| 摘要 |
<p>1,249,666. Protective arrangements. GENERAL ELECTRIC CO. 23 Dec., 1968 [26 Dec., 1967], No. 61018/68. Heading H2K. A reverse current protective arrangement, e.g. for a polyphase power rectifier 21 ... 23, comprises saturable current transformers 25, diodes 26 in parallel with the current transformer secondary windings 25s and diodes 27 in series with the secondary windings 25s, the series circuits 25s, 27 being connected in parallel with each other and to detecting means 24. The diode 26 are poled so to conduct when forward current flows in the current transformer primary windings and the diodes 27 are poled so as to conduct when reverse current flows in the current transformer primary windings. The cores of the transformers may have air gaps and be premagnetized by current flowing from a battery 41 through resistors 43 and diodes 42. The detecting means 24 has a control element 31 which initiates an indicating or protective function when a zener diode 35 breaks down to render a controlled rectifier 32 conducting. A further zener diode 36 prevents the premagnetising current from maintaining the rectifier 32 conducting.</p> |
