Bently 3500/04 136719-01 | Internal Barrier Earthing I/O Module – Field Service Notes

Description

Hard-Numbers: Technical Specifications

• Dimensions:
  • Internal Barrier Earthing Module (136719-01): 241.3 mm × 24.4 mm × 103.1 mm (9.50 in × 0.96 in × 4.06 in)
  • Internal Barrier I/O Modules (e.g., 135489-01/02/03/04, 136703-01, 136711-01/02, 137110-01): 241.3 mm × 24.4 mm × 163.1 mm (9.50 in × 0.96 in × 6.42 in)
• Weight:
  • Earthing Module (136719-01): ~0.46 kg (1.01 lb)
  • Internal Barrier I/O Modules: ~0.46 kg (1.01 lb)
• Approvals (per datasheet/approvals quick reference guide 108M1756):
  • CSA/NRTL/C: Class I, Zone 2 (AEx nA/nC ic IIC T4 Gc; AEx ec nC ic IIC T4 Gc); Class I, Division 2, Groups A, B, C, D
  • ATEX/IECEx: Class I, Zone 2; T4 @ Ta = -20°C to +65°C (-4°F to +149°F) when installed per drawing 149243/149244
  • CE/EMC: EN 61000-6-2, EN 61000-6-4; EN 55011 Class A; Electrical Safety EN 61010-1; LVD 2014/35/EU
  • RoHS 2011/65/EU
  • ABS (marine/offshore per DNV GL rules)
• Environmental:
  • Operating Temperature: 0°C to +65°C (+32°F to +149°F)
  • Storage Temperature: -40°C to +85°C (-40°F to +185°F)
  • Humidity: 95% non-condensing
• Electrical Ratings (per entity parameters in datasheet):
  • Proximity & Acceleration (applies to Aero/DP with mods):
    • Bandwidth: 30 kHz
    • Amplitude Accuracy: 3% @ 10 kHz; -15/+10% @ 30 kHz
    • Phase Accuracy: -11° @ 10 kHz
    • Channel Parameters (Um = 250 V): Uo = 27.45 V; Io = 113.24 mA; Co = 0.086 µF; Lo = 2.77 mH; Po = 726.96 mW
    • Circuit Power (PWR): Uo = 26.25 V; Rmin = 237.6 Ω; Io = 110.48 mA
    • Circuit Signal (SIG): Uo = 13.65 V; Rmin = 4985 Ω; Io = 2.74 mA
  • Velomitor:
    • Amplitude Accuracy: ±1%
    • Circuit: Uo = 26.25 V; Rmin = 297 Ω; Io = 88.39 mA
    • Channel Parameters: Um = 250 V; Uo = 26.25 V; Io = 88.39 mA; Co = 0.097 µF; Lo = 4.55 mH; Po = 580.02 mW
  • Temperature:
    • Temperature Accuracy: ±1°C @ +25°C; ±15°C over operating temperature
    • Phase Accuracy: -11° @ 10 kHz
    • Channel Parameters: Um = 250 V; Uo = 7.71 V; Io = 89.17 mA; Co = 9.3 µF; Lo = 4.55 mH; Po = 132.41 mW
    • Circuit B: Uo = 5.36 V; Rmin = 133.25 Ω; Io = 40.23 mA
    • Circuit C: Uo = 6.51 V; Rmin = 133.25 Ω; Io = 48.86 mA
  • Process Variable:
    • Channel Parameters: Um = 250 V; Uo = 27.98 V; Io = 279.34 mA; Co = 0.083 µF; Lo = 0.455 mH; Po = 842.89 mW
    • Circuit Power (PWR): Uo = 26.78 V; Rmin = 297 Ω; Io = 90.17 mA
    • Circuit Signal (SIG): Uo = 9.56 V; Rmin = 50.58 Ω; Io = 189.01 mA
• Cabinet Fit:
  • Standard 19-inch rack with internal barrier modules fits comfortably into 600 mm cabinets; bulkhead rack version available for cabinets with top/bottom bulkhead separation
  • When any internal barrier module is used, the rack is limited to a maximum of 13 monitor positions (IS Earthing Module consumes a dedicated slot)
  • Internal Barrier I/O modules increase rack depth by approximately 50 mm (2 in) to maintain the 50 mm physical separation between hazardous area and safe area wiring

BENTLY 3500/04 136719-01

The Real-World Problem It Solves

• Upstream oil & gas facilities with Zone 2 (Div 2) hazardous areas requiring CSA/ATEX/IECEx certification
• Refineries and chemical plants where conduits and external barriers would complicate cabinet layout
• Offshore platforms and marine applications needing ABS/IECEx/ATEX compliance with compact footprint
• Retrofits of existing 3500 racks to hazardous area duty without completely replacing standard monitors

Hardware Architecture & Under-the-Hood Logic

1. Dedicated Slot Occupancy: The IS Earthing Module consumes an entire I/O module position in the rack. This reduces a standard 19-inch rack from 14 to 13 available monitor positions when internal barriers are used.
2. Backplane IS Earth Distribution: The module routes a safety earth reference from the backplane to the barrier circuits within Internal Barrier I/O modules. This ensures all barrier channels share the same safety earth potential without requiring separate field grounding wires for each barrier.
3. No Signal Processing: The 136719-01 does not perform monitoring, alarm logic, or signal conditioning—it only provides the safety earth connection. All transducer signals are routed to their respective monitor modules (e.g., 3500/42M, 3500/40M, 3500/50, 3500/60/61, 3500/62) via the associated Internal Barrier I/O modules.
4. Compatibility with Internal Barrier I/O Modules: The IS Earthing Module works exclusively with 3500 Internal Barrier I/O modules. Standard (non-barrier) I/O modules do not require or use this module.
5. Mixed-Rack Operation: A rack can contain both Internal Barrier I/O and standard I/O modules. The hazardous area wiring connects to the barrier I/O modules above the rack; safe area wiring connects to standard I/O modules below the rack, maintaining at least 50 mm (2 in) separation between the two wiring zones.
6. Bulkhead Rack Configuration: For cabinets requiring physical separation between hazardous and safe areas (e.g., bulkhead), a bulkhead version of the rack maintains the 50 mm separation by routing hazardous wiring through the top of the cabinet and safe wiring through the bottom.
7. TMR Restriction: Racks configured for Triple Modular Redundancy (TMR) cannot use Internal Barrier I/O modules because connecting a transducer to multiple I/O module inputs compromises the integrity of the IS system.
8. Firmware and Software Requirements: The 3500 Rack Configuration Software must be Revision 2.3 or later to enable the use of internal barriers. Additionally, specific monitor firmware revisions (e.g., 3500/42 ≥ 1.06 D; 3500/50 ≥ 1.05 E; 3500/60/61 ≥ 1.06 E; 3500/62 ≥ 1.06 C) are required per the datasheet.
9. External Termination Unavailable: I/O modules with internal barriers do not offer an external termination option because hazardous area approvals prohibit the use of intrinsically safe wiring within multi-core cable assemblies that would be routed outside the hazardous area boundary.
10. Increased Depth Consideration: Internal Barrier I/O modules increase rack depth by approximately 50 mm compared to standard I/O modules. When planning cabinet depth, ensure sufficient space exists for both the module and any connectors/bulkhead requirements.

BENTLY 3500/04 136719-01

Field Service Pitfalls: What Rookies Get Wrong

• Field Rule: Any rack containing at least one Internal Barrier I/O module must have a 136719-01 installed in a dedicated I/O position. Always order and install it together with the barrier I/O modules.

• Field Rule: TMR rack options cannot use Internal Barrier I/O modules. For TMR systems requiring hazardous area protection, use external safety barriers (e.g., MTL796(-), galvanic isolators) instead.

• Field Rule: Place the 136719-01 in a rack position that provides easy access, such as at the end of a row of modules. Consider its position relative to adjacent internal barrier I/O modules and cabinet bulkheads when planning slot allocation.

• Field Rule: Route hazardous area wiring (from barrier I/O modules) above the 3500 rack and safe area wiring (to standard I/O modules, recorders, communication gateways) below the rack. Maintain at least 50 mm separation. In bulkhead cabinets, use the top routing for hazardous and bottom routing for safe area.

• Field Rule: Always install the connector shunt vertically on the terminal posts corresponding to the configured transducer type for each channel pair. Do not place the shunt over the “NOT USED” terminal posts, even if the channel pair is deactivated.

• Field Rule: When using Internal Barrier I/O modules, ensure the cabinet depth accommodates the increased rack depth. A standard rack with internal barrier modules fits comfortably in a 600 mm cabinet; verify dimensions before installation. Use the bulkhead rack version if cabinet depth is limited.

Commercial Availability & Pricing Note