The fault diagnosis and troubleshooting of synchronous transformers require a combination of electrical characteristics, physical phenomena, and historical data to quickly locate problems through systematic analysis. The following is a step-by-step diagnosis and exclusion strategy:

The fault diagnosis process of synchronous transformer:

1. Preliminary inspection

Appearance inspection:

Check whether the transformer casing, wiring terminals, and insulation layer are damaged or aged (such as cracking, discoloration, oil leakage).

Observe whether the heat dissipation device (such as radiator, fan) is working properly and whether there are any blockages or oil stains.

Basic parameter detection:

Measure input/output voltage and current to confirm compliance with rated values.

Check the temperature rise of the winding (infrared temperature measurement or temperature sensor), abnormal temperature rise may indicate overload or internal short circuit.

2. Electrical characteristic testing

Insulation resistance test:

Use a megohmmeter (shaker) to measure the insulation resistance between the primary and secondary windings, as well as between the winding and ground.

Normal value: Usually should be greater than 10M Ω (refer to the equipment manual for details).

Abnormal judgment: Low insulation resistance may be caused by moisture, insulation aging, or contamination.

DC resistance test:

Measure the DC resistance of the winding to determine if there is a turn to turn short circuit or poor contact (such as pin virtual soldering).

Unbalance rate: The difference in resistance between the windings of each phase of a three-phase transformer should be less than 5%.

Variable ratio test:

Check whether the primary to secondary voltage ratio meets the design value (such as 1:1 or customized transformation ratio).

Abnormal situation: If the ratio deviation is greater than ± 1%, it may indicate a magnetic circuit fault or winding short circuit.

No load test:

Apply rated voltage during secondary open circuit, measure no-load current and losses.

Abnormal judgment: Excessive no-load current may be due to a short circuit in the iron core or insufficient winding turns.

Load test:

Load test voltage regulation rate, efficiency, and temperature rise to verify performance under rated load.

3. Waveform analysis and dynamic testing

Oscilloscope monitoring:

Observe the waveform of input/output voltage and current, and check for distortion (such as harmonics and oscillations).

Common anomalies: saturated waveform (iron core flux overflow), spike pulse (switch noise).

Frequency response analysis:

Test the frequency characteristics of transformers by scanning frequency signals to determine winding distribution capacitance or magnetic resonance issues.

4. Special fault troubleshooting

Iron core malfunction:

Symptoms: surge in no-load current, abnormal noise, and uneven heating.

Inspection: Disassemble and inspect whether the silicon steel sheet of the iron core is short circuited (with damaged insulation paint), loose, or deformed.

Interturn short circuit:

Symptoms: Local overheating, burnt insulation, and unstable output voltage.

Inspection: Short circuit the winding layer by layer and test the resistance in sections, or use a turn to turn tester.

Magnetic circuit failure:

Symptoms: Ratio shift and increased no-load loss.

Inspection: Check whether the air gap of the iron core is too large and whether the magnetic shielding is ineffective.

5. Historical data analysis

Compare the operating data before and after the fault (such as temperature rise curve, load rate, ambient temperature) to identify progressive faults (such as insulation aging).

Based on equipment maintenance records, determine whether the malfunction is caused by long-term overload, frequent start stop, or environmental corrosion.

Preventive maintenance strategy for synchronous transformers:

1. Regular testing

Conduct insulation resistance, transformation ratio, and no-load tests every quarter, and record data trends.

Disassemble and inspect the iron core and winding status every year, clean up oil stains and dust.

2. Operation monitoring

Install temperature sensors and current monitoring devices to track temperature rise and load rate in real-time.

Avoid long-term overload operation and leave a sufficient power margin of 20% to 30%.

3. Environmental control

Keep the transformer room dry (humidity<70%) and install dehumidification equipment.

Stay away from corrosive gases (such as acid mist, salt mist) and dust environments.

4. Operating standards

Prohibit input voltage from exceeding the rated range.

Shorten operating time under light or no-load conditions to avoid overheating caused by ineffective power consumption.