I. A Typical Case of Transformer Abnormal Noise
During routine inspection at a substation, maintenance personnel detected a slight discharging sound with varying intensity from a 250 kva 3 phase transformer. Infrared inspection showed no abnormalities. Further investigation confirmed that the discharge sound of this 250 kva power transformer originated from the grounding terminal of the C-phase high-voltage bushing. Disassembly revealed loose screws on the sealing flange (lacking anti-loosening washers), which increased the grounding resistance and created a floating potential that discharged. By adding anti-loosening washers and tightening all loose screws, the abnormal noise of the 250 kva 3 phase transformer was completely eliminated, and it resumed normal operation.
II. Types and Characteristics of Transformer Abnormal Noise
1. Uniformly Increased Humming
Characteristics: Louder than normal but regular "humming" sound
Possible Causes: Power grid overvoltage (single-phase grounding or electromagnetic resonance), transformer overload
Diagnosis: Check if voltage and current meters exceed normal ranges. For 250 kva power transformer, focus on verifying if the load exceeds the rated value.
2. "Clinking" or "Rustling" Noise
Characteristics: Discontinuous mechanical collision or friction sounds
Possible Causes: Loose core clamping bolts, loose internal components, external collisions, worn cooling fan bearings
Diagnosis: Locate the sound source and press gently at the loudest point. For 250 kva 3 phase transformer, focus on the cooling fan and cabinet contact due to its compact structure.
3. "Crackling" Discharge Sound
Characteristics: Sharp discharge sounds, possibly with visible blue corona at night
Possible Causes: Internal discharge (poor core grounding), external discharge (polluted bushings, poor screen terminal grounding)
Diagnosis: Inspect for visible corona at night. The grounding screws of 250 kva power transformer are smaller and more prone to loosening, requiring key inspection.
4. "Gurgling" Boiling Sound
Characteristics: Sound similar to boiling water
Possible Causes: Severe internal winding faults (e.g., turn-to-turn short circuit) causing local oil boiling
Diagnosis: Check for abnormal oil temperature/level. This causes great damage to 250 kva 3 phase transformer windings and requires immediate shutdown.
III. In-depth Cause Analysis
|
Noise Type |
Root Causes |
Notes for 250kVA Models |
|---|---|---|
|
Uniform Increase |
Overvoltage or overload increases core magnetic density |
250 kva power transformer has concentrated insulation margin; long-term overvoltage accelerates aging |
|
Mechanical Noise |
Loose components or external collisions |
250 kva 3 phase transformer has compact structure; loose bolts have more obvious impact |
|
Discharge Sound |
Poor grounding or insulation defects |
Small screen terminal screws of 250 kva power transformer lack anti-loosening washers commonly |
IV. Systematic Solutions
1. Basic Handling Process
Initial diagnosis: Listen to sounds and monitor meters. For 250 kva 3 phase transformer, record three-phase current balance.
Infrared inspection: Focus on bushing terminals for overheating.
Report to dispatcher: Do not operate without confirmation.
Shutdown inspection: Mandatory for discharge or "gurgling" sounds; prepare load transfer plan first.
Targeted maintenance: Add anti-loosening washers, clean bushings, etc.
Testing & restart: Verify insulation and grounding before operation.
2. Key Solutions for Common Issues
Overload-induced Noise
Temporary overload: Monitor load and duration (1.2x rated load for ≤2 hours for 250 kva 3 phase transformer). Chronic overload: Transfer load or upgrade capacity.
Discharge from Poor Grounding
Check and tighten screen terminal screws; add anti-loosening washers. Measure grounding resistance (≤0.1Ω). For 250 kva power transformer, seal thoroughly to prevent water ingress.
"Gurgling" Sound
Shut down immediately. Conduct winding resistance test, insulation test and oil analysis. Repair or replace if necessary as damage to 250 kva 3 phase transformer windings is irreversible.
V. Preventive Maintenance Tips
Weekly inspection: Monitor sound, temperature and oil level; record load-sound correlation for 250 kva power transformer.
Monthly infrared scan: Focus on bushing terminals and connections.
Quarterly grounding check: Verify screen terminal resistance and anti-loosening measures for 250 kva 3 phase transformer.
Load management: Ensure three-phase balance (unbalance ≤10% for 250 kva power transformer).
VI. About JINSHANMEN TECHNOLOGY CO., LTD
JINSHANMEN TECHNOLOGY CO., LTD specializes in R&D and production of power transmission and distribution equipment. Our main products include oil immersed power transformers, dry-type power transformers, oil immersed three-dimensional coiled power transformers, dry-type three-dimensional coiled power transformers, mining explosion-proof dry-type transformers, mining explosion-proof mobile substations, amorphous alloy power transformers, on load capacity regulating power transformers, locomotive dry-type transformers, as well as prefabricated substations, modular substations, wind energy box type substations, high and low voltage switchgear and other transmission and distribution equipment. We provide professional technical support and customized solutions for 250 kva power transformer and 250 kva 3 phase transformer operation and maintenance to ensure long-term stable equipment operation.
VII. Conclusion
Abnormal transformer noise is an early warning of potential faults. For 250 kva power transformer and 250 kva 3 phase transformer widely used in industrial and civil scenarios, poor screen terminal grounding is a common cause that can be prevented by regular inspection and proper fastening. Establish sound files, conduct quarterly grounding tests and optimize maintenance procedures based on 250kVA model characteristics to ensure safe operation.