1)Simple apparatus shall not achieve safety by the inclusion of voltage and/or current limiting and/or suppression devices.
2)Simple apparatus shall not contain any means of increasing the available voltage or current, e.g. circuits for the genera- tion of ancillary power supplies.
3)Where it is necessary that the simple apparatus maintains the integrity of the isolation from ‘earth’ of the
4)
5)When simple apparatus is located in the hazardous area it shall be temperature classified. When used in an intrinsically safe circuit within their normal rating switches, plugs and sock- ets and terminals are allocated a T6 temperature classification
for Group II applications and considered as having a maxi- mum surface temperature of 85°C for Group I applications. Other types of simple apparatus shall be temperature classi- fied in accordance with clause 4 and 6 of this standard.
Where simple apparatus forms part of an apparatus containing other electrical circuits the whole shall be certified.
The principal author of this application note is L C Towle. BSc CEng. Chairman of Telematic Ltd. All Telematic Application Notes
have significant input from the staff at Telematic and its customers. If you have any comments (preferably constructive) on this document, please make them to the author so that the document can be amended and made even more useful.
03/99 Printed in the EU
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