The load that the transformer bears without thermal damage can be increased with the help of a suitable cooling system. This is because the resistance of a transformer is determined in part by its ability to dissipate heat. If the winding hot spot temperature reaches a critical value, overheating can cause premature damage to the transformer and accelerate the aging process of transformer insulation.
The cooling stations increase the transformer's resistance by increasing its ability to dissipate the heat generated by the electric current. In other words, a good cooling system allows the transformer to carry more load than it should without reaching critical temperatures in hot spots.
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One of the most common types of transformer cooling devices is the auxiliary fan. They can be used to support cooling radiator tubes, thereby increasing transformer performance. The fan should not be used in continuous operation, but only at temperatures that require additional cooling. Automatic control can be set to start the fan when the oil temperature or transformer winding becomes too high.
Cooling system maintenance:
If the cooling coil is removed from the transformer, the entire water cooling system can be tested. Here the winding is filled with water until the pressure reaches 80 to 100 psi and left under that pressure for at least an hour. Any drop in pressure could be a sign of a leak.
Cooling system type:
For oil-immersed transformers, the cooling system options are as follows:
- Naturally Immersed Natural Cooling
- Chill with oil
- Bubbles with air soaked in oil
- Water-cooled with oil
- Forced cooling by blowing air
- Natural air conditioning forced oil
- Forced oil with water cooling