New trends in explosion protection of electrical apparatus (2)

As a rule of thumb in intrinsically safe circuits the useful power is limited to less than one Watt. This is sufficient for many sensors and actuators optimised for process industries. Point-to-point connection is assumed. But how about newer technologies like Remote I/O orFieldbus? Here a close examination of the ignition curves or even spark testing of more complex circuits not yet analysed in detail helps. Also combining intrinsic safety with other methods of protection may help to overcome the well-know power limit. So far fibre optic cables have been recogized as potential hazard rarely. Optical power limitation will be the future comparable to intrinsic safety electrical limitations.