3.3.1 Insulated Tackle
1.Basic Structure and Function of Insulated Tackles
(1)Basic structure
Insulated tackle is composed of baffle,pulley,bearing,central shaft,pulling plate,lifting shaft and hook,as shown in Fig.3-24.The pulleys are generally made of materials such as nylon,polymethyl methacrylate or engineering plastics.They are formed by car or compression molding methods.The bearings are installed inside,the number of which is determined according to the load;the partition and the reinforcing plate are made of 3240 epoxy glass cloth.The hook is the same as the general tackle,and is forged from high-quality structural steel.The hooks of a few key insulation parts can also be made of 3240 epoxy glass cloth board.
(2)Basic function
It is used as a tool for guiding or carrying a load during hoisting of the live working.In the line operation,the operators shall use the insulated tackle to lift the insulator string,live working tools and instruments and the equipotential operators to enter and exit the electric field,and the operating force steering and the inverting need the insulated tackle.Depending on the work position,hooks of different shapes can be selected;depending on bearing capacity,the tackle blocks bearing corresponding tension can also be selected to save labor.
Fig.3-24 Structure of Insulated Tackle
1-hook;2-hanger shaft;3-pulling plate;4-tackle;5-central shaft
2.Classification and Technical Requirements for Insulated Tackles
(1)Classification
Insulated tackles are divided into 15 models,and their model specifications are shown in Table 3-5.The models are expressed by the first letter of pinyin and Arabic numerals:JH indicates insulated tackles,the number after JH indicates the rated load,the number after the dash indicates the number of pulleys,and the last letter indicates the structural characteristics.For example,B-side panel closed type,K-side panel open type,D-short hook type,C-long hook type,J-insulated hook type,X-conductor hook type.
Table 3-5 Model Specifications of Insulated Tackle
(2)Technical requirements
①Parts and assemblies can only be used and assembled after inspection according to the drawings.
②After assembly,the pulley shall be flexible on the middle shaft,without jamming and friction against the rim.
③Hooks and lifting rings shall be flexible on the lifting beam.
④The cotter pins shall not be bent outward and the excess shall be cut off.
⑤The lateral bolt is not more than 2mm above the nut.
⑥The side plate opening has no jamming in the range of opening and closing of 90°.
⑦All types of insulated tackles shall be tested for electrical performance in accordance with the relevant regulations.After the AC power frequency withstand voltage is conducted for 1 min,
there shall be no heat or breakdown.(https://www.daowen.com)
⑧The mechanical performance test shall be based on the load 1.6 times the rated load for 5 minutes without permanent deformation or cracking.The breaking force of the tackle shall not be less than 3 times the rated load.
3.Inspection Items of the Insulated Tackles
(1)The insulation part of the insulated tackle shall be smooth and free from air bubbles,wrinkles and cracks.
(2)The pulley shall be flexible on the middle shaft,without jamming and friction against the rim.
(3)The side plate opening has no jamming in the range of opening and closing of 90°.
(4)Before the insulated tackles are used,the test certificate shall be checked for validity period.Insulated tackles beyond the validity period cannot be used.
(5)Check if the insulated tackle is in compliance with the requirements.
4.Usage of Insulated Tackles
(1)According to the needs of use,select the tonnage of the insulated tackle.
(2)Short hook type or long hook type can be selected depending on the characteristics of the place of use.
(3)The pulley block is labor-saving when replacing the linear insulator,and the distance control is easier.Fig.3-25 shows the insulated tackle lifting tool.
Fig.3-25 Insulated Tackle Lifting Tool
5.Precautions for the Storage of Insulated Tackles
Fig.3-26 Example of Storage of Insulated Tackles
Insulated tackles shall be placed in a well-ventilated,clean and dry special room.If the storage period exceeds the production date by 12 months,the electrical performance test shall be carried out according to relevant standards.Fig.3-26 shows the storage of the insulated tackles.
6.Preventive Test of Insulated Tackles
The preventive test of the insulated tackles includes the following items.
(1)Electrical test.Mainly including the power frequency withstand voltage test.The test cycle is 1 year.
(2)Mechanical test.Mainly including the tensile test.The test cycle is 1 year.