VSD's and their Drive Belts.

Hi Guys!
Old School meets New School!

Over the last Year I have had several instances to question the old drive belt maxim of.-
If a drive belt starts to squeal check for tightness and it's wear rate? Change if necessary!.

I have not seen it in any training manual, but when some of the drive belts I have changed recently have occasionally started to squeal.

I have changed them to notice a huge drop in the VSD running amps.

Others I have changed as part of a maintenance routine, have also shown large running amp reductions.
Which leads me to believe that the soft start action of VSD drives, can hide drive belt wear and their reduced efficiency?

On one set recently the average running of 45hz instantly dropped to 35hz when I changed the belts. At the time I could see no physical evidence of any undue wear.
Has anyone seen similar?
Grizzly

Hi Grizzly
It is one of my pet hates about the continuous use of inverters just to be "Energy efficient" but no application is considered. If a motor drive runs at constant speed why the hell are you fitting an inverter should be the question! If you just require controlled start use a soft starter and minimise operational losses and induced bearing failures of the inverters.

Belt drives are an item that also gets my goat! As you have stated and observed the belt is a wearing item and as it wears the coefficient of friction changes and subsequently the power transmitted. The inverter will hide / compensate the wear.

Now the art of planned maintenance is disappearing where an item like a drive belt is only inspected for wear, it actually should be replaced periodically. The wear periods for drive belts has been long established. The periodical inspection is to be used between replacement periods to inspect for undue wear or condition changes causing premature wear. Try telling a customer that the £5 belt changed now saves a £300 return visit on critical failure and they slowly start to realise what the maintenance they are paying for does, never mind the energy saving you have just delivered for them!

Well done on your observations, hopefully others will read your post and apply to day to day practices.

Quote:

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Originally Posted by Grizzly

Hi Guys!
Old School meets New School!

Over the last Year I have had several instances to question the old drive belt maxim of.-
If a drive belt starts to squeal check for tightness and it's wear rate? Change if necessary!.

I have not seen it in any training manual, but when some of the drive belts I have changed recently have occasionally started to squeal.

I have changed them to notice a huge drop in the VSD running amps.

Others I have changed as part of a maintenance routine, have also shown large running amp reductions.
Which leads me to believe that the soft start action of VSD drives, can hide drive belt wear and their reduced efficiency?

On one set recently the average running of 45hz instantly dropped to 35hz when I changed the belts. At the time I could see no physical evidence of any undue wear.
Has anyone seen similar?
Grizzly

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Grizzly,
Have not seen it mainly because never seen VSD on a belt drive recip
Direct drive only a few.
I thought recips just load & unload & are efficient.
Using a temp gun might pick up slipping earlier.

Quote:

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Originally Posted by RANGER1

Grizzly,
Have not seen it mainly because never seen VSD on a belt drive recip
Direct drive only a few.
I thought recips just load & unload & are efficient.
Using a temp gun might pick up slipping earlier.

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Not really relevant to Comps my friend but the new style BAC (evaporative Condensers) and AHU's have VSD Belt drives.
Grizzly

maybe more modern belts are different.
Also maybe laser temp gun could pick up slippage due to excessive heat generated.
http://arrc.ebscohost.com/ebsco_stat...RIVE_BELTS.htm

Hi Grizzly
You and Hookster have raised some very good points about belt wear on VSD controlled compressors and routine checking.
Recently we installed two recip compressors with VSD's and after about 3 weeks it was noted that there was a bit of black dust around the belt guard but no apparent evidence of belt slippage / squealing while running.
When the guard was removed the belts were loose and had been slipping evidenced by all the black rubber dust on the bottom of the belt guard.
The belts were checked and appeared to be OK so were tightened didn't look at the amps or speed before or after as before reading your post had not considered this.
I am a firm believer in routine maintenance, I think the saying is "an ounce of prevention is worth a ton or cure".
I will pass this gem onto all our service guys that the belts need to be checked on a regular basis, thanks to both of you for the info.
Regards
Paul

Interesting topic thanks for information everyone, all taken on board and noted.
My biggest problem with belts is getting a matched set, from suppliers. Blank looks all round, am I old or stupid..... probably both.

One of the main causes I found for excesive belt wear on ahu's was poor alignment ,belts would be changed but poor alignment not corrected

Quote:

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Originally Posted by PaulZ

Hi Grizzly
You and Hookster have raised some very good points about belt wear on VSD controlled compressors and routine checking.
Recently we installed two recip compressors with VSD's and after about 3 weeks it was noted that there was a bit of black dust around the belt guard but no apparent evidence of belt slippage / squealing while running.
When the guard was removed the belts were loose and had been slipping evidenced by all the black rubber dust on the bottom of the belt guard.
The belts were checked and appeared to be OK so were tightened didn't look at the amps or speed before or after as before reading your post had not considered this.
I am a firm believer in routine maintenance, I think the saying is "an ounce of prevention is worth a ton or cure".
I will pass this gem onto all our service guys that the belts need to be checked on a regular basis, thanks to both of you for the info.
Regards
Paul

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Paul tensioning belts easy, it's removing guard & reinstalling that takes all the time for me.

I hate coupling guards, tiny bolts & screws that never quite line up or seem to get lost.

Worst experience was on rotary booster, someone changed cooling jacket pump years before, replacing it with pump 4x bigger than necessary, that took awhile to work out as they only ran it for 2 hours a month.

thanks also for the observations on drive belts and vsd.

Hi Ranger.
after leaving the meat plant industry a long time ago, I have not seen a rotary booster for years. Extremely noisy equipment, names as Fuller and Hick Hargreaves come to mind, as inter-stage boosters.
Have got to say do not miss them at all.
Give me a compounded screw system any day.
magoo

Quote:

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Originally Posted by Magoo

Hi Ranger.
after leaving the meat plant industry a long time ago, I have not seen a rotary booster for years. Extremely noisy equipment, names as Fuller and Hick Hargreaves come to mind, as inter-stage boosters.
Have got to say do not miss them at all.
Give me a compounded screw system any day.
magoo

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Magoo not many rosaries left now.
Once the asbestos blades were no longer available, not the same anymore.
On this plant they are backup only.
Got the parts from Farley Frigeration in USA, sound like real characters.

http://farleys-srp.com/wp-content/up...ey_catalog.pdf

Hi Ranger,
definitely the blades were the weak point in rotarys , get a smidgen hot they would fly to bits. will be interesting to see how the melimine ones react.

What a brilliant site, filed for reference. Definitely a family business and look a bunch of hard cases.
Living in a high population based country does have benefits for component supplies. NZ total does rate as even a large city, hence no one has stock levels, really frustrating.
magoo

Hi Guys!
I read Rangers excellent post earlier and missed the link, which as you say is an very interesting read.
When I read about the blades failing, it reminded me of a similar Hick & Hargreaves Booster we had in one of the Cold Stores.
Blades were a problem then.
Our Old Chief Engineer sourced some Teflon (Yellow) ones from somewhere in Scotland, Glasgow I think?
Anyway they were a rare commodity back then (1990's) so a link to a supplier relevant now.
Will surely be a big help to someone?
Thanks for the complement Magoo (another post) and I think the same about you Guys.

Grizzly

Was it the 2 Ronnies who had a character Arlie Farley.
Grizzly might remember if I 'm correct!

Just looked it up Charlie Farley & Piggy Malone, alway good for a laugh.