Process Improvement in Volume Resistivity Detection of Semi-Conductive Shield for Large-Scale Cables

By JianYunCable -

 


Introduction

The volume resistivity of semi-conductive shields plays a crucial role in determining the electrical performance of high-voltage cables. These shields help regulate electric field distribution, reduce partial discharge, and enhance insulation stability. However, traditional detection methods for large-scale cables suffer from several challenges:
✔ Manual sample preparation results in uneven surfaces, leading to inconsistent test data.
✔ Low testing efficiency makes large-scale quality control difficult.
✔ Current resistivity measurement techniques lack precision, particularly for high-resistance samples.

This study proposes an improved testing process using large-scale cutting machines, fixed mold techniques, and copper sheet molds to enhance the accuracy and reliability of volume resistivity detection for semi-conductive shields in large-diameter cables (64/110 kV and above).

1. Key Challenges in Current Testing Methods

1.1 Sample Preparation Issues

Large-diameter cables require precise sample preparation, but manual cutting methods introduce several problems:

  • Irregular sample surfaces → Affects contact between electrodes and sample.
  • Low efficiency → Time-consuming manual operations slow down testing.
  • High rejection rates → Errors in cutting lead to wasted samples.
FactorManual CuttingLarge-Scale Cutting Machine
Surface QualityRough, unevenSmooth, precise
Cutting TimeLong (5–10 min per sample)Short (1–2 min per sample)
SafetyRisk of hand injuriesControlled cutting process

➡ Conclusion: Upgrading to large-scale cutting machines significantly improves efficiency and safety.

1.2 Problems in Volume Resistivity Measurement

A. Conductor Shield Resistivity Testing Issues

Traditional conductive paste coating method for resistivity testing suffers from:

  • Long curing times (12+ hours at room temperature).
  • Electrode damage due to sharp contact points.

B. Insulation Shield Resistivity Testing Issues

The self-adhesive copper tape method, commonly used for insulation shields, has drawbacks:

  • Weak adhesion at high temperatures (90°C) → Copper tape falls off.
  • Uneven contact with the sample, causing measurement errors.

➡ Conclusion: A more stable and repeatable resistivity testing process is needed.

2. Proposed Process Improvements

2.1 Upgraded Sample Preparation Method

Large-scale cutting machines were introduced to replace manual cutting, ensuring smooth, uniform sample surfaces.
➡ Effect: Increased efficiency, improved cutting accuracy, and reduced sample waste.

2.2 Improved Volume Resistivity Testing Techniques

A. Copper Sheet Mold Method (Replacing Conductive Paste Method)

✔ Pre-fabricated copper sheet molds ensure stable contact with the sample.
✔ Eliminates long curing times, improving testing speed.

B. Fixed Mold Method (Replacing Self-Adhesive Copper Tape Method)

✔ Uses a tight-fit mold to secure copper electrodes against the sample.
✔ Prevents detachment at high temperatures, ensuring reliable data collection.

MethodAdvantagesReplaced Method
Copper Sheet MoldFast, repeatable, high accuracyConductive paste method
Fixed MoldNo adhesive issues, stable contactSelf-adhesive copper tape

➡ Effect: Enhanced measurement consistency, reducing error rates.

3. Experimental Validation and Results

3.1 Sample Quality Comparison

Cutting MethodSurface SmoothnessPreparation Time
Manual CuttingUneven~10 min/sample
Large-Scale CuttingSmooth~2 min/sample

➡ Key Finding: Automated cutting ensures smoother samples and faster preparation.

3.2 Volume Resistivity Test Results

Tested on 64/110 kV cables with different cross-sectional areas:

A. Conductor Shield Resistivity Results

MethodVolume Resistivity (Îİ·m) after Heating
Conductive Paste6.62 (0.5h) → 5.90 (1.5h)
Copper Sheet Mold5.91 (0.5h) → 5.66 (1.5h)

➡ Copper sheet method consistently produced lower and more stable resistance values.

B. Insulation Shield Resistivity Results

MethodVolume Resistivity (Îİ·m) after Heating
Self-Adhesive Copper Tape5.69 (0.5h) → 1.82 (1.5h)
Fixed Mold1.71 (0.5h) → 1.69 (1.5h)

➡ Fixed mold method significantly reduced resistance fluctuations, ensuring measurement accuracy.

4. Engineering Insights and Industry Implications

4.1 Impact on Quality Control

✔ Higher repeatability → Eliminates sample variation.
✔ Reduced testing time → Increases productivity in manufacturing QC labs.

4.2 Economic and Industrial Benefits

AspectImprovement
Production Efficiency+30% faster testing cycle
Testing Cost-20% material waste reduction
Compliance with StandardsMeets GB/T 11017.1-2014 requirements

➡ Manufacturers can improve efficiency while maintaining high-quality standards.

5. Conclusion and Recommendations

5.1 Summary of Key Improvements

✔ Large-scale cutting machines enhance sample preparation efficiency.
✔ Copper sheet molds eliminate inconsistencies in conductor shield resistivity testing.
✔ Fixed mold technique ensures reliable insulation shield resistivity measurement.

5.2 Future Research Directions


  • AI-driven automation for real-time defect detection.
  • Advanced materials for better shield conductivity and stability.
  • Integration with smart monitoring systems for in-line testing.


Final Verdict: These improvements enhance testing accuracy and efficiency, making them highly beneficial for large-scale cable manufacturers.

Keywords

  • Large-Scale Cables
  • Semi-Conductive Shield
  • Volume Resistivity Testing
  • High-Voltage Power Cables
  • Quality Control in Cable Manufacturing

References

  1. Li Mei (2025). Process Improvement in Volume Resistivity Detection of Semi-Conductive Shield for Large-Scale Cables. Wire & Cable, 68(1), 55-60. DOI: 10.16105/j.dxdl.1672-6901.20240095
  2. GB/T 11017.1-2014 – Test Methods for High Voltage Power Cable Shielding
  3. GB/T 3048.3-2007 – Electrical Performance Testing of Semi-Conductive Materials
Source: JianYunCable

Comments

Post a Comment

Popular posts from this blog

Understanding Voltage Levels and Cable Types in China's Power Industry

By JianYunCable -
Image
  In China's electrical power industry, voltage levels play a critical role in determining the type of cables used and their applications. Common voltage grades include 220V, 380V, 1kV, 10kV, 35kV, 110kV, 220kV, and 500kV. These are broadly categorized into three groups: low voltage, medium voltage, and high voltage. This article explores the differences between low-voltage and high-voltage cables, their structures, uses, production processes, and how to distinguish them in practice. Voltage Classifications in China Low Voltage (LV):  Typically 220V and 380V, primarily used for household electricity and small-scale applications. Medium Voltage (MV):  Ranges from 1kV to 35kV, serving as an intermediary for industrial and local distribution networks. High Voltage (HV):  Starts at 35kV and above (e.g., 110kV, 220kV, 500kV), mainly employed for long-distance power transmission. These classifications dictate the design and construction of cables to ensure safety and effic...
Read more

Comparison of Flame Retardant Standards for Electric Wires and Cables

By JianYunCable -
Image
  ​ Introduction With the increasing demand for  fire safety in electric wires and cables ,  flame retardant standards  play a critical role in preventing  fire hazards and the spread of flames . This paper compares the  domestic and international flame retardant standard systems , focusing on  GB/T 19666-2019  and  GB 31247-2014 , and analyzes the  key technical indicators, sample burning methods, and combustion test parameters . 1. Current Standards for Flame Retardant Cables 1.1 International Standards (IEC 60332 Series) IEC 60332-1-1:2015 ,  IEC 60332-1-2:2004 , and  IEC 60332-1-3:2004  focus on the  flame spread height  based on  non-metal content in cables . China adopts these standards through  GB/T 18380-2022 , which aligns with  IEC 60332 . 1.2 Chinese National Standards GB/T 19666-2019 : General rules for flame-retardant and fire-resistant electric wires and optical cables. GB 31247-2014 ...
Read more

What Are Trailing Cables and Where Are They Used?

By JianYunCable -
Image
  Table of Contents What Are Trailing Cables? Construction and Features Key Benefits of Trailing Cables Applications of Trailing Cables Limitations of Trailing Cables Trailing vs. Standard Cables Comparison Table Tips for Choosing Trailing Cables Conclusion What Are Trailing Cables? Trailing cables, also known as reeling cables or mining trailing cables, are specialized, highly flexible electrical cables designed to power mobile or frequently moving equipment in demanding industrial environments. Engineered to withstand mechanical stresses such as bending, twisting, stretching, and coiling, these cables ensure a reliable connection between power sources and equipment like excavators, cranes, and draglines. They are commonly used in industries such as mining, construction, and heavy manufacturing, where durability and safety are critical. Trailing cables comply with standards like AS/NZS 1747 (for mining cables) and IEC 60245, offering features like flame retardancy and grounding fo...
Read more

Understanding Low Voltage Power Cables: A Comprehensive Guide

By JianYunCable -
Image
Low voltage (LV) power cables are an essential component of modern electrical systems, facilitating the safe and efficient transmission of electricity for a wide range of applications. Defined as cables with a rated voltage not exceeding 0.6/1 kV (600 volts for DC or 1000 volts for AC), they are widely used in residential, commercial, and industrial settings. This article explores the key aspects of LV power cables, addressing common questions from multiple angles—design, applications, materials, and challenges—while providing clear answers backed by scientific principles and practical insights. What Are Low Voltage Power Cables ? Low voltage power cables are electrical cables designed to transmit power or signals at voltages up to 0.6/1 kV. Unlike high voltage (HV) cables, which handle large-scale power distribution (typically above 1 kV), or medium voltage (MV) cables (3-35 kV), LV cables cater to localized power needs, such as household wiring, industrial machinery, ...
Read more

Medium Voltage Cable Life Expectancy: Factors and Insights

By JianYunCable -
Image
Table of Contents What Are Medium Voltage Cables? What Is the Life Expectancy of MV Cables? Factors Affecting MV Cable Life Expectancy Single-Core and Multi-Core MV Cables MV Cable Insulation Comparison Table Maintenance Tips to Extend MV Cable Life Conclusion What Are Medium Voltage Cables ? Medium voltage (MV) cables are electrical cables designed to transmit power at voltages ranging from 3.6 kV to 35 kV, bridging the gap between low voltage (up to 1 kV) and high voltage (above 50 kV) systems. They are critical for power distribution in urban and rural networks, industrial facilities, mining operations, and transportation systems like railways. MV cables typically feature copper or aluminum conductors, insulation (often cross-linked polyethylene, or XLPE), and protective layers like metall...
Read more

4 AWG Wire: Definition, Specifications, Ampacity, and MM² Equivalent

By JianYunCable -
Image
  Table of Contents What is 4 AWG Wire? 4 AWG Wire Specifications Ampacity of 4 AWG Wire 4 AWG Wire in MM² Applications of 4 AWG Wire Summary of 4 AWG Wire Characteristics Tips for Selecting 4 AWG Wire Conclusion What is 4 AWG Wire? 4 AWG wire refers to a conductor sized according to the American Wire Gauge (AWG) system, a standardized method for measuring wire diameters in North America. The AWG system assigns smaller gauge numbers to thicker wires with greater current-carrying capacity. A 4 AWG wire is a relatively large conductor, suitable for high-current, low-voltage applications in residential, commercial, and industrial settings. It is commonly made of copper or aluminum, with copper offering higher conductivity and aluminum providing cost savings for larger installations. 4 AWG wire is used in applications requiring significant power delivery, such as service entrances or heavy equipment, as discussed in prior articles on AWG, 2 AWG vs. 2/0 AWG, and medium voltage cables. 4...
Read more

Optimized Design of Smooth Aluminum Sheath Thickness for High-Voltage Cables Using the Short-Circuit Capacity Method

By JianYunCable -
Image
  Introduction High-voltage and ultra-high-voltage underground power cables require  metal sheaths  to provide  mechanical protection, waterproofing, and electrical shielding . A  smooth aluminum sheath  offers advantages over traditional  corrugated aluminum sheaths , including  better electrical contact and lower risk of insulation failure . However, if the aluminum sheath  thickness is not optimized , it may  wrinkle during bending , compromising cable performance. This study introduces a  short-circuit capacity-based design method  for determining the  optimal aluminum sheath thickness , ensuring both  mechanical durability and electrical safety . 1. Influence of Aluminum Sheath Thickness on Cable Performance 1.1 Wrinkling and Mechanical Stability When designing aluminum sheath thickness, using values from  corrugated aluminum sheaths  can lead to  wrinkling  after bending, especially in  ...
Read more

0.6/1kV CU/XLPE/PVC Cable

By JianYunCable -
Image
  0.6/1kV CU/XLPE/PVC Cable Introduction Conductors Copper conductor Insulation XLPE (Cross-Linked Polyethylene) Outer Sheath PVC (Polyvinyl Chloride) Application These cables are used for electricity supply in low voltage installation system. They are suitable for installation in indoors and outdoors, in cable ducts, under ground, in power and switching stations, local energy distributions, industrial plants, where there is no risk of mechanical damage. Product Parameters Single core(unarmoured) Nominal Cross Section Diameter of Conductor (Approx.) Nominal Insulation Thickness Nominal Sheath Thickness Overall Diameter (Approx.) mm² mm mm mm mm 1x1.5 1.4 0.7 1.4 5.6 1x2.5 1.8 0.7 1.4 6 1x4 2.3 0.7 1.4 6.5 1x6 2.8 0.7 1.4 7 1x10 3.6 0.7 1.4 7.8 1x16 4.5 0.7 1.4 8.7 1x25 5.6 0.9 1.4 10.2 1x35 6.7 0.9 1.4 11.3 1x50 8 1 1.4 12.8 1x70 9.4 1.1 1.4 14.4 1x95 11 1.1 1.5 16.1 1x120 12.4 1.2 1.5 17.8 1x150 13.8 1.4 1.6 19.8 1x185 15.3 1.6 1.6 21.8 1x240 17.5 1.7 1.7 24.4 1x300 19.5 1.8 1.8 ...
Read more

Residential Wiring: Types, Gauges, Wires, and Standards

By JianYunCable -
Image
  Residential wiring is the foundation of a home’s electrical system, delivering power safely to outlets, lights, and appliances. Knowing the types of wires used, the appropriate gauge for outlets, the purpose of each wire in a circuit, and the standard wiring practices ensures safety and efficiency. This article addresses these topics through four key questions, using a table to organize wire types and analogies to make concepts engaging. Table of Contents What Type of Wire Is Used in Residential Homes? Should I Use 12 or 14-Gauge Wire for Outlets? What Are the 4 Wires in House Wiring? What Is Standard Electrical Wiring in a House? What Type of Wire Is Used in Residential Homes? Residential homes use specific types of electrical wires designed for safety, ease of installation, and compliance with local codes like the National Electrical Code (NEC). These wires are typically low voltage, operating at 120/240 volts in the US, and are insulated to prevent shocks. Here are the most co...
Read more

Single-Core Wires: Applications and Functionality

By JianYunCable -
Image
  Introduction to Single-Core Wires A single-core wire, also referred to as a single-conductor wire, consists of a single conductive core, typically made of copper or aluminum, surrounded by an insulating layer and, in some cases, an outer protective sheath. These wires are designed to transmit electrical power or signals in a variety of applications, offering simplicity and reliability for specific electrical and control systems. Single-core wires are fundamental components in electrical installations, valued for their straightforward design and versatility in both low- and high-voltage applications. Design and Construction Single-core wires are engineered to meet specific electrical, mechanical, and environmental requirements. Their key components include: Conductor:  The core is typically made of copper for high conductivity or aluminum for cost-effective and lightweight applications. The conductor may be solid (a single piece of metal) or stranded (multiple thin strands tw...
Read more

All Cable Products-Henan Province Jianyun Cable Co., Ltd.

Loading...