Sveba-Dahlen tJF

What does Sveba-Dahlen tJF mean?

The SD-180 converter has detected that its IGBT (Insulated Gate Bipolar Transistor) output module has overheated. The documented causes for this model are specifically a special motor or a motor whose power rating is not matched to the converter, or a motor that is not connected to the converter at all. An unloaded or mismatched drive output can cause abnormal switching losses that result in IGBT junction overheating.

Symptoms

• tJF displayed on the SD-180 touchscreen; converter shuts down to protect the output stage
• Converter heatsink is hot to the touch — measurably above ambient temperature — at the time of fault
• Fault occurs after extended run time rather than at startup, indicating thermal accumulation
• Fault may clear after the converter cools down but returns after a similar runtime, confirming a thermal issue
• Motor output cables confirmed disconnected or absent when tJF is triggered

Common causes

• Special motor or motor with power not adapted to the converter — motor kW rating mismatched to the SD-180's rated output (primary documented cause)
• Motor not connected to the converter output — drive switching into an open circuit causes excessive IGBT losses
• Converter cooling fan failed or blocked, reducing heatsink cooling capacity
• Ambient temperature around the SD-180 cabinet exceeding the converter's rated operating temperature
• Incorrect motor parameters (rated power, current) entered in the drive causing the converter to switch at inappropriate levels
• Blocked converter ventilation slots or dust-clogged heatsink fins reducing thermal dissipation

Diagnostic steps

1. 01

   Verify motor is physically connected to the converter output

   With power isolated, confirm that all three motor phase cables (U, V, W) are correctly terminated at both the converter output terminals and the motor terminal box; an open-circuit output is a direct documented cause of tJF on this model.

2. 02

   Confirm motor power rating matches the SD-180 converter rating

   Compare the motor nameplate kW rating to the converter's rated output power on its nameplate and in the SD-180 documentation; a significant mismatch — particularly an undersized motor — can cause abnormal IGBT operating conditions.

3. 03

   Inspect and clean the converter heatsink and cooling fan

   With the converter de-energised and cooled, inspect the heatsink fins for dust and grease accumulation and verify the internal cooling fan is operational; clean the heatsink with compressed air and confirm the fan spins freely.

4. 04

   Check the installation environment temperature

   Measure the ambient temperature inside the electrical cabinet or enclosure housing the SD-180 during operation; if the ambient temperature exceeds the converter's specification, improve cabinet ventilation or install additional cooling.

5. 05

   Verify motor parameters in the converter configuration

   Check that the motor's rated power, current, voltage, frequency, and speed are correctly entered in the Schneider drive parameters to ensure the converter's thermal model and switching strategy are appropriate for the connected motor.

6. 06

   Allow converter to cool fully, then reset and test

   After addressing the root cause, allow the converter heatsink to return to ambient temperature, clear the tJF fault on the SD-180 touchscreen, and run a complete bake cycle while monitoring for fault recurrence.

When to call a professional

Escalate to a Sveba-Dahlen authorised technician if tJF recurs after the motor connection and rating are confirmed correct and cooling is adequate, as this may indicate internal IGBT degradation or failure requiring converter repair or replacement. IGBT module replacement inside the Schneider converter requires specialist drive service capability and must not be attempted without proper training, tools, and access to the correct replacement parts.