12
7 SG9H 70 en
3.6
Electrical connections
The SG9000H is powered by a standard 4-20 mA current
loop that also functions as a carrier to the HART communi-
cation.
If a 24 V DC (or up to 230 V AC) output from the control sys-
tem is used, then an U/I converter is needed as shown in
Fig. 7 below. See typecoding in Chapter 14 for different con-
verter options.
The signal cables are led through M20 x 1.5 cable glands.
Cable shall be one or more single-twisted pair shielded or
multiple-twisted pair with overall shield. Single and multi-
ple-pair may be combined in a given network provided all
current input devices associated with multiple pairs of the
same cable shall be located nominally at one end of the
multi-pair cable. Unshielded cable may be used if it is
demonstrated that ambient noise or crosstalk does not
affect communication.
Connect the conductors to the terminal strip as shown in
Fig. 6. (Connections '+' and '-').
The optional position transmitter is connected to 2-pole
terminal PT as shown in Fig. 6. The position transmitter
needs an external power supply. The SwitchGuard and the
position transmitter circuits are galvanically isolated and
withstand a 30 V DC voltage.
The earthing of the cables shall be carried out at the DCS
end only.
NOTE:
The SG9000H equals a load of 485
Ω
in the current loop.
Fig. 6
Terminals when LUI is removed and position trans-
mitter option is in use.
HART connection
Fig. 7
SG9000H electrical connections with and without U/I converter.
See Section 11.6. for other installations.
SG9000H
DCS
AO
(4 - 20 mA
HART)
Safe area
Hazardous area
SG9000H
U/I converter
OUTPUT
INPUT
SUPPLY
DO
(0/24 V DC)
24 V DC
supply
