Power line monitor

An apparatus and methods are disclosed for monitoring the operation of an electrical power-transfer system and detecting and handling hazardous and undesirable system states. In accordance with one embodiment, an electrical signal is injected into the electrical power-transfer system. During or after the injection of the electrical signal, the following are measured: (1) an electrical property between a first sensor and a second sensor to obtain a first measurement, (2) the electrical property between the second sensor and a third sensor to obtain a second measurement, and (3) the electrical property between the first sensor and the third sensor to obtain a third measurement. The electrical power-transfer system is determined to be in a hazardous state based on the first measurement, the second measurement, and the third measurement, and in response to the determination one or more actions are performed to correct the hazardous state.