replacement, slip ring ring fire, and found that other carbon brushes have been red hair braid, minus excitation current, active reduced to 140MW adjustment and disposal is invalid, the solution of the shutdown. All the process of about 15min, the effect of 10 carbon brush braid blowing, part of the collection of electric ring and pin fixing hole burning, "V" part of the pin burning. 2 caused by carbon brush fever fever charcoal fever consists of three parts: carbon brush itself resistance fever, carbon brush touch pressure drop fever and friction fever. Carbon brush itself resistance heating power: W1 = I2R carbon brush touch pressure drop fever power: W2 = I △ E friction fever power: W3 = Fv during: I- flows through the carbon brush current; R-carbon brush resistance; Touch pressure drop; F-carbon brushing force; v-carbon brush and slip ring relative movement speed. 3 carbon brush fever causes 3.1 carbon brush in the process of increasing the resistance value will gradually increase the 500 D172HT-25 × 32 × 100 carbon brush, with the bridge method to measure the resistance of the unit after a period of time to replace the next Carbon brush measured resistance value of 0.0012 printed? 3.2 carbon brush card blocking carbon brush through the process after the current fever, brush swelling, easy card in the brush grip, this time pulling brush braid feeling very tight; part of the carbon brush because of the oscillation, brush grip Not straight and other reasons, will be in the side of the brush on the side and the other side of the attack along the hair significantly blocked, these several ways to block, with the clamp meter can still be measured current, simply misleading (brush braid Magnetic field is strong, the measurement method is not match, the clamp meter measured numerical error, the measured value only for qualitative analysis), carbon brush has been invalidated, resulting in other carbon brush to add the current to add, resistance to fever to add. 3.3 carbon brush pressure to reduce the non-constant pressure carbon brush, pressing the tension after the carbon brush touch pressure drop is small, less heat, in the carbon brushing short, the tension spring pressure is reduced, the pressure is small to a certain level, touch instability , Touch pressure drop increase, touch pressure drop fever added. 3.4 carbon brush touch surface composition film D172 carbon brush maximum circumference speed of 70m / s, the starting electromechanical slip ring diameter of 445mm, after conversion slip ring outline of the perimeter speed of 69.9m / s, carbon brush in the promise of the most Night speed running, it is very simple in the carbon brush touch surface hair film and beating, flowing through the carbon brush current instability. The slip ring is roughly opened in the groove and the abrasive carbon brush touches the surface to damage the film. But the open groove to reduce the actual touch area of the carbon brush. 3.5 slip ring oxide film composition slip ring oxide film is too thick, so that the carbon brush touch resistance to add, excitation current shunt to other circuit resistance on the small carbon brush. 3.6 damage to the current balance is usually the case, the non-constant pressure balustrade carbon brush on the exchange and compression tension spring, carbon brush and slip ring touch surface touch tight, that is, touch pressure drop is small, all 32 carbon brush Near the working conditions, the current of each carbon brush is close to the same, the average temperature of the brush body is low, the current between the carbon brush is relatively stable (called the strong balance). After a period of time, the amount of carbon brush near the wear, but the rise of the oxide film, film, jamming and other factors, the carbon brush is short or the pressure of the tension spring, the brush touch surface touch tightening force, Carbon brush between the current redistribution, each copper brush current difference increases, in an unstable balance (called weak balance). This period of time is long, gradually changing, not simply cause vigilance. When the state of temperature or excitation current to add, at any time can constitute a weak balance damage. 4 carbon brush side of the reasons slip ring roughly constitute a certain thickness of the oxide film, increasing the carbon brush touch pressure drop, coupled with individual carbon brush card resistance failure, carbon brush in a weak balance, the event when the indoor temperature is high, the unit load Fill, the excitation current to add, the weak balance between the carbon brush damage, the individual carbon brush current agility increase, severe overheating, brush body hair swelling, large current transfer to other carbon brush, and have been swollen Stuck, slip ring ring fire malignant growth, making a short period of time a large amount of carbon brush braid burning.