VFD Heat questons

Guys

I have a few questions for the VFD guys out there.

1. I have powerflex 40's and 70's running off of Ethernet. We are having some issues with a few of the drives faulting for Comms related faults.

What is the highest cabinet temperature that you would run a drive in using ethernet to avoid communication issues.

2. Assuming the same load on the motor running a VFD. (20 Amps)
Which VFD will generate more heat, a VFD running at 30Hz or a drive running at 60Hz, or does the Hz make a difference at all. Might be a silly question but I could not remember if the Hz played a roll in heat generation.

While I have seen plenty of causes for comm failure, I have never run into heat. I would just make sure I am below the rating on the 20-COMM-E module (40 deg C??). Have you proven to yourself that heat is actually the culpret (like running with the cabinet doors open and completely eliminating faults) or is it a logical conclusion?

There are other more experienced drive guys on the forum but I don't think the drive output frequency matters much in terms of drive heating. PWM frequency, however, will have an effect.

Keith

mrdmrd said:

Guys

I have a few questions for the VFD guys out there.

1. I have powerflex 40's and 70's running off of Ethernet. We are having some issues with a few of the drives faulting for Comms related faults.

What is the highest cabinet temperature that you would run a drive in using ethernet to avoid communication issues.

2. Assuming the same load on the motor running a VFD. (20 Amps)
Which VFD will generate more heat, a VFD running at 30Hz or a drive running at 60Hz, or does the Hz make a difference at all. Might be a silly question but I could not remember if the Hz played a roll in heat generation.

Click to expand...

What kind of faults are you having?
Are the drives running merrily along, then tripping ?
Do a media test on the ethernet cables first.
OR
do you have faults with the drives anytime you are commissioning with uploading and downloading? In that case, that is caused by a parameter in the COMMS section . who the drive behaves when PLC is in Program mode.

Also, as a rule of thumb, we always supply line reactors for any AB VFD.

Ian

On the powerflex 70's it is fault 75 DPI Port 5 fault. The drives it will be running along just fine then trip out.

On the Powerflex 40s I am not sure of the fault code. It will go into a comms fault of somesort and all that needs to be done is disconnect the ethernet for a few moments and reconnect. The fault goes away and everyone is happy.

I think that they have already tried to change the cable on the 40.

The reason that I brought up the heat is that we had the doors open on the panel for about 5 hours yesterday and nothing, then during the 4 hours after we closed the doors it tripped 3 times.

I know that there is quite a bit of heat in the cabinet for an outside temperature of around 75 degrees. Now the drives seem to be running fine there have not been any faults in the past 6 hours.

It is not the entire system, the small panel with the powerflex 70's in it has a total of around 10 drives in it 4 70's and 6 or so 40's

The larger panel has about 25 drives all power flex 40's. Each panel has 1 drive that is causing problems, a 40 in the large panel and a 70 in the smaller panel.

The panels are not conected to any other outside ethernet, just what is inside the cabinet.

Your drives are typically rated 40* C or 104* F.

I have found if you keep the inside temps at 95*F and below there usually is no heat issues. I have been many a 95*F control house. It will freak out those that think electronics rooms need to be cold enough to store meat safely.

One of the biggest problems is are all the drive cooling fans running? Are the heat sinks clear and not plugged?

Get your air hose with a regulator set to 35 psi and blow the cabinet clear.

mrdmrd said:

On the powerflex 70's it is fault 75 DPI Port 5 fault. The drives it will be running along just fine then trip out.

On the Powerflex 40s I am not sure of the fault code. It will go into a comms fault of somesort and all that needs to be done is disconnect the ethernet for a few moments and reconnect. The fault goes away and everyone is happy.

I think that they have already tried to change the cable on the 40.

The reason that I brought up the heat is that we had the doors open on the panel for about 5 hours yesterday and nothing, then during the 4 hours after we closed the doors it tripped 3 times.

I know that there is quite a bit of heat in the cabinet for an outside temperature of around 75 degrees. Now the drives seem to be running fine there have not been any faults in the past 6 hours.

It is not the entire system, the small panel with the powerflex 70's in it has a total of around 10 drives in it 4 70's and 6 or so 40's

The larger panel has about 25 drives all power flex 40's. Each panel has 1 drive that is causing problems, a 40 in the large panel and a 70 in the smaller panel.

The panels are not conected to any other outside ethernet, just what is inside the cabinet.

Click to expand...

Sounds like a heat issue then. Quick solution may be to mount a small fan inside the enclosure ( if possible ) to keep the air moving, and see if this helps with the time between failures.

If that solves the issue, then you know the enclosure needs a permanent method for cooling air.

Ian

Another handy utility on the powerflex 70 is the use of drive exploern with the 1203-sss cable and RS linx it' will show you the actual temperature that the drive is seeing however be forewarned the temperature it reports for the heat sink can be incorrect I have seen a powerflex 70 hit similar errors on temperature however not the same one as yours but they did relate to communications can't recall which one though

I believe you can monitor the temperature of the drives over ethernet, it may be worth trending the temp of each drive and finding what the temp is when it is faulting.


"People that say it cant be done should get out of the way of those that are doing it"

Just a thought, since I have run into this issue in cabinets before, verify proper spacing was used when mounting the drives. I have seen fans etc used to dispel heat in the cabinet but when the drives were too close the heat would accumulate until one of the drives faulted.

I have run into grounding problems manifesting as Comm errors on AB drives and PLCs. Cheaper to start there.

I'm with rsdoran. The little quick guide that comes with the drives shows the max heat and spacing requirements for your drives.

Heat output from AC drives is largely a function of output current and carrier frequency. Linear proportional with current and inverse proportional with carrier frequency.

I don't have the AB drive specs in front of me but you have to be careful with drive temp ratings. Almost all say 40 degrees C but some are not continuous but intermittent. A few even have 50 degree C ratings with a small output current derate. Read the fine print to be sure.

Limiting the inside of a control cabinet to 95 degrees F is good news for the Air Conditioner sales people but it is a bit too conservative in my opinion. You ought to be able to run the interior to 40 degrees C or 104 degrees F and use thermostatic controlled fans or coolers set to that temp.

Having the drives located too close together or too close to other controls is a sure way to make drive temp fault problems. Air has to move to meet the ratings. Also, don't put drives over/under each other. The upper drives breath hot air from the lower ones and are the first to overheat.

Don't have an opinion on Fieldbus comm faults. Don't do much fieldbus.

Personally, I would think of an EMC issue rather than an overheating problem.

With the doors closed, EM interference has to stay inside as well!

Opening the doors will allow a large part of the interference to be radiated to the outside world. So jraef's suggestion makes more sense than worrying about heat. Or you could try adding ferrite filters to all comm cable endings.

Personal opinion, would think ground etc before heat too.

I think original poster must have some reason to think heat though, so offered what I thought could be a problem.

Hope he comes back and tells us what the problem was if/when fixes it.

Ok here is a little update, I am starting to rule out heat. I do not think that if it was a heat issue it would only effect this one drive all the time. Just so that I know that we are all on the same page, this drive and all of the others around it (12 others) are all running the 22COMM-E ethernet adapter.

The Drive itself is not faulting, I am getting a timeout on the communications adapter. When the comm adapter faults all that needs to be done to get things back up and running is to unplug the ethernet cable for a bit then put it back in and give it a bit and it will start.

Also I can hook up the network and view the Adapters webpage.

Here is what I don't understand, If I start RSLinks and set up a new ethernet IP Driver (AB_ETHIP-1) I can view all of the drives on the network except for the one that I am having issues with. All of the drives are functioning as intended. I have full control from the HMI through the CLX processor and out to the all of the drives. All of the drives IP address are sequencial starting with 10.10.10.10 and ending with 10.10.10.22 but 10.10.10.17 is missing from the list. Not that it just can not communicate with it, but it does not even list. This is the one that I am having issues with.

My counter-part has made the change to the drive so that it will stay in its last state upon a communications loss. Don't worry the equipment is not super critical and does not effect the process much so it does not hurt it to just run at its previous speed.

The only thing that I can think of is the amount of communications that are taking place could be causing it but here again, why just this one drive?

Any thoughts????