Non-Incendive Pressure Transmitter Power Supplies

[bobdoug]

Planning an instrumentation system that includes non-incendive rated pressure transmitters located in a Class I, Div 2 Group B area. The transmitters are 24 VDC excitation power and 4-20 ma signal. The power supply and data acquisition components will be located in a non-hazardous area. The DAQ system is rated as non-incendive. The question is rating/type of the 24 VDC power supply. Can a standard instrumentation power supply be connected to the transmitters with standard instrumentation cabling under the assumption that the non-incendive pressure transmitter itself is the energy limiting device that makes it safe in the hazardous area? Or, is a current limiting, multi-channel power supply, similar to a multi-channel segment protector required to individually limit the current available to each connected transmitter? The transmitter comes with a control drawing.
Can you also list the NEC, or other codes that relate specifically to the power supply requirements? Thanks.

 

[xnuke]

I'm assuming you're in the U.S., since you mentioned the NEC. There are multiple methods for nonincendive design. You need to refer to ANSI/ISA-12.12.01-2013, "Nonincendive Electrical Equipment for Use in Class I and II, Division 2 and Class III, Divisions 1 and 2 Hazardous (Classified) Locations."

xnuke
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[bobdoug]

Thanks for the response. The ANSI/ISA-12.12.01-2013, "Nonincendive Electrical Equipment for Use in Class I and II, Division 2 and Class III, Divisions 1 and 2 Hazardous (Classified) Locations.", para. 7.6 has a note with an exception for 4-20 ma devices that "control it's own operating current", does that mean additional current limiting devices such as segment protectors are not required for 4-20 ma pressure transmitters rates as non-incendive?