Anand 28 April 2025

🌬️ Types of Cooling, Protective Devices, Bushings and Termination 🌬️

🧊 Types of Cooling Methods for Transformers

Cooling is essential for transformers to prevent overheating and ensure reliable operation. The main types of cooling are:

  • Air Natural (AN) 🌬️: Natural air circulation cools the transformer. Used for small transformers.
  • Air Blast (AB) 🌪️: Forced air through blowers or fans for high rating transformers.
  • Oil Natural Air Natural (ONAN) 🛢️🌬️: Oil circulates naturally inside and transfers heat to air naturally outside.
  • Oil Natural Air Forced (ONAF) 🛢️💨: Oil circulates naturally but air is forced with fans to cool the radiator.
  • Oil Forced Air Forced (OFAF) 🚀: Oil and air both are circulated forcibly using pumps and blowers.
  • Oil Forced Water Forced (OFWF) 🚰: Oil is circulated by pumps and cooled through water-cooled heat exchangers, used in large power transformers.

🛡️ Protective Devices Used in Transformers

Various protective devices are used to ensure the safety of transformers:

  • Buchholz Relay 🚨: Gas and oil operated relay for internal faults in oil-immersed transformers.
  • Pressure Relief Device 💣: Relieves internal pressure build-up by venting out oil and gases.
  • Oil Level Indicator 📈: Indicates the oil level to avoid running dry.
  • Temperature Indicators 🌡️: Monitors winding and oil temperature.
  • Breather 🌫️: Silica gel filled device to remove moisture from air entering the conservator tank.
  • Surge Protectors/Lightning Arresters ⚡: Protects transformer from high voltage spikes due to lightning or switching surges.

🔩 Bushings in Transformers

Bushings are insulated devices that allow current to safely pass through the grounded transformer tank wall.

Types of Bushings:

  • Porcelain Bushings 🏺: Made of porcelain and filled with oil or air, suitable for outdoor use.
  • Resin Bonded Bushings 🧵: Resin material with mechanical strength, used for indoor applications.
  • Capacitor Bushings 🧯: Designed to control electric stress in high-voltage applications.

🔌 Termination Methods

Termination refers to connecting transformer terminals to external conductors safely and efficiently.

Types of Terminations:

  • Indoor Termination 🏠: Used inside switchgear, control panels, and substations.
  • Outdoor Termination 🌳: Designed to withstand environmental conditions like rain, dust, and UV radiation.
  • Heat Shrink Termination 🔥: Shrinkable tubes used to insulate and seal cable ends.
  • Cold Shrink Termination ❄️: Pre-stretched rubber sleeves that contract onto the cable when installed.

🧠 Conclusion

Proper cooling, reliable protection devices, strong bushings, and efficient termination are critical to the safe and efficient operation of transformers. Their correct selection and maintenance ensure long transformer life and reliable power supply. ⚡🔧