KROHNE OPTITEMP TT 51 EN - Manual (Page 18)

4
ELECTRICAL CONNECTIONS
18
TT 51 SERIES
www.krohne.com 09/2010 - 4000754201 - MA TT 51 R01 en
4.4 Connection diagram of in-head transmitter (intrinsically safe)
Figure 4-2: Connection diagram
1 Input
2 Potentially explosive area
3 Safe area
4 Modem, Ex-approved
5 Modem
6 R
Load
, R ≥ 250 Ω
7 Zener barrier or voltage supply 10…30 VDC (intrinsically safe)
8 Output
9 See chapter "cable length"
INFORMATION!
The HART
® modem is connected parallel to the output load or parallel to the output of the
transmitter.
DANGER!
The transmitter may be operated in areas with potentially explosive atmospheres if the voltage
supply is ensured by means of an appropriate power supply unit or a Zener barrier!
In potentially explosive areas only Ex approved HART
® modems may be used. The safety
instructions for operation in potentially explosive areas must be observed.
In order to ensure reliable HART
® communication with this transmitter, the maximum cable
length of the output circuit must be observed. For detailed information refer to Cable length on
page 23
.