Water cooled MV drives Vs air cooled drives

[geefer]

The MV drive application we are considering at the moment falls into the absorbed power category where we could use either air cooled or liquid cooled drives. Some of my colleagues have reservations using about using liquid cooled drives with regard to the ancillary equipment required to cool the drive coolant ( heat exchangers etc) Myself I am concerned that the quality of the air may require changing of filters very frequently and this possibly encuring down time . Has anyone experience on this issue. The drives we are considering are the Siemens Robicon perfect harmony and the ABB acs 5000. The integral transformer being a major benefit to us with regard to location and space issues.

 

[Skogsgurra]

I have had prolonged problems with internal corrosion in water cooled systems. Also, when there is a leak, you have lots of bad effects. Yes, I know that there shouldn't be any leak. But I have seen too many leaks that "don't exist" to take the salesman's word for it.

All simple air cooled systems need filters. That's a fact. But it is a lot easier to supervise filter pressure drop and inverter temperature than finding a potential leak before water does any damage. If the drive is critical in any respect and if you got the space, use air cooling.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[OdessaEE]

In the last year I have been involved with the install of 4 4000HP Siemens air cooled drives and I am currently installing 4 more. Siemens recommends about 15Tons of HVAC for every 1000HP if you are exhausting directly into the building. We chose to actually build ducts into the building for the exhaust and inlet air. We also connected the exhaust and inlet ducts together so we could recycle warm air on cold days. This exhaust system was rather large and required ducts running the length of the drive.

With all this said we kind of regretted our decision not to use liquid since the return and supply lines to the outdoor heat exchanger would have been a 3" pipe in and out.

Liquid cooling has come a long way and I know both AB and Siemens offer a low pressure cooling system. Usually only about a pound so if a leak occurs it drips rather then sprays. Leak detection is also included. AB uses metal pipes while Siemens useS hoses. So the AB drives looks a little more stout.

This is a big decision, but if your drive is 4000HP and over I would recommend liquid cooling unless you can afford the HVAC bill.

 

[itsmoked]

Welcome to Eng-Tips OdessaEE.

If liquid is used what is the typical method of heat to environment transfer? Just a radiator/fans or cooling towers or ?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Skogsgurra]

Right, OdessaEE. Handling power is always tricky. Especially if inside buildings. If possible, put drives close to external wall.

My experience is that heat sinks with water channels in them corrode from inside out. And dripping is just as bad as spraying.

Yes. There are recommendations as to water quality, additives, inspection intervals and other means to reduce risk/damage. Still, as an independent drives engineer, I get calls from several sites where water is a problem in large drives.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ozmosis]

I've only ever used a Siemens liquid cooled drive before and while I have never actually had a problem, the cost of the cooling system was always extremely high. The quality of coolant was always an issue and this drove the premiums high.
The applications were on ships and this added to the restrictions.
Reliability comes in many forms. I would say that I never actually had a problem with water cooled drives as far as their functionality or any leaks, we installed as standard leak detectors in the cubicles and as OdessaEE mentions, it is fairly low level pressure. However, reliability is also a factor with the specialised nature of these drives and the need to look beyond the drives and have within your maint.program the chillers attached to the drives.
The need for such purity in coolant with these drives was the problem in my opinion. Especially on a ship.
Vacon have a range of water cooled drives that are stainless steel tubing and, I assume, this channels through the heatinks. They claim to be able to put any coolant medium through their WC drives, even sea water! but I wouldn't like to try that.
Air cooled has less to go wrong if the filters are maintained then they would be a safer bet.
It also depends on the industry you are in. Some textile applications and printing applications like water cooled then the filters don't clog up every 10 mins.
As the two companies mentioned do both, I would put the challenge to them to come to you with a realistic proposal outlining the pros-cons of each.

 

[oldfieldguy]

I have three Siemens GM150 water-cooled drives in the 7000-9000 horsepower range. We've had no problems with the cooling system in the year and a half they've been in service. Each installation has a small fin fan type radiator outside the drive's building to handle heat exchange to ambient. We do have some days where ambient temperature is near the recommended limit of the coolant and this causes a bit of a problem.

However, we'd have similar problems with using forced ambient air to cool, with added problems from contaminants such as dust, and would have similar or worse temperature limitations unless we added another cooling mechanism for the drive's cooling air supply.

Further, I don't think Siemens offers and air-cooled drive in our horsepower range.

old field guy

 

[Skogsgurra]

Eighteen months. Corrosion is a slow process...

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[roydm]

I worked with a PDL drive once that was installed in the switchroom wall, cooling fins on the outside. I thought that was a good idea.
Roy

 

[itsmoked]

Thanks oldfieldguy for that clarification.

Something I've seen used in the refrigeration industry is water spraying or misting onto the heat exchanger during really overly hot periods. It doesn't take a lot to greatly increase the cooling.

skogs; There are companies that specialize in preventing corrosion in recirc systems thru water quality maintenance. They are often the same people who do boiler feed maintenance.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[electricuwe]

I've done water-cooled High-Current rectifiers and induction melting and RF-equipment for years and a lot of experience with that.

Water cooling is a wonderful means to remove the losses of power electronics but it is only worth while the invest if there is a lot of power to remove and the enviroment is dirty. A medium voltage drive of the size cited would be a typical candiate if it is expected to operate under harsh envireomental conditions.

But newbys in watercooling can create a lot of trouble, if the install quick and dirty water cooled designs to save a few bucks on the power semiconductos.

 

[Skogsgurra]

I don't seem to get the message through.

There are at least three installations in paper mills that I know about. Every measure has been taken (like water purifiers, de-ionozation, conductivity supervision, anti-corrosive additives - you name it). And still, heat sinks corrode from inside. Water gets out.

Heat sinks have been replaced now. Not so sure we won't have same problem again within five or ten years.

I am not talking about cowboy installations. OK, seen them, too. But there, the problems are so obviuos. And the leaks usually start first year.

There are also installations that have been running with few problems for several years. True. But I would at least see that I got a prolonged guarantee (in writing) with a clause about indirect damages if I were to install a water cooled drive.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[electricpete]

"Something I've seen used in the refrigeration industry is water spraying or misting onto the heat exchanger during really overly hot periods. It doesn't take a lot to greatly increase the cooling."
It is sometimes done on transformers as well. But a very small amount of impurity in the sprayed water can cause problems since it forms scale when the water evaporates... reducing heat transfer.

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