Transformer Over Temperature

What does F68 mean?

This Automatic Fault occurs when the transformer temperature exceeds 140 °C, leading to a shutdown to prevent damage. The fault automatically clears when the transformer temperature falls to 125 °C.

• Sustained overload condition exceeding the transformer's continuous rated output power (e.g., 110% load for more than 30 seconds).
• Failure of the cooling fan or significant obstruction of airflow around the transformer windings and heatsinks.
• Ambient temperature within the enclosure exceeding the maximum specified operating limit (e.g., above 50°C).
• Internal shorted turns within the transformer primary or secondary windings, leading to increased localized heating.
• Faulty temperature sensor (e.g., NTC thermistor or PT100) providing an erroneously high reading (e.g., resistance drift).
• Accumulation of dust and debris on transformer fins and cooling passages reducing thermal dissipation efficiency.

Click steps to track your progress.

1. 1

   1. Verify the actual transformer casing temperature using an infrared thermometer (e.g., Fluke VT04A) and compare it against the inverter's internal sensor reading.

2. 2

   2. Inspect the operation of the cooling fan (e.g., fan motor voltage) and clear any obstructions from the airflow path to the transformer.

3. 3

   3. Measure the load current on the transformer's secondary windings (e.g., clamp meter on L1, L2, L3) and compare it to the transformer's nameplate rated current.

4. 4

   4. Check the ambient temperature inside the enclosure using a calibrated thermometer and ensure it is within the operational range specified in the inverter datasheet.

5. 5

   5. Disconnect the transformer's temperature sensor leads and measure its resistance value, comparing it to the manufacturer's resistance-temperature curve.

6. 6

   6. If an overload is confirmed, reduce the connected load or adjust system parameters (e.g., Parameter P1-54 for current limit) to prevent exceeding transformer ratings.