VFD life

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NE (9.06 miles @5.9 Degrees from Winged Horses)
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EC - retired
I know many things come into play but how long can a VFD be expected to last?

We installed a couple in 2006 and one has gone TU. They ran submersible wells, alternating as lead, lag and backukp when one pump was not enough. 24/7. 7 1/2 hp 230v. Cooling water for refrigeration equip @ a grocery store. Worked without one hickup until Monday.
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
Good question.

We've got quite a few several years old, I'd say around 5-7 years old on wells and whatnot and they're still running strong. Seems like the only problem we have on these well VFD's is the fans burning out after a while. No big deal though, especially for how many hours they run.

Do you oversize your drives at all?

We use strictly AB, but the Yaskawa rep has really been pushing one of our farm customers to use his IQpump controller drives. I wish powerflex 400's could show psi....
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
but the Yaskawa rep has really been pushing one of our farm customers to use his IQpump controller drives.

I have a couple of these that have been controlling big AHU's at a testing lab for a few years now, no call backs, easy set-up.
 

Jlarson

Member
Location
AZ
Just like you said it depends, I have seen some that have been going for years and years and some that are nothing but constant trouble.

These were DanFoss.

I have had problems with Danfoss drives at well sites. Then again the climate out here is a little more extreme.
 

mxslick

Senior Member
Location
SE Idaho
I've used Woods and Danfoss on my film projectors...the Woods have held up quite well, only one failure in over 10 years (at a site with notoriously bad power), Danfoss have only been in service for about 3 years so no idea on reliability yet, but the setup (for tach controlled operation tying two projectors in sync) was so complicated we took to calling them "Damn fussy". :grin:
 

broadgage

Senior Member
Location
London, England
Heat is enemy of electronics.
I would therefore expect the life of VFD, or other power electronics to be very dependant on the ambient temperature.

Some VFDs are attached to the motors, rather than being in a box on the wall, those driving chilled water pumps seem to last almost indefinatly, but those on heating systems last less well.
The conditions of service are identical except for the temperature of the water being pumped.
 

lakee911

Senior Member
Location
Columbus, OH
I've seen some old old beasts that in the field that have to be far more than 10 years old. I can't recall the brands though. If you keep them clean (PM cleaning of dust, changing filters, etc.) and you can keep them in a clean cool and dry environment (i.e. no H2S), they should last for a long time.
 

Jraef

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Staff member
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San Francisco Bay Area, CA, USA
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Electrical Engineer
The enemies of VFDs from my experience over 30+ years (feel free to add to the list from your experience):

Voltage issues; surges, brownouts, spikes etc. As one old boss of mine said after getting orders for 200+ drives right after a large storm front swept through the South East one year," Lightning been berry berry good to me" (reference to Garret Morris on Saturday Night Live of old)

Heat issues; heat x time = failure. More heat, less time necessary to get to the end of its service life. Most people buy the VFD and scrimp on the packaging at the last minute. It's like buying a new Mercedes and then parking it on the street in downtown Oakland for a week. You might get lucky, but probably not.

Moisture issues; water from anything, i.e. not just leaky doors, vented boxes in hose-down areas or bad conduit penetrations, but consider condensation. A really common one is a VFD outside; VFD runs all day, turns off at night. Warm VFD, cool night air = instant condensation. If you use heaters, make sure some smart ass doesn't kill the power to save energy, heaters no worky without electricity; happens a lot.

Maintenance issues; "cleaning" is way too vague of a term to use on VFDs. I have seen more VFDs blown up because someone used compressed air to blow them off than I have ever seen from being too dirty. You should CAREFULLY read the cleaning instructions in the manual. If you want to use air, use EXTREMELY DRY air. The "canned air" for cleaning PCs and other electronics is OK as long as the propellant is not conductive (most are that way, just be absolutely sure).

Extreme cold; VFDs have big capacitors in them, larger ones are almost always electrolytic (cheaper) which means if the power is removed from the VFD the electolyte can freeze. If it does the caps blow the instant the power is re-applied. It's usually a big mess when that happens. To protect from that, you have to use a "freeze stat", like the thermostat in your freezer that is open at 40 deg. F and below, closes on temp rise above 40F, feeding a contactor that keeps line power off of the VFD line terminals.

Application issues; People often expect miracles and VFDs are good, but not "Messiah good". They cannot resurrect the dead or cure the diseased. Putting a VFD on a bad system rarely fixes anything, it just adds another device that can fail.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
I believe your PowerFlex 400s will display the PSI. You have to scale a display in reference to your 4-20 ma input or 0-10v. The last time I did it we were using a 0-100 psi transducer. O psi would relate to 20ma, and 100 psi to 4 ma. 8ma = 50 psi, etc. Study your manual & you should get it.

Now that I explained it I don't remember who's drive it was.

VFDs do not always come easy for me but I still love to work with them.
 
The enemies of VFDs from my experience over 30+ years (feel free to add to the list from your experience):

Voltage issues; surges, brownouts, spikes etc. As one old boss of mine said after getting orders for 200+ drives right after a large storm front swept through the South East one year," Lightning been berry berry good to me" (reference to Garret Morris on Saturday Night Live of old)

Heat issues; heat x time = failure. More heat, less time necessary to get to the end of its service life. Most people buy the VFD and scrimp on the packaging at the last minute. It's like buying a new Mercedes and then parking it on the street in downtown Oakland for a week. You might get lucky, but probably not.

Moisture issues; water from anything, i.e. not just leaky doors, vented boxes in hose-down areas or bad conduit penetrations, but consider condensation. A really common one is a VFD outside; VFD runs all day, turns off at night. Warm VFD, cool night air = instant condensation. If you use heaters, make sure some smart ass doesn't kill the power to save energy, heaters no worky without electricity; happens a lot.

Maintenance issues; "cleaning" is way too vague of a term to use on VFDs. I have seen more VFDs blown up because someone used compressed air to blow them off than I have ever seen from being too dirty. You should CAREFULLY read the cleaning instructions in the manual. If you want to use air, use EXTREMELY DRY air. The "canned air" for cleaning PCs and other electronics is OK as long as the propellant is not conductive (most are that way, just be absolutely sure).

Extreme cold; VFDs have big capacitors in them, larger ones are almost always electrolytic (cheaper) which means if the power is removed from the VFD the electolyte can freeze. If it does the caps blow the instant the power is re-applied. It's usually a big mess when that happens. To protect from that, you have to use a "freeze stat", like the thermostat in your freezer that is open at 40 deg. F and below, closes on temp rise above 40F, feeding a contactor that keeps line power off of the VFD line terminals.

Application issues; People often expect miracles and VFDs are good, but not "Messiah good". They cannot resurrect the dead or cure the diseased. Putting a VFD on a bad system rarely fixes anything, it just adds another device that can fail.

Don't forget the limitied life of electrolytic capacitors. Some manufacturers have addressed the issue and they say the improved capacotirs within the units have an expected life of 10 years, after which they should be replaced. In practical terms these newer capacitors are most likely to last 15-20 years, it is just the Manufacturers way of assuring that if something goes awry: I told you so....

Your cooling fans will also need to be replaced and don't forget those pesky little batteries on the operating panels.

In general, ASD's in a NEMA 1 enclosure should be trated as any other ordinary electronic device.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Don't forget the limitied life of electrolytic capacitors. Some manufacturers have addressed the issue and they say the improved capacotirs within the units have an expected life of 10 years, after which they should be replaced. In practical terms these newer capacitors are most likely to last 15-20 years, it is just the Manufacturers way of assuring that if something goes awry: I told you so....
Yes, good point. Also, the capacitor life is even less if stored un-powered for a year or more.

Your cooling fans will also need to be replaced ...
I just worked yesterday doing PM on an old Siemens / Relcon VFD built in 1989, the fans had never been replaced. They had NOS spares on the shelf so I put them in anyway because I figured the entire drive only has a couple of years left in it, so they might as well get some benefit from having kept them all these years. But I seriously doubt that the fans used in new VFDs now are anywhere near as good, so your point is valid.

...and don't forget those pesky little batteries on the operating panels
Oh yeah, that's annoying. Especially in that you won't know there is a problem until power is removed and the system comes back stupid and reset to factory defaults when power is turned back on, if your even that lucky. But that problem exists for virtually every microprocessor based system now. That was one of the unsung benefits of the pre-digital electronic systems.
 
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garbo

Senior Member
VFD LIFE

VFD LIFE

We have over 200 VFD'S from 5 to 250 HP. At least 25 are over 10 years. Most run 24/7 at a reduced speed. Just changed out 3 IGBT'S and a control board on a 125 HP AHCU Supply fan that is 5 years old. Over $4,000 for these parts but well worth it on the energy saving. We change out about 10 boards, 8 fans and 5 operator control panels a year. Earlier post is right about the cooling fans. They only seem to last 5 to 8 years on a 24/7 operation . I can change out a fan on older style Danfoss VFD'S [ vlt6000's] in 21 minutes without shutting the drive down. Newer models over a hour after waiting up to 25 minutes for capacitor bank to discharge. tom grabowski
 

Open Neutral

Senior Member
Location
Inside the Beltway
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Engineer
Agree with all on fans, water & dirt.

Also, there was a major fracas with bad caps a decade back. Employee A snitched SekRet Formula for electrolytic caps, moved to company Q with same. Only after large production runs did Q and A figure he'd NOT gotten the whole formula; the part missing kept them working for more than N months...OOPS!

Millions of computer motherboards and much other gear failed. I know of no reason to think VFD's would be any different. Of course, MilSpec devices were unaffected {What's that you say, Lassie? Timmy's being held captive at the mill by an angry repair foreman...we better rescue him...} because no bad parts there, RIGHT?

Also consider the dichotomy: Laptops have a product cycle of 5-18 months, with a lifetime of ~3 years. Desktops are a little longer. But we expect 20-30 year old industrial controls to be supported and still sold...
 

nollij

Member
Location
Washington
Laptops have a product cycle of 5-18 months, with a lifetime of ~3 years. Desktops are a little longer. But we expect 20-30 year old industrial controls to be supported and still sold...

Which is why we pay so much for industrial equipment. You will never see me paying $1500 of my money for what amounts to a capacitor, resistor, varistor and a rectifier (MV motor starter part)!
 
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Besoeker

Senior Member
Location
UK
But we expect 20-30 year old industrial controls to be supported and still sold...
Partly agree.
We are supporting some of our drives that went into service some years before my first child was born. That was 34 years ago.
Would we sell the same now? Even if we wanted to, we couldn't. Many of the components have been discontinued or superseded.
 

shmojoe

Member
Location
ATX
Yes, good point. Also, the capacitor life is even less if stored un-powered for a year or more.

Do these cap's have a shelf life? Off topic, but just replaced a DC cap bank in a UPS which sat for 18 months. Manufacturer assured me that sitting unpowered was not a problem, but your comment made me wonder.
 

Open Neutral

Senior Member
Location
Inside the Beltway
Occupation
Engineer
Do these cap's have a shelf life? Off topic, but just replaced a DC cap bank in a UPS which sat for 18 months. Manufacturer assured me that sitting unpowered was not a problem, but your comment made me wonder.

Large capacity caps should be brought up to full voltage slowing {over an hour+} if stored for a few years.
 
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