FAULT CONDITION DETECTION SYSTEM AND METHOD

According to an example, an uninterruptible power supply is provided comprising a first input, a backup input, an output to provide output power, an inverter coupled to the first input, the backup input, and the output, a first sensor to detect a voltage at an inverter output, a second sensor to detect a voltage at the first input, a switch coupled between the first input and the output, and a controller coupled to the switch and the first and second sensors, and configured to determine a first voltage difference across the bypass switch using at least one of the first sensor or the second sensor, filter the first voltage difference, determine whether a value derived from the first filtered voltage difference exceeds a threshold, and output an indication of a failure of the bypass switch based on the value derived from the first filtered voltage difference exceeding the threshold.