KROHNE OPTISONIC 3400 EN - Manual (Page 40)

4
ELECTRICAL CONNECTIONS
40
OPTISONIC 3400
www.krohne.com 11/2013 - 4002037702 - HB OPTISONIC 3400 -en-R02
4.7.2 Description of the electrical symbols
mA meter
0...20 mA or 4...20 mA and other
R
L
is the internal resistance of the measuring point including the cable
resistance
DC voltage source (U
ext
), external power supply, any connection polarity
DC voltage source (U
ext
), observe connection polarity according to
connection diagrams
Internal DC voltage source
Controlled internal power source in the device
Electronic or electromagnetic counter
At frequencies above 100 Hz, shielded cables must be used to connect the
counters.
R
i
Internal resistance of the counter
Button, NO contact or similar
Table 4-1: Description of symbols