# Question about internal cooling fans - AB Powerflex 700H



## acro (May 3, 2011)

So we've got an AB 700H with the original 2006 SERIES A firmware(1.006)
Actual Cat # is 20CD385. 300HP 480V


Anyway, we have been getting an occasional F32 fault. This goes back a couple of years, but seems to be worse lately. It can go a week or two between faults, or 10 faults in 30 minutes sometimes.

There are two internal 230V 50Hz fans that we have replaced these several times - a few times for bearing failures. But I think that several times more we have replaced fans that where not actually faulty, just due to the F32 fault. Lately, we have been using "rebuilt" fans from radwel, but in the past, they had been original AB. AB has obsoleted the AC fans and offers a DC conversion kit for several $K. This has not been attractive as it approaches 50% of a new drive cost.
We have never replaced the capacitor, but do have a couple on hand. They are not a direct physical replacement, thought the size and voltage are appropriate.



My main questions are - 
What actually controls the operation of the fans? Are they variable speed?

What condition determines when the fault becomes active?

Any advantage to upgrading the firmware?

Could it be the capacitors?



In the recent past, we have ran the drive for several days with both of the fans removed and did not have a fault occur(cooling was provided via external fan and ducting). So, this has us thinking that possibly, we could possibly control the fans with an external method.

Any potential long term issue with this? There are other heat sink faults that would still protect the drive.

But, why did it not fault with the fans disconnected?


Often times when we observe the drive after a fault, but before clearing it, one of the fans has stopped turning, while the other is still running, or at least coasting down.


Most recently, after a fault, I cycle the power and enable the drive. I observe the fans and only one of them is turning. I poke at it with a zip tie to try and kick start it, but it has no effect. But I suppose that does determine the problem is not bad bearings, as it spins freely. After a bit of operation, they are both turning like one would expect. 

Are they controlled by heat sink temperatures?

We force feed the cabinet with unconditioned, outside air. Could we be over-cooling the drive?



Thanks


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## gpop (May 14, 2018)

I think the drive can run 0-40 degree C so over-cooling is probably not the problem. 
I haven't looked but i think there is a place in the program that reports actual heat sink temp. As long as the filters on the door are kept clean i haven't really seen a problem keeping them cool.

Years ago on a different drive i had a fan fail so we tie wrapped a computer fan to the grill then forgot to order the replacement. It ran that way until it was upgraded 5 years later so it can be done (not saying i recommend doing it).


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## acro (May 3, 2011)

Yes, the heat sink temp parameter is something that is accessible. Probably even remotely, but I haven't went very far down that path quite yet. 


It's just strange to me how the fault occurs, stops the drive, but then allows the drive to operate again with what would seem to be a condition that would generate a fault.


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## gpop (May 14, 2018)

acro said:


> Yes, the heat sink temp parameter is something that is accessible. Probably even remotely, but I haven't went very far down that path quite yet.
> 
> 
> It's just strange to me how the fault occurs, stops the drive, but then allows the drive to operate again with what would seem to be a condition that would generate a fault.


Heat sink temp is probably a tc/rtd stuck to the heatsink it may even be backed up with a temp switch. If its glitchy then you will get a false alarm. (it also may account for why the fans are not running). see if the temp is stable on the hmi.


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## gpop (May 14, 2018)

google "ab 700h heatsink temperature sensor"


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## varmit (Apr 19, 2009)

I have seen this fault, and other oddball faults that made no sense, on AB drives when a control board is failing.


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## gpop (May 14, 2018)

F32 is 
"Fan is not energized at start command"

238 bit 14 can make that go from hard fault to soft alarm.


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## acro (May 3, 2011)

gpop said:


> F32 is
> "Fan is not energized at start command"
> 
> 238 bit 14 can make that go from hard fault to soft alarm.



I'll look into that. Hope it was available in our version.

Thanks


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## gpop (May 14, 2018)

varmit said:


> I have seen this fault, and other oddball faults that made no sense, on AB drives when a control board is failing.


Next time you see this on a old drive try factory flashing it back to defaults then reprogram it.


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## JRaef (Mar 23, 2009)

The fan problems on 700H drives are well known and documented, it's one reason why A-B obsoleted them. That was actually a "stop gap" for PF700 drives over 250HP, because A-B didn't have their high HP design ready when the PF700 was released. So they brand-labeled a Vacon drive at those higher HPs, putting their PF700 control interface on it to make them program the same. But that screwy fan arrangement was Vacon's design (also the same as Cutler Hammer SVX drives, who had the same issues on the higher HP versions).

What Vacon did was to use 230V 3 phase 50Hz motor on the fans, but feed them with single phase and use a capacitor to make it spin, then de-rate the motor power by 50% from it's 3 phase rating. But that system NEVER lasted long because they ALSO had the issue of the V/Hz ratio of the fans being too far off with 60Hz and the result was a constant headache for A-B. That's why they later came up with a retrofit kit to make the fans DC and just rectify the 230VAC single circuit that was already there for it; that way the 50Hz vs 60Hz rating of the fans was no longer an issue. 

4 months ago we replaced 3 x 400HP versions of those 700H 18 pulse drives and used the new PF755TL low harmonic drives. The end user was so so happy to get rid of those old 700Hs... Those fans were a royal PITA to replace.


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## acro (May 3, 2011)

Thanks for that info. I wondered about the single phase / 3 phase thing. Didn't make sense that a 3 phase fan required a capacitor.

The new radwel fans do have the 60hz rating on the tag, where the AB fans of course just had the 50Hz. Perhaps they would be longer lived, but we don't seem to be loosing fans right now - just that damn fault.



Do you think it would be worth our trouble to retrofit the new capacitors we have?

It does seem that our firmware version does not support the change from a hard fault to a soft alarm.

I just wish we would commit to replacing this thing, but not quite yet, it seems. Some day, I suppose it will 100% fail. Then they will have a different opinion as this is a critical component to our process.


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