The high-voltage motor is the key equipment in the refinery production equipment and plays an important role in the production and operation of the equipment. It is important to analyze the faults of high-voltage motors and improve the maintenance and maintenance level of high-voltage motors by operators. It is of great significance to reduce the operating faults of high-voltage motors and reduce the frequency of fluctuations.
Through the principle, structure and problems that are easy to occur in the operation of high-voltage motors, we can achieve more discoveries, more observations, more analysis, and more summarization. Strictly perform standardized maintenance in the work, so that high-voltage motors can be safe, stable, long, full, and excellent. The operation guarantees the normal production of production equipment and brings more economic benefits to the enterprise.
1. The generation, damage and preventive measures of the shaft voltage of high voltage motor
The high-voltage motor generally has a large capacity, and its volume is large, and the magnetic circuit imbalance is likely to occur during manufacture, such as the difference in magnetization characteristics of the silicon steel sheet, the unevenness of the air gap, and the like. In addition, the stator winding is unbalanced, the three-phase power supply is unbalanced, the field winding is short-circuited, and the asynchronous motor is broken. These can cause the stator core of the motor to generate an alternating magnetic field around the core, thereby inducing an alternating voltage on the rotating shaft of the motor, which is the shaft voltage. When the shaft voltage reaches a certain value, it can break through the oil film of the bearing and generate a shaft current through the end cap casing or the bearing housing to form a loop. The shaft current can cause spot burns on the rollers and journals of the bearing bush and the journal or the bearing, and even damage the normal operation of the bearing in severe cases. In order to block the current circuit, for the i-drive of the bearing housing, an insulating pad is usually placed under the bearing seat of the counter-loading end, and the fixing screw of the shaft bearing is also provided with an insulating sleeve.
In motors with end cap bearings, if a plain bearing is used, an insulating mat is placed between the bearing shell and the shoe seat; if a rolling bearing is used, an insulating partition is provided on the bearing sleeve, and the fixing screw of the bearing sleeve is also carried. Upper insulation sleeve. The other is to directly use bearings with insulation, but the cost is higher.
2. Common causes of high vibration during operation of high voltage motors
The vibration of the motor, especially the vibration of the high-speed motor exceeds the standard limit, which will affect the normal operation of the motor and even damage the motor, causing the unit to stop abnormally and affect production. The vibration value and vibration frequency of the motor are measured using a spectrum analyzer or a vibration tester, and the measurement data is analyzed to diagnose the cause of the motor vibration. The motor is repaired for the cause of the vibration, which can reduce the blindness of the inspection, complete the inspection in the shortest time, and return the motor to normal.
The root cause of the vibration of the motor is electromagnetic vibration and mechanical vibration. The electromagnetic vibration is the inherent vibration of the motor. It is not considered here. The mechanical vibration of the motor is the vibration that can be changed with the operation of the motor and can be eliminated by inspection. Therefore, the motor is mainly analyzed here. Mechanical vibration.
The main reason for the mechanical vibration of the motor body is divided into two parts, namely the rotor part of the motor and the supporting part of the electric rotor. The cause of the vibration caused by the rotor of the motor is the deformation of the rotor core, the bending of the rotor shaft, the concentricity of the rotor bearing gear and the outer circumference of the rotor core, the wear of the rotor bearing gear or the size of the rotor, the rotor dynamic balance block loose, the open motor rotor The ash scale is not evenly detached. The cause of vibration caused by the rotor support portion of the motor is caused by deformation of the motor end cover, deformation of the motor bearing sleeve, wear of the inner hole of the end cover or the inner hole of the bearing with the bearing sleeve, and bearing damage.