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1. What is a shielded cable?

Shielded cable is a special transmission cable with a metal braid or metal foil (such as copper or aluminum) wrapped around the conductors. By grounding the shield layer, it effectively isolates or reduces external electromagnetic interference (EMI) and radio frequency interference (RFI), and prevents internal electromagnetic radiation from affecting nearby equipment. It is widely used in control, communication and signal transmission systems.

2. Key Points of Shielded Cables

2.1 Structure:

Composed of conductors (cores), insulation layer, shielding layer (metal braid/aluminum foil) and outer sheath.

2.2 Main Function:

Reduce interference and protect signal integrity. In power cables, it prevents partial discharge and protects personnel and equipment.

2.3 Shielding Types:

Include braided shielding (for low-frequency interference), aluminum foil shielding (for high-frequency interference), and combined shielding (braid + aluminum foil).

2.4 Usage:

Must be grounded. Single-end grounding is generally recommended to avoid interference currents caused by different ground potentials at both ends.

2.5 Typical Applications:

Industrial automatic control systems, frequency converters, monitoring systems, data centers and highly sensitive electromagnetic environments.

2.6 Advantages:

Significantly improve the anti-interference ability and ensure signal integrity.

2.7 Disadvantages:

Compared with unshielded cables (UTP), they are stiffer, heavier, more expensive, and more complicated to install.

3. Operating Characteristics:

Rated voltage U0/U 3.6/6 kV;

Long-term operating temperature of the cable conductor: 90℃;

Minimum bending radius: 6 times the outer diameter of the cable;

The cable shall not be exposed to direct sunlight for a long time;

The grounding core of the cable must be properly grounded.

4. Main Technical Performance

4.1 Finished cables shall pass power frequency AC voltage test: 11.0 kV for 5 min for power cores.

4.2 Transition resistance: Transition resistance of shielding or monitoring layer shall not exceed 3 kΩ.

4.3 Flammability test: Cables shall pass the burning test specified in GB12666.2 DZ---1.

4.4 Partial discharge test: Discharge quantity not exceeding 20 pC at 1.5U₀.

4.5 Dielectric loss tangent test: Not more than 0.035 at U₀.

4.6 Impulse voltage test: After 10 times positive and negative impulses at 60 kV at 95 °C, apply 11 kV power frequency voltage for 15 min on samples.

4.7 Cables shall withstand 3U power frequency voltage test for 4 hours.

5. Purpose of Shielding

Shielding is intended to ensure the transmission performance of a system in an electromagnetic interference environment. Anti-interference here includes two aspects: the ability to resist external electromagnetic interference and the ability to limit electromagnetic radiation emitted by the system itself.

In theory, covering cables and connectors with a metallic shielding layer can effectively filter out unwanted electromagnetic waves, which is the method adopted by most shielding systems. However, the effectiveness of this method depends heavily on proper grounding. A metallic layer alone is insufficient; the shield must be fully and correctly grounded to drain interference currents safely into the earth.

In practical installation, shielding systems face serious challenges. Strict grounding requirements often lead to poor grounding, such as excessive resistance or unbalanced ground potential. This creates a potential difference between two points in the transmission system, inducing current in the shield and breaking its continuity. In such cases, the shield itself becomes a major interference source, resulting in worse performance than unshielded systems.

For high-frequency transmission, both ends of the shield are usually grounded, which further increases the risk of potential differences. A complete shielding system requires continuous shielding at every point; any defect will degrade overall performance. However, most network hubs and computers on the market lack built-in shielding support, making full-link shielding difficult to achieve.

6. Choosing Taitong Cable’s shielded cables is the right decision:

As a trusted Chinese cable supplier with decades of experience and large-scale manufacturing facilities, Taitong Cable offers unparalleled procurement advantages. We deliver premium shielded cables embodying "Chinese Quality"—reliable performance, multiple specifications, and customizable solutions tailored to diverse needs. Taitong provides cost-effective pricing, backed by efficient production chains, to ensure competitive value. With professional pre-sales consultation and global after-sales support. Upholding "Global Service" commitments, enabling timely deliveries worldwide, Taitong is ready to partner with an experienced supplier that balances top-tier quality, flexible options, and dedicated service for your shielding cable needs.