Siemens SITRANS L Operating Instructions Manual page 40

Connecting
5.3 Nameplates for hazardous area installations
Entity concept
The Entity Concept allows interconnection of intrinsically safe apparatus to associated
apparatus not specifically examined in such combination. The criteria for interconnection is
that the voltage and current which intrinsically safe apparatus can receive and remain
intrinsically safe, considering faults, must be equal to or greater than the output voltage (Uo)
and output current (Io) levels which can be delivered by the associated apparatus,
considering faults and applicable factors. In addition, the maximum unprotected capacitance
(C ) and Inductance (L
i
must be equal to or less than the capacitance and inductance which can be safely connected
to associated apparatus.
FISCO concept
Under the FISCO evaluation concept, SITRANS LR200 has the following characteristics:
(input voltage) U
(input current) I
(input power) P
(internal capacitance) C
(internal inductance) L
The FISCO Concept allows interconnection of intrinsically safe apparatus to associated
apparatus not specifically examined in such combination. The criteria for interconnection is
that the voltage (Ui or Vmax), the current (Ii, or Imax) and the power (Pi, or Pmax) which
intrinsically safe apparatus can receive and remain intrinsically safe, considering faults, must
be equal to or greater than the voltage (Uo or Voc or Vi), the current (lo or Isc or li), and the
power (Po or Pmax) levels which can be delivered by the associated apparatus, considering
faults and applicable factors. In addition, the maximum unprotected capacitance (Ci) and
inductance (Li) of each apparatus (other than the termination) connected to the fieldbus
must be less than or equal to 5 nF and 10 μH respectively. In each segment only one active
device, normally the associated apparatus, is allowed to provide the necessary energy for the
fieldbus system. The allowed voltage Uo (or Voc or Vt) of the associated apparatus is limited
to the range of 14V dc to 24V dc. All other equipment connected to the bus cable has to be
passive, meaning that they are not allowed to provide energy to the system, except for a
leakage current of 50 μA for each connected device. Separately powered equipment needs a
galvanic isolation to assure that the intrinsically safe fieldbus circuit remains passive.
40
) of the intrinsically safe apparatus, including interconnecting wiring,
i
i
i
i
i
i
= 17.5 V
= 380 mA
= 5.32 W
= 0
= 0
Operating Instructions, 07/2021, A5E32337680-AF
SITRANS LR200 with PROFIBUS PA