DESCRIPTION

The Ex ic concept

In May 2013 the Ex nL certification method was removed from the IEC60079-15

standard, and replaced by intrinsic safety method Ex ic in IEC60079-11.  Although Ex

ic and Ex nL are broadly similar, Ex ic brings with it additional requirements that are

associated with the wider intrinsic safety approach.

Ex ic is a new level of protection under the intrinsic safety protection method,

suitable for use in Zone 2 only, where Ex ic circuits may be ‘live-worked’ in the

presence of a flammable atmosphere.  It follows the same energy-limitation principles

as all intrinsically safe circuits, but safety is maintained only in ‘normal operation’.

Host H1 control system

In a typical network installation using the F30 Ex ic Adaptor, F300 Megablock and

9192-FP power supply module, the H1 interface of the host control system is

electrically connected in parallel with the fieldbus trunk circuit. The H1 interface

and host control system are not required to carry hazardous area certification in

this application, but they must comply with electrical safety standards IEC61010 or

IEC60950.  Apparatus carrying a CE mark will comply with this requirement. This

requirement also applies to any other apparatus that is connected electrically in

parallel with the fieldbus trunk circuit.