Judging Transformer Faults: Techniques from Abnormalities in Appearance, Color, Sound, Temperature, and Oil Level
When a transformer malfunctions, its external appearance often undergoes various changes, typically accompanied by alterations in the color, odor, sound, temperature, oil level, and load of certain parts. These changes play a role in analyzing and comprehensively diagnosing the nature, extent, trend, and severity of the transformer fault.
1. Abnormal Transformer Appearance
(1) Cracking or damage of the explosion-proof cylinder film: If the explosion-proof cylinder film is damaged, it will render the explosion-proof tube ineffective, allowing water and moisture to enter the transformer and cause insulation dampness.
(2) Flashover discharge on bushings: Flashover discharge on bushings can cause heating, aging, short circuits, and even explosions.
(3) Oil leakage: Oil leakage is a common problem in transformers, mainly occurring at the joint between the top cover and the main body, the oil drain valve, and the radiator.
2. Abnormal Transformer Color
(1) Abnormalities caused by overheating at wire clamps: Loose connections at the clamping points between bushings and equipment wires, severe oxidation of contact surfaces, etc.
(2) Abnormalities caused by severe contamination or damage of bushings: Severe contamination or damage of bushings can lead to flashover discharge, producing a special burnt odor.
(3) Rapid discoloration of silica gel: Poor sealing of the silica gel tank, cracks or damage in the silica gel glass cover, or no oil or low oil level at the bottom of the silica gel tank.
(4) Gas present in the transformer gas relay.
3. Abnormal Transformer Sound
(1) Increased AC hum: This may indicate overvoltage or overload conditions.
(2) Presence of noise: If the sound is louder than normal with obvious noise, it may be due to loose internal clamps or screws pressing the iron core, causing increased vibration of the silicon steel sheets.
(3) Accompanied by discharge sounds: If there is internal discharge, the transformer should be immediately de-energized for inspection.
(4) Mixed with boiling water sounds: If there is a boiling water sound and rapid temperature changes, it may indicate severe overheating due to a short circuit or poor tap changer contact.
(5) Mixed with crackling sounds: If the sound contains uneven crackling, it may be due to insulation breakdown inside the transformer or on its surface. The transformer should be immediately de-energized for inspection.
4. Abnormal Transformer Temperature
(1) Temperature abnormalities caused by internal faults: Internal faults such as overheating or multiple grounding points of the iron core can cause abnormal temperatures.
(2) Temperature abnormalities caused by blocked radiator valves: When the radiator valves are forgotten to be opened after new installation or major overhaul.
(3) Temperature abnormalities caused by blocked breather or severe oil leakage.
(4) Temperature abnormalities caused by abnormal operation of the cooling device.
5. Abnormal Transformer Oil Level
(1) False oil level: Causes of false oil level during operation include blockage of the oil level gauge tube, blockage of the oil conservator breather, and blockage of the explosion-proof tube vent.
(2) Low oil level: Low oil level can cause light gas relay operation, and in severe cases, expose internal windings and reduce insulation.
