Danfoss Turbocor TT Series, Service Manual

Page: 237 / 294

5. Test each pin to ground; reading should be open or infinite.
6. If the integrity of the bearing sensor feedthrough is in question, isolate the compressor, recover the
refrigerant according to industry standards, remove the feedthrough and repeat the above steps
directly at the internal sensor connector.
Table 4-48 Bearing Sensor Coil Resistance
Pin Combination Front Sensor Rear Sensor
5-2 2.0Ω to 3.5Ω 2.0Ω to 3.5Ω
5-3 2.0Ω to 3.5Ω 2.0Ω to 3.5Ω
6-7 2.0Ω to 3.5Ω 2.0Ω to 3.5Ω
6-8 2.0Ω to 3.5Ω 2.0Ω to 3.5Ω
1-4 2.0Ω to 3.5Ω Open
1-9 2.0Ω to 3.5Ω Open
Figure 4-263 Bearing Sensor Pin Locations
4.30.3.2 Bearing Sensor Cable Verification
If any unexpected behavior exists, it could be the result of an intermittent connection. If not properly diagnosed, the
issue may lead to unnecessarily replacing components in the bearing control loop, such as the BMCC, PWM, Bearing
Power Feedthroughs, or Bearing Sensor Cables.
This section provides verification details should a compressor experience a bearing fault type where other
verification, testing, and troubleshooting processes have not been able to identify the cause.
1. Remove the Modbus and Interlock connections from the compressor I/O Board.
2. Connect to the compressor using the SMT software and open the Calibration Tool.
3. Perform a bearing calibration by clicking on “Start Calibration.”
4. After calibration is complete, review the data. Do all orbits and gain values appear normal?
a. Yes: Continue to Step 5.
b. No: Continue to Step 7.
5. Perform a validation by clicking on “Validate.”
6. After validation is complete, did the shaft levitate as expected?
a. Yes: Continue to Step 21.
b. No: Continue to Step 7.
7. Isolate compressor power.
8. Remove the Service Side Cover. Refer to Section 4.1.3.1 Service Side Cover Removal and Installation on
page 54.
9. Disconnect the Bearing Sensor Cables from J9 and J10 at the Backplane.
M-SV-001-EN Rev. H-1/23/2023 Page 237 of 294