Bently Nevada Intrinsic Safety — The 3500 Internal Barrier System

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.

This restriction does not apply to RS422 and RS485 connections to the rack. 

Monitors that support RS422 and/or RS485 connections include the 3500/20, 3500/90, 3500/92, 3500/93, and 3500/95.

• You must not use the 3500/94 VGA Display in internal barrier systems.

• You must not use bussed transducers, as internal barrier systems do not allow bussed transducers. See the TMR section of this manual for more information.

3500 Internal Barrier System Features

• The earthing module supports dual IS Earth connections for cables with cross-sectional areas up to 10 mm2. This module lets you test IS Earth continuity online.

• The design of the internal barrier I/O modules provides the 2 inches (50 mm) of separation required between safe and hazardous area field wiring.

• The connectors for safe areas and hazardous areas have different field wiring colors (green for safe and blue for hazardous) and connector pitches. 

This helps to avoid incorrect field wiring installation.

• Quick connect/disconnect connectors simplify field wiring installation and removal.

• You can locate standard and internal barrier I/O modules in the same 3500 rack. 

We recommend that you group the modules together as shown in Figure 2-10 to facilitate connection to field wiring.