Differences Between Cold Shrink Cable Accessories and Heat Shrink Cable Accessories

Cross-linked cable head design principle:

First of all, the design principle of all cross-connected cable heads should follow the principle of the recovery cable body structure. Therefore, the design concept of the joints should meet the electrical standards of China's GB 12706-4 and IEC 60502-4: 1997, and must be satisfied Its electrical, physical and chemical properties to ensure the normal operation of the cable head for a long time and the safe operation of electrical equipment.

Second, principle and difference

The design principle of the cable head should meet and meet the requirements: the cable can operate safely in any natural environment. In order to achieve this, it is necessary to pay attention to four key factors, namely: seal, insulation, electric field, process and other factors, which are also the four major issues to solve the cable head.

First, seal

1 Since most of the cable heads are installed in outdoor overhead, direct burial and other environments, waterproof and moisture-proof gas are one of the keys to ensure the safe operation of the cable heads, and their sealing performance and methods should also be considered. At present, there are two methods for sealing: one is the method of potting with asphalt or epoxy resin. This method is complicated and difficult to control, and it is also not conducive to maintenance; the other new method is also the current domestic and foreign professional The manufacturer's preferred method is to use a highly elastic sealant, which has a simple process, reliable performance, easy maintenance and installation, and these unique advantages also make it the mainstream of use. With this new method, the first thing to consider is the performance of the sealant. Because the quality and performance of the sealant directly affect the sealing performance of the joint, a glue that can be firmly bonded to the surface of the cable body and the surface of the attachment material can be selected, and at the same time, it can satisfy different temperature variations. The glue that can be used is very important.

2 This full-cold-shrinkage power cable accessory is actually an elastic cable accessory; that is to say, the elasticity of the liquid or solid silicone rubber itself is pre-expanded in the factory to be put into the plastic and the support bar. Go to the scene and set it to the designated position, and withdraw the support bar to make it shrink naturally. This technology is the cold shrink technology. This accessory is a cold shrink cable accessory. Therefore, this kind of cold shrinkable accessory has good “elasticity” and can avoid the thermal expansion and contraction of the cable due to the atmospheric environment and the load of the cable during operation. That is, the gap between the insulation resulting from "cable breathing" causes a breakdown accident. The biggest drawback of heat shrinkable attachments is that they are not elastic. Can't breathe with the cable. Therefore, the fully cold-shrinkable accessory is the best choice for use in hell with large temperature difference and large impact on the environment.

Second, insulation

The insulation requirement of the cable head is to meet the two insulations between phase and phase insulation and relative ground. Claim:

1, the relative phase of the insulation is silicone rubber, heat shrinkable materials, two kinds of insulation material, usually insulation performance but also according to the unit of the material insulation index combined with the thickness of the material to meet the requirements. The company's full shrinkage attachment is selected from Dow Corning's liquid laurel rubber as raw material. Its performance index is 24kV/mm. The design running thickness should be 12mm thick, and it can stand the test of lightning impact and overvoltage. The heat-shrinking attachment is made of a mixture of various composite materials and has heat shrinking function after irradiation and processing. Its unit insulation index is 1.8-2.0kV/mm, so the design thickness is relatively thicker than the silicone rubber material 3-4mm units, namely: 15-16mm thick can reach the operating requirements.

2. Relative insulation is to prevent the charge from climbing from a high potential to a low potential to a safe distance. The cold-shrinkable silicone rubber material has a good elasticity, and as long as the design is reasonable, its strong resilience has sufficient holding force. Regardless of the thermal expansion or contraction of the environment, the shrink-fit attachments are tightly held around the cable. This prevents the inhalation of water and moisture, and the safe inner creepage distance is well ensured. At the same time, the inner creepage distance of the full shrinkage cable head is theoretically as long as 70mm is enough, and in a more secure consideration, the design is still running. The distance is 90MM.

The contraction temperature of the shrink cable head is 100oC-140oC, and the temperature can meet its shrinkage condition only when it is installed. When the temperature is low, since the thermal expansion coefficient of the cable is different from the thermal expansion coefficient of the heat-shrinkable material, it is entirely possible that delamination occurs in an environment of 80° C. or lower, and cracks occur. This will allow water and moisture to enter under the influence of the breath, thus destroying the system's insulation. However, when the conditions of the environment change, because there is no elasticity like silicone rubber, it will also affect the safety, which is the shortcoming of heat shrinkable materials.

Third, electric field:

The geometric method is applied to the electric field processing of the shrinkable cable head. The change of the electric field distribution through the stress cone is solved with a certain geometric shape and an accurate R angle. This method is easier to control and test. It can be ensured and implemented at the factory. The electric field treatment method of the shrink cable head is to use the linear parameter method to change the distribution of the electric field, must rely on two important parameters: a volume resistance, 108-11Ω; b dielectric constant 25; due to its complex production process, subject to environmental factors Large changes, the team is difficult to control the stability of the parameters, so the quality of the product will have an impact on the stability.

Based on the above analysis, there is an essential difference between the cold shrinkable middle head and the heat shrinkable cable head. But as long as the normal conditions of operation can meet the safety requirements; but with the changes in the environment, shrinkable cable head compared with the shrink cable head has unparalleled differences and advantages; In addition, the whole shrink cable head is made of special mold Made, the shape after installation is very beautiful; installation and construction speed is rapid; save time; anti-pollution and other advantages.

Today we are in a rapidly developing city, and its power system often needs to face high loads, high temperatures, low temperatures, and coastal rain and rain. Therefore, it is very important to use high-performance cable head accessories in the power system. The company's full shrink attachment can help you

Comparison table of the overall performance of total shrinkage and heat shrinkable power cable accessories:

Shrinkable power cable accessories

Full-cold power cable accessory

material

Rubber and plastic materials

Silicone Rubber

elasticity

difference

it is good

structure

Electrical stress control tube insulation protection tube and sheds and other independent production supporting construction

Stress cone, outer insulation protection tube and umbrella skirt as one

Ground connection

Need to be welded

Constant force springs, no welding

Shrinkage method

Heated with fire

Extract the core

Electric field control

Parametric stress tube

Geometric stress cone

Partial Discharge

Big

small

Construction space requirements

Large space requirements

Low space requirements

Construction speed

SLOW

fast

shape

Not beautiful

Beautiful

Digital Receiving Box is in two current and adorable colors, Cable Storage Box Plastic Grey and Cable Storage Box Plastic White. With large dimension, enough space is available for multiple cables, cords, adapters etc., all in one box.

Features: 

• Simple design: easy for installation
• Anti-skid Design: higher external rim; protecting iwatch from skidding
• High quality material: ABS plastic and rubber; fire prevention; scratch resistant
• Kids and pets protector: prevent electric shock while carelessly touching cables
• Digital devices protector: prevent cables from dust, water; reduce ageing, ensure normal life span within warranty years

Specifications:

Installation Manual: 

Cable Storage Box

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Ningbo Sinco Industrial & Trading Co., Ltd. , http://www.newsinco.com