| 摘要 |
PURPOSE:To prevent the adverse effect on the system by comparing the phase angle calculated with the control angle thereby detecting the abnormality of any of the synchronous phase detection circuit, the phase control circuit, and the pulse amplifying circuit of a converter. CONSTITUTION:A phase angle operating circuit 14 calculates the operating phase angle of a converter by the DC current of a main circuit, which is detected through a DC current detector 7, the DC voltage of the main circuit, which is detected through a DC voltage detector 8, the leakage impedance of the transformer for converter, which is known from the test results of the transformer for converter and the converter, the equivalent internal resistance, which is capable of previous calculation from the resistance of the winding and the amounts of the forward voltage drop of the converter, and the unload DC voltage of the converter, which is capable of easy calculation from the tap position of the tap changeover switch at load of the converter for converter. A phase angle comparison circuit 15 compares the operating phase angle of the converter calculated by the phase angle operating circuit 14 with the control angle operated by the control operating circuit, and in case that they are not equal, the occurrence of abnormality is judged. |
