Brush and set the loop electrosurgical common failure causes and solutions:
Brush in the operation of the most common faults are fever, generate sparks, severe burning electric brush grip and slip ring. From overheating failure, mainly the following aspects:
1 mainly because the cooling air duct is clogged, the collector ring surface ventilation groove, clogging of the ventilation holes, decline in circulating fan air volume and other reasons, especially when slip rings running in the collector ring surface temperature is too high due to a result of poor ventilation, heating: poorly ventilated , leading to increased brush wear, increased accumulation of carbon may clog the cooling channels of the surface of the collector ring. Therefore, the size of the repair, should the collecting ring surface ventilation trenches, holes, and cooling duct filters to clean up, to keep them open.
2, the heat generated by the contact resistance is too large or uneven distribution: the collector ring and brush by sliding contact with each other conduction of excitation current, depending on the capacity and model, each collector ring about the distribution of the number of ten brush, since the contact resistance of the differences in the distribution of the different current will cause fever unevenness, there are several reasons: (1) the brush with the slip ring surface contact resistance, the brush and brush braid contact resistance, brush braid contact resistance with the brush holder lead is too large. The contrast between each other to check can be carried out by measuring the a single brush total pressure drop, brush contact voltage drop, the brush body drop, pressure rotating joints drop links, brush braid drop. (2) brush pressure uneven or does not meet the requirements, there may be too short brush, spring changes due to overheating and loss of elasticity of soft aging reasons. Spring balance should be used to check the brush pressure. Constant pressure spring should complete mechanical damage, the pressure should be consistent with the provisions of its products on the same pole spring pressure deviation should not exceed 5%.
3, caused by overheating due to mechanical friction: the collector ring and brush overheating fault, a large part is due to mechanical friction causes overheating, if not yet in the boot plus excitation, it has been found that the collector rings and brushes high temperature, or the temperature is too high in the running, pull out a few brushes, the temperature but reduced it basically certainly due to mechanical rotary union and friction caused. Mechanical and friction causes fever situation is very complex, mainly the following aspects: (1) brush contact surface grinding bad or excessive brush run a replacement. If a lot of time to replace the brush overhaul, should be put into operation pediment rpm, to brush the surface of the formation of the oxide film leave enough time sufficient. (2) brush holder and collector ring surface gap is too large. Material more brittle brush when the brush holder and slip ring surface gap is excessively large, run the brush can not integral contact electrode collector ring, with the collector electrically ring beveled contact, is likely to cause the brush chipping.
Of a symmetrical three-phase windings wound on the winding type motor, the rotor of the collector ring. During normal operation, the three-phase winding leads to the collector ring by resistor short-circuited. Startup, the rotor winding string into a start-up resistor to reduce the starting current of the purpose. Since the startup resistor may be piecewise resection string into appropriate starting resistor, it is possible to achieve the maximum torque of the electric motor, the starting torque to shorten the startup process. Resistor in series with the rotor can be governor squirrel cage motors, it is characterized by complex motor structure, high cost, operation and maintenance inconvenient, maintenance workload. Taking into account the replacement wound motor, motor start performance can be improved, but does not fundamentally solve the problem of frequent starting of the motor, and needs to be replaced with new motor investment, energy-saving effect is not ideal.
Collector ring brush not only using a graphite brush, but also in order to improve the current density of the brushes, and sometimes also using the metal-graphite brush, therefore, must also be considered abnormal residual expansion and other factors. Even for many turbine generator as high-speed motor or run the motor, totally enclosed gas medium and hydrogen medium problem.
Collector ring and brush with the When too strong abrasive brush and collector ring material is too soft, and often occurs in the collecting ring ladder wear equivalent to the brush width. Especially the fully enclosed motor, high temperature and low humidity are more prone to brush or excessive wear and tear collector ring. Re-like scars is formed such that, at the beginning only a very small wounds in these parts, the brush collector poor produce sparks. Once produce sparks, the wounds gradually deteriorated expanded together, and finally form the same size with the size of the brush-sliding contact surface wounds. Thus, a collector ring brush, but also must be noted even if the very small spark is generated.