Bently 3300/20-01-04-01-00-00 Dual Channel Thrust Position Monitor (Product Description)

I. Product Overview

The Bently 3300/20-01-04-01-00 is a dual-channel thrust position monitoring module in the 3300 series mechanical protection system of Bently Nevada (now part of GE). It is used to continuously monitor the axial displacement (thrust gap) of rotating machinery rotors, warning of thrust bearing failures, axial movement, and dynamic-station friction, and is widely used in key units such as steam turbines, centrifugal compressors, gas turbines, and large pump sets for protection and condition monitoring.

Code meanings of the model:

3300/20: Basic model, dual-channel thrust position monitor;

01: Range ±25 mil (±0.635 mm);

04: Compatible with 3000 series eddy current preamplifier, sensitivity 200 mV/mil;

01: Alarm relay is epoxy resin sealed type;

00: No dangerous relay output (only warning, no hard contact for tripping);

00: No safety barrier (non-ia type, used in non-explosion-proof areas).

II. Working Principle

Based on the eddy current measurement principle, equipped with 3000 series eddy current probes and preamplifiers: The probe is aligned with the thrust disk of the rotor, converting the axial gap change into high-frequency impedance changes, and the preamplifier linearly converts them into gap voltage signals and sends them to the monitor. The module independently samples, filters, and calculates the dual-channel signals, and outputs the axial displacement value in real time; compared with the user-defined alarm threshold, if it exceeds the limit, it drives the warning relay to act; this model has no dangerous trip relay, only providing warning without directly triggering shutdown. The dual channels support redundant installation and can be configured with "AND/OR" logic to reduce false alarm risks, in line with API 670 standards.

III. Core Functions

Dual-channel independent monitoring: 2 completely independent axial displacement measurement channels, which can be separately configured with ranges and alarm thresholds; a single-channel failure does not affect the normal operation of the other channel, improving the monitoring continuity.

Precise measurement and real-time display: Measurement accuracy reaches ±0.33% full scale (typical), with a maximum error of ≤±1% full scale; frequency response DC–1 kHz, covering low-speed to high-speed rotating machinery; the front panel displays the displacement value (mil/mm) and channel status in real time.

Single-level warning protection: Equipped with epoxy resin sealed type warning relay (Alert), dust-proof, moisture-proof, and vibration-resistant; no dangerous (Danger) relay; customizable alarm thresholds, triggering the relay output when the displacement exceeds the limit, used for DCS/PLC alarms or audible and visual prompts, without direct tripping.

Standard signal output: Provides 4–20 mA analog output (optional 0–10 VDC), linearly corresponding to the full range of displacement, suitable for various recorders, DCS/PLC systems, for remote monitoring and data collection.

Comprehensive self-diagnosis: Real-time monitoring of probe circuit breakage / short circuit, preamplifier signal abnormality, module power supply and internal circuit faults; when a fault occurs, it locks the output and lights the front panel fault light to avoid false alarms.

IV. Technical Parameters

Model: 3300/20-01-04-01-00-00

Type: Dual-channel thrust position monitor

Measurement parameters: Rotor axial displacement (thrust position)

Range: ±25 mil (±0.635 mm, code 01)

Compatible sensor: 3000 series eddy current preamplifier, sensitivity 200 mV/mil (code 04)

Measurement accuracy: ±0.33% full scale (typical), ±1% full scale (maximum)

Frequency response: DC–1 kHz Channel quantity: 2 independent inputs

Alarm configuration: 1 epoxy resin sealed warning relay (code 01), no hazardous relay (code 00)

Analog output: 4–20 mA (default)/0–10 VDC (optional), with an accuracy of ±0.1%

Probe power supply: -24 VDC (provided by the module internally)

Operating power: 110/220 VAC, 50/60 Hz

Power consumption: ≤5.5 W (typical)

Operating temperature: 0℃～+60℃

Storage temperature: -40℃～+85℃

Humidity: 5%–95% (no condensation)

Dimensions: 165 mm×114 mm×64 mm (width × height × depth)

Weight: Approximately 1.1 kg

Certifications: CE, UL, CSA, compliant with API 670 standard

Installation method: Standard 19-inch rack slot installation of the 3300 series

V. Model Configuration Description

3300/20: Dual-channel thrust position monitor (core function)

01: Full-scale ±25 mil (±0.635 mm)

04: Compatible with 3000 series preamplifiers, 200 mV/mil

01: Alarm relay is epoxy resin sealed (dustproof, moistureproof, vibration-resistant)

00: No hazardous relay (only warning, no trip output)

00: No safety barrier (non-explosion-proof design, for ordinary industrial environments)

VI. Application Scenarios

Power industry: Thermal power / nuclear power turbine, generator rotor axial displacement warning monitoring;

Petroleum industry: Centrifugal compressor, ethylene / propylene unit, large pump set thrust bearing condition monitoring;

Metallurgical industry: Blast furnace blower, sintering main exhaust fan, etc. high-speed rotating equipment;

General machinery: Large motors, gas turbines, screw compressors, etc. key units' non-tripping protection.

VII. Installation and Maintenance Tips

Installation: Standard 3300 rack vertical slot installation, ensure good heat dissipation; probe installed above the thrust disk, initial gap controlled at 0.5–2.5 mm, avoid oil and water vapor erosion.

Wiring: Connect the preamplifier and the monitor with high-frequency coaxial cable, length ≤ 5 m; Analog output uses shielded twisted pair, single-ended grounding, keep away from power cables to reduce electromagnetic interference.

Calibration: At least calibrate once a year, use a standard displacement simulator to verify the range, accuracy and alarm threshold, ensure error ≤ ±1% of full scale.

Maintenance: Regularly check probe gap, cable insulation and relay contacts; prioritize troubleshooting the probe circuit, preamplifier power supply and signal status when self-diagnostic alarms occur.

VIII. Advantages and Features

High compatibility: Designed for 3000 series preamplifiers, matching 200 mV/mil sensitivity, strong signal compatibility;

High reliability: Epoxy resin sealed relay, wide temperature design, anti-electromagnetic interference, suitable for harsh industrial environments;

Safe warning design: No hard trip contacts, only provides warning signals, avoiding machine stoppage affecting continuous production;

Easy integration: Standard 4–20 mA signal output, compatible with mainstream DCS/PLC, quick integration into existing systems;

Redundant safety: Dual-channel independent monitoring + self-diagnosis, effectively reducing false alarms / missed alarms risk;

Long life: Industrial-grade components, no wear parts, normal maintenance life ≥ 10 years.