Bently Nevada 18745-03 Proximitor Sensor | 7200 Series Eddy Current Proximity Transducer

Overview:

The Bently Nevada 18745-03 is a critical component from the 7200 Series Proximity Transducer System. This Eddy Current Proximitor Sensor is designed to measure the static and dynamic distance between a probe and a target (typically a rotating shaft). It converts this distance into a proportional DC voltage, essential for monitoring machinery vibrations and positions. The 18745-03 model is specifically calibrated for a 5-meter total system length, making it ideal for applications requiring precise radial vibration, axial position, and speed measurements in turbines, compressors, and motors.

Key Features:

1. Eddy Current Measurement Technology:
   The 18745-03 Proximitor generates a high-frequency RF signal from the probe tip. When the probe approaches a conductive target, such as a metal shaft, eddy currents are induced in the target, causing energy loss. The proximitor detects this loss and calculates the "gap" or distance between the probe and the target.

2. Signal Conditioning and Output:
   This device serves as a signal conditioner, powering the probe and processing the return signal. The output typically comes in the form of a negative voltage, ranging from -2V to -18V DC, depending on the distance. The signal can be used to measure both static position (e.g., thrust or axial position) and dynamic vibration (AC component of the signal).

3. Calibration and System Length:
   The 18745-03 model is calibrated specifically for a total system length of 5 meters (16.4 feet), including both the probe's integral cable and any extension cable. Using a system length other than the calibrated 5 meters (e.g., a 9-meter setup) may lead to calibration inaccuracies.

4. Temperature and Environment Resistance:
   This sensor operates effectively in challenging industrial environments, with a wide operating temperature range of -35°C to +85°C (-31°F to +185°F). It is designed for long-term use in harsh conditions such as those found near rotating machinery.

5. Interchangeability within 7200 Series:
   The 18745-03 is a legacy component of the 7200 Series, known for its compatibility with various probes, including 5 mm and 8 mm proximity probes. While the 7200 Series has been largely replaced by newer systems such as the 3300 XL, it remains a widely-used, reliable choice for existing plants.

Technical Specifications:

Applications:

The Bently Nevada 18745-03 Proximitor Sensor is critical for accurate vibration and position monitoring in a variety of industrial machines, including:

• Turbines: Ensures precise monitoring of axial and radial position, as well as vibration.

• Compressors: Provides essential data for dynamic vibration and position measurements.

• Motors: Measures the shaft position and vibrations to protect motor health.

• Industrial Equipment: Commonly used in machinery protection systems, especially in environments where high precision is required.

Application Notes:

• API 670 Compliance: This Proximitor is designed to meet API 670 standards, ensuring reliable protection for critical machinery.

• Hazardous Area Use: Often used with Zener barriers or galvanic isolators for installations in Class I, Div 1 or Div 2 hazardous environments.

• Legacy Component: While this is part of the legacy 7200 Series, it remains effective for many existing installations, though newer systems like the 3300 XL are preferred for new installations due to enhanced performance.

Maintenance and Replacement:

When troubleshooting systems that use the Bently Nevada 18745-03 Proximitor Sensor, check for the following:

• Link Failures: Issues related to signal transmission between the probe and the proximitor.

• Communication Errors: Problems in transmitting distance data from the sensor.

• Control System Power Loss: Ensure all components are powered correctly and check for wiring issues.

Important: Always confirm that the probe, extension cable, and Proximitor are rated for the same system length (e.g., 5m) to ensure accuracy in measurements. Before replacing the sensor, de-energize the system and allow for proper discharge of capacitors.

Frequently Asked Questions (FAQ):

Q1: Can I use the 18745-03 Proximitor with a longer cable system?

No, the 18745-03 is calibrated for a total system length of 5 meters. Using a longer cable system will result in calibration errors, and a different model, like the 18745-04, should be used for a 9-meter system.

Q2: What types of probes are compatible with the 18745-03?

The 18745-03 works with 5 mm and 8 mm proximity probes, commonly used for measuring distances in rotating machinery.

Q3: How should I install the 18745-03 Proximitor?

The 18745-03 Proximitor can be mounted on a DIN rail using an adapter or in a bulkhead mount. Ensure that all wiring is properly connected and the system is powered down during installation.