Configured for absolute structural thermal growth measurement in large steam turbine housings, the Bently Nevada 24765-02-01 (24765 DC LVDT Assembly) provides direct physical/electrical execution. This linear variable differential transformer utilizes internal conditioning circuitry to convert mechanical armature travel into a highly linear DC voltage output, allowing the continuous tracking of machine casing expansion relative to the foundation floor block during thermal transients.

Selection Matrix Breakdown

• 24765 : Base Model Identifier for the DC Linear Variable Differential Transformer Assembly
• -02 : Linear Range Option: 50.8 mm (2.00 inches) mechanical stroke length
• -01 : Spring Option: Internal spring return mechanism included for continuous surface contact

Core Hardware Parameters

Rotor Dynamics and Cross-Talk Suppression

The 24765-02-01 works alongside proximity probe systems to maintain independent verification profiles of overall structural machine expansion. While eddy-current probe scaling is dedicated to high-frequency fluid-film bearing vibrations and -10 VDC gap voltage targets, this DC LVDT addresses slow-moving, low-frequency structural displacements. Internal core insulation layouts prevent high-frequency electrical fields and electromagnetic cross-talk from corrupting the low-voltage DC linear tracking output, ensuring clean displacement values are transmitted back to the primary Turbine Supervisory Instrumentation (TSI) processing card.

Supply Manifest

• 1 x Bently Nevada 24765-02-01 DC LVDT Assembly
• 1 x Factory Calibration Data Card
• 2 x Hexagonal Jam Mounting Nuts

Mechanical and Field Setup Protocols

• Surface Interface Check
  • The machine casing contact block must be machined parallel to the LVDT core travel axis to prevent sideload friction on the internal bearing guides.
• Armature Centering Alignment
  • Pre-load the internal spring return assembly to the mid-point of its physical 50.8 mm stroke length during ambient machine turnaround to allow symmetric tracking.
• Conduit Routing Restraints
  • Isolate the LVDT direct current signal wiring within dedicated flexible steel conduits to prevent electromagnetic induction from nearby AC power lines.
• Shield Ground Isolation
  • Terminate the cable outer foil shield strictly at the TSI monitor panel chassis common grounding strip while leaving it ungrounded at the LVDT head.

Technical Validation FAQs

• Can this LVDT assembly be serviced or replaced while the machine is running?

  Yes, because this device tracks external casing growth rather than internal rotor dynamics, the physical mounting can be handled externally without breaching the machine lubrication boundary.

• What happens if the LVDT core experiences mechanical displacement beyond the 50.8 mm range?

  Displacements past the 50.8 mm threshold cause severe output scale factor non-linearity, and the signal voltage will saturate near its positive or negative rail limits.

• Does this specific hardware variant require an external AC carrier amplifier module?

  No, the 24765 series contains internal electronic oscillators and demodulator circuits that accept standard DC input power and generate a pre-conditioned DC voltage output.

• How does a 15 Hz frequency response affect the system's ability to track machinery faults?

  The 15 Hz cutoff is optimized for slow thermal expansion tracking while suppressing high-frequency structural building noise and casing vibrations from affecting the measurement.

• What is the consequence of applying uneven force to the internal spring return shaft?

  Excessive sideload or bending forces cause binding within the precision internal guide bearings, leading to permanent calibration drift or premature mechanical stick-slip errors.

• Is it necessary to perform field calibration checks on the 0.404 V/mm scale factor?

  The scaling factor is set at the factory, but field verification using a micro-meter calibration jig is required before final mechanical lock-in to confirm loop integrity.

• What failure state is indicated if the LVDT output drops to exactly 0 VDC?

  A constant 0 VDC output typically indicates an open circuit loop fault, a loss of primary DC excitation power, or a total grounding short circuit in the interconnecting cable.

• How should the physical probe tip be protected against outdoor atmospheric corrosion?

  The assembly features a rugged protective housing, but outdoor field deployment requires an external weather-proof protective boot or metal shield enclosure to prevent grit binding.