The primary use of disconnect switches is to:

Disconnect switches are crucial components in electrical systems, predominantly used to isolate equipment during maintenance. This isolation is essential for the safety of maintenance personnel, allowing them to work on parts of the system without the risk of electrical current flowing through the equipment being serviced. When a disconnect switch is opened, it physically separates the circuit, ensuring that no power reaches the components associated with that part of the system.

This function enhances safety by preventing accidental energization of equipment when maintenance is being performed. Additionally, disconnect switches can be utilized for maintenance checks, troubleshooting, or system modifications, reinforcing their role in ensuring safe operational practices.

Options related to measuring system performance, increasing power distribution, or connecting circuits in parallel do not pertain to the primary function of disconnect switches, as these tasks involve different electrical devices and mechanisms that specifically handle performance assessment, load management, or circuit configuration.