Bently Nevada 3300 XL 11 mm Selection Guide for Extended-Range Measurements

Choose a Bently Nevada 3300 XL 11 mm system when the measurement requires more linear range than a standard 8 mm system provides and the target geometry can accommodate the larger sensing field. The current 11 mm system offers a 4.0 mm (160 mil) linear range, a 3.94 V/mm (100 mV/mil) scale factor, and system lengths of 5.0 or 9.0 m. Selection starts with the required movement, target material, target size, and probe placement. Only then do you define the matched probe, the 330730 extension cable (if required), and a 330780 Proximitor® Sensor such as 330780-51-00.

Start with Required Movement, Not Probe Diameter

The 11 mm probe is the right choice when the measurement envelope requires its 4.0 mm (160 mil) linear range. The standard linear range runs from approximately 0.5 to 4.5 mm (20 to 180 mil) from the target, with a recommended gap of 2.5 mm (100 mil). The nominal scale factor is 3.94 V/mm (100 mV/mil).

Bently Nevada also publishes an extended linear range of approximately 5.0 mm (200 mil), specified with a wider deviation-from-straight-line (DSL) tolerance. The extended range does not apply when zener barriers are used, and it should not be treated as an extra 1.0 mm of standard range.

Define the required movement before choosing the sensor:

• Axial (thrust) position: Calculate the full expected position change in both directions from the proposed cold gap.
• Ramp differential expansion: Convert the expected axial motion into gap change using the actual ramp geometry, and confirm that radial shaft motion will not distort the reading.
• Rod position or rod drop: Define the mechanical travel, target presentation, and minimum acceptable clearance.
• Tachometer, zero-speed, or phase reference: Confirm that the target, signal amplitude, gap, and monitor input suit the intended channel.
• Radial vibration: Verify that the larger target and probe-separation requirements can be met.

The machine type alone, such as a turbine generator or hydro unit, does not determine the probe family. Base the choice on the machine drawing and the predicted movement. A standard 8 mm system remains the better choice when its range covers the task and its target and mounting requirements are met.

Build the Complete 11 mm Measurement Chain

A 3300 XL 11 mm measurement chain consists of one 11 mm probe, one 330730 extension cable when the selected lengths require it, and one 330780 Proximitor Sensor. These components are calibrated together as a system with a defined total length.

The length rule is:

Total probe length + 330730 extension cable length = 330780 system length

A 1.0 m probe plus a 4.0 m 330730 cable forms a 5.0 m system. A 1.0 m probe plus an 8.0 m cable forms a 9.0 m system. A 5.0 m probe connects directly to a 5.0 m Proximitor Sensor without an extension cable, and the same applies to a 9.0 m probe and a 9.0 m sensor.

Do not use the probe's case length in this calculation. Case length determines the mounting geometry, while total probe length determines the electrical system length.

Decode 330780-51-00 as the Sensor Baseline

330780-51-00 is a 3300 XL 11 mm Proximitor Sensor for a 5.0 m system, with DIN-rail mounting and no agency approvals. It is a sensor only, not a probe, extension cable, or complete kit.

The part number follows the 330780-AA-BB pattern:

Other AA options cover 5.0 and 9.0 m system lengths with panel, DIN-rail, or no mounting hardware. The selected sensor must match both the probe-plus-cable total length and the mounting method inside the enclosure.

You can request a quote for this exact model on our 330780-51-00 product page. Make sure the quotation states whether mounting hardware, manuals, test records, or other accessories are included, rather than assuming they ship with a standalone sensor.

Confirm the Target and Probe Arrangement

Standard 11 mm performance is specified against an AISI 4140 steel target at least 30.5 mm (1.2 in) in diameter. The published performance and interchangeability values do not automatically apply to other target materials.

Check the following:

Bently Nevada publishes one qualified exception for smaller shafts; it is not a general waiver. On a 76.2 mm (3.0 in) shaft, cross-talk stays below 50 mV when probe-tip separation is at least 64 mm (2.5 in) for axial position measurements or 58 mm (2.3 in) for radial vibration measurements. Apply this exception only when the complete arrangement matches the published conditions.

For ramp differential expansion, document the ramp angle, target width, probe axis, expected axial travel, radial shaft movement, and the conversion from ramp movement to measured gap. The 4.0 mm linear range alone does not confirm that the ramp arrangement covers the required machine travel.

Define Probe Geometry and Cable Construction

Once the measurement range and target pass review, select the probe body. The 11 mm family offers 1/2-20 UNF and 5/8-18 UNF threads on English (inch) probes and M14 x 1.5 and M16 x 1.5 threads on metric probes, with armored and unarmored versions available.

For English standard-mount probes, the unthreaded length and overall case length are specified in 0.1 in increments, and the unthreaded length must be at least 1.0 in shorter than the case length. Total probe length options are 1.0, 5.0, and 9.0 m. Connector and cable options cover standard or FluidLoc cable, with or without a connector protector.

The mechanical specification should include:

1. probe thread and mating-hole thread;
2. unthreaded length and overall case length;
3. required insertion depth and target gap;
4. armor and the 25.4 mm (1.0 in) minimum cable bend radius;
5. standard or FluidLoc cable construction;
6. connector protection requirement;
7. total probe length and any 330730 extension cable;
8. 330780 system length and mounting hardware.

The 11 mm cable is triaxial. Do not substitute a 75-ohm coaxial NSv cable or an 8 mm cable just because the connectors look similar.

Control Calibration, Temperature, and Approval Scope

The system specification must state the conditions under which the published performance applies. Standard performance is specified at a defined supply voltage, load, AISI 4140 target, target size, gap, and temperature range.

Record the target material before ordering. If it is not AISI 4140 steel, request the applicable calibration data or a sensor calibrated for that material. Do not apply the standard 3.94 V/mm value to another material without supporting data.

Record the ambient temperature at the probe, extension cable, and Proximitor Sensor locations separately. Performance over the extended temperature range carries wider scale-factor and linearity tolerances than the standard 0 to 45 °C (32 to 113 °F) reference range.

For hazardous-area applications, identify the destination country and area classification. Approval options are ordered per component; they do not by themselves establish compliance for the complete installation, including the probe, cable, sensor, barrier or isolator, enclosure, wiring, and monitor.

Summarize Your 11 mm System Requirements Before Requesting a Quote

Before requesting a quote, gather all of your requirements into one summary so they can be reviewed in one place rather than across multiple emails. Include the following information:

Browse our 3300 System product category or submit your completed requirements summary. We will verify the part numbers and supply documentation for the units we quote. The asset owner or an authorized engineer remains responsible for approving the measurement range, target, calibration, mechanical installation, hazardous-area arrangement, and monitor configuration.

Release the 11 mm Specification for Procurement

The 11 mm selection is complete when the required movement fits within the linear range, the target and probe placement meet the published performance conditions, and the total probe length plus the 330730 cable length equals the selected 330780 system length. For 330780-51-00, that means a 5.0 m system with DIN-rail mounting and no agency approvals.

Submit the request only after the drawing reference, target data, full part numbers, system length, installation environment, required approvals, and requested supply documentation are all documented. Leave any missing engineering input as an open item; do not fill it with assumptions during quotation.