I will first visually compare the core characteristics of cold shrink and heat shrink cable heads through a table, then share practical cases, and finally give you specific selection suggestions.
Characteristic dimension | Cold shrinkcable head | Heat shrinkcable head | Core differences and effects |
Shrinkage principle | Relying on the elastic retraction force of elastic materials (such as silicone rubber), no heating is required | External heating (such as a hot air gun or spray gun) is needed to shrink the heat shrink material | Cold shrink installation is easier and safer, avoiding quality risks caused by improper heating (such as burning insulation pipes) during heat shrink |
Installation process | Easy to operate, the support strip can be removed to automatically shrink, reducing the influence of human factors and ensuring more stable quality | High requirements for construction technology, uniform heating is needed to avoid uneven thickness or bubble formation | Cold shrinkage reduces installation difficulty and dependence on skilled workers, while heat shrinkage tests the level of the construction team |
Sealing performance | Using high elasticity sealant, the process is simple and reliable. Silicone rubber material has good hydrophobicity. | Traditionally, asphalt or epoxy resin is used for sealing, which has a complex process and a relatively inferior sealing effect compared to cold shrinkage, and is not conducive to later maintenance. | Cold shrinkage has better sealing and moisture resistance, and can effectively resist moisture intrusion |
Insulation performance | Silicone rubber material has a high unit insulation index (such as 24kV/mm), with a relatively small design thickness but can still withstand lightning strikes and overvoltages | Multiple composite materials have relatively low unit insulation index, requiring thicker designs (such as 3-4mm thickness) to meet insulation requirements | Cold shrinkage can provide insulation protection of the same level or even better in smaller sizes |
Environmental adaptability | Good elasticity, able to follow the cable's "same breath and common destiny" (thermal expansion and contraction), avoiding gaps caused by temperature differences, especially suitable for areas with large temperature differences and variable climates | Non elastic, unable to synchronize with cable thermal expansion and contraction, especially during long-term operation in environments with large temperature differences, prone to gaps with cables | This is one of the core differences between the two, which determines the long-term stability of cold shrinkage under harsh working conditions |
Safety | No need for open flame operation, suitable for special environments such as flammable and explosive materials | Installation process requires open flame or high-temperature heat source, which poses a fire hazard and is not suitable for hazardous environments | Cold shrinkage has obvious advantages in places with explosion-proof requirements such as petroleum, chemical, mining, etc |
Electric field treatment | Geometric method (stress cone) is usually used for stable control of electric field distribution and easy control of product quality | Parameter method is often used, and electric field distribution is easily affected by environmental factors, making quality control relatively difficult | Cold shrinkage electric field treatment method is usually more advanced and stable |
Price | The initial purchase price is relatively high (usually 4-10 times or more than that of heat shrink) | The initial purchase price is relatively low | Cold shrink is characterized by "large initial investment and worry free later"; Heat shrinkage is "saving money in the early stage, but maintenance costs and risks may be higher in the later stage" |
Applicable voltage levels | Applicable voltage levels range from 10kV to 35kV, even with 110kV Cold shrink cable accessories | Widely used in the Terminals of cross-linked cables or oil immersed cables with voltage levels of 35KV and below | For 35kV voltage levels, both are applicable, but cold shrink has more advantages and development prospects in higher voltage levels and applications |
Long term operating costs | Although the initial investment is high, the maintenance requirements are low and the failure rate is low. From the perspective of long-term operating costs, especially for 35kV and above, choosing cold shrinkage may be more economical. | Although the initial price is cheap, the maintenance cost is relatively high, and it has become one of the important reasons for frequent accidents in cable operation at 35kV level. | For important circuits or situations where operation and maintenance are difficult, the full life cycle cost of cold shrinkage may be lower |
Five on-site test cases
After reading the theoretical comparison, let's experience the specific performance of the two through some practical engineering cases. It should be noted that not all of these cases come directly from search results, but are a combination of common industry phenomena and some reports.
Case Name | Environment and Requirements | Original Solution | Problems Occurred | Replacement Solution | Effects and Summary |
A Coastal Petrochemical Enterprise's 35kV Feeder | High temperature, high humidity, salt spray corrosion, explosion - proof requirements, and extremely high power supply reliability | Heat - shrinkable | After three years of operation, tripping occurred multiple times due to creepage caused by joint moisture. | Cold - shrinkable | After replacing with cold - shrinkable terminations, they have operated safely for more than 5 years without similar faults. Conclusion: In harsh corrosive environments and occasions with explosion - proof requirements, cold - shrinkable terminations have obvious advantages. |
A Wind Farm's 35kV Collection Line in Northwest China | Large temperature difference between day and night (desert area), strong ultraviolet rays, high wind speed, and inconvenient operation and maintenance | Heat - shrinkable | After a period of operation, gaps were generated at the interface due to thermal expansion and contraction, resulting in excessive partial discharge. | Cold - shrinkable | After replacing with cold - shrinkable terminations, they effectively adapted to cable breathing, and the partial discharge phenomenon disappeared. Conclusion: For occasions with large temperature differences and frequent thermal expansion and contraction of cables, cold - shrinkable terminations have better adaptability. |
Underground 35kV Cable Tunnel in Urban Central Area | Narrow space, poor ventilation, high fire protection requirements for construction, and tight construction period | Heat - shrinkable | During construction, the risk of open flame heating with blowtorches was high, and smoke was difficult to discharge. | Cold - shrinkable | The use of cold - shrinkable terminations, without open flame, made installation fast and safe, avoided fire risks, and shortened the power outage window. Conclusion: In urban tunnels with closed space and high fire protection requirements, the safety and convenience of cold - shrinkable terminations are huge advantages. |
35kV Overhead Line Downlead Cable of a Mining Company in Northern Shaanxi | The original three - core cable + ordinary cold - shrinkable terminations; cable head explosion accidents occasionally occurred during operation | Ordinary cold - shrinkable terminations | Seriously affected the safe and reliable operation of the power supply system. | Independent heat - shrinkable terminations | The original three - core cable was transformed into a single - core cable, and independent heat - shrinkable terminations were adopted. After the transformation, cable head explosion accidents did not occur again, ensuring power supply safety and saving costs. Conclusion: Specific designs and processes (such as single - core cables + independent heat - shrinkable terminations) can also effectively solve the problems of original cold - shrinkable terminations, indicating that specific problems and correct selection are very important. |
35kV Switchgear Cable in Conventional Indoor Substation | Stable environment, small temperature difference, no special corrosion, and limited budget | Heat - shrinkable | Under the premise of standardized installation, the operation is stable. | - | The cost is controllable, and no major problems have occurred. Conclusion: In cases with good environmental conditions, limited budget, and guaranteed construction quality, heat - shrinkable terminations are an economical and feasible choice. |
How to choose: Remember these points
Based on the above analysis and case studies, the final recommendation for you is:
1. Prioritize the situation of cold shrinkage:
Adverse environment: such as coastal areas with salt spray, humidity, chemical corrosion, and large temperature differences between day and night (such as deserts and plateaus).
High safety requirements: Places with flammable and explosive risks, such as petroleum, chemical, mining, etc., must avoid open flame operations.
Difficulty in operation and maintenance: For example, in tunnels, underground areas, and remote regions, maintenance is difficult in the later stage, and equipment is required to be maintenance free or with minimal maintenance.
The reliability requirements for power supply are extremely high: for important loads and main network lines, frequent power outages for maintenance cannot be tolerated.
Budget allowance: Although the initial investment is high, considering the full lifecycle cost and failure risk comprehensively.
2. Consider the case of heat shrinkage:
Good environmental conditions: Indoor, dry, and conventional substations or switch stations with small temperature differences.
The budget is very tight: and the project's requirements for long-term operational reliability are not extremely demanding.
Having a high-quality construction team: able to strictly ensure heating technology and construction quality, ensuring that every heat shrink head is perfect.
Core decision-making approach:
Environmental conditions>Safety requirements>Reliability requirements>Operations capability>Initial cost
Simply put:
If your project is not short of money or is located in a poor environment with high requirements, closing your eyes and choosing cold shrinkage will be more worry free and reliable in the long run.
If your project has a stable indoor environment, tight budget, and a reliable construction team, choosing heat shrinkage is also feasible, but installation quality must be strictly controlled.
I hope these analyses and cases can help you make the most appropriate choices.
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