Description
Bently Nevada 3300/20-12-01-02-00-02 Dual Thrust Position Monitor
Configured for axial displacement monitoring in the Bently Nevada 3300 Machinery Protection System, the Bently Nevada 3300/20-12-01-02-00-02 (base model 3300/20 Dual Thrust Position Monitor) provides direct measurement and tracking of two independent shaft axial displacement signals derived from eddy-current proximity probes, converting mechanical position into proportional DC voltage outputs for protection logic execution.
Suffix Breakdown & Model Matrix
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Option Code
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Parameter
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Configuration Details
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3300/20
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Monitor Type
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Dual Thrust Position Monitor
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-12
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Full-scale Range Option
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1.0 - 0 - 1.0 mm
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-01
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Transducer Input Option
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3300 or 7200 Proximitor® Systems (200 mV/mil or ~7.87 V/mm)
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-02
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Alarm Relay Option
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Hermetically-sealed relays
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-00
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Agency Approval Option
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Not required
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-02
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Safety Barrier Option
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Internal Safety Barriers
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Hardware Specifications
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Parameter
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Specification
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Model Brand
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Bently Nevada
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Origin
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USA
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Weight
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1.0 kg
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Dimensions
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1 rack slot width (3300 series rack)
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Operating Temp
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0 degC to +65 degC
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Power Consumption
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7.7 W nominal
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Input Impedance
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10 kΩ
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Transducer Power Supply
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-24 VDC or -18 VDC (current limited)
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Recorder Outputs
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+4 to +20 mA, 0 to -10 VDC, or +1 to +5 VDC
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Buffered Output Impedance
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100 Ω
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Alarm Accuracy
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±0.39% of full scale
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Display Resolution
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±1.6% of full scale
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Eddy-Current Probe Scaling and Gap Voltage Validation
The monitor’s input scaling is fixed to the transducer’s linear range, requiring precise gap voltage validation prior to commissioning. For standard Bently Nevada 3300 probes, the target gap voltage is nominally -10 VDC when the probe tip is at the calibrated clearance from the thrust collar. Accurate scaling ensures that axial displacement values remain within the defined 1.0 - 0 - 1.0 mm range without cross-talk between channels. Rotor dynamics effects are mitigated by maintaining symmetrical probe mounting and verifying signal isolation per channel.
Frequently Asked Questions
Q: Can the alarm relays be reconfigured for different voting logic without replacing hardware?
A: Yes. The 3300/20 supports both “AND” and “OR” voting logic configurations via internal DIP switch settings; no hardware replacement is required.
Q: Is hot-swapping supported while the machinery is operational?
A: No. Removing or inserting the module during operation may cause transient signal loss; power-down of the rack slot is recommended before servicing.
Q: What is the maximum cable length between the proximity probe and the monitor?
A: Industry practice limits extension cable runs to 15 meters to maintain signal integrity and avoid attenuation beyond the specified accuracy tolerance.
Field Installation Guidelines
Mount the monitor in a standard 3300 rack slot, ensuring rear-panel terminal connections are torqued to 0.5 N·m. Use shielded twisted-pair cable for transducer wiring with the shield grounded at the monitor end only. Verify gap voltage at each probe before final assembly. Maintain separation of 50 mm minimum between signal and power cables to prevent electromagnetic interference. Perform functional testing after installation by applying a known mechanical displacement and confirming proportional output change.
