The foundation of electrical maintenance of crown block is electrical maintenance knowledge, especially electrical drive control circuit. First of all, you should be familiar with the principle of electric drive control and be able to correctly analyze the working principle and action sequence of the circuit diagram. Secondly, we should be familiar with the disassembly and internal structure of various electrical components of the crown block and the normal and dynamic action process of the lower component mechanism. Thirdly, the running status and equipment status of the responsible crown block should be recorded, and problems can be found through spot inspection and patrol inspection, which is helpful to find fault-prone points. Fourth, we should strengthen communication with crane operators and be familiar with their understanding of cranes and the characteristics of fault reflection. When dealing with the actual fault, we should first understand the fault situation and determine the approximate location and severity of the fault according to the reflection of the operator. And start the backup crown block to take over, and then analyze the fault according to the description of the operator and the specific fault phenomenon combined with the circuit diagram, and finally determine the fault location. Generally, it is not the electrical parts that are prone to failure, but the mechanical moving parts of various components, followed by switches and contacts. Finally, it is the real line fault. It takes a period of familiarity and accumulation to be fully qualified for maintenance work.