3.2.2 Insulated Rope Ladder
1.Basic Structure and Function of Insulating Rope Ladder
(1)Basic structure
The side rope and the endless rope of the insulating rope ladder shall be made of mulberry silk or flame-retardant insulating fiber raw materials not lower than the performance of mulberry silk.The cross pedal shall be made of epoxy phenolic laminated glass cloth tube raw materials.
Fig.3-20 shows the insulating rope ladder.
Fig.3-20 Insulating Rope Ladder
(2)Basic function
In the process of live working,the insulating rope ladder is used for climbing at high places,working at high places and equipotential working.
2.Classification and Technical Specifications of Insulating Rope Ladders
(1)Classification
①According to the step distance of insulating rope ladder,there are three kinds of insulating rope ladders:300mm,400mm and 500mm.
②According to the electrical performance in damp conditions,insulating rope ladder can be classified as conventional type and moisture-proof type insulating rope ladder.
(2)Technical specifications
①It is used as a cross pedal's laminated epoxy glass cloth tube,its outer diameter is 22mm,the wall thickness is 3mm,the length is 300mm,the nozzles at both ends are arc-shaped R1.5,It shall be flat and smooth,with the outer surface coated with insulating paint.
②The rope diameter of the endless rope and the side rope is 10mm,and the laying length of the strand is 32±0.3mm.
③All parts of the rope ladder head shall shall be subject to anti-corrosion treatment.
3.Inspection items of insulating rope ladders
(1)The connection of each component shall be tight and firm,and the overall structure is good.
(2)The main components of the rope ladder head shall have a smooth surface and no defects such as sharp edges,brushes,notches and cracks.
(3)The connection between the endless rope and the side rope shall be firm and flat,and the twisted synthetic rope strands shall be tightly twisted without looseness or separation.There shall be no fold marks,bulges,crushing,reverse strands,cramps and other defects on each strand of the rope and silk threads of each strand,and there shall be no disorganized or intersecting filaments,wires or strands.
(4)Before the insulating rope ladder is used,the 2500V and above tramegger or insulating detector shall be used for segmented insulating detection(electrode width 2cm,interelectrode width 2cm),and the resistance value shall not be less than 700mΩ.(https://www.daowen.com)
(5)After the installation of the insulating rope ladder,the impact test of the force must first be carried out to check the installation and bearing capacity of the insulating rope ladder.Fig.3-21 shows the force check before the insulating rope ladder is used.
Fig.3-21 Stress Check before Using the Insulating Rope Ladder
(6)Before the insulating rope ladder is used,the test certificate shall be checked for validity period.Insulating rope ladders beyond the validity period cannot be used.
4.Precautions for Use Insulating Rope Ladders
(1)The length of insulating ladder shall be selected according to the height of the operation point.
(2)When the operator enters the equipotential electric field,the somersault tackle and lifting rope shall be hung first;then the insulating rope ladder and backup protection rope shall be lifted through lifting rope.
(3)A backup protection rope must be used to climb the rope ladder.There are two ways to climb,namely side climbing and front climbing.
(4)When the potential is transferred between the climbing rope ladder and the ladder head,attention must be paid to the distance between the exposed part of human body and the electrified body.
(5)For operation with rope ladder or mobile operation with ladder head on the overhead line,only 1 person is allowed to work on the rope ladder or ladder head.The seal of the ladder head shall be reliably closed before the staff reaches the ladder head and the ladder head begins to move.Otherwise,the protection rope shall be used to prevent the ladder from being unhooked.Fig.3-22 shows the use of an insulating ladder in equipotential operation.
Fig.3-22 Use of Insulating Rope Ladder in Equipotential Operation
5.Precautions for Storage of Insulating Rope Ladders
Insulating rope ladders shall be placed in special tool bags,tool cars or special tool cars during transportation to prevent moisture.injury.The insulating rope ladders shall be stored in a clean and dry special room with good ventilation,infrared light bulbs or dehumidifying equipment.If the storage period exceeds the production date by 12 months,the electrical performance test shall be carried out according to relevant standards.Fig.3-23 shows the storage of the insulating ladders.
Fig.3-23 Example of Storage of Insulating Rope Ladder
6.Preventive Test of Insulating Rope Ladders
The preventive test of the insulating rope ladders includes the following items.
(1)Electrical test.Mainly including the power frequency withstand voltage test and the operating impulse withstand voltage test.The test cycle is 1 year.
(2)Mechanical test.Mainly including the tensile test of the insulating rope ladder and the dynamic and static load tests of the rope ladder head.The test cycle is 2 years.