Danfoss Turbocor TT Series Service Manual page 256

Compressor Status
Trigger Method
Description
High Discharge AFT
Temperature Fault
Low Suction Pressure DFT
Fault
High Discharge AFT
Pressure Fault
3-Phase Over-Current AFT
Fault
High Cavity AFT
Temperature Fault
Page 256 of 294 - M-SV-001-EN Rev. H 1/23/2023
Troubleshooting
Verification on page 73.
Verify the solenoid actuators. Refer to Section 4.6.3 S olenoid Verification on page 73.
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Verify the Serial Driver. Refer to Section 4.26.3 S erial Driver Verification on page 217.
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Review the fault log for actual Inverter temperature and other conditions that are
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recorded at the time of fault.
The I nverter requires replacement i f the embedded temperature sensor is determined
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faulty.
Suggests insufficient charge (i.e., low gas), the condenser temperature has increased,
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check valve has failed to open or the compressor has been running in surge condition
for an extended period of time.
Check the chiller gas charge, entering condenser air/water conditions and operational
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settings.
Verify check valve opens during compressor operation.
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Verify the discharge pressure/temperature sensor. Refer to Section 4.32.3
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Pressure/Temperature Sensor Verification on page 246.
Review the fault log for actual discharge temperature and other conditions that are
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recorded at the time of fault.
Suggests insufficient charge, insufficient system load, or a sudden drop in evaporator
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entering air/water temperature or flow.
Check the charge, system load and entering air/water conditions.
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Review the fault log for actual suction pressure and other conditions that are recorded at
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the time of fault.
Consequence:
Results in an Instantaneous Lock-Out Fault - pre-CC4.0.0
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Recommendation:
Suggests the condenser may be faulty or insufficient air/water flow.
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Check the condenser and air/water flow.
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Review the fault log for actual discharge pressure and other conditions that are recorded
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at the time of fault.
Consequence:
During startup mode, all alarms are ignored by the control system, but faults are not.
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Therefore, when the FLA current (3-Phase Alarm Limit) is reached, the compressor will
continue to accelerate if startup requirements are not satisfied. After Startup is
complete, alarms will slow the compressor speed. Results in an Instantaneous Lock Out
Fault - pre-CC4.0.0.
Requires a power cycle to reset.
Indicates the compressor is drawing current greater than the 3-Phase Current Fault
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Limit.
Recommendation:
Review the fault log for recorded 3-Phase Current level, demand, entering air/water
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temperature (if available) and other conditions that are recorded at the time of fault.
Usual causes are start speed set too high , minimum pressure ratio set too high at start-
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up, power control integral (loop) gain set too high. Can also be related to sudden
increase in load/demand or system changes.
Consequence
Indicates the motor cooling is insufficient.
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CAUTION: Repeated occurrences of this fault can result in shaft demagnetization or Back EMF is low