Danfoss Turbocor TT Series Service Manual page 262

Motor/System Trigger
Status Description Method
Generator Mode DFT
Active
EEPROM INS
Checksum Fault
SCR Ripple AFT
Voltage Fault
Page 262 of 294 - M-SV-001-EN Rev. H 1/23/2023
Troubleshooting
Compare the Back EMF value to the displayed readings in the Compressor Monitor Tool and Fault
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and Event Log details to determine conditions related to the fault.
Permanent damage to Back EMF can be caused by insufficient motor cooling, repeated overheating
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of cavity, faulty Inverter, faulty BMCC, repeated Rotor Starting Torque or Single phase Over-Current
faults. Refer to Inverter Error on page 260.
Verify the Inverter. Refer to Section 4.22.2 I nverter Verification on page 176.
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Verify the Stator. Refer to Section 4.23.4 M otor Verification on page 195.
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Indicates, at greater than 0 RPM, the measured actual DC Bus voltage has fallen below the Generator
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Mode Enabled Level value. Also, could be electronic "noise" when no actual drop in voltage has
occurred.
Measure the incoming main AC voltage.
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Measure the DC bus voltage using the DC Bus Test Harness.
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Compare the measured voltages to the displayed readings in the Compressor Monitor Tool and Fault
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and Event Log details to determine conditions related to the fault.
Typically, this fault is recorded when power to the compressor is removed while it is running.
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Indicates there is an error reading the EEPROM in the BMCC.
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Perform a bearing calibration and save to EEPROM, cycle the power.
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If the error is still present, the BMCC must be replaced.
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Suggests that a voltage or current imbalance may exist between the incoming AC phases to the
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SCRs.
Measure the difference in current and voltage between the AC phases.
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If there is a current imbalance (more than 5%) between the phases, verify the incoming AC power
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supply.
Review the Compressor Monitor Tool for SCR Voltage Ripple readings at the time of the fault.
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Phase imbalance can also be caused by a faulty SCR, SCR Gate, Gate control from the Soft Start
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Board, or a faulty power capacitor.
Verify the SCRs. Refer to Section 4.18.2 S CR Verification on page 142.
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Verify the Soft Start Board. Refer to Section 4.14.2 S oft Start Verification on page 115.
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