Bently Nevada 3500/50 133388-02 Tachometer Module

Description

The 3500/50, designated under spare part number 133388-02, is a 2-channel hardware component engineered to determine shaft rotative speed, rotor acceleration, or rotor direction within the 3500 Machinery Protection System. The module interfaces directly with raw proximity probe transducers or passive magnetic pickups to monitor physical asset dynamics. Acting as an analytical interface layer, it continuously compares acquired frequency data against user-programmable alarm setpoints, changing states to trip automated safety alarms when thresholds are exceeded. Configurable through the 3500 Rack Configuration Software, the module can supply conditioned Keyphasor signals to the backplane network, eliminating the need for independent Keyphasor hardware installations. The instrument outputs an independent +4 to +20 mA analog recorder signal for each measurement channel to supply plant operations and logging utilities with deterministic diagnostic indicators.

Features

• Dual independent channel capabilities for multi-point frequency or rotational direction tracking.
• Versatile sensor acceptance supporting both eddy current proximity systems and passive magnetic pickups.
• Four standard firmware options comprising speed monitoring, speed band, zero speed, acceleration, and reverse rotation tracking.
• Integrated peak hold logic capturing maximum forward speed, maximum reverse speed, and cumulative reverse rotations.
• Internal rack signal distribution delivering conditioned Keyphasor reference data to adjacent 3500 series monitors.

Applications

• Industrial steam and gas turbine rotor shaft speed tracking and peak rotation monitoring.
• Centrifugal process gas compressor acceleration observation and emergency shutdown interface.
• Large-scale cooling tower fan zero speed validation and reverse rotation notification.
• High-horsepower industrial gearbox input-to-output shaft speed ratio monitoring.

Ordering Information

Technical Specifications

Connections/Interfaces

Installation Guidelines

• Grounding Control: Terminate field sensor cable shields explicitly at the designated SHLD pins on the rear termination blocks to build an effective faraday path against high-frequency electrical noise.
• Slot Alignment: Insert the main front module into any available full-height slot location, pushing firmly along the alignment tracks until the card engages with the rack backplane power lines.
• Sensor Exclusions: Do not map magnetic pickup inputs to zero speed or reverse rotation notification functions, as low shaft velocity cannot generate sharp edge signals for proper trigger interpretation.
• Ventilation Integrity: Ensure clearance tracks are maintained on both the front face and rear interface regions to facilitate ambient forced-air cooling paths through the instrument chassis.

Compliance and Certifications

• CE Mark Directives: EN50081-2 Radiated and Conducted Emissions (Class A), EN50082-2 Industrial Susceptibility Standard.
• Low Voltage Directives: EN 61010-1 Environmental Safety Requirements for Electrical Equipment.
• CSA / NRTL / C: Certified for Class I, Division 2, Groups A through D installations when combined with matching standard termination modules.

Technical & Procurement FAQ

Q: Can this instrument independently control plant machinery overspeed trip valves? A: No, Bently Nevada tachometer modules are not engineered as components for standalone speed control or direct overspeed protection, as they lack the critical structural redundancy needed for machinery trip functions.

Q: What is the physical operational difference between part number 133388-02 and the 3500/50 series designation? A: The 3500/50 identifies the overall functional tachometer module design family, while the reference 133388-02 dictates the specific warehouse spare component identifier for the front card assembly.

Q: Is manual calibration necessary for the analog output loop upon deployment? A: No field-level calibration routines are necessary, since all transmitter input ranges, voltage thresholds, and discrete parameters are processed digitally using the 3500 software layer.

Q: Can a magnetic pickup be safely assigned to verify reverse rotation behavior? A: No, passive magnetic pickups fail to deliver a distinct or clean signal edge during slow or stopping shaft cycles, which can cause severe faults or incorrect direction tracking within the logic layer.

Q: How does a sudden external short circuit on the analog recorder loop affect overall speed tracking? A: The primary speed tracking, alarm monitoring, and backplane processing operations remain completely uninfluenced by short-circuit faults across the external recorder line loops.