ELECTRICAL CONNECTION INDICATOR M10
5
25
BW25
www.krohne.com
10/2008 • 4000432301 MA BW25 R01 en
The circuitry to other devices must be designed with especial care. In some circumstances
internal connections in these devices (e.g. GND with PE, ground loops) may lead to
impermissible voltage potentials, which can compromise the function of the device itself or a
connected device. In such cases a protected extra-low voltage (PELV) is recommended.
HART
TM
communication
When HART
TM
communication is carried out with the M10, this will not in any way impair analog
measured data transmission (4...20 mA).
Exception for multidrop operation. In multidrop operation, a maximum of 15 devices with
HART
TM
function can be operated in parallel, for which the current outputs are switched to
inactive (I approx. 4 mA per device).
Power supply
The required supply voltage can be calculated using the formula below:
U
B
= R
tot
.
22 mA + 16 V
where
U
B
= the minimum supply voltage and
R
tot
= the total measuring loop resistance
Figure 5-2:
Power supply M10 with electrical isolation
1
Terminal connection
2
Converter supply isolator with electrical isolation
3
Power supply (see supply isolator information)
4
Measurement signal 4...20mA
5
External load, HART
TM
communication
INFORMATION!
The supply voltage has to be between 16 VDC and 32 VDC. This is based on the total resistance of
the measuring loop. To determine this, add up the resistances of each component in the
measuring loop (not including the flowmeter).
MA_BW25_R01_en_PRT.book Page 25 Thursday, October 30, 2008 3:49 PM
