Intrinsic Safety Calculation by Loop - Intergraph Smart Instrumentation - 13.1 - Reference - Hexagon PPM

Intergraph Smart Instrumentation Safety Equations

PPMProduct
Intergraph Smart Instrumentation
PPMCategory_custom
Reference
Version_SPI_custom
13.1

To initiate an intrinsic safety calculation by loop, in the Wiring Module window, on the Associations menu, click Intrinsic Safety Loop Calculation. For details, see Calculate Intrinsic Safety for a Loop. For a summary of the differences between intrinsic safety (IS) calculation by circuit type and by loop, see the following table:

Feature

By Circuit Type

By Loop

Level

Circuit type

For all the tags in a loop

Cables

One Cable A and one Cable B

All cables in the circuit for which the IS check box is selected

Parameters Considered

Resistance

Resistance

Inductance

Inductance

Capacitance

Capacitance

 

L/R

Result

Maximum permissible length of Cable A

Pass / fail for all tags associated with an IS circuit type

parameter that limits length

Report

Full diagram with calculation results;

Instrument & barrier safety characteristics;

Calculation explanation

List of IS cables and their characteristics;

 

If Pass, calculated results, including (L/R) cables

Assumptions

For each tag in a loop, the intrinsic safety calculation considers the following values:

  • The parameters of the hazardous area field device: Rhaz tag, Lhaz tag, and Chaz tag.

  • The parameters of the safety device in the non-hazardous area: Rsafety, Lsafety, Csafety, and L/Rsafety.

  • Parameters associated with Cablei (i= A, B).

    • R_factCable i, L_factCable i, and C_factCable i, all of which are determined by the cable type.

    • LengthCable i

Calculating Cable Parameter Values

For each cable, the software calculates the following values:

Determining Whether a Circuit is Intrinsically Safe

For each tag in the loop, if all the following are true, the software certifies the tag circuit as intrinsically safe: