(I know this thread's a year old, but I've heard that it's polite to re-use an old thread rather than post a new one.)
I've got a new installation using a AD DL-06. The PLC is going to be outside, BUT inside a Nema 4X case (based on the recommendation in this thread), which in turn will be in a sealed aluminum unit (design spec). The PLC is only going to burn about 5W, but that's enough to potentially go over the 55C operating temperature on a hot day if the sun is beating down on it.
It's going to be near the ocean, so there'a a chance of salt fog, splashes, and rain. Will IP65 (or equivalent) switches be suitable, or will I have to up them to IP67 (or equivalent)? The outdoor ******t temperature will be between -20C and +40C. (Those are record-breaking temperatures for the area). The PLC can run from 0C to +55C. It's a hydraulic ramp lift for transporting disabled sailors on a gangway so they can get to their boats when it's not high tide.
So, my questions are:
1. If I use the cabinets listed above, is that enough protection from the salt air? Do I have to worry about the salty air getting into the cabinet during maintenance, or is that such a small amount that I can neglect it? What about humidity? Will the heater eventually dry out the air in the cabinet enough so that it drops below the 5% minimum, or am I worrying about nothing?
2. Can I use IP65 switches outside, exposed to the elements, near the ocean? There's a jetty with a breakwater, so there's not a huge swell or anything. There's just some chance of salt spray. Going to IP67 is an enourmous jump in price. (For example, the joystick changes from ~$60 to ~$400.) A sales rep from a switch company told me that the Coast Guard uses the IP65 switches all the time, and they keep buying more. (Yes, he sells IP67 switches, too, so it wasn't a matter of him wanting to just sell his products.)
3. For cooling, my choices are basically to put in some passive cooling and hope that the internal temperature doesn't get too high and frap the PLC (the vendor said, "erratic behaviour or fail and replace") or put in a small heat exchanger and not worry about it. Uhh... now that I put it that way, never mind. I'll just put in the heat exchanger so I can spend the sunny day in my basement with an iced tea instead of out on a repair.)
4. I had the same question about heating, but I feel the same about the cooling, except "living room" and "hot chocolate". For the minor cost of a little heater, I can "not worry about it". Problem solved. (Isn't it funny how saying problems aloud makes them solve themselves sometimes?)
5. Is it a good idea to have the PLC control the heater and the cooler, or is it a better idead to run that on a seperate system that shuts off the PLC when the temperature goes beyond the operating temperature?
6. What else should I watch out for? Obviously, the switches will be rated to withstand the elements, and the work is going to require approvals from P.Engs and the safety inspectors, but I want to know what else I'm missing. This is my first PLC work, and I'd like to avoid as many mistakes as I possibly can.
Thank you for reading.