Storage Of Live Working Tools
DL/T 974 "Tool Warehouse for Live Working" specifies the general requirements for the environment, space, doors and windows, fire protection, lighting, decoration materials, etc. of the construction of live working tool warehouses for power distribution and transmission, as well as the requirements for the configuration of main facilities, measurement and control functions and devices, storage facilities, information management systems, and warehouse inspection. This article only focuses on the storage of insulation tools and does not involve the construction and management requirements of warehouses.
1. Overall Requirements
The overall requirements for the storage of live working equipment include:
- Store in zones according to voltage levels.
- Classify and store according to their intended use.
- The temperature in the warehouse should be between 10 ℃ and 28 ℃, and the humidity should not exceed 60%
2. Effects of Temperature and Humidity
The commonly used insulation materials for live working in power distribution include rubber (insulation gloves, sleeves, insulation boots, soft wire shielding covers, cross arm shielding covers, insulation pads), epoxy resin (insulation clothing, insulation blankets, insulation operating rods), and insulation ropes (silk, nylon). Temperature has a significant impact on their electrical and mechanical service life. The following briefly explains the impact of temperature and humidity on insulation materials.
2.1 The Effect of Temperature on the Aging of Rubber Materials
High temperature can increase the vibration amplitude of rubber molecular chains, weaken the intermolecular interaction forces, accelerate the occurrence of oxidation reactions, degrade (crack) or crosslink (structure) molecular chains, and affect their physical properties (including mechanical and electrical properties). After aging, rubber materials become harder and more brittle, with a decrease in tensile strength and an increase in compressive permanent deformation. Taking the soft wire shielding cover as an example, this aging phenomenon is usually manifested as fine axial cracking at the bottom of the corrugated groove. Experiments have shown that when the temperature increases from 25 ℃ to 50 ℃, the aging rate of rubber will significantly accelerate, and even increase several times. Therefore, when storing and using rubber products, it is advisable to avoid high temperature environments and maintain an appropriate temperature range.
2.2 The influence of humidity on the aging of epoxy resin
Epoxy resin undergoes changes in its molecular structure in high temperature and high humidity environments, resulting in a sharp decrease in mechanical strength. At the same time, its insulation performance decreases due to the absorption of moisture. Practice has shown that when the temperature is 25-30 degrees and the
relative humidity is 75% to 95%, it is a good condition for mold growth. Mold contains a large amount of moisture, which greatly reduces the insulation performance of equipment. For some porous insulation materials, mold roots can also penetrate deep into the interior of the material. Epoxy resin is prone to deformation after absorbing moisture.
2.3 The influence of humidity on insulated ropes
The leakage current of insulated ropes after moisture exposure is 10-14 times higher than that of dry ropes under the same test voltage and length. The wet flashover voltage of silk ropes decreases by 26% and nylon ropes decreases by 33.5%. The insulation rope that has been dampened may experience increased leakage current, which may cause the insulation rope to heat up and melt during use.
3. Storage Method
Different types of tools and instruments have different storage methods due to the different characteristics of the materials and objects.
3.1 Hard insulated tools
Vertical suspension method is adopted for insulation operation rods, suspension support rods, etc. The spacing between each member should be 10cm to 15cm, and the spacing between each row should be 30cm to 50cm.
3.2 Soft insulation tools
Insulation ropes, rope sleeves, etc. are suspended vertically. The distance between insulated rope hooks should be between 20cm and 25cm, and the distance between
the lower end of the rope and the ground should not be less than 20cm.
3.3 Insulation shielding equipment and protective gear
Separate storage without being squeezed or folded.
3.4 Bypass equipment
Separate storage and keep clean.
3.5 Instrumentation
Separate storage and keep clean.
