A disconnect switch is a type of safety device used in electrical circuitry. The purpose of a disconnect switch is to guarantee that a particular electrical circuit is de-energized in the case of an emergency stoppage, service, or maintenance.

The disconnect switch allows operators to power down the circuit entirely, creating a safe environment for the operator to complete any necessary repairs, maintenance, or inspections. It ensures a lack of energy feeding through the circuit, relieving concerns of electrical risks. 

Disconnect switches are critical in many electrical applications, including electrical distribution and industrial applications. Adjustments on industrial machinery are standard, which requires an interruption in the power flow.

Or, in power distribution, emergency situations may demand a quick shut down of power or transfer from one output to another. Since the disconnect switch guarantees a lack of power in the electrical circuit, individuals working on the issue can safely complete the repair.

If the problem is isolated to a specific area of a facility, disconnect switches allow operators to shut down the isolated area by itself. While operators or technicians handle the repair, the rest of the facility can continue operating normally. In turn, this ensures productivity levels stay relatively consistent.

More info on disconnect switch here

You might also want to read Circuit breaker