Which connection is used for a transformer rated at 7200/12470Y-120/240 when connected to a system voltage of 7200 volts?

For a transformer rated at 7200/12470Y-120/240 connected to a system voltage of 7200 volts, the correct connection type is delta. Utilizing a delta connection in this scenario is appropriate because it allows for a three-phase system that effectively handles higher voltages, like 7200 volts, typically used in distribution systems.

Delta connections are beneficial for supplying three-phase power and generally provide a lower voltage drop compared to other connection types, especially over longer distances. They can create a closed loop among the phases, which offers redundancy and helps to maintain balance in the system during load variations.

In this case, the specification of 7200 volts suggests a system that is probably primarily three-phase, and while a wye connection might also work for certain aspects of voltage transformation, the delta design is more commonly employed for higher voltage applications like this when dealing with direct connections in distribution circuits.

Thus, understanding the nature of three-phase power systems and the advantages of delta connections is key in recognizing why it is the suitable choice in this context.