Exn System Flashcards
1
Q
What is Exn?
A
Protection applied to electrical apparatus such that, in normal operation it is not capable of lighting a surrounding explosive atmosphere
2
Q
Ruels for Exn?
3
A
- Suitable for zone 2 only
- No live maintenance permitted
- Minimum IP54
3
Q
What are the ‘N’ standard sub categories?
5
A
nA nR nL nZ nC
4
Q
What is nA?
A
Non- sparking, designed to prevent any means of ignition
5
Q
What is nR?
A
Restricted breathing enclosures, often applied to luminaries and minimum IP65 required
6
Q
What is nL?
A
Energy limited apparatus, designed to limit the ignition energy if the circuit - being replaced by Exic.
7
Q
What is nZ?
A
Enclosures with ‘n’ pressurisation
8
Q
What is nC?
A
Sparking where the contacts are suitably protected other than by type R, L or Z.
E.G. Circuit breakers, Relays, Contact Switches
