KROHNE ALTOSONIC V12 EN - Manual (Page 28)

4
ELECTRICAL CONNECTIONS
28
ALTOSONIC V12
www.krohne.com 04/2013 - 4002643502 - MA ALTOSONIC V12 R02 en
4.4 Serial data communication (RS 485)
4.5 Power connection
Figure 4-5: Connection of serial data communication
INFORMATION!
For more information about Modbus, refer to Modbus protocol description and set-up on page
111
.
WARNING!
• Use a 24 VDC power supply to power the flowmeter, which complies to NEC class 2 (max. 100
VA, 24 VDC
± 10% , see also IEC 61010-1, clause 6.3.1 and 6.3.2). The maximum power
consumption is 17 W. The power supply must be able to supply 3 A (needed during start-up).
• The protective earth conductor (1...4 mm
2
, AWG 17...AWG 11) of the power supply must be
connected to the protective conductor clamp terminal size M5, which is press-fitted in the
terminal compartment.
• Use a cable entry to lead the power supply cable to the electronics. The power delivered from
the power converter inside the unit is limited to a maximum of 15 W according to the
“ fold-
back
”
principle (when the admissible internal power consumption is exceeded the delivered
power is reduced to zero). Separately the current consumption is limited to appr. 1A.
Requires typically 3 x 1.5 mm
2 (AWG 15) conductors.
• Connection to a flow computer, a data acquisition system or process control system by
means of digital output signals; requires as a maximum 4 pairs of wires of 0.75 mm
2 (AWG
18) copper each.
• Connection by means of a RS 485 data line to a device for logging or monitoring data or
running a software service tool for performing a function check or a service jobs; requires a
shielded pair of two twisted conductors of 0.75 mm
2
(AWG 18) copper each.
• Connection to a data acquisition system by means of digital signals; requires a shielded pair
of two twisted conductors of 0.75 mm
2 (AWG 18) copper each.
• Connection to safety / protective ground (earthing) ; requires insulated wire, minimum copper
cross section area 4 mm
2 (AWG 11).
INFORMATION!
• The protective conductor clamp or GND of the connector can be used for the shielding of the
cable.
• The electronics is protected against connecting a power supply with the wrong polarity.