After a long time operation of a diesel generator, its brushes may spark. When this happens, users must not panic, they should immediately cut off the power, and then call the manufacturer's after-sales phone to listen to the opinions of professional and technical personnel to operate. In view of this situation, Starlight Power Generation Equipment summarizes the reasons for the sparking of the four-point diesel generator brushes, and hopes that users can promptly investigate according to the following content when encountering this situation.
1. Large bearing vibration. Due to the many additional equipment in the bearing, it is naturally difficult to control the vibration to a minimum. Diesel generators run for a long time, fatigue, aging and other complex factors cause bearing vibration to increase. With the vibration of the brush, the friction of the brush column will be uneven, the lead wire and the spring will be loose, and the occurrence of local sparks will gradually further affect the overall situation.
2. The surface of the brush is dirty. This is the most overlooked point. The normal running diesel generator brushes are sealed in a closed cabinet. There is a gear-shaped axial flow fan sleeved on the shaft between the two-pole brushes. The graphite carbon powder and the brushes are ground by the rotation of the rotor. The heat is removed in time to achieve the effect of cleaning and cooling. If the cabinet door is not closed tightly or the door is forgotten to close during the inspection, the dust from the outside will be sucked into the brush along with the hot air and attached to the brush column, which will affect the heat dissipation of the brush. On the other hand, when the electric brush sparks, the surface of the brush post is not clean, and the insulation strength between the brush posts is not enough, so it is easy to ring fire. In addition, the slip ring has a spiral groove on the car, which is to increase the heat dissipation area of the brush, improve the contact with the brush, so that the brush can be more fully cooled, and the toner can be more easily removed. If the cabinet door is not closed tightly, the fan dust will easily adhere to the spiral groove if the fan's suction is insufficient, and the consequences can be imagined.
3. The brush pressure is uneven or does not meet the requirements. When the brushes leave the factory, the manufacturer has relevant regulations: the brush pressure is adjusted to the lowest pressure that does not cause sparks. After scientific demonstration and practice summary, the minimum pressure is generally 200～300ɡ/c㎡, that is, 0.02～0.03MPa, and each brush is required. The pressure between them should also be uniform, and the difference should not exceed 10. In the long-term operation of the diesel generator, if the friction of a certain brush is too short, or the brush is stuck in the brush frame, the pressure will appear uneven. In addition, the pressure cannot reach the minimum theoretical requirement that the brush does not generate sparks due to factors such as the mechanical and the spring itself being heated and soft. In addition, when pressing and pulling the carbon brushes, sometimes relying on feelings and no accumulation of experience, the operation error is very large.
4. The brush current density is too large. In actual operation, if one or two brushes are stuck due to mechanical reasons, insufficient spring pressure and other reasons, the current through other brushes will increase in order to maintain the normal load. The frictional brush has an increased flow density on the contact surface due to the reduced contact area with the slip ring. According to Q=I*IRT, the heat generation is proportional to the square of the current. When the accumulated heat cannot be dissipated, the temperature rises sharply, and sparks will be generated on the contact surface of the brush and the slip ring. In addition, after the sparks are generated, the working environment of the electric brushes becomes worse, and the vicious circle makes the sparks of the electric brushes more serious. When this situation is serious, a ring fire will occur.
It can be understood from the above that the sparking of diesel generator brushes is mainly related to bearing vibration, brush cleanliness, pressure and current density, etc., especially the cleanliness of brushes, which is easily overlooked by people. If you are using a diesel generator in the process of such a phenomenon, do not panic, you must make a judgment and deal with it as soon as possible.
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