| 摘要 |
PURPOSE:To eliminate the generation of an arc as well as to prevent the boost of abnormal voltage in an airtightly sealed chamber by a method wherein a trouble detecting device is connected to an arrester, and between the terminals of the transformer main body is short-circuited using an AC switch when a trouble detection signal is outputted from the trouble detecting device. CONSTITUTION:When both arresters 2a and 2b are destructed, a short-circuit current Ic which passes through an airtightly sealed chamber 3 runs by the infiltration of lightning surge, and said current Ic is finally shut off by cut-out switches 5a and 5b. The time duration of said short-circuit current is long as 10msec, the output 201 of a current detector 9 becomes the waveform of time duration having a long and gentle wave crest, and the output of a waveform shaping circuit is continued until the output 201 of the current detector 9 disappears. Accordingly, after the lapse of the above-mentioned lag time after the infiltration of lightning surge, a trouble determination circuit 15 receives the output 202 of the waveform shaping circuit and the output 203 of a pulse generating circuit, and a trouble detection signal 204 is generated. Consequently, as a turn-ON signal 205 is generated by a thyristor turn-ON device 20 and thyristors 8a and 8b are turned-ON, most of the short-circuit current runs through either of the thyristors based on the phase of an AC power source 6, and almost no short-circuit current runs to the arrestors 2a and 2b. |
