Calculating Maximum Permissible Length of Cable A - 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

For the circuit type that you selected, the software calculates the maximum permissible length of Cable A – the cable that connects the hazardous area with the non-hazardous area. The calculations are all based on the requirement that the total load of a given parameter (resistance, inductance, or capacitance) may not exceed the ability of the safety device to control the load.

Resistance

Inductance

Capacitance

Maximum Permissible Length for Cable A

The software then sets the minimum among the maximum lengths calculated by R_fact, L_fact, and C_fact as the maximum permissible length for Cable A.

L/R Limitation

The intrinsic safety report also allows you to verify visually that the total of the L/R factor for Cables A and B does not exceed the L/R protection of the isolator safety device. To include cable L/R factor in a pass/fail calculation, see Intrinsic Safety Calculation by Loop.