保护重要电动机的自启动
Protecting the Self-Starting of Important Motor
当电动机的供电母线电压短时降低或中断又恢复时，为防止线路上电动机同时自启动使电源电压严重降低，通常会在次要电动机上装设低电压保护。当供电母线电压低到一定值时，低电压保护动作，将次要电动机切除，使供电母线电压恢复到足够的电压，以保证重要电动机的自启动。
When the supply bus voltage of the motor is reduced or interrupted and restored for a short time, low voltage protection is usually installed on the secondary motor in order to prevent the serious reduction of the supply voltage caused by the simultaneous self-starting of the motor on the line. When the voltage of power supply bus is low to a certain value, the low voltage protection action will cut off the secondary motor, so that the voltage of power supply bus can be restored to enough voltage to ensure the self-starting of the important motor.
保证技术安全及工艺过程的特点
Ensuring Technical Safety and Characteristics of Technological Process
在某些情况下，当电压长期消失时（如10S左右）根据技术安全的条件及生产工艺过程的特点，需将某些电动机切除。因为在这段时间内锅炉已熄灭，自启动已经没有必要了。为了保证工艺联锁动作，应装设低电压保护动作于跳闸。另外，还有一些带恒定阻力矩机械的电动机，如磨煤机等，在电压降低时不可能自启动，这些电动机也应在电压降低时切除。
In some cases, when the voltage disappears for a long time (such as about 10S), some motors need to be removed according to the technical safety conditions and the characteristics of the production dipinh.89ix.comdipingg.89ix.comzhusuji.89ix.comceshi.89ix.commend.89ix.comprocess. Because the caiguangwa.89ix.comboiler has been extinguished during this period, self-starting is no longer necessary. In order to ensure interlocking operation, low voltage protection should be installed to trip. In addition, there are some motors with constant resistance moment machinery, such as coal mills, which can not start themselves when the voltage is reduced. These Motors should also be removed when the voltage is reduced.