Bentley 3500/45 Position Monitor

Bentley 3500/45 Position Monitor

Product Overview and Core Features

The 3500/45 position monitor is a 4-channel precision monitoring device developed by Bently Nevada, specifically designed for monitoring position related parameters of rotating machinery. Its core function is to receive signals from proximity sensors (Proximitors), rotary position sensors (RPTs), AC/DC linear variable differential transformers (AC/DC LVDTs), and rotary potentiometers. Through signal conditioning and comparison with user programmable alarm thresholds, it achieves mechanical protection and status monitoring.

Core competencies:

Multi parameter monitoring: supports 8 measurement functions including axial (thrust) position, differential expansion, casing expansion, valve position, etc. Channels are programmed in pairs (such as channels 1-2 and 3-4 can perform different functions separately, but casing expansion only supports channels 3-4).

Flexible configuration: Customize the full-scale range, filtering parameters, and alarm thresholds through the 3500 configuration software to adapt to different mechanical operating conditions.

Redundancy design: Supports TMR (Triple Modular Redundancy) configuration, improves system reliability through a 2 out of 3 voting mechanism, and is suitable for monitoring critical equipment.

Application scenarios:

Used for monitoring parameters such as axial displacement of rotors, thermal expansion difference between shafts and casings, valve opening, etc. in large rotating machinery such as steam turbines and compressors, to prevent equipment failures such as rubbing and overload caused by abnormal positions.

Detailed explanation of technical specifications

1. Input characteristics

Signal type: Supports sensor inputs such as Proximitor (e.g. 3300XL series), DC LVDT (25-508 mm range), AC LVDT (25-254 mm range), rotary potentiometer (50 ° -300 ° rotation range), etc.

Impedance and power consumption:

The input impedance of DC LVDT is 1M Ω, the Proximitor/RPT is 10K Ω, and the rotary potentiometer is 200K Ω.

The power consumption varies depending on the I/O module: typically 7.7W when using position I/O modules, 8.5W for AC LVDT modules, and 5.6W for rotary potentiometer modules.

2. Sensitivity and accuracy

Thrust position: Sensitivity 3.937 mV/mm (100 mV/mil) or 7.874 mV/mm (200 mV/mil), accuracy ± 0.33% of full scale (typical), maximum ± 1%.

Differential expansion:

Standard single slope: Sensitivity 0.394-7.874 V/mm (10-200 mV/mil), accuracy varies depending on the slope angle and range, with a maximum error of ± 2% (such as when the full-scale span is less than 3 Vdc).

Shell expansion: DC LVDT sensitivity is 0.05-0.20 V/mm (1.25-5.00 V/in), AC LVDT is 9.45-28.74 mV/V/mm (0.24-0.73 mV/V/mil).

Valve position: The sensitivity of the rotary potentiometer is 41 mV/degree, the RPT is 50-140 mV/degree, and the AC LVDT is 3.94-28.74 mV/V/mm.

3. Output characteristics

LED indication:

OK light: It lights up when the module is running normally.

TX/RX light: Flashes when communicating with other modules in the rack.

Bypass light: It lights up when the channel is bypassed.

Analog output:

The recorder outputs 4-20 mA, proportional to the full range (such as 20 mA for a full range of 10 mm), with a load resistance of 0-600 Ω, a resolution of 0.3662 μ A/bit, and a temperature drift of ± 0.7%.

Buffer sensor output: 1 coaxial interface per channel, short circuit protection, DC LVDT channel 3-4 offset -10 Vdc, AC LVDT output is the DC characteristic value of the AC signal.

4. Signal conditioning and filtering

Frequency response:

Thrust/differential expansion: Direct filter -3 dB at 1.2 Hz, gap filter -3 dB at 0.41 Hz.

Shell expansion/valve position: Position filter -3 dB at 0.41 Hz, suitable for low-frequency mechanical displacement monitoring.

Alarm mechanism:

The Alert threshold can be set to 0-100% full scale, and the Danger threshold supports any two proportional value configurations, with a time delay of 1-60 seconds (Alert) or 0.1 seconds (Danger), and an alarm accuracy of ± 0.13% of the target value.

Configuration plan and I/O module

1. I/O module types and adaptation scenarios

Module model and function applicable to sensors

01 Internal terminal module directly connects to Proximitors, RPTs, DC LVDTs, suitable for non hazardous areas such as 3300XL series, 25 mm Extended Range, etc

02 External terminal module is connected to external terminal blocks through cables, simplifying rack wiring as above

03 Discrete TMR External Module Triple Redundancy Configuration, with independent sensors for each channel, enhances reliability Proximitor/DC LVDT

05 AC LVDT internal module is dedicated to AC LVDT signal conditioning, supporting a range of 25-254 mm AC LVDT 25 mm/50 mm, etc

The internal module of the 07 rotary potentiometer is compatible with rotary potentiometers (50 ° -300 °) for valve opening monitoring

2. Key points of TMR configuration

Discrete and bus modes:

Discrete mode (module 03): Three independent sensors are connected to three modules respectively, suitable for critical measurements (such as thrust position).

Bus mode (module 04): Single sensor signals are distributed to three modules through the bus, which has lower cost but slightly lower reliability.

Voting mechanism: When the deviation between the output of a module and other modules exceeds the set threshold (such as 5%), an event log is triggered to ensure data consistency.

3. Typical configuration examples

Turbine thrust monitoring:

Sensor: 3300XL 8mm Proximitor with a sensitivity of 200 mV/mil.

Channel configuration: 1-2 channels are set as thrust positions, with a full range of 25-0-25 mil, an Alert threshold of 15 mil, a Danger threshold of 20 mil, and a filtering frequency of 1.2 Hz.

Boiler pipeline expansion monitoring:

Sensor: 50 mm DC LVDT, sensitivity 0.10 V/mm (2.50 V/in).

Channel configuration: 3-4 channels are set for chassis expansion, with a full range of 0-50 mm and an alarm delay of 2 seconds, adapted to the slow change characteristics of thermal expansion.

Ordering and installation information

1. Component numbering rules

3500/45-AXX-BXX：

AXX: I/O module type (e.g. 01=internal terminal, 05=AC LVDT).

BXX: Authentication options (01=CSA/NRTL/C Class I, Div 2).

Example: 3500/45-01-01 represents an internal terminal module with CSA certification.

2. External components and spare parts

Terminal block:

Proximitor/DC LVDT: 125808-06 (Euro interface) or 128015-06 (terminal block).

AC LVDT: 141208-01 (Euro interface), supports signal conditioning and isolation.

Cable:

Sensor to terminal block: 129525 series, length 5-100 feet, supports assembly/non assembly.

Spare parts:

Module spare parts: 176449-04 (3500/45 complete machine), 135137-01 (internal terminal module).

Consumables: 00530843 (I/O module four pin splitter), used for sensor type matching.

3. Installation requirements

Space occupancy: The monitor occupies one full height front slot, and the I/O module occupies one full height rear slot, which needs to be used in conjunction with a 3500 rack.

Environmental compatibility:

Working temperature -30 ° C~65 ° C, storage -40 ° C~85 ° C, humidity ≤ 95% non condensing, in compliance with EN 61000-6-4 electromagnetic compatibility standard.

Explosion proof certification: Equipped with CSA certification module, suitable for Class I, Div 2 Groups A-D hazardous areas, meeting the needs of petroleum, chemical and other scenarios.

Application precautions

Sensor matching:

Differential expansion requires the use of an Extended Range Proximitor (e.g. 25 mm) to ensure that the range covers the expansion difference between the shaft and the casing.

It is recommended to use DC LVDT for casing expansion to avoid AC LVDT phase drift affecting accuracy.

Software version requirements:

TMR configuration requires 3500 configuration software 2.41 or above, and when using RPT for valve position, software 3.00 or above is required.

Maintenance suggestion:

Regularly verify the alarm function (such as triggering Alert/Ranger with input analog signals), and check the consistency between the LED status and the recorder output.

When hot plugging modules, power should be turned off to avoid static electricity damaging the circuit board (it is recommended to wear an anti-static wrist strap).

Summary

The 3500/45 position monitor provides accurate position parameter monitoring for rotating machinery through multi-channel and high-sensitivity design. Its modular configuration and TMR redundancy mechanism ensure system reliability, making it suitable for key fields such as power, petrochemicals, and metallurgy. Users can choose the appropriate combination of I/O modules and sensors based on the type of machinery and monitoring requirements, and achieve customized protection solutions through flexible software configuration, providing data support for the safe operation of equipment.