| 摘要 |
<p>PURPOSE:To resume secondary AC-excited operation quickly upon recovery from abnormal state by commonly connecting the intermediate points of two diodes connected in series, provided for a GTO of each phase of a secondary exciter, firing the GTO partially and short-circuiting the secondary circuit of a secondary AC-excited synchronous machine upon occurrence of an abnormal voltage and forcibly extinguishing the GTO upon elimination of the abnormality. CONSTITUTION:Upon occurrence of an abnormal voltage on the secondary of a secondary AC-excited synchronous machine, the abnormal voltage detected through an overvoltage detector and a part of negative and positive pole GTOs 9, 11, 10, 12 is fired according to the potential difference between respective phases thus short- circuiting the secondary AC-excited synchronous machine on the secondary through the GTO and a short-circuiting diode 8. In other words, a short circuit current flows from phase U to phases V and W, as shown by arrows, during a time interval t1. (Only dark shaded element is turned ON). When the short circuit current flows instantaneously, energy to be transferred to the secondary is consumed completely. Upon subsequent elimination of abnormal condition on the primary, conducting GTOs are extinguished forcibly to interrupt fault current followed by resumption of secondary AC-excited operation.</p> |
