Which device provides protection against brownouts?

The device that provides protection against brownouts is a battery backup. A battery backup, also known as an uninterruptible power supply (UPS), offers a continuous power supply during electrical disturbances such as brownouts, which are characterized by a temporary drop in voltage. When a brownout occurs, the UPS switches to its internal battery to maintain a stable voltage to connected devices, thus preventing potential disruptions and damage.

While surge suppressors protect against voltage spikes, and line conditioners stabilize voltage fluctuations to some degree, they do not provide a battery-powered backup during a brownout. Rack grounding is important for safety and minimizing electrical interference but does not address voltage drops itself. The battery backup is specifically designed to handle these types of situations, making it the best choice for protecting against brownouts.