VEGA VEGAFLEX 55P (Profibus PA) - Manual (Page 11)

VEGAFLEX 55P (Profibus PA) 11
Product description
Ex environment
In Ex environment, intrinsically safe (EEx ia)
PA sensors are used with Ex segment cou-
plers. Generally, the number of PA sensors
on a segment coupler (Ex or non Ex) de-
pends on the current requirement of the
sensors and on the current supplied by the
segment coupler. Segment couplers for
EEx ia environment provide 90 … 110 mA.
The number of sensors results from the sum
of:
- the basic current intake of all sensors
- plus 9 mA communication signal
- plus the leakage currents of all sensors
- plus a recommended current reserve
(approx. 10 mA)
The min. basic current has been set at 10 mA
according to the Profibus specification.
VEGA Profibus sensors constantly consume
a basic current of 10 mA and operate without
leakage current requirement, so that in Ex
environment, up to max. ten VEGA sensors
can be operated on one segment coupler.