What is the main function of a disconnect switch in a substation?

The primary function of a disconnect switch in a substation is to provide a safe means of isolating electrical circuits for maintenance purposes. Disconnect switches are critical for ensuring that workers can perform repairs, inspections, or maintenance on electrical systems without the risk of accidental energization. By isolating the section of the circuit where work is being performed, the disconnect switch protects personnel and helps maintain system reliability.

In operational scenarios, when maintenance is required, the switch can be opened (disconnected), effectively removing that segment of the circuit from the live electrical system. This ensures safety and allows technicians to work without the danger of electrical current flowing through the equipment they are handling.

The other options describe functions that are not associated with disconnect switches. Measuring current flow and voltage is performed by instruments such as ammeters and voltmeters. The conversion of AC to DC power is done by rectifiers and other power electronics components, not by disconnect switches. Regulating the temperature of transformers typically involves cooling systems and temperature sensors, which are also separate from the function of disconnect switches.