Phase sequence must be same
Type must be same
Polarity must be same
Capacity must be same
Transform 3 phase to 2 phase
To stabilize the output voltage
To get rated power output
Transform 3 phase to 6 phase
Natural air method
Oil blast method
Air blast method
Forced circulation of oil
To improve the efficiency
To protect the winding from damage
To regulate the voltage
To increase the life of transformer oil
Forced oil and water cooled
Oil and water cooled method