HV Cable Failures? Top 3 Installation Errors & Fixes

2025-05-24 13:40:16

The installation quality of medium and high voltage cable accessories (Terminals/intermediate joints) directly affects the reliability of the power grid. This article focuses on three core misconceptions: preprocessing, stress control, and size matching, providing practical optimization solutions to reduce installation failure risks by over 60%.   

Misconception 1: Improper pre-treatment before installation

Typical problem:

-The residual semiconducting particles on the surface of the main insulation cause partial discharge (partial discharge>20pC).   

-The steel armored grounding wire is not firmly crimped, with a contact resistance greater than 50 μ Ω, resulting in abnormal current circulation in the protective layer.   

Solution:

1. Deep cleaning:

-Use non-woven fabric and anhydrous alcohol for one-way wiping (insulation → semiconductive layer), and prohibit reciprocating motion.   

-The roughness of the conductor after polishing is ≤ 0.02mm (detected by a white light interferometer).   

2. Grounding standardization:

Hengli spring crimping (tension ≥ 500N), dual ground wire separation design (steel armor and shielding layer independently grounded).   

Misconception 2: Failure to meet stress control standards

Typical problem:

-The stress cone offset is greater than 5mm, the electric field concentration area is not covered, and the insulation life is shortened by 50%.   

-Uneven application of silicone grease and residual air gaps at the interface (thickness>0.5mm).   

Solution:

1. Precise positioning tool:

Laser positioning device assisted installation, with an error of ≤± 2mm (refer to GB/T 12706.4).   

2. Quantitative management of silicone grease:

Use a grease gun to inject a quantitative amount (0.10.3mm) and squeeze out excess silicone grease.   

Misconception 3: The size of the accessories and cables does not match

Typical problem:

-Cold shrink attachment interference deviation (measured<2mm or>5mm), risk of sealing failure.   

-The prefabricated accessory trial installation is missing, and the interface pressure is insufficient (<0.3MPa).   

Solution:

1. Digital selection:

Scan the cable cross-section in 3D and generate compatible accessory models (such as the SmartFit system of Hellenic Cables).   

2. Pre installation verification process:

Pre tension test for cold shrink accessories (elastic modulus ≥ 1.5MPa), pressure testing for prefabricated accessory trial assembly.   

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