Reasons For Transformer Overheating
Transformers are the most important machine used in electric power system to step-up and step-down the voltage and current level. Overheating is one of the major problem that occurs in transformers. Overheating of the transformer increase power losses in the transformer, damage to the insulation and reduces the lifespan of the transformer.
Transformer may get over-heated due to various reasons. Some of the major reasons responsible for the overheating of a transformer are listed below.
- Overload on transformer
- Low Transformer Oil Level
- Moisture in Transformer Oil
- Failure of Cooling System
- Current in Neutral
- Sustained Over-Voltage
- Unbalanced Load to the Transformer
- Fluctuated Load
- Leakage Current
- High Ambient Temperature
- Poor Contact Point of Tap Changer
- Short Circuit Between turns of Winding Coils
- Short Circuit Between Laminated Core Sheets
Explanation
1) Overload on transformer
2) Low Transformer Oil Level
When transformer oil level in transformer is low, it reduces the cooling capacity of the transformer resulting overheating of the transformer. Insulating oil level in transformer must be checked regularly either by visual inspection or using oil monitor device like MOG (magnetic oil guage) and must be maintained to prevent the low transformer oil level.
2) Moisture in transformer oil
Moisture in transformer oil reduces reduces its insulating properties resulting in breakdown of transformer oil. Due to the presence of moisture, bubbles are formed in transformer which disrupt the flow of transformer oil and reduce cooling capacity of the transformer oil resulting increase in overheating of the transformer.
3) Failure of cooling system
Malfunctioning of the cooling equipment such as blockages in the transformer oil circulation, dust in air vent and failure of the cooling fans results overheating in a transformer.
4) Insulation failure
Damaged or wore insulation of a transformer lead to arcing and heat up results overheating of the transformer.
5) Current in Neutral
Current appeared in the neutral of the transformer due to unbalanced load between the phase resulting overheating of the transformer.
6) Sustained Over-voltage
Excessive voltage for long period of time can overexcite the transformer resulting overheating of the transformer.
7)Unbalanced Load to the transformer
High difference in load between the phases of a transformer results in overheating of the transformer.
8) Fluctuated loads
Excessive fluctuation of load on a transformer results in overheating of the transformer.
9) Leakage current
Leakage current through weakened part of the insulation results in overheating of the transformer.
10) High Ambient Temperature
High ambient ( surrounding ) temperature results in overheating of the transformer.
11) Poor Contact Point of Tap Changer
During operation, the contact resistance of tap changer increases due to insufficient contact pressure and contamination at the contact point of the tap changer. Increase in contact resistance generate heat resulting overheating of the transformer
12) Short Circuit Between turns of Winding
Due to insulation damage between adjacent turns of the winding, short circuit occurs which generate heat result in overheating of the transformer.
13) Short Circuit Between Laminated Core Sheets
Due to any external force or insulation ageing, insulation between the laminated core sheets gets damaged resulting increase in eddy current that results in overheating of the transformer.
Conclusion
Hope, you have clearly understand about all the reasons responsible for overheating in transformer in electrical power system. Make sure to leave your opinion and suggestion about this in the comment section below.