The 3500/40M Proximitor Monitor is a four-channel monitor that accepts input from Bently Nevada eddy current proximity transducers. It conditions the signal to provide various vibration and position measurements and compares the processed signals against user-programmable alarm setpoints.
Broadly speaking, the 3500/40M refers to an integrated system consisting of a front card and a rear card. More specifically, it strictly denotes the front card with the part number 176449-01.
The 3500/40M integration includes a fixed and unique front card with the part number 176449-01. The rear card has three configuration options:
125680-01 Proximitor I/O Module with Internal Terminations
126615-01 Proximitor I/O Module with External Terminations
135489-04 Proximitor I/O Module with Internal Barriers and Internal Terminations
Both the 3500/40M and 3500/42M belong to the 3500 Series Monitor Modules. A partial comparison between them is shown below:
| Feature | 3500/40M Proximitor Monitor | 3500/42M Proximitor Seismic Monitor |
| Core Function | Shaft-relative vibration and position monitoring | Shaft-relative vibration + Absolute structural vibration monitoring |
| Supported Transducers | Eddy Current Proximity Probes | Eddy Current Proximity Probes |
| Velomitor® Velocity Sensors |
| Seismoprobe® Accelerometers |
| Key Measurement Functions | Radial Vibration | All functions of 40M, plus: |
| Eccentricity | Acceleration |
| REBAM (Rolling Element Bearing Activity Monitor) | Velocity |
| Thrust Position | Shaft Absolute Vibration |
| Differential Expansion | Circular Acceptance Region |
| Static Values | Direct, Gap, 1X/2X Amplitude/Phase, Not 1X, Smax | All static values of 40M, plus: |
| RMS/Peak Acceleration/Velocity |
| Band-Pass Peak values |
| Bias Voltage |
| I/O Module Types | Dedicated to proximity probe signals | More diverse options, including: |
| • Prox/Seismic combo I/O modules |
| • Prox/Velomitor combo I/O modules |
| • Shaft Absolute I/O modules |
| Outputs | -24 Vdc Probe Power | All outputs of 40M, plus: |
| Buffered Transducer Outputs | +4 to +20 mA Recorder Outputs (to DCS/recorders) |
| Power Consumption | 7.7 Watts (typical) | 7.7 Watts (typical) |
| Typical Applications | Shaft protection for rotating machinery: | Comprehensive machinery protection: |
| • Steam/Gas Turbines | • All applications of 40M |
| • Centrifugal Compressors | • Machines requiring both shaft and casing/case vibration monitoring |
| • Pumps, Fans | • Gearboxes, Reciprocating Compressors |
| • Vibration monitoring for large structures (with appropriate sensors) |
Thus, it can be concluded that:
The 3500/40M is primarily used in the following scenarios:
Monitoring shaft-related parameters of rotating machinery, such as radial vibration, axial displacement, differential expansion, and eccentricity.
Sensor systems entirely composed of eddy current proximity probes.
Core shaft protection for standard steam turbines, gas turbines, and centrifugal compressors.
In contrast, the 3500/42M has a broader range of applications:
When building a comprehensive mechanical protection system that requires simultaneous monitoring of shaft-relative vibration and absolute vibration of bearing housings or casings.
When monitoring gear mesh frequencies, high-frequency bearing faults, and other phenomena that effectively require accelerometers for detection.
When the monitoring system must provide direct 4-20 mA analog outputs to the plant DCS or other recording systems.
When dealing with diverse equipment types, including reciprocating compressors, large fans, and gearboxes, which typically require composite vibration monitoring.
The 3500/40M ensures equipment protection by实时分析来自连接传感器的输入数据流来确保设备安全 (Note: this phrase appears to be partially in Chinese and should be fully translated. Based on context, it should be: "real-time analysis of input data streams from connected sensors"). This data is continuously evaluated against user-defined alert and danger thresholds. Once any parameter exceeding these predefined limits is detected, the module automatically triggers alarm outputs.
The 3500/40M processes raw sensor signals and seamlessly relays them to control room operators and maintenance teams, providing a clear and immediate overview of machine health status.
Additionally, each input channel is equipped with advanced signal conditioning capabilities. This processing converts raw input into a set of refined metrics called static values, which represent specific physical parameters (e.g., vibration amplitude, gap voltage). The system offers flexible alarm management: alert setpoints can be assigned to each active static value, while more critical danger setpoints can be configured for any two key parameters to prioritize the most severe fault conditions.
