Method for detecting disconnection of machine-end PT (potential transformer) loop without being influenced by operation condition of generator

The invention relates to a method for detecting disconnection of a machine-end PT (potential transformer) loop without being influenced by operation condition of a generator, and belongs to the technical field of voltage transformer disconnection detection. According to the method, firstly, an external 20Hz injection type low-frequency square wave power supply is coupled to the primary side of a generator through a generator neutral point grounding transformer or a grounding arc suppression coil, and then is converted to the secondary side through a machine-end PT; then, the 20Hz three-phase phase voltage, frequency and interphase voltage of the secondary side of the PT at the generator end of the generator are detected in real time; and finally, the intact condition of the machine-end PT loop is judged according to a detection result. The method for detecting disconnection of a machine-end PT loop of the generatoris not influenced by the operation condition of a unit, effectively eliminates the PT disconnect