To provide Intrinsically Safe (IS) vibration and process variable monitoring,

the 3500 system has a range of I/O modules with internal zener barriers.

When you install these modules in a 3500 rack with a 3500/04-01 Earthing Module, 

they provide an integrated solution for explosion protection for approved Bently Nevada

transducer systems that are located within all classifications of hazardous areas (surface industries other than mining).

3500 Internal Barrier System Restrictions

• You must install 1 earthing module in each rack in the internal barrier system. 

The earthing module occupies 1 slot position in the rack when it uses Internal Barrier I/O modules.

• You must change the grounding configuration of the 3500/15 Power Supplies from the default factory setting.

See the 3500/15 Operation and Maintenance Manual (PN 129767-01) for instructions.

• You must isolate any RS-232 connection to any 3500 module. Monitors that support RS232 connections include Rack Interface Modules, 

Communication Gateways, and the 3500/95 PC Display. See the 3500/20 Operation and Maintenance Manual (PN 129768-01) for instructions.