Non-Sparking Wiring - Siemens SITRANS L Operating Instructions Manual

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.
Under the entity evaluation concept, SITRANS LR250 has the following characteristics:
(input voltage) U
(input current) I
(input power) P
(internal capacitance) Ci
(internal inductance) Li
Under the FISCO evaluation concept, SITRANS LR250 has the following characteristics:
(input voltage) U
(input current) I
(input power) P
(internal capacitance) Ci
(internal inductance) Li
5.3.3

Non-sparking wiring

The ATEX and UKEX certificates listed on the nameplate can be downloaded from our
website:
Product page (http://www.siemens.com/LR250)
Go to: Support > Approvals/Certificates.
SITRANS LR250 with FOUNDATION FIELDBUS
Operating Instructions, 09/2021, A5E32221411-AH
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5.3 Wiring setups for hazardous area installation
= 24 V
= 250 mA
= 1.2 W
= 0
= 0
= 17.5 V
= 380 mA
= 5.32 W
= 0
= 0
Connecting
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