Electronic marshalling goes intrinsically safe

Building on its electronic marshalling and single-channel characterization module (CHARM) technology, Emerson Process Management announces intrinsically safe CHARMs. IS CHARMs provide intrinsically safe circuitry for field wiring into hazardous areas, including Zone 1, Zone 0 or Class 1 Div 1 and extends the scope of the electronic marshalling concept, which claims to eliminate two-thirds of the wiring and connections needed in conventional marshalling cabinets

I/O in hazardous areas traditionally requires explosionproof mounting or isolation barriers, which is costly, requires space, and needs ongoing maintenance to ensure safety requirements continue to be met. IS CHARMs remove the need for separate barriers and the associated inter-cabinet wiring. A smaller footprint and fewer connections improves the reliability of the installation and delivers significant cost savings, says Emerson

The DeltaV CHARM I/O Card (CIOC) supports both conventional and IS CHARMs, providing flexibility in control system I/O topology. Each I/O channel has a dedicated CHARM that provides both signal characterization and galvanic isolation for intrinsically safe applications. IS barriers are integrated inside the CHARM to provide single channel fault isolation as well as electrical isolation and energy limiting circuitry that meets IEC Ex ia ratings. IS CHARMs signal types include: IS AI 4-20 mA HART, IS AO 4-20 mA HART, IS DI Namur, and IS DO 24 VDC.

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