Bently Nevada 21508-02-12-10-02 Proximity Probe

The 21508-02-12-10-02 functions as a proximity probe within the Bently Nevada 21508 series. This eddy-current sensor measures radial vibration and axial position on steam turbines and compressors. Its compact tip fits tight mounting spaces where larger probes cannot reach.

Technical Specifications

Measurement Principle and Interface

Eddy-current technology enables non-contact displacement measurement on ferrous targets. The driver sends a high-frequency signal through the coaxial cable to the probe coil. Subsequently, target movement modulates coil impedance and produces a proportional voltage output. The 21508-02-12-10-02 pairs with extension cables and Proximitor drivers for signal conditioning.

Installation and System Integration

Operators mount the probe through a threaded hole with a locknut. A minimum target size of 20 mm diameter ensures accurate linear response. Meanwhile, the 8 mm tip suits standard bearing housing and shaft monitoring points. This design reduces cross-talk in dense sensor arrays. The system also supports reverse-mount configurations for confined spaces.

Energy Storage and Power Considerations

The Proximitor driver draws power from a -24 Vdc rail, typically 12 mA maximum. No internal battery or capacitor stores energy in the probe itself. Instead, external modules handle signal demodulation and power regulation. Therefore, system designers must budget for a dedicated DC supply per channel.