Common Faults and Quick Solutions for Oil-Immersed Distribution Transformers
Time：2025-11-29 Auther：ZTelec-www.ztelectransformer.com
Oil-immersed distribution transformers are widely used in urban and rural power networks, industrial facilities, and commercial infrastructures. Once a failure occurs, it may lead to power outages, equipment shutdowns, and economic losses. Understanding common transformer faults and mastering quick troubleshooting methods helps operation and maintenance personnel improve reliability, reduce risks, and extend transformer service life.
Seven Common Faults and Quick Solutions
1. Insulating Oil Deterioration
Symptoms include darkened oil color, increased acid value, and decreased breakdown voltage. Deteriorated oil weakens insulation strength and can result in internal arcing or short circuits.
Quick Solutions:
Perform oil sample tests such as chromatography and physicochemical analysis to determine deterioration levels. Use vacuum oil filtration to remove moisture and gases. Replace expired silica gel with dry blue silica gel.
2. Oil Leakage
Oil stains may appear on transformer valves, flanges, welds, or accessories. Continuous leakage causes low oil level, reduced insulation, and increased overheating risks.
Quick Solutions:
Clean the leakage area, replace aged sealing rings, and repair weld defects. After repair, refill the transformer with the same type of insulating oil if the oil level is below standard.
3. Abnormal Temperature Rise
Excessive top oil temperature indicates insulation aging, overloaded operation, or cooling system failure. Overheating severely shortens the transformer’s service life.
Quick Solutions:
Check load condition and reduce load if necessary. Clean radiator fins using air or water. Inspect fan motors and oil pumps for faults. If the problem persists, perform oil chromatography to detect internal overheating.
4. Breather Failure
If the silica gel inside the breather quickly turns pink or red, moisture is entering the oil conservator, accelerating oil deterioration.
Quick Solutions:
Replace the silica gel with dry blue silica gel. Ensure the oil seal cup contains sufficient insulating oil for proper air filtration.
5. Tap Changer Failure
Difficult operation, abnormal DC resistance, or poor contact may cause localized overheating and damage to the tap changer or windings.
Quick Solutions:
Perform chromatography to analyze acetylene (C₂H₂), a gas indicating arcing. After power-off, have professionals inspect contacts and operating mechanisms. Repair or replace damaged parts.
6. Gas Protection Activation
Light gas signals indicate minor internal faults, while heavy gas trips signify severe internal problems such as arcing or winding failure.
Quick Solutions:
For light gas: Record the alarm, observe operation status, and collect gas samples for testing. If non-flammable, it may be air. Continue monitoring.
For heavy gas: De-energization is mandatory. Analyze gas composition and measure DC resistance and insulation resistance before deciding on overhaul.
7. Bushing Flashover or Explosion
Discharge marks, cracks, or explosions on the bushing surface may cause phase-to-phase faults or grounding failures.
Quick Solutions:
Shut down the transformer immediately. Replace the damaged bushing. Enhance maintenance by cleaning bushings regularly and installing bird guards.
How to Prevent Oil-Immersed Transformer Failures?
Regular Inspection (6–12 Month Cycle)
Dissolved gas analysis (DGA), oil quality tests (breakdown voltage, moisture, acid value), temperature controller calibration, and infrared scanning of bushings.
Operating Environment Requirements
Ensure proper ventilation, avoid corrosive gas environments, and maintain a solid, vibration-proof foundation.
Proper Installation and Commissioning
Conduct acceptance tests according to standards, minimize vibration during transport, and follow vacuum oil filling procedures strictly.
Oil-immersed distribution transformer failures typically show clear warning signs. By identifying early symptoms, applying rapid troubleshooting techniques, and performing scientific preventive maintenance, power operators can greatly enhance reliability, reduce downtime, and ensure safe, efficient, and economical power distribution.
