KROHNE H250 M40 EN - Manual (Page 28)

4
ELECTRICAL CONNECTIONS
28
H250 M40
www.krohne.com 11/2012 - 4000640702 MA H250 M40 R02 en
Power supply Power supply Power supply Power supply
The required supply voltage can be calculated using the formula below:
U
ext.
= R
L
. 24 mA + 14 V
where
U
ext.
= the minimum supply voltage and
R
L
= the total measuring loop resistance.
HART HART HART HART ® communication
When HART ® communication is carried out with the ESK4, the analogue measured data
transmission (4...20 mA) is not impaired in any way.
Exception for multidrop operation. In multidrop mode, a maximum of 15 devices with HART ®
function can be operated in parallel, whereby their current outputs are switched inactive
(I approx. 4.5 mA per device).
INFORMATION!
The feed voltage must be between 14 VDC and 30 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 level meter).
INFORMATION!
The power supply has to be able to supply a minimum of 30 mA.
MA_H250_M40_R02_en_640702_PRT.book Page 28 Wednesday, November 28, 2012 12:23 PM