what are the various types of three phase transformer connections?

Three-phase transformer connections primarily include Delta (?) and Wye (Y) configurations. In a Delta connection, each transformer winding is connected end-to-end, forming a closed loop, which provides high starting torque and is suitable for industrial loads. In contrast, the Wye connection connects one end of each winding to a common point, allowing for neutral grounding and lower phase voltages. Additionally, there are combinations like Delta-Wye (?-Y) and Wye-Delta (Y-?) used for specific applications, enhancing voltage transformation and phase shift.