L68A1 Mast Section Using practical experience to quickly eliminate the electrical fault of tower crane
(1) determine the location of electrical fault by inquiry division method
L68A1 Mast Section：
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That is to say, by asking the field operators to understand the operation of the main control system, lifting system, rotation system, luffing system, crane traveling system and other parts, to distinguish the primary and secondary, to eliminate some doubts, and to find out the system with possible faults.
(2) clear obvious electrical faults by observation, spring pressure and knocking
The methods are as follows: open the electric cabinet, first check whether the electric appliance has obvious signs of damage, scorch and loose connecting wire; then check the sensitivity of armature of contactor, wheel cleaning on various travel limit switches, start brake button, etc. If it is confirmed that everything is normal, a rubber hammer can be used to knock the working components, especially the moving components, when the tower crane is powered on. If the circuit fault disappears suddenly, it means that there is poor contact near the knocking component or the knocked component itself, which should be eliminated immediately.
(3) use short circuit method and component replacement method to quickly remove electrical faults
That is, according to the electrical schematic diagram, the suspicious circuit parts are short circuited in turn to verify whether other components of the system are normal. If other parts are normal, the fault exists in the components of the short circuit part. At this time, the same components of other systems in the main control cabinet can be removed and replaced. If the fault is removed, the replaced components are damaged. For example, when a QTZ80 tower crane is lifting under light load, everything is normal. When it is heavy load, gears I, II and IV are also normal, but there is no gear III. because there is no transition gear (gear III) between low speed (gear I) and high speed (gear IV) in the process of heavy load lifting, the tower crane is greatly impacted when it is changing speed, and the tower body shakes violently, which affects the safety of human and machine, so it must be eliminated immediately.
L68A1 Mast Section：
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Then open the main control cabinet first, find the lifting system, check the appearance, and no obvious damage, scorch and loose connecting wire are found. As it is normal in gear I and II, the eddy current (ybhe) part and KHL shall be normal (see Figure 1); when the heavy load of tower crane changes from gear I and II to gear III, the contactor and time relay Khe, kth1, Khu, KHB, kth2, KHJ, KHL, kth3, KHL, kth5, KH2, kth6 and kh3 in the main control cabinet operate in turn, but the lifting speed has no obvious change.
