Product Core Brief
- Model: 136703-01 (3500/50 I/O Module with Internal Intrinsic Safety Barriers + Internal Terminations)
- Brand: BENTLY Nevada
- Series: 3500 Series Turbomachinery Protection Rack System
- Core Function: Dual-channel Keyphasor/tachometer input module with factory-integrated intrinsic safety barriers, collects pulse signals from proximity probes or magnetic pickup sensors to calculate shaft rotational speed, acceleration, rotation direction, and trigger overspeed alarms for gas/steam turbines and compressors. Built-in internal barriers eliminate the need for external IS safety isolators for hazardous field wiring.
- Product Type: Full single-slot rack plug-in I/O monitoring card
- Key Specs: 2 independent speed measurement channels | Onboard intrinsic safety barrier circuit | Built-in terminal block termination | ATEX/CSA Zone 2 / Div 1 hazardous area certification | TDXnet rack backplane communication
- Condition: New Original (New Surplus)
Product Introduction
The BENTLY 136703-01 is a dedicated 3500/50 tachometer I/O module with fully integrated intrinsic safety barriers and internal wiring terminals, designed for machinery protection systems deployed in oil & gas, petrochemical, power plant classified explosion hazard areas. It accepts pulse signals from 3300 XL proximity Keyphasor probes or magnetic speed pickups, processes real-time rotational speed data, and communicates speed, acceleration, fault status to the 3500 rack CPU via TDXnet bus.This internal barrier variant removes external safety barrier installation work, cutting field cabinet wiring layout space consumption by roughly 40% compared to standard external-barrier 3500/50 modules. Its internal termination design avoids multi-core cable IS wiring compliance risks; onboard sensor open/short fault diagnostics automatically flag broken probe wiring without manual inspection—though your mileage may vary when mixing long unshielded signal cables alongside high-current AC power wiring.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Rack Slot Format | Full-width single slot for standard 3500 series 14-slot rack chassis |
| Backplane Supply Voltage | 18 V DC ~ 32 V DC nominal 24 V DC rack rail power |
| Max Module Steady-State Power Draw | 7.5 W dual-channel full-load operation |
| Independent Tach Input Channels | 2 fully isolated pulse input channels |
| Supported Sensor Types | Eddy-current proximity Keyphasor probes, magnetic variable reluctance pickups |
| Measurable Rotational Speed Range | 0 ~ 100,000 RPM; configurable pulse per revolution (PPR) scaling |
| Alarm Logic Function | User-programmable overspeed/underspeed alarm thresholds + acceleration rate limits |
| Safety Structure | Fully integrated intrinsic safety barrier circuit (internal barrier model); internal terminal block termination (no external barrier allowed) |
| Backplane Communication Bus | TDXnet proprietary rack bus for real-time trend and fault reporting |
| Continuous Operating Ambient Temp | -20 °C to +65 °C cabinet air; storage -40 °C ~ +85 °C |
| Unit Outer Dimensions | 241.3 mm × 24.4 mm × 163.1 mm (L × W × D) |
| Net Assembly Weight | 0.7 kg fully assembled aluminum shielded housing |
| Compliance & Safety Standards | API 670 Rev 4, CE EMC Class A, SIL 2 capable, ATEX Zone 2, CSA Class I Div 2 intrinsic safety certification |
| Built-In Diagnostics | Probe open/short-circuit fault detection, backplane power loss, TDXnet communication fault LED status indication |
Quality Control Process (Engineer’s Perspective)
- Incoming Verification: Cross-reference serial numbers against OEM production logs, scan factory anti-counterfeit QR labels, inspect aluminum housing for bent edges, cracked internal terminal blocks, or discolored onboard IS barrier resistors.
- Live Functional Test: Insert the unit into a calibrated 3500 rack, supply nominal 24 V DC backplane power, run a 24 hour stability test with simulated Keyphasor pulse signals cycling across both channels; log speed measurement error and alarm trigger response hourly.
- Electrical Parameter Test: Execute a 500 V Megger insulation resistance sweep; pass threshold reads >10 MΩ between each sensor input terminal and rack backplane ground plane.
- Firmware Verification: Read and record module internal monitoring firmware revision; this module requires rack monitor firmware v1.05E or newer for full internal barrier function compatibility, photograph terminal screw torque tension consistency.
- Final QC & Packaging: Wipe assembly with anti-static isopropyl wipe, seal inside shielding ESD bag, attach printed QC Passed sticker stamped with exact test completion date.
Replacement Pitfall Guide
❗ Firmware Mismatch: 3500 rack monitor firmware older than Revision 1.05E cannot recognize internal barrier safety logic on this module. Always upgrade rack monitor firmware to v1.05E or newer before physical swap.❗ DIP Switch / Jumper Misconfiguration: Factory default pulse scaling is set for 1 PPR Keyphasor probe; magnetic pickup sensors require manual PPR reconfiguration to produce accurate RPM readings.❗ Terminal / Cable Incompatibility: Do not route AC motor power cables parallel to Keyphasor input wiring; induced electromagnetic noise creates unstable speed pulse signals and intermittent NOT OK channel faults.❗ Power Supply Mismatch: Each fully populated 3500 rack with multiple internal barrier I/O and vibration monitor modules adds heavy DC load; calculate total rack power draw with a mandatory 20% load headroom to avoid backplane voltage droop during equipment startup transients.❗ ESD Damage: Low-humidity winter cabinet air raises static discharge risk by 3.8x. Place a dedicated anti-static foam mat under the rack before hot-swapping this live backplane module.Keep these in mind and you’ll cut 90% of rework time.
Compatibility Matrix & Benchmarks
Compatibility Matrix
- 136703-01 → All standard 3500 Series Rack CPU, Power Supply, Vibration Monitor Cards : Direct — TDXnet backplane bus match, zero adapter hardware required
- 136703-01 → External standalone IS safety barriers : Incompatible — Internal barrier model prohibits external barrier wiring per hazardous area certification rules
- 136703-01 → 3500/50 external-termination non-barrier modules : Needs Adaptation — Requires full field wiring rework to remove external barrier circuits for zone classified site acceptance
Benchmarks
- Full-span rotational speed measurement linear error: ≤0.25% (24 V DC backplane supply, 25 °C controlled ambient)
- TDXnet dual-channel full speed/status refresh latency: 3.0 ms minimum read/write cycle
- Internal terminal screw wire cycle durability: 1,000 insert/remove cycles with no contact resistance shift exceeding 0.12 Ω
