PROXIMITY PROBE SYSTEMS CUSTOMER SUPPORT HUB

The calibration sheet shows nonlinear behavior beyond 70 mils (FFv^TM), 90 mils (8mm), 180 mils (11mm), 475 mils (25mm). Is this expected?

Yes. The stated calibrated linear range for this proximity probe system is 10-70 mil (for FFv^TM systems), 10-90 mils (for 8 mm systems), 20–180 mils (for 11 mm Systems) and 25-475 mils (for 25 mm Systems). At this time, linearity is not certified beyond 70, 90, 180, or 475 mils dependent on system type, and this limitation is documented in the system manual.

Beyond the calibrated linear range, some non‑linear behavior is expected. The system linearizes a fundamentally logarithmic sensor response, and behavior outside the certified range should not be interpreted as indicative of probe or driver performance within specification.

Can the 4–20 mA output range be expanded to past the current stated linear range?

No, not currently as part of the standard offering.

Must the voltage output connections remain isolated from the 4-20 mA power connections?

Yes. The voltage output connections must remain electrically isolated from the 4-20 mA power connections.

Specifically, the V_T ("-", typically GND on the voltage supply) connection must not be tied to the COM or VOUT connections. Shorting COM to V_T can result in permanent damage to the driver electronics.

A DM918-1A Voltage Regulator mitigates the damage done to the board if V_T is connected improperly.

Note that the outer shell of the BNC is tied to COM; if this is tied to the same node as V_T, permanent damage to the unit can occur.

Can I return my proximity probe system to CTC for recalibration?

No. Proximity probe systems are not accepted for return to CTC for recalibration. Instead, CTC provides an in-field verification solution to allow customers to check probe system performance on site. 

CTC offers the DT902 Series Proximity Probe Field Calibration Kit, which is designed to verify proximity probe system output and linearity in both shop and field environments.

The DT902 allows users to confirm probe performance across the calibrated linear range using a precision micrometer and a probe target material that matches the shaft material the driver was configured for. 

What should I do if the linear performance of the proximity probe system in the field does not match the calibrated performance supplied by CTC?

If the proximity probe system is not exhibiting the linear performance stated on the calibration sheet, review the following items before concluding there is a hardware issue:

1. Verify All Components are CTC PRO Line

• Confirm that the proximity probe, optional extension cable, and driver are all CTC PRO Line components.
  
  
• Mixing probes, cables, and/or drivers from different manufacturers, or combining PRO Line components with non-PRO-Line hardware, can result in non-linear behavior and invalid calibration comparisons.
  
  

2. Confirm Stated Total System Length Matches the Driver Configuration

• Verify that the stated probe length + stated optional extension cable length matches the stated system length that the driver is configured for.
  
  
• Use the driver part number and reference the CTC website or datasheet to confirm the intended system length configuration.
  
  
• A mismatch between stated system length and driver configuration is a common cause of linearity issues.
  
  

3. Ensure All Components Are the Same System Series

Make sure all part numbers belong to the same proximity probe system family, for example:

• 8 mm
  
  
• 11 mm
  
  
• FFv^TM
  
  
• 25 mm

Mixing components from different size systems (even within the PRO Line) will result in non-linear behavior.

4. Confirm Target Material Matches Driver Configuration

• The shaft material being monitored must match the target material to which the driver was factory configured.

Important notes:

• If the shaft has a coating (e.g. chrome plating, spray coatings, cladding), this may impact effective target material response and linearity.
  
  
• Coated or non-homogeneous materials may require additional evaluation or may fall outside standard calibration assumptions.
  
  

5. Verify Measurement Within the Certified Linear Range

• Ensure measurements are being taken within the calibrated linear range stated on the calibration sheet and system manual.
  
  
• Behavior outside the certified linear range is expected to deviate from the linearity and should not be used for comparison.
  
  
  

6. Check Mechanical Setup and Alignment (If Performing Field Verification)

• Ensure the proximity probe and target are clean, undamaged, and properly aligned.
• Confirm the probe tip and target surface are parallel and centered.
  
  
• Mechanical misalignment or deflection can affect observed linearity even if the electronics are correct.
  
  
• Ensure probes have appropriate clearance as stated in the system manual.

On Voltage Drivers, should the BNC provide the same output as the terminal blocks?

Yes. if you are not seeing the same values, it is likely due to the input impedance of the device connected to the BNC output.

The BNC output requires an isolated, high-input impedance measurement device to avoid signal output plateauing. Most digital multimeters have an input impedance of approximately 10 MΩ and are suitable for making these measurements. Analog multimeters and other devices without input impedance below 10 MΩ may result in signal output plateauing. 

For example, the Alta Solutions AS1250 does not have sufficient input impedance to accurately read data directly from the isolated BNC output. However, measurements taken from the terminal block connections will provide accurate results.