Operating Instructions

Table Of Contents
Connecting HART
Typical PLC/mA configuration with HART
4
1
3
2
5
6
Power supply Active PLC
SITRANS LR250 HART modem
R = 250 Ω HART communicator
Note
Depending on the system design, the power supply may be separate from the PLC, or
integral to it.
HART resistance (total loop resistance, that is, cable resistance plus 250 Ohm [resistor])
must be limited according to the allowable operating area as shown in either Curve 1
(Page 245) (General Purpose, Intrinsically Safe, Non-Sparking, Non-incendive) or Curve 2
(Page 246) (Flameproof, Increased Safety, Explosion-proof).
5.3 Wiring setups for hazardous area installations
There are six wiring options for hazardous area installations:
Intrinsically Safe wiring (Page 40)
Non-Sparking wiring (Page 41)
Non-incendive wiring (US/Canada only) (Page 41)
Flameproof wiring (Page 42)
Increased safety wiring (Page 42)
Explosion-proof wiring (US/Canada only) (Page 43)
In all cases, check the nameplate on your instrument, confirm the approval rating, and perform
installation and wiring according to your local safety codes.
Connecting
5.3 Wiring setups for hazardous area installations
SITRANS LR250 with mA/HART
Operating Instructions, 10/2019, A5E32220602-AG 39