KROHNE DK 32-DK 34-DK 37 EN - Manual (Page 19)

ELECTRICAL CONNECTIONS
4
19
DK32 - DK34 - DK37
www.krohne.com 06/2014 - 4000287103 MA DK32-34-37-R05-en
4.5.1 Power supply
The required supply voltage can be calculated using the formula below:
U
ext.
= R
L
* 22mA + 14.8V
where
U
ext.
= the minimum supply voltage and
R
L
= the total measuring loop resistance.
4.5.2 Load for HART ® communication
The maximum load impedance is calculated as follows:
4.5.3 Parametrization
The M8E electronic display can be parametrized via HART ® communications. DD (Device
Descriptions) for AMS 6.x and PDM 5.2 and a DTM (Device Type Manager) are available for
parametrization (download center).
The current flowrate can be transmitted using the integral HART
® communications. A flow
counter can be parametrized. Two limit values can be monitored. The limit values are assigned
either to flow values or to the counter overflow. The limit values are not depicted on the display.
INFORMATION!
The supply voltage has to be between 14.8VDC and 30VDC. 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 meter).
INFORMATION!
The power supply has to be able to supply a minimum of 22mA.
INFORMATION!
For HART
® communication a load of at least 230 ohm is required.
DANGER!
Use a twisted two-core cable to prevent electrical interference from impeding the DC output
signal.
In some cases a shielded cable may be necessary. The cable shield may only be earthed
(grounded) at one place (on the power supply unit).
MA_DK32_34_37_R05_en_287103_PRT.book Page 19 Friday, June 6, 2014 11:42 AM