Cleaning a frequency drive 1

[Thedroid]

What would be the best way to clean out a frequency drive that is exposed to a dusty environment. We have three ABB ACS 600's that are mounted to dollies that we use to run bucket elevators slowly so that the repairmen can inspect them. These elevators are located in a cement mill building, and the drives get pretty dusty in the process. I would like to clean them out every so often, but I had heard that a few had been ruined by static from blowing them out. We have an old 3M electronics vacuum, that claims to have a conductive hose and tip. I used this to clean one today and hopefully didn't ruin it. It was full of dust!! Is there a better way or recommended method for cleaning these drives. The manual doesn't give specifics, but it does say that it's alright to blow out the drive.

Cement Plant Electrician and
Instrumentation Technician

 

[davidbeach]

Well if they allow blowing it out then try that, but a vacuum cleaner is much less likely to cause the dust to get into worse places.

 

[Thedroid]

The boss won't allow blowing them out because two were ruined already by this practice. The drives are for 100 hp motors, so I'm sure they weren't cheap. I'm trying to clean them out now, so hopefully they will stay troublefree.

Cement Plant Electrician and
Instrumentation Technician

 

[ozmosis]

Firstly, stop the dust getting in there. Having a maintenance program where dust is getting into drives is real short term policy and fraught with problems.
Focus your maint.policy on cleaning filters on the panels, especially if it is cement dust.
Regarding cleaning and to take advise from a a former president somewhere: you should suck and not blow. An ESD proof vacuum cleaner as mentioned (3M) is preferred.

 

[geefer]

If you ground youself the drive and the vacuum cleaner so that all are at the same potential you will have no isssues

 

[Thedroid]

That's what i'm doing is grounding everything including myself. These drives don't have any filters. They are not in an enclosure, just mounted to a dolly for quick access. We have plugs mounted at the disconnect, that allow us to hook up the drive just to do inspections. They only see a couple of hours of use a week, but in that time they do see alot of dust. The idea is a good one, but we do need some type of enclosure. Money is supertight right now, so getting anything will be like pulling teeth.

Cement Plant Electrician and
Instrumentation Technician

 

[DickDV]

I've used compressed air to clean out ACS600 heatsink fins and fans for years and have not had any failures. Being sure you and the air wand are grounded is good practice too.

The problem with cement dust is that it tends to stick to everything and corrode many metals. If there was a way to wrap a filter cloth blanket around the drive when operating, it would be much better. Just unwrap it when you are done and take it outside to shake or blow it out.

 

[ozmosis]

A useful read from the makers of your drive:

https://www.abb-drives.com/StdDrive... to Maintain a Drive - A Primer - Release.pdf

 

[LionelHutz]

To answer you first question. We have blown out lots of stuff with compressed air and not damaged it. We even will wash circuit cards and use compressed air to dry them. I find it hard to believe you killed 4 drives from ESD blowing air through them.

You can buy rolls of filter material cheap. You can even get filter material with a sticky substance that helps trap dirt. You could rig up a big piece of this to the inlet grills on the side of the VFD. Maybe get some filter material and some of those magnet strips that are meant to mount on the wall to hold tools. Clip the magnet strips all the way around the filter to keep the dust from going around the filter material. If these are the drives I'm thinking about, you may still need to do some sealing around the terminals at the bottom. Just be creative.

 

[jraef]

One of the worst dangers of compressed air is the moisture, more so than the static. Combine moisture and cement dust, you get a VERY corrosive effect. I have used compressed air that came from an industrial duty instrument air drier, but I would not recommend using just any compressed air source.

Use the Lewinski method with an ESD proof vacuum cleaner, plus a natural bristle paintbrush in the nooks and crannies that you can safely get to.

As to properly enclosing the drives:
Money is tight? How much is a replacement drive going to cost? In the words of Robert Burton*, "Penny wise, pound foolish".

_{*Often attributed to Ben Franklin, but that is incorrect. He used it, but it was already an old maxim by his time.}

 

[itsmoked]

I cannot imagine a vacuum doing a twit of good on cement dust. I just tried a powerful vacuum on the control boards of a generator that was slung under a rail car. Not a word or color could be made out on any of the components before vacuuming. After a thorough vacuuming... Not a word or color could be made out!

150PSI air run thru a hose barb fitting damaged nothing and left everything readable and all colors visible. It promptly became clear that the circuit board was the standard green even.

I cannot see why air blowing, verses sucking is going to cause damage. Using air to blow it off is less likely to cause damage because you need to actually touch the boards with a vacuum whereas you don't with compressed air.

I can see where someone's compressed air could deliver water onto the boards. A few minutes for drying before energizing the system should suffice to remove even that aspect.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Pythagorus]

I thought I'd raise some issues which jump at me in this question series. I am going to make minor forays into te issues which, for me, arise from what I have read here in the mixed replies. A big thing generated from a little thing if you like.

I am looking at a bigger picure without at all ignoring the fix-now problem. This initial fix should be a proper clean and thorough inspection and testing by the manufacturer's enginering staff, or one of their competent sales-engineers educating the company maintenance person at the same time and writing a full report on past present and future of the situation and suggestions for rectification, to the senior management.

This report should include production risk factors, possibilities and likelihoods....and rectification suggestions and costs.


The background problem, as I deduce it,may well in practical "in my square metre" terms be a dirty drive scenario, already four time damaged but it is also a management problem possibly through board (or equivalent) ignorence or being kept ignorent.

The technical solution isn't massive, it's straight forward but is being blocked by what is purported by someone to be management policy or criteria.

The management solution only looks massive because the company people sound as though they are walking on eggshells...Reluctance to spend money or some person defending their fear of being in the limelight recommending money be spent, doesn't mean it isn't there to spend.

A corporation is a living entity. It requires sustinence and being kept in good health. Profit is largely intended for that....not for diversion elsewhere. merely requires comprehension,unbiassed technical options, clarifying choices, engaging commitment,providing funds, enactment.

I add that it seems odd to me that the group/ company will not properly protect essential motor drives (from dust) and spend to do so. Drives are, initially, a large investment, no doubt about that. This environment, however was an installation where day-one protection of equipment was obvious.

Perhaps the company doesn't care about risk management, don't have the business integrity to understand that maintenance tax deductions and depreciation write-offs are for a purpose...to maintain and replace (or re-house) equipment.

Perhaps it is a tin-pot organisation run by self protective personnel, all too busy worrying about their image rather than proper running of the company. Perhaps maintenance staff want to keep their heads down rather than be forthright. Perhaps no one is doing the task comparison pricing...looking at the "what if's"

Tax allowance...depreciation for capital costs , deductions for maintenance, money allowed by Government to hold more money in business coffers is a most pertinent issue here.It may be affected by some expansionary vision, but right now we have to deal with short and the medium terms.

These allowances should be organisationally viewed as having the purpose it was designed to have. It's not windfall money for a new boat or a new house for a director or higher management salaries or a new advertising campaign nor corporate networking dinners or a big fully maintained Kompressor Benz car for the boss or the coupe version for his mistress.

It is there to serve a purpose of maintaining viable production. Depreciation and maintenance sums ought to be account protected for that purpose only and properly itemised, not lumped.

Integrity-based, intelligent, management-planning uses all leger-heading funds solely for the purpose intended and leaves accounts to hold unused elements of any particular account sums in the account for that , say "depreciation, crusher equipment" to continue to grow, suitably invested to follow appreciating costs.

On reading the 'ins and outs' here, I also wonder about the corporation personnel...how well they receive OH and S protection from this invasive material.It doesn't sound likely they spend money there either. Perhaps that's an issue worth addressing as well, the situation with the VFD merely being symtomatic. Sadly Boards of Companies are often held in the dark and /or then too lacadasical or too network, rather than expertise, based to make dilligent inquiries after the health of the company.

The three wise monkey approcah hasn't disappeared from management, rather has ameliorated through fear in the tragedy of "Economic Rationalisation" and "learn by rote" management. Good managers are born to it,immediately adaptable. Few make it into top management but spend their lives in inferior postions someties as tradesmen or stay in "lesser" posts in the 'globalisation' theme park stuck there through the resume iconised processes of lazy minded HR policies. The result is simply whet we see here...poor management. Good management engages on 'reflective' maintenance,listening, adjusting, reviewing, enacting.

For a good manager by inheritance, management study fits them into the network and a predictable and uniform process. It isn't the deciding factor of management excellence but looks good on the paperwork. A good manager knows that spending money wisely is actually investing money in profitable return.

It seems odd to me that an enginer, whenever it happened, would have these installed drives in a vulnerable location. Perhaps ignorence was rampant, perhaps the drives bought-in from elsewhere and installed "on the cheap"....to make it look like a real installation now and pay the price later. Perhaps some maintenance type handled the installation with limited outlook, or decided their job was just to install the drives and say nothing, or was told to mind his own business and just get on with it when raising the issue of the hazardous environment

Heat producing equipment is generally designed presuming free air transfer in a known ambient range, unless purpose built. The proper solution is, therefor, to remove the adverse environment from the drives or the drives into a suitable environment... not to be doing high risk , moist finger in the air clean up jobs. You can clean the dust out to some degree but the environment is still hazardous and corrosive. The solution is a one step solution. It is to rectify the environment issue.

It might take only one weekend of building,or be done in shut-down maintenance occurring each year to rehouse the drives... I can't say on evidence. Firstly as I said at the outset, contract the manufacturer to clean and inspect drives then seal them until the environment is replaced in that same time period....if not replace them with environmentally suited ones unless building new room/s or moving the drives to a clean air environment elsewhere.

In general terms the matter at hand requires it seems a proper solution soon and not a continuing finger in the dyke approach.

That the technician has to, or has chosen to, write to a forum rather than have proper engineering solutions readily sought commercially by the maintenance management suggests several scenarios.....however...to replace the drives with environmentally suitable ones still invites the contamination during service or someone storing opening the doors to their lunch or tools inside the cabinet....This invites periodic ingress of invasive and damaging dust.

Looking at it all together ...I'd say management needs to act...spend to invest and profit. House or re-house the drives and feed their own environment with multi-stage redundant filters to maintain air integrity whilst cleanng from outside in.

Humidity to be devised to prevent dry air static but also to not create more than design parameter condensation. Temperature to be controlled by air space size or by air conditioning operating into the multi-stage redundant filters which have a cleaning facility which prevents cement and other material entering the drive area during cleaning. It's money well spent.

The present situation, on slim evidence but my experience with cement dust, is a "from day one stuff-up".

Replace or repair the drives as you will...but whatever route is taken prevent recurrence and allow for the future. The "finger in the dyke" approach, required from maintenance staff through the "seat of your pants management flying", is most unprofessional on one hand but also an literally and unarguably improper use of maintenance and depreciation allowances.As I said, the actual clean up is a minimal issue which I resolved in transit but the ongoing problem is a different story. Cheers,

 

[itsmoked]

Well...

Nothing like jumping in with both feet.

Welcome to Eng-tips Pythagorus.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Thedroid]

Actually it was two drives that I was told were damaged before I started working here. They were blown out by a blow off station not compressed air. The tech from ABB told the electrical department not to mess with the inside of the drive at all. No blowing off, no vacuuming, etc. I wanted to clean the drives without damaging them. If I were to blow out a drive, and all of a sudden it stops working, especially after I was told that two were ruined would make for a bad day. The drives are to mounted in a dusty environment, they are mounted on dollies to be wheeled out and connected to a piece of equipment in order for mechanics to perform an inspection. Most of the time it's not terribly dusty, but sometime it is. The company has spent quite a bit of money to keep there drives running well. Every permanently mounted drive is in a climate controlled positive air drive room, that never see's a temp above 70f. The portable units are designed to be portable. The drives are heavy enough as it is on the dolly, installing them in a nema enclosure our something would be great for the drive, but bad on the electrician.

Just looking for suggestions, or experiences with cleaning these drives, not the full lecture on the virtues of management and this and that.

Cement Plant Electrician and
Instrumentation Technician

 

[LionelHutz]

There could be a component or components on the circuit board that are damaged by the powerful blast of compressed air. I seem to recall that ABB has some transformers that are not potted on the IGBT boards in their drives. Basically a core with some windings on both sides.

 

[roydm]

Can't help with the cleaning as I have no experience with cement dust but following the thread my thoughts were.
This dust is pretty nasty and even a short exposure with any moisture has to be damaging to sensitive electronics.
Since the drives are used to run the bucket elevators slowly they can't be generating a lot of heat., perhaps they don't need a fan sucking in air and dust.
Perhaps it could be argued that the drives in their present situation present a safety hazard.

Have you thought about sealing the enclosure all together, removing fans, pressurizing the enclosures with a dry air source?
If cooling is required there are compact air conditioners used for hazardous area enclosures that just circulate and cool rather than draw in fresh air.
A 100 Hp drive is a large investment, it's worth spending a few K for a permanent fix.
Regards
Roy

 

[Pythagorus]

Hi Ok, thanks to "it smoked" for the reply ..nice of you. Much appreciated.

Re the thread, I decided to make an approach which took into account symptoms such as "They only see a couple of hours of use a week, but in that time they do see alot of dust. The idea is a good one, but we do need some type of enclosure. Money is supertight right now, so getting anything will be like pulling teeth."

I also read "It was full of dust!! " So dust is an issue whether in or out of storage and damage may already be effected by the time you get to cleaning it. Even if stored with dust in them and no more enters the room, is incorrect storage.

I addressed the management issue, which gets to that point so often, as others were competently handling the direct question.

When no money is around to fix gear it means usually poor management in the areas I spoke about and it is something not all technicians know about or care about but it affects outcomes.

There is now some extra information in the reply I received from 'the droid' which actually makes a difference to the solution....much simpler. Lionel and Roy made some good new points then.

Three particular things happen with airblast other than oil/moisture/static..one is shock which might affect a crook board, dry solder joints, material down inside plug-in IC sockets,another (depending on circumstances) is rapid change of temperature, air blast is cooling, which might exacerbate a problem.

The last is air blast dislodging or skewing something plugged into a socket.Perhaps a report exists on Company or ABB files as to the repairs then effected, locating the problem areas for you.

Going over the board for such simple items as dislodged components is not so hard.

I agree with Roy that there are several ways of approaching creating the correct environment. To not provide this and the correct ambient doesn't help.

Knowing whether cleaning is done when rolled out and hooked up might also make a difference as to where the fault actually lies.

One thing is certain...these have not been correctly stored whether in use or out of use..and that dust ,if completely removed from the equation leaves a simplified fault finding experience.

The new information of great value included

"The company has spent quite a bit of money to keep there drives running well. Every permanently mounted drive is in a climate controlled positive air drive room, that never see's a temp above 70f. The portable units are designed to be portable. The drives are heavy enough as it is on the dolly, installing them in a nema enclosure our something would be great for the drive, but bad on the electrician."

I can say that commercial perspex enclosures may be available to cover all...and be able to have filters fitted but my last thought on the matter is that as I said ABB should be called to do a full service and check and clean, and then you know where you are.

That was the point...to get back to a benchmark of "all is ok". All voltage and current checks on and off a particular, repeatable load could well be taken and stored as reference points for futire fault finding.

Management ought to understand that ABB assumes enormous amounts of experience in many environments ...well over and above service techos in one environment. One spruce-up might make a world of differecne and you get training in precisely how to clean that gear. Win-Win.

There could also be modifications ABB's man knows about which rectify or avert other problems or perhaps the ones you may have. Anything can deteriorate with time...and anything can be found manufacturer or spec. defective in service. Components are often updated or voltage current spec's upgraded through experience with faults...you see where I am going?

An up to date service manual from the manufacturer could be a good investment at that time...or perhaps negotiated as a "freebie"

Even a good technician doesn't always have access to that list of "known failure points" manufacturers have through their vast experience.

Cement dust may well not have been the environment on which these drives were chosen, or they may have been incorrectly chosen (etc ..my letter). Cement dust is so fine it permeates and sticks.

I think that's all I can add on top of the excellent responses which followed your more detailed descriptions. Perhaps my other points benefitted someone...mais....qu'il ya.....est qu'il ya.

 

[sibeen]

I used to run a UPS service organisation which had 25 odd field staff which performed installation, commissioning and maintenance of a wide variety of UPS brands.

All the field staff had a Makita 4014NV blower as a standard part of their tool kit. I'd nearly go as far as to state that this tool was as important as a multimeter in performing maintenance on a UPS system.

In the 10 years that I ran this organisaton, and thousands upon thousands of maintenances performed, there was never a failure of a UPS that could be attributed to the use of the blower.

 

[Thedroid]

I'm new to this company, been there 3 months. The first time I was called to hook up one of these portable VFD's, I was shocked to see that they were getting dust inside of the drive. I then recommendeded some type of cleaning program or possible enclosure to keep the dust levels at a minimum, or just keep the dust out altogether.

I was then told the story about the guy that blew out two drives with a blow off station and fried them. ABB was contacted concerning this issue, and told management not to blow out the drives, that they were very sensitive to ESD.

When asking about the enclosure, I was told that the budget was real tight. As everyone knows, the housing market is a disaster. That means that cement is not in high demand and management is in a panic. It's not plant management, it's corporate management that issued a memo requesting no expenses unless it's absolutely necessary. I had trouble getting a pack of stickybacks and ty wraps.

Anyway I cleaned all of the drives last week, and hopefully they all fire up when we use them. I'd still like to see a better solution sometime down the line. Enclosing them somewhere won't work, because there is three portable drives that we use to inspect 20 bucket elevators in different locations.

I'm not a head down walking on egg shells electrician. If I have an idea I like to bring it up no matter how expensive it might be. The hard part is that i've only been on the job for 3 months, and really don't have a feel for the culture yet. Judging from the condition of the plant and equipment, I'd say that the company doesn't think twice about spending money on upgrades and protection. The plant was built in the 50's, but over the last 5yrs has been completely automated, and every reasonable upgrade made. I'm not sure how tight everything is right now, but it sure seems pretty darn tight.

Cement Plant Electrician and
Instrumentation Technician

 

[electricuwe]

The idea of providing an enclosure is not as easy as it might sound as the first glance. It has to be considered that a drive has a significant heat dissipation from the power semiconductors heatsink as well as from passive components and control boards. If an enlcosure is provided without considering that you might end up with the drives failing from overheating.

There are some drives on the market beeing designed for such enviroments. Buy such a unit when you have to replace the existing ones.