Bently Nevada 3300/20-12-01-02-03-02 Thrust Position Monitor

This dual thrust position monitor measures axial shaft movement in rotating machinery. It detects thrust bearing wear and predicts potential rotor instability issues. The unit integrates into the Bently Nevada 3300 monitoring system rack.

Technical Specifications

Parameter	Specification
Model Number	3300/20-12-01-02-03-02
Product Type	Dual Thrust Position Monitor
Supply Voltage	24 V DC ±10%
Power Consumption	9 W (maximum)
Input Channels	2 x proximity probe (dual, differential)
Input Range	-24 V to -3 V DC (proximity)
Measurement Range	0 to 2.5 mm (configurable)
Resolution	14-bit (including sign)
Accuracy	±0.5% of full scale (at 25°C)
Outputs	2 x 4–20 mA (isolated, configurable)
Alarm Relays	4 x Form C (SPDT, 2 A at 30 V DC)
Communication	1 x RS-485 (Modbus RTU)
Sensor Power	-24 V DC (regulated, per channel)
Status Indicators	6 x LED (Power, 2 x OK, 2 x Alarm, Fault)
Mounting	Backplane rack
Dimensions (W x H x D)	26 mm x 223 mm x 175 mm
Weight	0.44 kg

Mechanical Design and Rack Integration

This position monitor follows the standard 3300 series rack form factor. Its 26 mm width occupies a single slot in the chassis. The unit weighs 0.44 kilograms and features a rugged front panel. All connectors and indicators are front-accessible for easy installation.

Power Supply and Electrical Characteristics

The device operates from a 24 V DC supply with a ±10 percent tolerance. It consumes a maximum of 9 watts during full operation. The module provides regulated -24 V DC for each proximity probe channel. Internal circuitry includes reverse polarity and overvoltage protection.

Input Configuration and Differential Measurement

Two independent channels each accept a standard proximity probe input. The input range covers -24 V to -3 V DC for reliable gap detection. The module measures the differential position between the two probes. This differential configuration cancels common-mode thermal drift errors.

Position Measurement and Scaling

The measurement range spans 0 to 2.5 millimeters of axial movement. Users can configure the scaling to match specific bearing clearances. The 14-bit resolution delivers precise position readings across the full range. The accuracy reaches ±0.5 percent of full scale for critical applications.

Output and Alarm Capabilities

Two isolated 4–20 mA outputs transmit position data to control systems. Users can configure each output with independent scaling parameters. Four Form C relays provide alert, danger, and shutdown functions. These relays handle up to 2 amperes at 30 V DC. The module also includes a relay for overall system fault status.

Communication and Remote Monitoring

An RS-485 port supports Modbus RTU for remote configuration and data access. This interface enables integration with SCADA and DCS networks. Users can read real-time thrust position and alarm status remotely. The module also logs peak values for trend analysis.

Diagnostic Features and Status Indication

Six front-panel LEDs provide immediate operational feedback. The Power LED confirms correct supply voltage is present. Two OK LEDs indicate normal sensor operation for each channel. Two Alarm LEDs illuminate when thrust position exceeds thresholds. A Fault LED signals any internal or sensor-related issues.

Application Suitability

This thrust position monitor serves critical rotating machinery across many industries. It works effectively with steam turbines, gas turbines, and centrifugal compressors. The device also monitors axial thrust in pumps and large motors. Its operating temperature ranges from -20°C to +65°C.