Hi Mel. You asked:
<I have a customer asking if our parts meet European "intrinsic safety requirements". What in the world does this refer to?> Intrinsic Safety is pretty well as you suggested, devices operating at such low power that they are 'intrinsically safe'. It's related to ignition of flammable atmospheres, primarily in the Oil and Gas industries, but also on any system which uses flammable materials such as flour dust, alcohol, etc. etc. The rationale is that you keep the maximum possible energy dissipatable in a fault to below that necessary to cause ignition of a flamable atmosphere. This is done by things called Zener Barriers and Safety relays which have very low excititation circuits. Zener barriers are essentially a network via which EVERYTHING in the flammable area is connected through (the ZB's are in the safe area). The ZB's limit the maximum voltage on the hot side, and series resistors limit the maximum current such that in an Open Circuit or Short Circuit fault the let-through energy is limited. High Voltage stuff, motors etc. are cabled up in high quality cables and conduits which are gas proof etc. and have cast junction boxes with wide metal/metal joint faces such that inthe event of an explosion within the motor/box the flame propagation is limited by the gas having to squeeze through a very small gap between cooling metal, and the cases so thick that they won't burst. In the UK etc. these things are built to Baseefa requirements, and have labels marked Ex or EEx. People such as Measurement Technology Ltd. in the UK specialize in such equipment and have an excellent set of (free) Application reports that describe things much better than I. I'm sure others on the group will give you much more information, hope that helps a bit. Chris Dupres Surrey UK.
