Which piece of equipment is used to step voltage up or down in an electrical system?

The piece of equipment that is specifically designed to step voltage up or down in an electrical system is a transformer. A transformer works on the principle of electromagnetic induction and consists of two or more coils of wire (windings) that are linked by a magnetic field. By adjusting the number of turns in the primary and secondary coils, a transformer can increase (step up) or decrease (step down) voltage levels while keeping the power (more or less) constant, barring any losses in the system.

This capability is crucial in electrical distribution systems, where high voltages are transported over long distances to minimize energy losses, and then transformed to lower voltages suitable for use in homes and businesses.

The other equipment mentioned does not serve the same purpose. A generator converts mechanical energy into electrical energy but does not adjust voltage levels. A converter generally refers to equipment that changes alternating current (AC) to direct current (DC) or vice versa, and a rectifier is specifically designed to convert AC to DC. While converters and rectifiers may involve voltage changes, they are not intended to simply step up or down voltage in the same way that a transformer does.