW shorted), but there was no response — no indication on the Control Unit (CU) or the Basic Operator Panel (BOP).

• We also attempted to power the drive with 440 V AC via the line input, along with the fan supply, but still received no response.

We would appreciate your clarification on the following points:

1. Is the brown substance on the capacitors considered normal (e.g., from manufacturing), or does it indicate potential damage due to moisture or storage conditions?

2. For initial power-up (just to activate the CU and BOP), is it sufficient to supply 230 V AC to terminals 5U1 and 5N1, or is additional wiring or a specific startup sequence required?

Photos of the drive’s internal components — including the capacitors — are attached for your reference.

Hi, that is most definitely not normal.

Those caps look badly corroded and possibly fungal growth on other components/surfaces

Did you observe the correct environmental storage conditions i.e. cool and dry

Regards,

Graeme