North Ghawar Maintenance Division
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System Description

The 3300 Series Proximity Transducer System measures machine vibration and the position of a shaft or other machine part relative to the location of the probe tip. The system consists of a 5 mm or 8 mm proximity probe, an extension cable and a Proximitor® sensor.

The components of the 3300 Transducer System are designed to work as a single unit and are calibrated for a target material that is AISI 4140 steel. The system measures displacement by using the eddy current principle and provides a negative voltage proportional to the distance between the target and the probe tip. This voltage signal may be applied to a monitor, portable instrumentation or diagnostic equipment.

    Application Advisory

The 3300 Proximity Transducer is designed for measuring position or vibration within a frequency range of 0 to 6.5 kHz. Typical applications of this system include radial vibration and position, axial position and Keyphasor® measurements.

    Application Alert

Although the terminals and connector on the Proximitor® sensor have protection against electrostatic discharge, take reasonable precautions to avoid electrostatic discharge during handling.

    Receiving, Inspecting, and Handling the System

The probe, extension cable and Proximitor® sensor are shipped as separate units and must be interconnected at the installation site by the user. Carefully remove all equipment from the shipping containers and inspect the equipment for shipping damage. If shipping damage is apparent, file a claim with the carrier and submit a copy to the nearest Bently Nevada office. Include part numbers and serial numbers on all correspondence. If no damage is apparent and the equipment is not going to be used immediately, return the equipment to the shipping containers and reseal until ready for use.

Store the equipment in an environment free from potentially damaging conditions such as high temperature or a corrosive atmosphere. See Specifications, pages 21, 23 and 24 for environmental specifications.


This section contains a checklist of items that you must consider when you install a 3300 Transducer system. For detailed information about designing installations for specific applications refer to document AN028.

    Installing the Probe

The following figures show the probe sizes and the minimum values for probe separation, side clearance and target configuration. Refer to Specifications for proper torque and the dimensions of the thread.Adjust the distance between the probe tip and the shaft using one of the methods shown in the following figure. The electrical method for setting the probe gap is preferred. (Refer to document AN028.)

Application Alert Mounting dimensions and target size affect the scale factor of proximity transducer systems. The minimum recommended dimensions above were chosen to minimize error yet retain flexibility for different mounting situations. Consult performance specification 155687 to determine the effect of each of the above factors for your particular installation.

    Mounting the Proximitor® Sensor

Mount the Proximitor® sensor in a location that is compatible with its environmental specifications. Consider the local electrical codes and the presence of hazardous or explosive gas at the installation site. (Refer to document AN015.)

    Routing the Extension Cable and Field Wiring

Route the extension cable using the following guidelines. (Refer to document AN028).

    Check that the extension cable and probe lead length add to equal the Proximitor® sensor system length. (For example, a 9 metre Proximitor® sensor will work with an 8 metre extension cable and a 1 metre probe.)

   Secure the extension cable to supporting surfaces by using mounting clips or similar devices.

   Identify the probe and both ends of the extension cable by inserting labels under the clear Teflon sleeves and applying heat to shrink the tubing.

   Join the coax connectors between the Proximitor® sensor, extension cable and probe lead. Tighten connectors as follows:

Connector Type Tightening Instruction
Two 3300 XL gold “click” type connectors Finger tight
Two non-XL connectors (“non-click”) or one non-XL connector and one 3300 XL connector Finger tight plus 1/8 turn using pliers

   Use either a connector protector or self-fusing silicone tape to insulate the connection between the probe lead and the extension cable. DO NOT use self-fusing silicone tape to insulate a connection made inside of a machine.

   If the probe is in a part of the machine that is under pressure or vacuum,seal the hole where the extension cable leaves the machine by using appropriate cable seals and terminal boxes.

Use the following wiring diagrams to connect the field wiring between the Proximitor® sensor and the monitoring instruments. (Refer to documents AN013 and AN015.)

    Maintenance and Troubleshooting

This section shows how to verify that the system is operating properly, adjust the system and identify parts of the system that are not working properly.

The transducer system does not require verification at regular intervals. You should, however, verify operation by using the scale factor verification on page 7 if any of the following conditions occur:

   components of the system are replaced or disturbed

   the performance of the system changes or becomes erratic

   you suspect that the transducer is not calibrated correctly

Use the adjustment procedure on pages 8 through 10 when a special calibration is required. For target materials other than AISI 4140 steel and for other special applications, contact your local Bently Nevada office.

Note: Hazardous Locations Area must be free of hazardous material before any maintenance or troubleshooting can be performed.

The scale factor verification and the adjustment procedure require the following instruments and equipment:

   Digital multimeter

    spindle micrometer

    fixed resistor

    10 kW 1% soldering iron and solder

    power supply (-24Vdc ±1)

The special calibration procedure requires the following additional items:

    variable resistor, 0 to 100 kW

    vulcanizing compound (for example, Dow 3110 RTV)

The scale factor verification and the adjustment procedure both use the test setup as shown in the following figure:

    Scale Factor Verification

If the incremental scale factor (ISF) or the average scale factor (ASF) of the system is out of tolerance, contact Bently Nevada Corporation for further information on possible calibration problems or perform the following adjustment.

    Adjustment Procedure

Application Alert Electrostatic discharge on the exposed calibration resistor terminals can cause the accuracy of the system to go out of specification or cause the system to fail. Use a grounding strap or equivalent precaution during this procedure.


This section shows how to interpret a fault indication and isolate faults in an installed transducer system. Before beginning this procedure, be sure the system has been installed correctly and all connectors have been secured properly in the correct locations.

When a malfunction occurs, locate the appropriate fault, check the probable causes for the fault indication, and follow the procedure to isolate and correct the fault. Use a digital voltmeter to measure voltage. If you find faulty transducers, contact your local Bently Nevada Corporation office for assistance.

The troubleshooting procedures use measured voltages as shown in the following figure and tables:

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