What piece of equipment is specifically responsible for converting AC to DC?

The piece of equipment responsible for converting alternating current (AC) to direct current (DC) is the rectifier. Rectifiers function by allowing current to flow in only one direction, effectively converting the bidirectional flow of AC into a unidirectional flow of DC. This is essential in various applications where DC is required, such as in battery charging, powering DC devices, or in power supply systems where DC output is necessary.

Transformers are used to change the voltage level of AC but do not convert AC to DC. Inverters perform the opposite function of rectifiers; they convert DC to AC. Circuit breakers are safety devices designed to protect electrical circuits from overload or short circuits, but they do not convert current types. Thus, the rectifier is the correct answer due to its specific role in the conversion process between AC and DC.