KW4-Dustproof Miniature Micro Switch
Features
â—† Inner Housing tunnel design, silicone ring sealing design, stable Wireless Micro Switch,Micro Touch Switch,Ip60 Dustproof Switch,Dustproof Miniature Micro Switch Ningbo Jialin Electronics Co.,Ltd , https://www.donghai-switch.com
sealing IP60.
â—† Small Compact Size,Safety Approvals.
â—† Long life & high reliability.
â—† Wide Range of wires Terminals.
â—† Variety of Levers.
â—† Suit of harsh environment applications, Such as vacuum cle
analysis! Power cable failure and pre-control measures
The installation of cables underground is a key trend in urban modernization. As the number of cable lines increases and their operational years grow, the occurrence of cable faults has also risen significantly. Faults in the cable body, accessories, and during operation have become more frequent. Based on many years of maintenance experience, it is clear that the main fault locations are concentrated in the insulation, accessories, and outer sheath.
**Analysis of Insulation Failure Causes**
1. **Insulation Faults**
Cable insulation aging typically occurs in the later stages of operation, often after 15 years or more. This leads to a sharp increase in failure rates. Insulation aging can be categorized into dendritic aging, electrical aging, and thermal aging. Air gaps within the insulation medium can cause ionization under electric fields, generating substances like ozone and nitrate, which corrode the insulation layer. Moisture can further degrade the insulating fibers, reducing insulation strength.
Overheating accelerates this aging process. Internal air gaps generate local heat, leading to carbonization of the insulation material and a drop in dielectric strength. Cables installed near heat sources or in poorly ventilated areas without proper insulation can overheat, causing premature damage to the insulation layer.
Long-term exposure to electricity and heat changes the physical properties of the insulation, resulting in reduced dielectric strength or increased dielectric loss, ultimately leading to breakdown. Key causes include:
- Improper cable selection leading to long-term overvoltage.
- Proximity to heat sources causing early aging.
- Exposure to chemically reactive environments.
- Poor contact between parallel cables.
- Insecure crimping of cable connectors causing overheating.
**2. Accessory Issues**
Cable joints and terminations are often installed on-site, making them prone to leakage if not carefully handled. Accessory failures account for a large portion of cable line faults, with common issues including interface discharge and material aging. Poor manufacturing processes, such as bubbles, moisture, or impurities inside the accessories, can lead to partial discharges and insulation breakdown.
Common problems include:
- Low-quality intermediate joints and terminal heads.
- Improper removal of semi-conductive layers, leading to electric field concentration.
- Poor crimping of metal connectors, causing high resistance and overheating.
- Inadequate sealing allowing moisture ingress, degrading insulation.
- Poor conductor connection tube handling, leading to uneven electric fields.
- Incorrect installation of stress tubes, causing charge accumulation and overheating.
- Unreliable grounding connections increasing induced overvoltage and insulation breakdown.
During operation, temperature fluctuations can cause expansion and contraction, affecting the seal of heat-shrinkable accessories. If the seal is compromised, moisture can enter, causing internal short circuits.
**3. Outer Sheath Problems**
The outer sheath is the first line of defense for power cables. Its integrity directly affects the safety and lifespan of the cable. Common reasons for sheath failure include:
- Damage from hard objects or external forces, especially in high-traffic areas.
- Defects during construction, such as cracks or improper bending.
- Termite attacks, though less common in northern regions.
**Preventive Measures**
To prevent cable failures, a comprehensive approach is essential. From design to operation and maintenance, all stages must be carefully managed.
- Ensure proper cable selection and grounding system design to avoid overvoltage.
- Avoid placing cables in areas with heat, corrosion, or external damage risks.
- Strengthen quality control during selection, factory supervision, and on-site inspection.
- Train personnel thoroughly and enforce certification requirements.
- Improve quality checks on hidden works and intermediate steps.
- Use online monitoring technologies to detect faults early.
Only through strict quality control at every stage—production, transportation, laying, installation, testing, and inspection—can cable faults be minimized, ensuring safe and reliable long-term operation.