Bentley 3300/20 - 01-01-01-01-01-02 Dual-channel Axial Displacement Monitor Detailed Product Description

I. Product Overview

The Bentley 3300/20 belongs to the 3300 series of industrial mechanical protection monitoring equipment. This 3300/20-01-01-01-01-02 is a customized configuration version of the dual-channel axial displacement (thrust position) monitoring module, strictly following the API 670 industry standard. It is mainly applied to steam turbines, gas turbines, centrifugal compressors, large rotating pumps, industrial turbines, and other key rotating equipment in the fields of thermal power generation, petrochemicals, metallurgy, etc. Its core function is to continuously monitor the axial movement of the rotor and the clearance between the thrust bearing, achieving status warning and safety interlock protection. The entire machine adopts a frame-type modular design, compatible with the standard system architecture of the Bentley 3300 series. The model suffix code defines the input, measurement range, output, alarm logic, and additional functions. It is the core unit of the shaft system protection for industrial units.

II. Model Code Interpretation

The complete model 3300/20-01-01-01-01-02 represents different configuration parameters for each section. The detailed explanations are as follows. 3300/20 is the main model of the equipment, representing a dual-channel thrust/axial displacement monitor. The first code 01 represents the input specification, compatible with the standard eddy current sensor system of the Bentley 3300 series, matching the accompanying probe, preamplifier, and signal cable. The second code 01 represents the standard measurement range, with a default range of ±1.0 millimeters, which is the mainstream application range in the field. The third code 01 represents the analog output type, using a 0 to 10 volt direct current voltage output mode, different from current output. The fourth code 01 represents the alarm and trip logic configuration, enabling the standard two-level alarm and trip combination logic, supporting channel voting function. The fifth code 02 represents the additional functions and hardware version, including special configuration functions and corresponding certification configuration, different from the basic standard version.

III. Core Functions

The equipment is equipped with two independent measurement channels, supporting simultaneous collection of rotor axial displacement data. Channel voting logic can be set, relying on the redundant monitoring structure to reduce false actions caused by a single sensor failure, improving the stability of the entire protection system operation. The equipment collects and analyzes eddy current sensor signals in real time, continuously tracking the axial position changes of the rotor, capable of identifying potential faults such as thrust bearing wear, abnormal axial load, deteriorated lubrication conditions, and unbalanced axial force on the rotor in advance, avoiding major accidents such as rotor friction, shaft system damage, and equipment shutdown from the source. The module configuration has hierarchical protection logic, integrating warning, danger-level alarm, and emergency trip relay output. All alarm thresholds and trip thresholds can be freely set through local buttons, meeting the protection logic requirements of different units. It has a complete sensor circuit diagnosis function, capable of real-time detection of the state of the probe, extension cable, preamplifier, and the entire sensing circuit. When abnormal situations such as open circuit, short circuit, or signal over-range occur, it will immediately trigger a sensor fault alarm, alerting maintenance personnel to troubleshoot the fault and avoiding ineffective monitoring and incorrect interlock. This machine is equipped with a digital display panel and operation buttons, allowing on-site viewing of real-time displacement values, circuit voltage, alarm status, and equipment operation status. It also supports configuration of range, alarm values, output parameters, and relay status, and the parameters are automatically saved after setting. The data will not be lost after power loss. It is equipped with a 0 to 10 volt standard voltage conversion output, signal isolation processing, and can be directly connected to DCS, PLC, and upper-level monitoring systems to achieve remote data collection, trend recording, and centralized monitoring.

IV. Working Principle This equipment completes signal acquisition and conversion based on the principle of eddy current non-contact measurement. The accompanying eddy current probe is connected to a high-frequency alternating current. When the probe approaches the surface of the metal rotor thrust disk, an eddy current is induced on the metal surface. The gap size between the probe and the thrust disk directly affects the intensity of the eddy current and the equivalent impedance of the probe. The weak signal generated by the gap change is transmitted via an extension cable to the preamplifier. The preamplifier completes signal amplification, shaping, and compensation processing, and outputs a continuous changing DC voltage signal to the 3300/20 monitoring module. The internal circuit of the module performs arithmetic processing on the input signal and converts the analog voltage signal into precise axial displacement values. On the one hand, it compares the measured values with the preset alarm and trip thresholds to reach the set value and drives the corresponding relay to act, outputting a switch quantity interlock signal; on the other hand, it linearly converts the displacement value into a 0 to 10 volt standard voltage signal for external output. The two channels independently complete signal acquisition and processing, and cooperate with the internal voting logic to achieve redundant monitoring, ensuring the reliability of measurement and protection.

V. Main Technical Parameters

The measurement channels are two completely independent eddy current signal inputs, and are equipped with the 3300 series sensing components from Bently. The system power supply is -24 volts DC. The standard measurement range is ±1.0 millimeters, and supports on-site configuration for fine-tuning the range. The overall measurement accuracy is excellent. Under normal temperature conditions, the full-scale error does not exceed one percent, and the single-point measurement deviation does not exceed 0.03 millimeters. The resolution meets the requirements of high-precision industrial monitoring. The frequency response range is from DC to 1 kilohertz, suitable for monitoring scenarios of static axial displacement and low-speed rotating equipment. The input impedance is 10 kiloohms, which can perfectly match the output characteristics of the accompanying preamplifier. The switch quantity part includes one warning relay, two dangerous trip relays, with rated parameters of 250 volts AC, 3 amperes, and the contact mode can be set as normally open or normally closed. The analog output is isolated 0 to 10 volt DC voltage output, and the output signal linearly corresponds to the measurement range of the equipment. The external load is compatible with conventional industrial control acquisition modules. The equipment's working power supply is -24 volts DC, and the allowable voltage fluctuation range is ±10 percent of the rated value. The overall operating power consumption is approximately 5.5 watts. The normal operating temperature range is 0 degrees Celsius to 60 degrees Celsius, and the storage temperature range is -40 degrees Celsius to 85 degrees Celsius. The relative humidity of the working environment does not exceed 95 percent, and there is no condensation or corrosive gas inside the environment. The equipment has a standard 19-inch rack structure, single-slot installation, and the overall weight is approximately 1.4 kilograms. The product has multiple international certifications such as CE, UL, CSA, etc., and the overall design complies with the API 670 rotating machinery protection specifications.

VI. Installation and System Configuration

The equipment is installed in a standard rack, which can be directly installed in the dedicated system rack of the 3300 series from Bently, occupying a single slot. Installation and disassembly are simple, and the cabinet wiring is neat, suitable for the standard cabinet layout of the industrial control room. When installing the accompanying sensors, the two eddy current probes are axially aligned with the rotor thrust disk, using a symmetrical layout method. The initial installation gap of the probes is set at the midpoint of the sensor's linear range to ensure that the entire measurement is within the effective linear range. After the equipment is powered on, local configuration operations can be carried out. Enter the configuration menu through the panel buttons, and complete the settings of measurement range, warning alarm value, dangerous alarm value, trip action value, voltage output correspondence, relay contact type, dual-channel voting logic, and fault alarm mode. All parameter settings are automatically saved, without the need for an external upper-level software. All debugging work can be completed on-site. The equipment wiring is divided into sensor signal wiring, power supply wiring, relay interlock wiring, and analog output wiring. The wiring distinguishes between positive and negative poles and signal types, and can be connected strictly according to the equipment identification to ensure normal operation.

VII. Application Scenarios

It is mainly applied to large steam turbine generators and gas turbine generators, mainly monitoring the axial movement of the rotor, protecting thrust bearings, shaft seals, and internal flow components. It is widely used in centrifugal compressors and reciprocating units of the petrochemical industry, preventing excessive axial thrust from causing rubbing between the rotor and stator, and damage to blades. It is applicable to large industrial pumps, induced draft fans, booster fans, etc., real-time monitoring of the axial position of the shaft system, avoiding bearing burnout and shaft instability faults. At the same time, it can be used in various industrial expansion machines and power turbines, providing axial displacement safety protection for the entire process of unit start-stop, load variation, and steady operation.

VIII. Product Advantages

The dual-channel redundant monitoring architecture combined with loop self-diagnosis function can avoid single-point failures from both hardware and software, significantly reducing the probability of false alarms and false trips, ensuring continuous and stable operation of the unit. It adopts mature eddy current measurement technology, non-contact measurement without mechanical wear, combined with high-precision signal processing circuits, ensuring stable and accurate measurement data, with small long-term drift. This device is equipped with 0 to 10 volts voltage output and multi-channel relay switch quantity output, with rich interface forms, and can seamlessly connect with mainstream industrial control systems on the market, with low system integration difficulty. The entire machine is designed for industrial use, with a wide temperature and humidity adaptation range, and can operate continuously in industrial environments with complex conditions such as power plants, chemical plants, and metallurgy. The full-function local operation interface enables maintenance personnel to complete status viewing, fault judgment, parameter modification on-site, and daily maintenance and repair are convenient and efficient. The modular design facilitates spare part replacement, and when a fault occurs, modules can be quickly replaced to shorten equipment downtime.

IX. Component Description

This monitoring module needs to be coordinated with the same series of sensing components to work together. The core supporting components include the 3300 series eddy current probes, selected according to the on-site installation size and range requirements. It is equipped with the 330180 series preamplifier, responsible for powering the probe and completing the original signal pre-processing. It is also equipped with the 330130 series high-frequency coaxial extension cable, used to extend the sensor signal transmission distance, suitable for the layout distance between on-site equipment and cabinets. The entire machine operates based on the 3300 series standard installation frame and the negative 24 volt DC power supply module, providing a fixed installation position and stable working power supply for the monitor.