Vacon Frequency Drive - 37KW

These people can help.

It is not easy or simple to use tech support in companies like this. They usually want a fat pipe into your cash flow. Often they want to send staff to inspect and bring your 'neglected installation' up to date etc.

Often installations can be repaired by a shut down and thorough clean and seal of all current carrying pathways, which have often degraded over years to increase resistance etc.

Better do this yourself instead of paying someone $1000/day per person, plus expenses, to do this.

Secondly, look for an experienced VACOn repair person who might offer better rates.

The original poster gives no information on the remaining product warranty, nor what steps have been taken to derive Technical Support during that period. The original poster gives no information on what product support leverage is available at the facility with a view to deriving support or facing loss of future sales.

The remaining invitations are declined, as there is no Vacon drive installed here.

I assumed he does not use the phone for help option because he encountered a financial thicket that he lacked the ability to spend past.

It is axiomatic to call the maker, sadly, all such expertise, after initial warranty, often comes at a large cost, especially in other countries, and thus have a huge incentive to fix it themselves. They may, in fact, be hoist on their own petard, having represented themselves up to the task.?

This is a classic equipment protection system (EPS) interlock problem. The EPS is probably not failing when it trips and prevents your good equipment from running. The EPS system is probably detecting a subtle failure in your equipment and preventing it from becoming a major failure in your equipment. Examine the alarm codes presented by your EPS (you've not identified these to us) and fix your ailing equipment. If somebody dislikes the cost of this new repair (and previous attempts) then test equipment monitoring the same signals (current, voltage and time) the EPS uses to monitor the equipment. This method can identify if the EPS or the equipment is failing. Fix accordingly.

What PLC make and model, and what fault code(s) does it show?

This sounds like a typical hardware (EMC) problem to me.

Since you are not providing a detailed information of your installation and probably hardly anyone would be interested in working hard in your behalf, I recommend you any of the following.

1. Contact an EMC consultancy company and ask them to solve it for you.
2. Learn EMC Engineering. Henry Ott has a great book about it!

Regards.

This: vacon manual

10 Fault tracing 148

10.1 Resetting a fault 148

10.2 Fault codes 150

Why do you suspect the VFD, for causing the tripping of the PLC?

You ask about adding filtering for the VFD. Has it not been installed as per the specification in the technical manual?

Can you supply us with an Electrical Schematic of the VFD installation?

Can you identify any changes to your installation; not just with the VFD, but with the PLC; that coincides with the problems you're experiencing?

You said...
'we suspect that the issue was due to harmonics coming from the VFD'

Have you proved it? If not, then do so!

Call the vendors/manufacturers for both items of equipment, and tell them what you've told us, and as it's their equipment, they will be better placed to advise.
Have you done that yet? If not why not?

Yes there are filters to reduce VFD harmonic output, but again you should contact the VFD vendor/manufacturer for expert help and guidance. But adding filters goes back to my previous point, do you have harmonics?

The overall point here is that your problem cannot be solved in this forum! We can only give you pointers as to what it MIGHT be, or who to contact, or where to look.

Reading the previous posts you've had all that.. follow the advice!

If the problem goes away when the Vacon is switched off, then you have a cable or motor fault. It is unlikely that a sudden power supply problem with the PLC (assuming a general failure = trip?) is an installation design problem.

It would be helpful to have more detail on trip, what exactly does than mean?

Make sure the PLC control wiring is isolated from the VFD motor wiring.

A common filter used with VFD's to limit harmonics is called a line reactor. It is basically an inductor and it will throw off some heat, so where it is mounted is important to consider as well. They are typically 3% to 5% reactive (relative to your load) and are in series with your VFD.

Look up Control Electronics magazine and search for electrical noise. Read the article.

Make sure your PLC power supply is not running at full capacity. Too many people do that and the inrush current of some connected device will "trip out" the PLC.

I'm curious how a PLC 'trips'.

PLCs are designed to run continuously. What does a PLC trip look like in this case?

Does the PLC flash a fault code and the CPU refuses to execute?

Does the fuse to the PLC power supply blow?

Or some other manifestation?

What do you do to get your PLC out of "tripped state"?

RFI if high enough signal could disrupt connections to the PLC communications with local panels (depending on what is present on site), and the PLC might then "trip" by losing communication hand-shake, or so I believe.

Ground loop potentials if large enough could cause signal error and trip the machine (not really the PLC).

1. Does "the PLC" have any function tied to VFD? Or is PLC concerned with completely separate function?
2. What is physical distance between VFD and PLC?
3. Do PLC and VFD have any shared cable trays or ducts in which transfer of Electro-magnetic Interference (EMI) can occur? Separation is more effective than screening.
4. If changing VFD reduced trouble, have you considered that you may have fixed only one end of a corroded earth bonding or deterioration from what was OK when plant was new?
5. Are supplies (and EMI) shared between VFD and PLC? If this is the problem, a filter in PLC supply is cheaper & easier than in VFD supply - but it will not work if cables from filter to PLC PSU share a loom/duct with other cables.
6. Have you checked the PLC Processor PSU is all OK, free of abnormal voltage outputs or ripple indicating out-of-spec vulnerability to voltage dips or EMI? Changing load by disconnecting racks or adding resistive load is suggested.

I would suggest pulling any PLC power input cables or rack-rack power or comms cables out of any trays/ducts looms they share with other cables to give as much physical separation from other cables/magnetic fields as possible. Panel builders are fine at making things "tidy", but often do it without thought to EMI. Unless watched, they can loom up the output of those signal isolating devices (designer thoughtfully provided) with anything convenient.

Any PLC AC input filter you fit must have its earth connected to PLC PSU earth terminal by shortest practical wire.

Wires loomed or trayed together finish up with the same RFI voltages due to capacitance and magnetic coupling.

It may be more difficult/costly to put right, but any close proximity between VFD cables and other cables is bad. Wires directly from VFD to PLC are suspect as a "most likely" EMI route.

Power supplies do not care much about harmonics, most nowadays have rectifiers with reservoir capacitors & switching regulators which make plenty of harmonics anyhow.

Interesting. I have also wondered about cable trays carrying both signal wiring and power cabling where VFD's are active.