3.1.1 Insulating Bar
1.Basic Structure and Function of Insulating Bar
(1)Basic structure
①Insulating bar is composed of two parts:joint and insulating rod,and some insulating bars are equipped with grab handle at the end.The joint of can be fixed type or disassembled type,and the joint fixed on the bar is made by high strength material.Fig.3-1 shows the structure of the insulating bar.
Fig.3-1 The Structure of the Insulating Bar.
②The length of each part of the insulating bar shall meet the requirements of Table 3-1.
Table 3-1 Requirements for Length of Each Part of the Insulating Bar
(2)Function
In live working,operators shall install corresponding accessories on the insulating bar,so that they can use the insulating bar to complete multiple operations such as lead disconnection and connection while maintaining a safe distance from the electrified body.
2.Classification and Technical Specifications of Insulating Bars
(1)Classification
①The insulating bars can be divided into 3m,4m,5m,6m,8m,and 10m insulating bars by length.
②Insulating bars can be divided into 10kV,35kV,110kV,220kV,330kV,and 500kV insulating bars according to voltage class.
③Insulating bars can be classified into two types according to the material:manual roll forming bar with FRP epoxy resin bar and mechanical pultrusion bar.The two types of insulating bars have their own advantages:The advantage of the manual roll forming bars is that the tension is large,but the longitudinal strength is relatively small compared with the mechanical pultrusion bars;the advantage of the mechanical pultrusion bars is that the strength is large,but the transverse tension is relatively small compared with the manual roll forming bars.
④Insulating bars can be classified as interface insulating bar,retractable insulating bar and maneuver insulating bar according to the structure.The interface insulating bar is a commonly used insulating bar.The spiral joint is used at the section separation part,which can reach 10m at most.It can be conveniently carried as the sections can be bagged.The retractable insulating bar is designed with 3 sections that are retractable,which can generally reach 6m at most.It is light in weight,small in size,and easy to carry and use.It can be telescopically positioned to any length according to the used space,effectively overcoming the shortcomings of the inconvenience to use of interface insulating bars due to the fixed length.The maneuver design is adopted for the interface of the maneuver insulating bar,so it does not overturn when it is tightened.
(2)Technical specifications
①The insulation length of the insulating bar shall not be less than 0.7m.
②The material of the insulating bar has the advantages of high compressive strength,corrosion resistance,moisture resistance,good mechanical property,light weight and portability.
③The connection between the three sections shall be firm and reliable and they must not fall off during operation.
3.Inspection Items of Insulating Bars
The insulating bar must be inspected before use as follows.(https://www.daowen.com)
(1)First check whether the specifications of the insulating bar are the same as the working line voltage class.It is forbidden to use the insulating bar that does not meet the specifications.
(2)Check whether the test certificate of the insulating bar is within the validity period.
(3)Check the appearance of the insulating bar for external damages such as cracks and scratches.
(4)The connection between the insulating bar sections shall be firm and reliable.
4.Usage of Insulating Bars
(1)When it is necessary to operate outdoors in rainy and snowy days,special insulating bar with rain and snow cover shall be used.
(2)When connecting the insulating bar,screw thread connecting section and section shall be off the ground,so as to avoid weeds or soil from entering the screw thread or adhering to the surface of the rod.The screw thread shall be tightly fastened before use.
(3)When in use,the bending force of the rod shall be minimized,so as to avoid damaging the rod body.The usage of the insulating bar is as shown in Fig.3-2.
Fig.3-2 Usage of Insulating Bar
5.Precautions for Storage of Insulating Bars
(1)After the insulating bar is used,the surface shall be wiped clean in time.
(2)The insulating bar shall be stored in a well ventilated,dry environment and stored in a well ventilated,clean and dry rack or suspended.
(3)The insulating bar must be kept by a specially assigned person.
Fig.3-3 shows the tool cabinet for storing insulating bars.
Fig.3-3 Tool Cabinet for Storing Insulating Bars
6.Preventive Test of Insulating Bars
The routine test of the insulating bar shall include the following items.
(1)Electrical test.For the electrical test of the insulating bars,the samples with voltage class of 220kV and below shall be able to pass the short-duration power-frequency withstand voltage test,and the samples with voltage class of 330kV and above shall be able to pass the long-duration power-frequency withstand voltage test and operating impulse withstand voltage test.The test cycle is 1 year.
(2)Mechanical test.The mechanical test items of the insulating bar include a bending static load test and a bending dynamic load test.The test cycle is 2 years.