What is the main function of a relay in an electrical system?

The main function of a relay in an electrical system is to use a small control signal to switch a larger load. A relay operates as an electromechanical switch that allows a low-voltage control circuit to manage a high-voltage or high-current circuit. When a small voltage is applied to the coil of the relay, it creates a magnetic field that moves an armature to either open or close the contacts, thus enabling or disabling the flow of current to the larger load.

This functionality is crucial in various applications where precise control is necessary without direct manual intervention. For example, relays are frequently used in automation systems, safety systems, and control panels where low-power signals can control high-power devices while providing electrical isolation between the control and output circuits.

In contrast, the other options do not accurately reflect the primary role of a relay. Controlling the frequency of an AC signal, regulating voltage levels, and measuring electrical resistance are functions associated with other components like oscillators, voltage regulators, and ohmmeters, respectively. Therefore, the correct understanding of a relay's role in an electrical system lies in its ability to manage larger loads with smaller signals efficiently.