How To Calculate The Age Of The Transformer? Just Look At The Colour Of the Oil!
In the hidden world of power equipment, transformer oil is like a mobile vital signs instrument. Shanghai a substation engineers found that the operation of 8 years of transformer oil from the honey colour into a deep amber, the furfural content in the oil has exceeded the standard by 3 times - this indicates that the winding insulation paper aging degree reaches the warning line. Oil chromatography analysis unveiled a shocking fact: the actual aging of this 'middle-aged' transformer is equivalent to the normal use of 15 years of equipment.
I.The oil colour code: liquid time recorder
Newly injected transformer oil as the morning dew in early spring, showing transparent yellowish, its dielectric strength of up to 60kV/2.5mm. when the equipment is running full 3 years, the oil colour gradually changed to amber, when the acid value will break through the 0.1mgKOH/g warning line. Dark brown oil often means that the equipment has been in service for more than 10 years, at this time the dissolved gas content in the oil may be more than 150 μL / L, of which the acetylene concentration of 5 ppm that is a sign of discharge failure.
Black oil is a dangerous sign of aging. A chemical plant transformer in a sustained overload after 3 months, the oil colour as black as ink, testing found that the oil sludge content of up to 0.3%, the dielectric loss factor exceeded 0.04. This state of the oil insulation performance has decreased by 70%, equivalent to the 70-year-old's degree of hardening of the blood vessels.
II.Oil detection: five-dimensional aging diagnosis
Professional oil chromatographs can capture failure signals at the level of one billionth of a degree. When the hydrogen concentration exceeds 150μL/L, it implies that there is partial discharge in the winding; when the ethylene content reaches 50μL/L, it indicates that the hot spot temperature has exceeded 700℃. These data constitute the 'biochemical report' of the equipment, than the oil colour change 6 months in advance warning of failure.
The water content is a key indicator for determining the age of the oil. The water content of new oil is usually below 15ppm, and when the value exceeds 35ppm, the breakdown voltage of the oil will plummet from 40kV to 25kV, and together with the acid value test, the remaining life of the oil can be accurately calculated: when the acid value reaches 0.5mgKOH/g, the antioxidant capacity of the oil is only 30%.
III.The secret of life extension: intelligent maintenance revolution
Vacuum oil filtration technology is like 'haemodialysis'. A substation for 12 years of operation of the transformer three vacuum filtration, the oil particles from NAS 8 level purification to level 5, water content from 45 ppm to 8 ppm, equivalent to let the equipment rejuvenation 5 years. With the addition of 0.3% DBPC antioxidant, the service life of the oil can be extended by 40%.
The online monitoring system builds up a 'digital immunity network'. Micro water sensors installed in the oil sill track ppm water changes in real time, and the dissolved gas analysis module updates the fault gas concentration map every 6 hours. When the system detects that CO concentration is increasing at a rate of 5 μL/L per day, it automatically triggers an insulation deterioration warning.
In practice at Tokyo Electric Power Company, preventive maintenance based on oil conditions has extended the average transformer life from 25 to 35 years. When we gaze at the transformer oil window, the flowing colour is not only a mark of the equipment's age, but also a history of its health written in molecules. Regular oil testing is like a full-body physical examination arranged for power equipment. Behind the dark brown oil, there is a scientific and technological code to extend the equipment's youth.