Honeywell Safety Manager and Intrinsic Safety Isolators/Barriers

J

Thread Starter

Jian Chew

At one of our client's site, we are using Honeywell's new safety manager. Honeywell has only certified this to work with isolators. However, the current system at site has most of the IS circuits involving the MTL-100 series zener barriers, which still work perfectly fine.

The problem lies in the fact that the Honeywell analogue FTA (Field Termination Assemblies) are designed to have its own floating I.S. earth. We have only got one at each site, thus have connected the -VE side of the FTA power supply to the I.S earth point, which the zener barriers share.

This lies in the problem with Honeywell unsure whether it will still be intrinsically safe, because it doesn't have a dedicated I.S earth just for the power supply. From my point of view, it should be as using basic ohm's law show that it should not fail. However, Honeywell has not confirmed with me as to whether they approve of this, because they are completely unsure about it.

Has anyone on these forums experienced this problem before with similar safety managers?
 
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