Siemens PLC with surge protection upstream. 

 

Is there an easy way to test the little bugger? 

Not really.  What you can do is open it up and, assuming the protection is from MOV, you can visually inspect.  If the MOV is burned or cracked, it is most likely not working.  If you don't see visual damage, you can de-solder a lead and test with meter set to K-ohm.  Should be close to or at highest reading possible.  Replace any defective MOV with same.

Cheers we are trying not to buy a manufacturer specific test box otherwise we get locked into that supplier. 

Exactly what are you trying to test (photo)?

 

As noted above, there's not a lot you can do with a MOV other than look at it.

 

29 minutes ago, VocalNeal said:

Cheers we are trying not to buy a manufacturer specific test box otherwise we get locked into that supplier. 

Or, is it the PLC you want to test?  Above my pay grade for that.

Anyway... if it is the suppressor, the problem with MOV testing is that testing will change/degrade the characteristic.  Same if you get a lot of surges, after so many, the MOV will lose its mojo.

MOV or GDT surge protection can be tested by applying clamping voltages with current limit. A full test would destroy the components.

SPDs usually have an indication whether it You are fully protected but this does not tell you what capacity is left. It is best of you replace them every two years or if you know you have taken a couple of hits.(or if the indication light tells you to do so). It maybe cheaper to replace them yearly than buy the test gear which will tell you that you have to replace them anyway.


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