ABB Drives Blown Boards.

[itsmoked]

Apparently there is a problem with ABB drives that are part of a packaged air handler. They seem to blow their "power supply boards" frequently and with such regularity that refrigeration guys carry spare ones in their trucks.

Anyone else heard of this or know anything about it?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Skogsgurra]

Not over here. What power range? What voltage? Grid type?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[wayne440]

If the subject units are like the few HVAC units I have worked on, most of the components are specified "to the ragged edge", just large enough to last until the warranty expires. Could be they are simply using a too small drive.

 

[DickDV]

Haven't seen this with any of the ACS or ACH units. It would be helpful to be more precise as to which models are having trouble.

 

[itsmoked]

Not sure Skogs. In this case these air handlers are used with 365 ton centrifugal chillers. They're likely med voltage but the air handlers are probably 460V.

wayne; I suspect you are exactly right.

I'll see if I can dig up some more info DickDV.



Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Keith,
There are issues with many EU design drives with regards to grounding and the fact that they have no need to consider un-grounded delta supplies, such as 240V Delta systems often found in commercial installations, or 208Y120 systems where they don't run the Neutral to the HVAC equipment because they don't think it's necessary for a motor. That leaves us with potential grounding issues and most VFD mfrs include instructions as to how to remove a Y bonding jumper in in the cap bank for those cases. Also if they are using drives with built-in EMI filters on ungrounded delta systems, they must remove or disable the filters because they too are referenced to ground.

Unfortunately a lot of HVAC equipment is installed by mechanical contractors as part of their package, but the installers don't bother to read instructions, nor are they likely to understand them if they do and so they ignore it because (and I have heard this directly from some) "It's just grounding stuff, no big deal".

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[itsmoked]

Jeff thanks! Makes sense.

Here's the further info I was able to get.

They are ABB ACH 550 HVAC series drives, with the bypass.
The fans are 10-15hp.

The AHU is a Haakon - a division of Trane IIRC.

I'm sure that the drives are stock items, and probably not purpose built for this AHU. The reason is because we have the same drives running our tower fans and they have been great, except the fact that the clocks on them lose about 30 minutes a day - glad we are not using the built in PLC functions!

We wanted the bypass just for this reason - if the drive goes out, we can bypass the drive and send full line voltage (480V) to the motors. NOT so with this board going out. It's just a few resistors next to the transistor that let their smoke out.

Still seems to fit with your cautions Jeff.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Here is what I found in my ACH550 manual:

WARNING! To avoid danger, or damage to the drive, on IT systems, corner-earthed TN systems and residual current circuit breakers, see section Disconnecting the internal EMC filter on page 45.
R5
X0013
Power output to motor
(U2, V2, W2)
Power input
(U1, V1, W1)
GND
F2
F1
F1
PE
GND
PE
Power output to motor
(U2, V2, W2)
F2
R6
GND
Power input
3-phase: U1, V1, W1
1-phase: U1 (live), W1

Installing the drive 45
ACH550-01 User's Manual
Disconnecting the internal EMC filter
On certain types of systems, you must disconnect the internal
EMC filter, otherwise the system will be connected to earth
potential through the EMC filter capacitors, which might cause
danger, or damage the drive.
Note: When the internal EMC filter is disconnected, the drive is
not EMC compatible.
The following table shows the installation rules for the EMC filter screws to connect or disconnect the filter, depending on the system type and the frame size. The locations of the screws EM1 and EM3 are shown in the diagram on page 43. The location of the screws F1 and F2 are shown in the diagram on page 44.

One problem is, they use the term "IT or TN System" which has no meaning here in the US, nobody knows what it means. I've had guys tell me they thought they only had to do something special if it was located in the IT department (as in Information Technology) or that TN meant there were special rules for Tennessee!

So basically if they didn't run the ground out to the drive, or they grounded to the AHU frame without thinking about the fact that it's on rubber isolators (that happens too), they have set the drive up for failure.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[Skogsgurra]

A classic!

Well, you all know - of course - that IT is Isolé Terre where the I refers to how the transformer neutral is connected to ground (Isolé is French for Isolated) and the T says how the motor or other device frame/housing shall be connected (Terre is French for ground).

There is no such ting as an open delta in the European thinking and that may cause a problem.

It is really bad that they haven't translated those terms into a description that the US user can understand. I thought better of the American ABB organisation. Beancounters rule again?

BTW, the TN and TN-C* system means that transformer neutral is connected to ground (Terre) and that the motor frame shall be connected to PE/Neutral (French Neutre). This is also known as 'four-wire system' and is more and more abandoned for the TN-S where you have a separate Neutral and PE conductor. That system is also known as a 'five-wire' system.

Yankees think the European system is funny and the Europeans think that the US system is unbelievable. It is all a question of what you are used to. But not to transkate such things in an understandable manner is criminal.

*The 'C' in TN-C says that PE and Neutral are combined (Combiné) in one wire while the TN-S (S is Separé) says that there are separated PE and Neutral wires.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[itsmoked]

Well! That certainly helped you guys. Thanks for the quote Jeff and thanks for the interpretation Gunnar. It helped clear it up for me.

I'll go back to the guy and see what his power system is like.

Here's the board that reliably toasts. I included the one meg close-ups only as links.(for those with pathetic bandwidth LOL)

+1meg link

+1meg link

+1meg link

Just glancing at this it looks like those three resistors are in parallel. They obviously had a wheee bit much to drink.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Looks like they suffered from an MSEE, Magic Smoke Expulsion Event.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[itsmoked]

One of the negative aspects of smoking.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[niallnz]

They have the same type of drives on the tower fans and they have been "great". It would be interesting to do a comparison to see if the tower fan drives have had the internal EMC filters disconnected. It seems odd that these drives should fail regularly and others on site of the same type do not.

Cheers niallnz