Bently Nevada 24765-01-01 Case Expansion Transducer Assembly

Description

Product Introduction & Engineering Value

Large rotating equipment does not fail only from vibration. Thermal movement creates mechanical stress when turbine casings cannot expand as designed. The Bently Nevada 24765-01-01 provides a dedicated measurement channel for monitoring casing growth relative to the foundation, helping operators verify proper machine movement.

Built around a DC LVDT measurement principle, this assembly combines a 25.4 mm linear measurement range with spring-return positioning for repeatable displacement tracking. It is commonly integrated into turbine monitoring systems where accurate case expansion data is required.

Technical Specifications

Field Application & The “Trench” Experience

A turbine maintenance group at a power generation facility noticed abnormal startup behavior after a scheduled overhaul. Vibration readings remained acceptable, but operators saw inconsistent expansion values during warm-up. Investigation showed the existing case expansion sensor had drifted outside expected calibration limits.

The replacement requirement was not simply “find another sensor.” The team needed the correct Bently Nevada assembly, matching linear range, spring configuration, and electrical characteristics. Installing a mismatched expansion transducer could create false indications and complicate turbine clearance evaluation.

The 24765-01-01 is commonly applied in scenarios such as:

• Steam turbine shell expansion monitoring during cold start and hot restart cycles
• High-pressure turbine casing movement measurement in turbine supervisory systems
• Sliding-foot expansion monitoring where thermal growth must remain balanced across the machine base
• Large generator turbine trains requiring continuous mechanical position feedback

24765-01-01

24765-01-01

Transparency SOP: QA & Testing

Every 24765-01-01 unit should be evaluated as an instrumentation device, not just an electrical spare.

Inspection procedure:

1. Identification check
   • Verify manufacturer marking and complete part number.
   • Confirm the unit matches the required linear range and spring option.
2. Mechanical inspection
   • Check probe movement, housing condition, mounting threads, and cable integrity.
   • Inspect for contamination, corrosion, or impact damage.
3. Electrical verification
   • Confirm DC supply requirements.
   • Measure output response through the operating displacement range.
4. Calibration review
   • Compare measured output scale factor against the expected 0.346 V/mm specification.
   • Verify linearity before installation.
5. Documentation
   • Record test results, condition grade, and warranty information.

For new surplus or refurbished inventory, suppliers should clearly identify whether the unit is unused stock, repaired equipment, or tested used inventory. Warranty terms should be provided separately from the product condition description.

The Veteran’s Tech Trap Guide

⚠️ PRO TIP #1 — Do not ignore the spring configuration.
The final digits in Bently Nevada ordering codes often define configuration options. The 24765-01-01 includes the spring-return option. Replacing it with a different configuration may affect mechanical installation and measurement behavior.

⚠️ PRO TIP #2 — Verify the measurement range before installation.
The 24765 family includes multiple linear-range options. A 25.4 mm unit is not automatically interchangeable with longer-range versions.

⚠️ PRO TIP #3 — Calibration drift can hide behind normal vibration readings.
Case expansion measurement is a separate turbine protection parameter. A machine can show acceptable vibration while thermal movement measurement is incorrect.

Dynamic FAQ

What is the Bently Nevada 24765-01-01 used for?

The 24765-01-01 is a Case Expansion Transducer Assembly used to measure turbine casing thermal expansion relative to the foundation. It is part of turbine supervisory instrumentation applications.

What is the measurement range of the 24765-01-01?

The unit provides a 25.4 mm (1.00 inch) linear range with a scale factor of 0.346 V/mm (8.79 V/in).

Does the 24765-01-01 require external power?

Yes. Published specifications identify a +24 VDC input supply with minimum 30 mA current requirement.

Is the 24765-01-01 compatible with all turbine monitoring systems?

Not automatically. Compatibility depends on the installed Bently Nevada monitoring architecture, channel configuration, mechanical mounting arrangement, and required measurement range.

How should a new surplus 24765-01-01 be verified before installation?

The unit should be checked for correct part number, physical condition, electrical response, displacement output, and documentation history before being installed in a critical turbine application.

What warranty is normally supplied for this part?

Warranty depends on the supplier and inventory condition. New surplus and refurbished units should include written warranty terms covering the specific item supplied.