KROHNE OPTIFLUX 4040 C Ex EN - Manual (Page 15)

ELECTRICAL CONNECTIONS
3
15
OPTIFLUX 4040 C
www.krohne.com 09/2010 - 7312232100 - AD EX OPTIFLUX 4040 C R01 en
Example with typical parameters:
The voltage drop across the end-to-end resistance of the zener barrier is 22 mA x 340 Ω = 7.5 V
This means that the external power supply must supply an output voltage to the zener barrier
that lies in the range somewhere between 21.5...25.5 V. The voltage over the terminals of the
additional power supply of the OPTIFLUX 4040 C-EEx is in that case between the required
14.0...18.0 V
Zener barrier data: U
o
= 28 V
I
o
= 93 mA
Maximum working voltage = 25.5 V
End-to-end resistance 340 Ω