24765-03-01 Bently Nevada Case Expansion Transducer Assembly

Bently Nevada 24765 Case Expansion Transducer Assembly (DC)

The Bently Nevada 24765-03-01 is a precision direct-current LVDT-based case expansion transducer assembly designed to measure thermal growth and differential expansion on large steam turbines. This rugged measurement system translates mechanical casing displacement into a reliable DC voltage signal for turbine supervisory instrumentation.

• Base Model: 24765 – DC Case Expansion Transducer Assembly Series
• Linear Range Option: -03 – 101.6 mm (4.00 in) extended linear measurement range
• Spring Option: -01 – Integrated spring return mechanism for positive plunger contact

Technical Specifications

Selection Comparison & Technical Guidance

When selecting case expansion monitors within the 24765 family, matching the stroke length and spring return configuration to your turbine thermal growth profile is critical. Below is a technical comparison with a related variant:

• Model Comparison: Compare against the alternative variant 24765-02-01. While both units incorporate a spring return mechanism (-01), the -02 variant provides a shorter linear range of 50.8 mm (2.00 in) with a higher scale factor of 0.404 V/mm (10.25 V/in) and a longer physical length of 328 mm, whereas the 24765-03-01 is engineered for larger thermal expansions requiring the full 101.6 mm (4.00 in) stroke.
• Selection Advice: Calculate your turbine casing's maximum anticipated thermal growth during cold-to-hot transitions. If expected expansion exceeds 50 mm, select the 24765-03-01 to prevent core saturation or plunger bottoming out.

Installation Guide & Mounting Best Practices

• Secure the transducer mounting foot rigidly to the turbine foundation or reference bracket using the 1/4-20 UNC-2A machine end.
• Connect the plunger tip securely to the turbine casing attachment point using the 6-40 UNF-2B core end thread.
• Ensure the spring return mechanism maintains smooth, binding-free linear travel across the full 101.6 mm stroke without lateral side-loading.
• Shield and ground the 25 AWG Teflon-insulated lead wires properly to prevent electrical noise induction from nearby heavy-duty actuators.

Typical Equipment & Application Scenarios

• Large Steam Turbines: Monitoring high-pressure and intermediate-pressure cylinder thermal expansion relative to the foundation.
• Gas Turbines: Tracking axial casing growth during rapid startup and shutdown cycles.
• Industrial Compressors: Measuring structural frame displacement under high operating temperatures.

Diagnostic Capabilities & Maintenance

• The 10 Hz frequency response filters out high-frequency mechanical dither while capturing true thermal growth trends.
• Built-in spring return architecture ensures positive continuous contact with the moving casing, eliminating lost motion errors.
• Rugged Series 400 magnetic stainless steel body resists corrosive steam environment degradation.

Packaging, Warranty & Shipping

• Package List: 1 x Bently Nevada 24765-03-01 Case Expansion Transducer Assembly unit.
• Warranty: Backed by a comprehensive 12-month quality assurance warranty.
• Logistics: Rapid 24-48 hour dispatch via Fedex, UPS, and DHL.

Buying Guide & Selection Tips

• Verify that your monitoring rack supplies a stable +24 Vdc excitation voltage capable of handling at least 30 mA per transducer channel.
• Check physical clearance dimensions around the turbine bearing pedestal to accommodate the 117 mm width and 88.9 mm height profile.

Frequently Asked Questions

Question
What is the total linear measuring range of the 24765-03-01 transducer?

Answer
The -03 configuration provides an extended linear measurement range of 101.6 mm (4.00 in).

Question
What purpose does the -01 spring option serve in this assembly?

Answer
The -01 suffix indicates an integrated spring return mechanism that maintains continuous mechanical contact between the plunger and the expanding turbine casing.

Question
What power supply is required to excite this DC LVDT assembly?

Answer
It requires an input power source of +24 Vdc with a current capacity of at least 30 mA.

Question
What are the environmental operating temperature limits for the unit?

Answer
The operating temperature range spans from -18°C to +71°C (0°F to +160°F), with environmental limits extending up to +85°C.

Question
How is the transducer connected mechanically to the turbine casing?

Answer
It features a 6-40 UNF-2B thread on the core end for the plunger attachment and a 1/4-20 UNC-2A thread on the machine end for the body bracket.

Global PLC Spare HUB's Insight

Global PLC Spare HUB's Insight reveals that erratic jumps in case expansion readings during turbine load changes are frequently caused by mechanical binding of the LVDT core rather than electrical faults. If the mounting bracket shifts slightly due to thermal gradients, side-load forces are transmitted directly to the 6-40 UNF plunger tip, causing premature wear on the internal coil form. Field engineers must use alignment gauges during initial installation to ensure the transducer body and moving plunger remain perfectly axial throughout the complete thermal expansion stroke.

Tags