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Intrinsic Safety Barrier for FOUNDATION Fieldbus & PROFIBUS PA


The Intrinsically Safe technology incorporated in the SB312-LP totally isolates the control network on the hazardous side of the barrier. The I.S. values of the power supply are designed for fieldbus devices, which comply with the FISCO model.

The incorporation of a fieldbus repeater which complies with IEC 61158-2, 31.25 kbits/s essentially cleans and boosts the incoming communication signal transmitting it to hazardous environment. The networks of the hazardous and safe sides of the SB312-LP are completely independent of each other.

  • H1 isolated barrier and I.S. power supply ;
  • Built-in H1 fieldbus signal repeater ;
  • Bus termination on hazardous side ;
  • Provides up to 80mA @ 14V to the hazardous network for field devices;
  • Can be installed in safe area (Div. 2/Zone 2 or Div. 1/Zone 1);
  • In compliance with IEC 61158-2, 31.25 Kbit/s standard for FOUNDATION fieldbus and PROFIBUS;
  • Complies with FISCO I.S. model;
  • FM & CENELEC Intrinsic Safety standards certified;

Based on PTB Report W-53, “Investigations into Intrinsic Safety of Fieldbus Systems”.


Some Characteristics:

Power Supply Input (Safe Area)

Voltage: 24 Vdc ± 5 %

Power Supply
(Hazardous Area)

Maximum voltage available at the barrier terminals: Us=14 Vdc
Maximum current in typical operation: (considering Us = 14 Vdc) : Is=80 mA

Safety Parameters
(Hazardous Area)

Maximum output voltage (Uo):15 Vdc
Short circuit current (Io): 221.7 mA
Maximum output current (Is): 125.8 mA @ 15V
Maximum output power ( (Po): 1887 mW
Current limiting resistor (Ri): ≥ 156.42 Ω
Characteristics: Trapezoidal

* Refer to FISCO standard to see other restrictions applied.




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