Bentley preamplifiers are an important part of the eddy-current sensor system, which is mainly used to provide high-frequency AC current to the probe coil and process the signal detected by the probe to output a voltage signal that changes linearly with the gap between the probe end face and the metal conductor being measured. Here is its overall description and related parameters:

Overall description
Bently preamplifiers typically have a rugged housing design that can withstand harsh industrial environments and operate reliably in temperatures ranging from -34°C to 66°C. It receives signals from non-contact 3300 series or 3300 XL proximity probes and extension cables for transmission to Bently 3500 modules, 2300/20, 1900/65 and other vibration monitor products. The preamplifier is highly resistant to radio interference and is not susceptible to interference from nearby radio signals, even when installed in a fiberglass enclosure.

parameter
Supply Voltage: A reliable DC supply voltage of -17.5V to -26V DC is typically required, and the power supply and sensor are connected via VT and COM terminals.
Sensitivity: For example, the 3300 XL system comes with a front processor with a sensitivity of 7.87 mV/μm, which accurately measures even the smallest gap changes.
System length: The number in the model number often represents the total length of the system and the installation method, such as 330180-51, 51 means using a 4-meter extension cable and a 1-meter probe, that is, 5-meter installation; x0 for panel mount, x1 for DIN mount, and x2 for no mounting hardware.
Output signal: Output a linear voltage signal proportional to the gap between the probe face and the metal conductor to be measured, which can be used for shaft vibration measurement, axial displacement measurement, tachometer and zero speed measurement.
Electrical length matching: The electrical length of the probe after connecting with the extension cable should match the electrical length of the preamplifier, and the tolerance should be within ±0.2% of the nominal length to ensure the measurement accuracy.
Signal Transmission Distance: The maximum length from the front amplifier to the 3500 monitor is 305 meters, which can meet the signal transmission needs within a certain range.