Cement mill main motor bearing bush burn-out accident analysis and processing | | high voltage brushless dc motor YRKK brushless dc motor - The brushless dc in the south of anhui

【Introduction 】 brushless dc motor in the south of anhui: a cement plant 2 models for YRKK800 - cement mill main motor8, the power of 2500 kw, its bearing bush for babbitt watts, material by tin, lead, antimony, copper metal composition, quality of a material soft low temperature characteristics, babbitt watts maximum temperature of 100 ℃, to protect bearings, bearing temperature protection for intermediate ceiling set at 63 ℃, more than the set value, chain grinding out the main motor is controlled by DCS. Mill main motor lubricating thin oil terminal 2 pressure switch, pressure is set to 0, respectively. 12 mpa and 0. 2MPa。 About 0 station runtime oil supply pressure is normal. 25 mpa, if the oil pressure is lower than 0. 2 mpa, then start the standby pump to meet the demands of the main motor bearing lubrication oil pressure; If the oil pressure is lower than 0. 12 mpa, explain the lubrication system failure, oil pressure signal chain grinding main motor jump stop, to avoid the bearing shell temperature burning bush. 1, fault phenomenon on January 7, 2015, the plant no. 2 is controlled by DCS cement mill power failure tripping, cause cement grinding system DO signal loss, cause 2 cement grinding system jump stop all low voltage apparatus. Post personnel inspection found when grinding main motor is still running, then immediately press the stop button, stop by the electrical inspection found that the main motor rotor shaft neck wear serious, before and after bearing shell are due to the high temperature burn out. DCS system failure led to dilute gas station jump stop after the oil pressure is lower than 0. 12 mpa didn't jump stop the main motor chain, bearing shell temperature ultra-high nor jump stop the main motor chain, which is caused by the main motor rotor journal wear, the root cause of the bearing shell burn out. 2, the cause of the problem analysis of cement mill main motor for high voltage electrical equipment, the principle of start-stop circuit shown in figure 1. As shown in figure 1, drive relay K1, K2, respectively from the DCS system pulse trigger switch, two break-brake coil to realize the main motor rev. Stop. DCS system, after losing electricity centralized break-brake command by K2 to stop the operation of the main motor; Gas station, on the other hand, low oil pressure and bearing shell super WenLianSuo jump stop signals are also controlled by DCS output break-brake coil, DCS fault can trigger the car brake circuit breaker points, resulting in protection system failure, parking equipment can't fault. 3, fault processing mill main motor brake circuit controlled by DCS system soft chain, when the design is not fully consider the effect of DCS faults on the equipment, and hard chain can solve this problem. Hard wiring, will dilute lubrication station low oil pressure signal to grind the main motor brake circuit, high voltage points but dilute lubrication oil station set up at the scene, the scene from the high voltage far, time consuming and high cost of cable laying directly. Electrical maintenance personnel according to the field situation, decided to use thin oil terminal at close range and main motor abrupt stop button box, after signal shunt into high voltage. For collection is bearing shell temperature signal, so there is no modification. After transforming the control principle and shown in figure 2. As shown in figure 2, through the increase in the lubricating thin oil terminal control box ALC2 intermediate relay K3, K4 implementation of main motor chain of soft and hard chain control. K3 auxiliary contacts connected to DCS cabinet DI point for soft control of break-brake coil, K4 auxiliary contact in parallel to the machine button box ALC1 direct role in the device's trip circuit realization of break-brake coil hard control, after successful commissioning exercise brake. And then respectively for grinding head of dilute oil station, thin oil terminal and grinding main reducer of dilute gas station also renovation and the low hydraulic oil pressure signal in parallel to brake circuit of figure 2 points, and in this way, any station fault can be timely jump stop the main motor, through the soft and hard chain chain, double insurance, increase the reliability of the mill main motor fault, stop. 4, and end with the accident exposed the equipment hidden trouble, when the design should pay special attention to when designing the equipment of different voltage grade between the chains of mutual connection, more thinking on the impact of different fault conditions of equipment, timely find parking equipment operation and control of blind Angle, perfect design, good maintenance equipment safe operation and safe production of the enterprise. This article is from the 'cement'.