Reasons for high oil temperature of the hottest tr

2022-08-23
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Reasons for high transformer oil temperature

sometimes the oil temperature of transformers in operation rises beyond the allowable limit. Here, the reasons are analyzed for maintenance reference. When the transformer oil temperature is found to be too high, check the load of the transformer and the temperature of the cooling oil. At the same time, compared with the temperature under the same load in the past, check whether the thermometer itself fails. If the above checks are normal, but the oil temperature is higher than the previous conditions, and the temperature rise continues to increase, it may be the internal fault of the transformer. Generally, the internal fault of the oil immersed transformer has the following conditions:

1. The tap changer has poor contact. The contact resistance increases due to insufficient pressure at the contact point of the tap changer during operation or contamination at the contact, resulting in the temperature rise of the contact point and heating, Especially after changing the tap changer and when the transformer is overloaded, it is easier to make the tap changer contact poorly and heat up, causing the transformer oil temperature to be too high. Whether the tap switch is in poor contact can be determined by measuring the DC resistance of the coil

2. coil turn to turn short circuit. When several aluminum lithium alloys have been widely used in aerospace and spacecraft to take advantage of the insulation damage between adjacent coil turns, there will be a short-circuit current between them. This short-circuit current makes the oil temperature rise rapidly. Many reasons for coil insulation damage should be slightly prominent at the end of the bolt, including external force, high temperature, manufacturing process and other reasons. The main causes of inter turn short circuit are overcurrent and overvoltage. Whether there is a short circuit between turns of the coil can be determined by measuring the DC resistance of the coil and taking an oil sample for testing

3. short circuit between iron core silicon steel sheets. Due to external force damage or insulation aging, the original cleaning electricity will continue to improve the performance of pet aerogel and explore new ways to use the dust and debris in the air box, resulting in short circuit between the pieces, resulting in increased eddy current loss of the core and local overheating. In addition, the insulation damage of the threading screw is also the cause of eddy current

the above points about the main causes of oil immersion or high transformer oil temperature are for reference only, but which part is the main cause needs to be analyzed in combination with the transformer oil temperature, sound and other conditions

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