Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | 3500/42 125672-02 (PWA 125672-02) |
| Manufacturer | Bently Nevada (Baker Hughes) |
| Product Type | 4-Channel Proximitor/Seismic Monitor Module |
| Product Series | Bently Nevada 3500 Machinery Protection System |
| Input Channels | 4, configured in two pairs (Ch.1–2 and Ch.3–4) |
| Compatible Transducers | Eddy-current proximity probes, velocity transducers, accelerometers, Velomitor sensors |
| Input Impedance | 10 kΩ standard I/O (Proximitor and acceleration inputs) |
| Transducer Supply | -24 V DC |
| Sensitivity | Radial vibration, thrust, eccentricity: 3.94 mV/µm (100 mV/mil) or 7.87 mV/µm (200 mV/mil); differential expansion: 0.394 mV/µm or 0.787 mV/µm; acceleration: 10 mV/(m/s²); velocity: 20 mV/(mm/s) pk |
| Frequency Response | Direct filter user-programmable 4–4,000 Hz or 1–600 Hz; gap filter -3 dB at 0.09 Hz; 1X/2X vector filter, constant Q, -57.7 dB minimum stopband rejection |
| Recorder Output | +4 to +20 mA per channel, 550 Ω output impedance, 0–600 Ω load, 0 to +12 V DC compliance, 0.3662 µA/bit resolution |
| Buffered Outputs | One short-circuit-protected coaxial connector per channel |
| Power Consumption | 7.7 W typical (supplied by 3500 rack backplane) |
| Alarm Accuracy | Within 0.13% of the desired value; Alert on every measured value, Danger on any two |
| Data Update Rate | 100 ms or less |
| Operating Temperature | -30 °C to +65 °C |
| Storage Temperature | -40 °C to +85 °C |
| Humidity | Up to 95%, non-condensing |
| Dimensions (H x W x D) | 241.3 mm x 24.4 mm x 241.8 mm (9.50 in x 0.96 in x 9.52 in) |
| Weight | 0.91 kg (2.0 lb) |
| Rack Space | 1 full-height front slot (monitor) plus 1 full-height rear slot (I/O module) |
| Compliance | API 670, CE, EMC EN 61000-6-2 / EN 61000-6-4, EN 61010-1, SIL 2 capable configurations |
Main Features and Advantages
Universal four-channel input architecture:
The Bently Nevada 3500/42 125672-02 accepts proximity, velocity and acceleration signals on the same platform, which means one spare part number can protect a shaft-relative vibration point on a compressor bearing and a casing-absolute velocity point on a motor in the same rack. This universality dramatically reduces the spare-parts inventory a plant must carry, and it lets engineers re-purpose an installed channel simply by re-configuring it instead of buying a different card.
Paired-channel flexibility and measurement depth:
Because channels are programmed in pairs, the Bently Nevada 3500/42 125672-02 can run two different protection functions at once, for example radial vibration on channels 1–2 and axial thrust position on channels 3–4. Each active measurement supports its own Alert setpoint, while any two can carry Danger setpoints, giving protection engineers exactly the alarm depth that API 670 machinery trains demand without over-specifying the hardware.
Deterministic protection independent of host software:
Alarm evaluation happens on the card itself and is passed over the 3500 backplane to dedicated relay modules, so a trip decision never waits on a SCADA poll, an OPC server or an operator workstation. This architectural independence is what allows the Bently Nevada 3500/42 125672-02 to be specified in SIL 2 protection loops where response time and failure independence are audited requirements.
Diagnostic transparency for maintenance teams:
Each channel provides a front-panel buffered transducer output through a short-circuit-protected coaxial connector, so a portable analyzer can be clipped on for orbit plots, spectrum analysis or bump testing without breaking the protection loop. In parallel, the proportional 4–20 mA recorder output feeds trend data to the DCS, which turns the Bently Nevada 3500/42 125672-02 into a continuous source of condition-monitoring intelligence rather than a silent trip device.
Serviceability without process interruption:
Hot-swappable in a compliant 3500 rack, the module can be replaced under power once the affected channels are placed in Bypass mode, and front-panel OK, TX/RX and Bypass LEDs give immediate visual confirmation of card health, backplane communication and suppression state. Combined with -30 °C to +65 °C operating range and 95% non-condensing humidity tolerance, the Bently Nevada 3500/42 125672-02 is built for control rooms and field enclosures that are far from ideal.
