In the United States, installation must be in accordance with the applicable requirements of
ANSI/IS
A RP12.6 and the national electrical code (ANSI/NFPA 70). In Canada, installation
must be in accordance with the applicable requirements of Canadian electrical code part I
C22.2.1 section 18 and appendix F. Associated Apparatus manufacturer’s installation drawing
shall be followed when installing this equipment.
Ex ia is defined as intrinsically safe. The intrinsic safety concept allows the interconnection of
two intrinsically safe devices. FM approved and CSA certified entity parameters are not
specifically examined in combination as a system when:
• Uo or Voc or Vt <= Vmax
• Io or Isc or It <= Imax
• Ca or Co >= Ci + Ccable
• La or Lo >= Li + Lcable, Po < Pi
Control equipment connected to the Associated Apparatus shall not use or
generate more than 250 Vrms or V DC. Use supply wires suitable for 5 K above
surrounding environment.
CAUTION!
For Division 1 installations, the c
onfiguration of Associated Apparatus shall be FM
Approved/CSA Certified under Entity Concept.
Cables for intrinsically safe installation
• 10 m (33 ft) cable, part number PR‑8230‑010, connecting the Indicating transmitter STR
and the Isolator unit. The maximum cable length is 100 m (330 ft).
• 10 m (33 ft) power cable, part number PR‑8250‑010, connecting the Indicating
transmitter STR and the Isolator unit, part number PR‑8250‑010. The maximum length
is 100 m (330 ft).
• The intrinsically safe cable between isolator unit and sensor, part RP‑8260‑xxx, where
xxx is the cable length in meters. The maximum length is 200 m (660 ft). For cable
connections see Figure 89 (page 166) and Figure 91 (page 169).
Isolator/Barrier Unit can also use an optional
external +24 V DC power supply instead of
the +24 V DC power supply from the transmitter. +24 V DC is connected to terminals 13
and 14. If +24 V DC is used, the PR‑8250 power cable is not used at all.
10.10.3 Isolator/barriers
The following figure explains the isolator unit wiring.
PR-23 Series User Guide
IM-EN-PR23-E
168
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