The Bently Nevada 3300/47 Differential Expansion Monitor is a specialized rack-mount module engineered to track the relative thermal growth between a turbine rotor and its casing. By monitoring this critical clearance, the system prevents mechanical interference during startup, shutdown, and steady-state operation of large steam turbines. The unit processes signals from proximity probes to ensure real-time status monitoring and provides integrated alarm functionality to protect rotating equipment from damage.
Features
Continuous monitoring of rotor-to-casing differential expansion.
Integrated signal conditioning for proximity probe inputs.
Dual relay outputs configured for Alert and Danger alarm thresholds.
Front-panel LED status indicators for OK, Bypass, Alert, and Danger conditions.
Designed for seamless integration within standard 3300 series monitoring racks.
Ordering Information
Model Component
Description
3300/47
Differential Expansion Monitor Base Module
XX
Measurement Range (Full-scale)
03
Proximity Probe/Proximitor Sensor Interface
01
Dual Relay Output Configuration
00
Standard Agency Approval
Technical Specifications
Parameter
Specification
Operating Temperature
0 to 60 degC
Power Consumption
1.5 W (typical)
Signal Sensitivity
200 mV/mil (8 V/mm) or 100 mV/mil (4 V/mm)
Accuracy (Signal Conditioning)
+/- 0.33% (typical) / +/- 1% (max at 25 degC)
Outputs
+4 to +20 mA, +1 to +5 VDC, 0 to -10 VDC
Installation Guidelines
Ensure the 3300 rack is powered down before inserting or removing the module to prevent electrical damage.
Verify that all proximity probes are correctly calibrated and connected via shielded cabling to minimize EMI interference.
Module should be installed in a clean, dry environment within the specified temperature range to ensure long-term reliability.
Ensure proper grounding of the 3300 system chassis to the main plant instrumentation ground bus.
Check all terminal connections for tightness and ensure wire routing avoids high-voltage power lines.
FAQ
What is the primary function of the 3300/47 monitor?
This module measures the differential thermal expansion between a turbine rotor and its casing, providing critical data to prevent mechanical contact or damage during thermal transitions.
What type of sensors does this module support?
The 3300/47-XX-03-01-00 is specifically configured to interface with proximity probes and their associated Proximitor sensors.
Does this unit include alarm relays?
Yes, this specific model includes dual relay outputs that are activated based on configured Alert and Danger setpoints.
