Which component controls all primary functions in a UPS system?

The logic board is fundamentally the control center of a UPS (Uninterruptible Power Supply) system. It manages critical operations such as monitoring input and output power conditions, regulating the charging and discharging of the battery, and ensuring a seamless transition between the primary power source and battery backup in the event of a power failure.

With its firmware and circuitry, the logic board communicates with other components in the UPS, interpreting various signals, executing commands, and maintaining system integrity. It plays a vital role in the overall functionality of the UPS, as it is responsible for processing all operational data and making real-time adjustments to maintain uninterrupted power supply.

In contrast, while the battery backup stores energy for use during power interruptions and the power supply delivers energy to the connected devices, neither of these components has the overarching control capability that the logic board possesses. The power management unit, while involved in energy distribution and regulating power consumption, typically works under the direction of the logic board rather than independently controlling the UPS functions. Therefore, the logic board's central role in managing and coordinating the functions of the UPS makes it the correct answer in this case.