Surge Suppressor for PLC

I have two plc's in a a hardwood flooring sawmill. These two are the first and second time I've had a plc "loose" it's ladder program of the hundreds that I have installed. One the other day and one last year (both times in the dead of winter). The tech support (Automation Direct) told me that the only way it can loose the ladder is from a voltage spike. And he recommended that I install surge supperessors. I assume a TVSS would be the ticket.

Is there any surge surpressors that stand out in the croud and do any need to be avoided? I just want to avoid the USB/Serial adapter problem where this one don't work and this one did...

Thanks
John

I assume a static spike. Someone's charged up and touches the touch panel. If that's what's happening, surge suppressors aren't going to help.
Ask factory to install humidifier (the PLC and HMI should have a humidity spec.).
Check grounding of HMI case.
Add optoisolation to HMI.
Change brand of HMI.
If it's the pushbuttons, change to the armored metal type.
Added grounded static pad to floor area in front of operator panel.

Static is tough to deal with. Adding humidity is the easiest way to deal with it.

Thanks for your ideas.

There is no operator interface and the pb's are all 30mm heavy duty type (both of them). In both cases the plc lost it's program when no one was touching it afaik. Keep in mind this is in a saw mill basicly outside with a roof on it so doing the things you describe would be impossible. The humidity is generally pretty high here so static is not likly. The tech was pretty confident that the voltage on the supply was the reason for the loss of the ladder not voltage on the I/O...

John

Waco http://64.78.1.67/products/345.htm makes one and also Islatrol http://www.control-concepts.com/prod_isElite.asp

MOV's are great, but not enough in my book. I want some caps and inductors too. From the 2 choices above, I like the design of the control concepts product. I has almost every goodie in it.
The only thing missing would be an isolation transformer. For those who must have the best in isolation, check out Oneac.
In this case, and Oneac may be a bit much. The Islatrol Elite should do the job.

AD is now selling some. I would use what they sell then if it happens again you can tell tech support you are using all thier stuff.

Charles, that's a good idea.

Thanks
John

That's interesting - I've had to add a humidifier for a printer in dry environments, but never thought to do so with a PLC. It defies my intuative "common sense", but sounds correct.

To the OPs original question - any recommendation on a good surge suppressor, or just use any?