| 摘要 |
A method and an apparatus are provided for safely testing an autotransformer of power distribution lines which has an identified centre tap ground connector, a primary winding terminal and a secondary winding terminal. The method for safely testing the autotransformer includes the steps of disconnecting the terminals and connector of the autotransformer from the distribution lines, applying a first testing AC voltage having a maximum value of substantially one volt only between a first of the terminals and the ground connector, measuring a first value of an AC voltage between the first terminal and the ground connector, and measuring a second value of an AC voltage between the second of the terminals and the ground connector. Thereafter, the method includes the steps of applying a second testing AC voltage having a maximum value of substantially one volt only between the second terminal and the ground connector, measuring a third value of an AC voltage between the second terminal and the ground connector, and measuring a fourth value of an AC voltage between the first terminal and the ground connector. Then, the method further includes steps of comparing the four measured values to predetermined constants, and generating corresponding signals indicating that autotransformer is short-circuited or that the same is open-circuited. When, the autotransformer being test is not short-circuited nor open-circuited, the method includes the step of generating a signal indicating that the first terminal is the secondary winding terminal or the first terminal is the primary winding terminal, whereby the primary and secondary terminals are clearly identified.
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