Selecting a smart relay for a project?

I'm working on a project where I think a smart relay would be perfect.

I need to controll two 220v 8A loads using timers and maybe two I/Os.
I need one calendar timer to control the first load, and then some logic to control the other load based on if the first load is active or not (also a countdown timer).

The relay and plc should preferebly be one single unit.
It should handle temperatures down to -10 or -15 degrees C.
I need either a simple HMI to be able to switch on and off the calendard timer or an external switch to control this. Thus an I/O or a display/HMI.

I needs to have backup battery so that it doesn't loose its program memory.

What relays do you suggest?
The one I have seen so far are:
Siemens Logo! series - is software free for these? Do they have the 220v relay built in?
Electrodepot EL6ACU - no I/O and no display. Expensive programmer
Schneider Electric SR2A101FU - don't know anything about this..
Zelio SR2A101FU - don't know that much either.
Velocio Ace - don't have relay built in, but is cheap.

Any suggestions or discussion about the above smart relays/PLCs?

I would suggest that you NOT switch those 220v 8A loads directly but use an interposing relay instead. The relay outputs might be rated for that load but if something unexpected occurs it is a whole lot easier and cheaper to replace a $5 external relay than the whole unit. It also opens up more possibilities to use for this application.

You should put it in an enclosure with a heater to handle -15C. Use Hockey puck style SSR's for the 8 Amp loads.

I would NOT use a Velocio with those environmental requirements. Those Velocios seem to me to be something for hobbyists, not for industrial machinery.

Also, as others said, switching loads directly with a PLC output is a bad idea. Even if the PLC output is rated for it, the lifespan of an output is usually a lot less than an interposing relay. Plus, replacing a relay is a lot easier than replacing the entire PLC.

You could do an Allen-Bradley Micro810 here. The software (Connected Components Workbench) is free.

Here's a link: http://ab.rockwellautomation.com/Programmable-Controllers/Micro810#overview

+1 on the interposing relays, and on the enclosure heater. All of the smart relay products on the market now are rated down to 0 deg. C, not -15. Siemens used to have an extended enviromnetal rated version of their LOGO! that would have handled it, but they discontinued that in favor of a similarly specified "Siplus" version of the S71200. It is rated down to -40C. But the software is not free, and the unit is expensive by comparison. It would be far far simpler to use a panel heater and the AB Micro810 (software is free).

One important aspect of the decision is also consideration given to the user and support later on. Using something like the AB or Siemens versions is going to be a lot easier for the user to get replacements and support on 5 years down the road. Some of the lesser known smart relays that were very popular 5 years ago are now non-existent. Schneider has even changed their versions so many times that I can't keep up any more.

maxomolo said:

Schneider Electric SR2A101FU - don't know anything about this..
Zelio SR2A101FU - don't know that much either.

Click to expand...

The above "two" are actually the same unit, and the one I would pick in your situation, the software is easy to use and free, BUT you need to buy the programming cable.
and unless I'm mistaken, these Schneiders are around for years and changed a lot less often than the Siemens Logo's.

OR

the Siemens Logo 6ED1052-1MD00-0BA8.
The cable is free (well nearly, it's a standard RJ45 patch lead, BUT you have to buy the software. Another advantage, you can plug it straight to your router and download the Siemens app for your smart phone to monitor it.

The AB Micro 810 is another option, cheap cable, free software and in my opinion horrible, bloated software, but each to their own preference, I guess.

Having used the Zelio's and had to troubleshoot the program via its built in screen it was difficult but I managed to save the day. I had the laptop software (free trial) ready to go but this unit was a stripped down version with no comm ports. if you do go Zelio get one you.can setup with laptop as well IMO

DwSoFt said:

Having used the Zelio's and had to troubleshoot the program via its built in screen it was difficult but I managed to save the day. I had the laptop software (free trial) ready to go but this unit was a stripped down version with no comm ports. if you do go Zelio get one you.can setup with laptop as well IMO

Click to expand...

Never heard of such a Zelio, "with a screen, but with no connection to a laptop".

http://www.schneider-electric.com/en/product-range-selector/531-zelio-logic/?parent-category-id=2800

I had this. Zelio Logic 2. 120v ac. 12 in 8 out. it may have had the can bus but the converter for.programming it was expensive where as other models had a connection on the front behind the cover for either ethernet or maybe serial. either way I was surprised when it wasn't so I went through the logic with the screen and solved a problem an electrician had spend 4 months and 1000s of dollars on. all it was was a pressure switch not working correctly. calibrated it and life was good

keithkyll said:

You should put it in an enclosure with a heater to handle -15C. Use Hockey puck style SSR's for the 8 Amp loads.

Click to expand...

Actually, most of the switches I looked at has a lowest operating temperature of -15C. The Velocio Ace has -40C as lowest operating temperature.

maxomolo said:

Actually, most of the switches I looked at has a lowest operating temperature of -15C. The Velocio Ace has -40C as lowest operating temperature.

Click to expand...

Don't be fooled. The controller itself is basically just a CPU chip, it needs a 5VDC power supply, and even the terminal adaptors need a separate power supply because they are relays. That temperature spec can be met with just about any decent industrial grade CPU chip.

The power supply is what will not be able to take the extreme cold, because of the capacitors it will have inside of it. Good luck finding a power supply that says it will operate at -40C.

All of the others mentioned are just being more honest about the temperature range, because their power supplies are built-in. Take note of the fact that Velocio doesn't show you the temperature range of their power supplies. That to me says they are being deliberately deceitful because they understand that is the real limitation, but they are trying to bolster their claim of how rugged the controller appears to be.

If you don't need a lot of power you can use an on board power supply, such as http://www.trcelectronics.com/minmax/medical-industrial-power-supply-ajm-24.shtml Range from -40 to +80c. Hardest part would be attaching it to you panel and the leads to the pins