TFT problems with temperature

Hi All

How hot does it get in North Carolina? I supply the controls for some mobile machines, PLC, HMI, etc. The HMI screen needs to be positioned so that is easy to see but that means it can be in direct sunlight. In the UK we have no problems but in North Carolina the HMI TFT screen (mono not colour) is getting so hot that it goes black. The guys on site fix it by getting a bag of ice so that they can work the machine but that is less than optimal. The HMI I use is a Biejer one that is rated up to 50C (122F). I have asked them to get me a surface temperature reading so that I know how bad it gets, but since our guy arrived there it has been raining everyday. So anybody know of HMIs that will survive at a temperature just this side of Hell and that will work with the Siemens S7-200 range of PLCs.

Thanks

Bryan

Here in a plant in South Carolina, near the North Carolina boarder, during the summer, outside temperatures reach 100 degrees F, while inside the plant it can reach 115 degrees F. It is also gets very humid.

I'd imagine North Carolina is similar (unless maybe you are closer to the mountains)

we have an application sat inside a compressor building that got up to 140degf this summer and the HMI worked just fine.

It is a Xycom 2600 series.

I was surprised it survived as the screen was almost too hot to touch.

According to my ASHRAE data the 99% winter / 1% summer temps range from Ashville 10/89 °F to Fayetteville 17/95. If the panel is outdoors in sunlight or indoors in a hot environment you can be exposed to a lot wors.

You should consider vent fans, air conditioners, or those cute little compressed air coollers.

Thanks for the replies guys. I have found out that it is in Charlotte, Google maps puts it near the border with South Carolina and reasonably close to the mountains. The temperatures don't seem too bad, we have rigs in far worse places that seem to cope. The machine has moved around a bit, it has been in the UK, Canada and now the States, supplied originally in 2003 so it could be that the HMI is reaching the end of the road.

Tom - We took the decision that reduced life of components was better than adding too much sofisication. These machines take a beating and the more stuff we add the more there is to go wrong. They get dragged around the country, dropped on and off low loaders and bounced down rough roads behind big tractors.

I have been pondering and think my simplest solution would be to have them add a smoked glass screen infront of the HMI with a one inch air gap. I hope the smoked glass would take the sting out of the direct sunlight. And besides it might even look cool, add some go faster stripes, maybe alloys and a sun roof.:nodi:

Bryan

BryanG said:

I have been pondering and think my simplest solution would be to have them add a smoked glass screen infront of the HMI with a one inch air gap. I hope the smoked glass would take the sting out of the direct sunlight.
Bryan

Click to expand...

If your talking about a sealed cover that might actually make it worse.
Think about a car left in the sun or a greenhouse.
The shade is a good idea but make sure theres plenty of air circulation to stop heat buildup.

We put sunshades on most of our control panels as Utah gets about 250 sunshine days a year and the average summer temp is well in the 90's.

SLC - Totally agree about not sealing the system, I was thinking of just simple stand off pillars. Anyone got experience with glass with a polarised filter?

The sunshade seemed like the simple solution to me, but the guys on site think it is a problem. I guess it is because the machine is mobile you never know where the sun is going to come from.

Had a look at the Pro-face (Xycom) website. I would like to move to colour screen but how well do they work in sunlight, can you still read them. The mono screen that I use has a contrast adjustment that means you can view it any conditions.

Thanks

Bryan

The Xycoms are pretty bright and from what I remember easy to see in sunlight.

Maybe you can get a demo unit and try it out.

The polarising filter would work but I would go with one of those plastic ones you get for laptop screens rather than glass one. The only problem with those is you can only view it head-on, once you view from the side it goes black.