节电型三相交流电动机缺(断)相保护器（Power saving type three-phase AC motor fault (break) protector）.doc

节电型三相交流电动机缺(断)相保护器（Power saving type three-phase AC motor fault (break) protector） Power saving type three-phase AC motor fault (break) protector Because of the power grid itself or the unreliable connection of the power input, the switching power supply sometimes has the situation of short (off) phase operation, and the lack of phase operation is difficult to be found. With the development of industrial and agricultural technology, industry, agriculture and urban and rural industrial and commercial households are increasing rapidly with motors. However, factories, individual businesses, and rural areas generally lack electrical and technical personnel, with the use and management of poor maintenance, often lack (break) phase, resulting in AC three-phase motor burning incidents increasing. The author and colleagues in the electrical and electronic newspapers and periodicals published three-phase AC motor lack (break) phase protection principle diagram for analysis and use for reference. In accordance with the requirements of the diagram, also produced several times, are the lack of production parameters. In the process of making the experiment, found that when the motor is running, man-made phase AC contactor is not released, three-phase motor only two-phase power or work, especially a small three-phase motor fault phase current, contactor is not released. The reason is that this phase line has feedback current from the motor operation, just to maintain the contactor coil to attract, so it does not release. And ended in failure. The author is not reconciled to setbacks and production failures, in the failure to find success, and more repeatedly pondering, after many long-term production experiments, and finally achieved good results. It has been proved by practice that it is not only of long service life, but also of high sensitivity. Here dedicated to the readers. The circuit is very simple and reliable, easy to manufacture, without complex debugging, and as soon a