What is the fault of dry type substation transformer noise?

1. Normal vs. Abnormal Sound Baseline

• Normal Sound: A low, uniform “hum” (caused by magnetic flux vibration in the iron core), stable and free of fluctuations.
• Abnormal Sound: Sudden increase in volume, or special sounds (discharge, boiling, crackling)—all indicate potential faults, even if current/voltage appears normal.

2. Common Noise Types & Fault Diagnosis

(1) Simple increase in noise (without special timbre)

• Core Fault: Internal clamping parts or core screws loosen, leading to increased vibration of silicon steel sheets.
• Key Feature: Noise is louder than normal but uniform; current/voltage may remain normal.
• Handling Measure: Inspect the core clamping structure after shutdown, tighten loose screws, and check for silicon steel sheet displacement.

(2) Discharge sound (sharp “sizzling” sound, accompanied by blue light

• Core Faults:
  1. Severe pollution of insulation bushings or poor contact of equipment terminals—blue corona/sparks appear near bushings at night or on rainy days.
  2. Electrostatic discharge of ungrounded parts inside the transformer, or poor contact of the tap changer.
• Handling Measure:
  • First, clean the insulation bushings and re-tighten terminal connections.
  • If sparks persist, stop operation immediately and conduct insulation resistance and partial discharge tests to locate the fault.

(3) The sound of boiling water (” gurgling “, accompanied by a sudden rise in temperature

• Core Fault: Transformer winding short circuit, or severe poor contact of the tap changer—causing local overheating.
• Key Feature: Sound mixes with boiling-like gurgling; temperature rises rapidly (no “oil position” change, as dry-type transformers have no oil).
• Handling Measure: Shut down the transformer immediately to avoid insulation breakdown or fire; test winding continuity and tap changer contact status.

(4) Crackling sound (uneven and crisp sound

• Core Fault: Internal or surface insulation damage of the transformer (e.g., turn-to-turn short circuit of windings, insulation layer cracking).
• Key Feature: Intermittent, uneven crackling sounds—indicating progressive insulation deterioration.
• Handling Measure: Stop operation at once; conduct insulation resistance and winding DC resistance tests to identify damaged insulation and repair/replace affected parts.

3. Critical Handling Principles

• Prioritize safety: For discharge, boiling, or crackling sounds, shut down immediately to prevent fault expansion.
• Avoid blind operation: Do not continue using the transformer due to “normal current/voltage”—hidden faults (e.g., loose core, insulation damage) may worsen over time.
• Post-repair verification: After handling, confirm the sound returns to normal and conduct electrical tests (insulation, resistance) before restarting.