Endress+Hauser PROline 93 II2G Serie Bedienungsanleitung Seite 64

26
Step 2 – technical safety considerations
This step uses the existing data to check whether connecting the equipment is permis-
sible from the point of view of technical safety. The conditions shown in Table 5
(Page 24) apply to these safety considerations. First the functional data of the equip-
ment used is compared. In this consideration it is crucial that the maximum output volt-
age and output current of the bus power supply does not exceed the permitted maxi-
mum input voltage and input current of the individual field devices. Here we consider
possible error behaviour by the bus power supply that could result in the stated maxi-
mum values on the intrinsically safe sides.
Intrinsically safe equipment
Prosonic Flow 93
U = 30 V
i
I = 500 mA
i
P = 5.5 W
i
As a further condition galvanic isolation must be provided due to the local
Cerabar S
U = 24 V
i
I = 250 mA
i
P = 1.2 W
i
FBT1
U = 30 V
i
P = 1.2 W
i
In addition to these values the limit values and the maximum permissible external
capacitance C and inductance L
o
the sum of all effective inductance and capacitance in the hazardous area is formed (the
internal capacitance of the bus termination is assumed to be 0). The resulting value
must be less than the maximum permissible value specified by the fieldbus power
supply.
The equivalent concentrated capacitance and inductance in the hazardous area is
calculated as follows:
C = (C
eff. i/Prosonic Flow 93
= (5 nF x 4) + 95.6 nF
= 115.6 nF
L = (L
eff. i/Prosonic Flow 93
(10 µ H x 4) + 383.1 µ H
=
423.1 µ H
=
PROline Prosonic Flow 93 FOUNDATION Fieldbus
Condition Associated equipment
MTL 5053
≥
U = 22 V
o
≥
I = 216 mA
o
≥
P = 1.2 W
o
supply
≥
U = 22 V
o
≥
I = 216 mA
o
≥
P = 1.2 W
o
≥
U = 22 V
o
≥
P = 1.2 W
o
must be observed for the supply circuit. To do this
o
x 2) + (C x 2) + C'
i/Cerabar S
x 2) + (L x 2)+ L'
i/Cerabar S
Condition met?
Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

+ C
eff./cable i/bus termination
eff./cable
Endress+Hauser