Page 327 - Offshore Electrical Engineering Manual
P. 327
314 CHAPTER 4 Hazardous Area Installation
FIGURE 5.4.3
Typical IS loop calculation.
addition of simple apparatus will not affect the compatibility, except that the system
temperature might be derated.
The system will be categorised according to the least favourable components of
the barrier category and the apparatus category. For example, a barrier of (Ex ia) IIC
with a field device of Ex ia IIC T6 will categorise the system as Ex ia IIC T6. The
addition of a field device of Ex ia IIC T4 will change the system category to Ex ia
IIC T4.
