A microcontroller-based system for monitoring and controlling the operation of an uninterruptible power supply

The design of a real-time system that measures and monitors the fundamental parameters of an uninterruptible power supply (UPS) in which it is incorporated is described. The system is based on a microcontroller (MCS-96 family) with a built-in 10-bit A/D converter. The parameters being measured in real-time are the amplitude, the frequency and the distortion of the UPS output AC signal. The charging state of the battery cells, the supply current of the battery and the signal level at specific test points on the UPS circuit board are also measured and monitored. These parameters are used in the real-time calculation of the remaining time before the UPS battery is exhausted and, in case of malfunction, the fault is located and the UPS is safely turned off.