ATEX approved small PLC

[apatjr]

We're trying to design a small control panel for use in an ATEX Zone 1 area. So far we've found all the end devices that are suitable for this area.

We usually use an Allen-Bradley Micrologix 1500 in the US as we only have 5 inputs/7 outputs and 2 anlaog inputs through an expansion module.

Does anyone know of a small PLC like the Allen-Bradley Micrologix 1500 that is rated for use in an ATEX Zone 1 area.

 

[Ashereng]

I believe ATEX Zone 1 is the same as Class 1 Div 1 under the old standards.

Most PLC/DCS/SCADA/control equipment in general are rated to Class 1, Div 2, Groups A, B, C, D.

I am not familiar with any that are rated to Class 1 Div 1 (or ATEX Zone 1, or Class 1 Zone 1).

 

[ADMIRALKEN]

You most likely have to use a non-rated PLC, in a rated enclosure, that is NEMA 7 or perhaps a purged one.

 

[apatjr]

Thanks guys, I was so focused on finding a rated PLC that I didn't think of the obvious.

Your input is much appreciated.

 

[ScottyUK]

The previous posts seem to have it sorted out, but it's worth nothing that ATEX Zone 1 is not a direct equivalent to Class 1 Div 1, at least in Europe where the ATEX standard originates. They are broadly similar, but certification under one scheme does not imply that a recip[rocal certification exists under the other system. If a piece of equipment is rated for an ATEX Zone 1 environment, it will state this explicitly.

You will be looking for an Ex 'D' enclosure (flameproof) or Ex 'P'enclosure (pressurised). An Ex 'D' enclosure large enough to accomodate a PLC will be expensive and massively constructed; an Ex 'P' enclosure will be a permanent drain on your instrument air system. You also need to consider the contingency arrangements for failure of the instrument air.


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