Description
1. Product Overview
Part Number: 3500/45, Order No. 176449-04
Manufacturer: Bently Nevada. It is a standard full-height single-slot core module for the 3500 rotating machinery TSI condition monitoring & protection system. 176449-04 is the fixed factory part number and hardware revision, natively supporting TMR triple modular redundant configuration. It serves as the standard critical spare part for axial displacement, differential expansion, casing expansion and valve position monitoring of steam turbines, gas turbines and large process compressors.
Compatible Rack: Designed for standard 19-inch 3500 system racks, adopting split front-main card + rear I/O terminal board architecture. It can be networked with system power supply, frame interface, relay output and communication modules. Channel configuration, measuring range, alarm thresholds and filter parameters are programmed via 3500 Rack Configuration Software. Measured data is uploaded to System 1 asset management platform and plant-wide DCS/SCADA systems, meeting SIL2~SIL3 functional safety requirements for power generation units.
Product Definition: 4-channel universal displacement position monitoring main card, accepting input from eddy current probes, Rotary Position Transducers (RPT), AC/DC LVDTs and rotary potentiometers. Each channel can be independently configured for 7 measurement modes including axial thrust displacement, multiple types of differential expansion, casing expansion and valve opening. It integrates signal conditioning, AD conversion, multi-stage alarm logic judgment and fault diagnosis, outputs Alert pre-alarm and Danger trip interlock commands, and provides 4 independent 4~20mA analog transmission outputs. It is the most widely used core monitoring card for TSI protection systems of large rotating machinery.
2. Six Core Hardware Functional Units
2.1 4-Channel Isolated Sensor Power & Signal Conditioning Unit
Four fully isolated input loops with configurable dedicated power supply per channel: -24VDC for eddy current probes, +15VDC for DC LVDT, 2.3Vrms 3400Hz sine excitation for AC LVDT, -12.38VDC for rotary potentiometers. On-board surge clamping, multi-stage EMI filtering and differential amplification eliminate ground loop interference and electromagnetic noise from long field cables, preventing reading drift and false alarms. Channels are electrically isolated to avoid crosstalk between measuring points.
2.2 Programmable Measurement Algorithm & Threshold Calculation Unit
7 standard configurable measurement modes per channel: axial thrust position, standard single-ramp differential expansion, non-standard single-ramp differential expansion, dual-ramp differential expansion, complementary differential expansion, casing expansion and valve position. Upper/lower pre-alarm and trip setpoints plus action delay are customizable via software, with adjustable bandpass filter bandwidth to distinguish slow displacement drift and transient impulse noise. The module automatically detects open/short circuit, over-range and power supply faults with latched fault codes to differentiate sensor failure and actual equipment over-displacement faults.
2.3 Front Panel Indication & Bypass Management Unit
Three front-panel LEDs: OK steady on for normal self-test and backplane power; TX/RX flashing for backplane bus communication; Bypass lit when the whole module is bypassed with alarm and protection logic locked. Two bypass modes are supported: single-channel independent bypass and full-module bypass. Maintenance on a single measuring point only disables the corresponding channel while other protection loops remain active without unit load reduction or shutdown.
2.4 Analog Transmission & Relay Alarm Output Unit
One isolated 4~20mA analog output per channel with maximum 500Ω load capacity, directly connectable to PLC AI modules and paperless recorders for on-screen display and process closed-loop control. Multiple passive SPDT relay contacts are integrated with response time＜10ms for audible/visual alarm and hardwired trip interlock; relay contact rating is 3A/240VAC complying with protection interlock specifications.
2.5 Backplane Bus & Redundancy Voting Unit
Rear gold-finger edge connector interfaces with the 3500 parallel backplane bus to upload displacement values, fault codes, SOE events and self-test status. It supports simplex, dual redundant and TMR triple redundant deployment. In TMR mode, three identical modules execute data voting to eliminate maloperation and protection refusal risks caused by single-point hardware faults, complying with redundancy safety standards for critical nuclear and thermal power units.
2.6 Industrial Reinforced Conformal Coating Unit
The full multi-layer gold-plated FR-4 PCB is coated with moisture, salt-fog and corrosion resistant conformal coating. Fanless passive heat dissipation relies on rack airflow. No adjustable potentiometers or consumable fuses are equipped. It withstands high temperature inside sealed cabinets, long-term low-frequency vibration of unit base and humid coastal environment, enabling 24/7 unattended maintenance-free continuous operation.
3. Technical Specifications
3.1 Basic Hardware Specifications
| Item | Specification |
|---|---|
| Model | 3500/45 Order No.176449-04 4-Channel Position Monitor Main Card |
| Rack Slot | 1 standard full-height slot of 3500 rack, requiring matched rear I/O terminal board |
| Input Channels | 4 fully isolated displacement measuring channels with configurable measurement type per channel |
| Supported Transducers | Eddy current probe, RPT, AC/DC LVDT, rotary potentiometer |
| Typical Power Consumption | 7.7~8.5W (varies with rear I/O board and transducer type) |
| Net Weight | Approx. 0.91kg |
| Dimension | 241.3mm × 24.4mm × 241.8mm |
| Origin | Original USA Manufacture |
3.2 Core Electrical & Measurement Parameters
- Typical Measuring Range: Axial displacement -2mm~+2mm, zero point software adjustable, resolution 0.1μm, linear error ≤±0.5%FS at 25℃
- Frequency Response Bandwidth: DC~5kHz (-3dB), expandable to 10kHz via software configuration
- Alarm Logic: Independent Alert pre-alarm & Danger trip thresholds per channel, delay time programmable
- Analog Output: 4 isolated 4~20mA outputs, maximum load impedance 500Ω
- Relay Output: Passive SPDT contacts, rated 3A/240VAC, response time ＜10ms
- Backplane Communication: Native 3500 parallel backplane bus, Modbus RTU supported for upper system data transmission
- Redundancy Rule: TMR triple redundancy requires three identical modules installed on adjacent rack slots for automatic voting after configuration
3.3 Environmental & Safety Compliance
- Operating Temperature: -30℃ ~ +65℃
- Storage & Transport Temperature: -40℃ ~ +85℃
- Humidity: 5%~95%RH non-condensing, no corrosive gas or salt fog deposition
- Ingress Protection: IP20, for installation only inside sealed industrial control cabinets
4. Product Advantages
- High integration of 4 measuring channels per single slot, greatly reducing rack slot occupation, cabinet wiring and spare part inventory management workload.
- Full compatibility with all mainstream displacement transducers; measurement mode and sensor type can be switched purely via software configuration without hardware modification or rewiring, offering extreme flexibility for on-site renovation.
- Split front-rear card structure with field wiring terminated on rear terminal boards only. Replacement of front main card does not disturb field primary cables, eliminating recabling work and shortening unit maintenance outage duration.
- Fine-grained channel-level bypass and comprehensive self-diagnosis accurately locate open/short circuit, power loss and over-range faults with pop-up alarm hints on upper HMI to simplify troubleshooting.
- Native compatibility with the entire 3500 ecosystem; configuration files support backup and import, and drop-in replacement of identical part number units is automatically recognized by the rack without reconfiguration.
- TMR triple redundant voting architecture eliminates single-point fault risks of false trip and protection failure, fully meeting strict interlock safety standards for power, chemical and nuclear critical units.
5. Application Scenarios
1. Combined-Cycle Gas & Steam Turbine Power Plant TSI System
Online monitoring of thrust bearing axial displacement, HP/LP cylinder differential expansion, casing thermal expansion and governor valve opening. Overtravel triggers unit turbine trip, serving as standard core hardware for GE & Siemens gas turbine 3500 TSI systems.
2. Petrochemical Large Process Compressor Units
Monitoring of shaft axial displacement and casing expansion for cracking gas and recycle hydrogen compressors to predict rotor drift and rubbing risks, interlocking anti-surge and unit shutdown protection to guarantee continuous chemical production safety.
3. Large & Medium Hydropower Unit Governor & Shaft Monitoring
Measurement of turbine main shaft axial displacement, runner play and wicket gate valve opening adapted to humid hydropower plant environment, coordinating with governor system for grid connection and load regulation.
4. Metallurgy Blast Furnace Main Fans & Large Pump Station Equipment
Early warning of main fan bearing wear and rotor offset via shaft displacement and casing expansion monitoring to prevent severe rubbing damage to rotating equipment.
5. Legacy 3500 TSI System Expansion & Spare Replacement
Direct in-situ addition or replacement for aging displacement monitor cards with damaged channels or insufficient measuring points; existing configuration parameters are imported for reuse with minimal system modification.
