Unshielded vs. Shielded: Strategies for breaking through electromagnetic interference in 5 kV cables

Coaxial Cable

5 kV (kilovolt) cables are usually used for high-voltage power transmission or specific industrial applications, where the concepts of “shielded” and “unshielded” are mainly applied to control or signal cables, rather than directly referring to high-voltage power cables. However, we can discuss the characteristics of shielded and unshielded cables in a general sense and try to apply their concepts to possible scenarios of 5 kV rated control or signal cables. Unshielded 5 kV cables have been in use for many years because they are less expensive, take up less space, have smaller terminations and are less costly than shielded cables. However, cable users sometimes encounter problems with unshielded installations that can be solved by using shielded 5 kV cables.

In cable technology, there are significant differences between shielded and unshielded cables in several ways, especially when dealing with high voltages such as 5 kV. The following is a detailed description of TST CABLES’ approach to shielded vs. unshielded 5 kV cables:

  1. Definition and construction

Shielded cable:
DEFINITION: It is usually wrapped with one or more layers of metallic shielding, such as woven metal mesh, metal foil or a combination of both, around the outer layer of its conductors, sometimes with a layer of insulating material as a protective film. This shielding can be single-ended or two-ended grounding, to absorb external electromagnetic interference (EMI) and prevent the internal signal radiated out.
Structure: Includes conductor, insulation, shield and jacket. The conductor is responsible for the transmission of electrical signals, the insulation layer maintains the isolation between the conductors, the shielding layer prevents electromagnetic interference, and the sheath protects the cable from external mechanical damage and environmental impact.

Unshielded cable:
Definition: Unshielded cables are cables without a metal shield inside, consisting only of conductors, insulation and possibly an outer sheath, usually wrapped only in a protective layer of plastic or other non-metallic material, mainly used for transmitting signals and electrical energy.
Structure: usually consists of conductor, insulation and outer sheath, no special shielding layer to reduce electromagnetic interference.

  1. Functions and Characteristics

Shielded cable:
Strong anti-interference ability: the shielding layer can effectively suppress electromagnetic interference and ensure the stability and reliability of signal transmission.
High safety: the insulation layer and shielding layer have good flame retardant properties, which can effectively prevent fire and electric shock and other safety accidents.
Widely used: It is widely used in occasions that require high reliability signal transmission, such as industrial control, commercial buildings, scientific research institutions and other fields.

Unshielded cable:
Good signal transmission: As there is no shielding layer, the signal transmission will not be interfered with, suitable for occasions that do not have high requirements for signals.
Easy to install: no additional shielding layer, the installation process is relatively simple.
Strong withstand capacity: due to the absence of shielding layer, it can withstand higher voltage and frequency, suitable for power transmission system with high power load.

  1. Application Scenarios

Shielded cable:
Industrial control field: such as signal transmission and power supply for automated production lines, robots, sensors and other equipment.
Commercial buildings: such as signal transmission and power supply for equipment such as elevators, access control systems, fire-fighting systems, etc.
Scientific research institutions: for signal transmission and power supply of experimental instruments and equipment in laboratories, research institutes and other places.

Unshielded cable:
Audio and video transmission: used to transmit high-fidelity audio and video signals.
Computer Network: Provide high-speed, efficient and secure data communication in Local Area Network (LAN) or Wide Area Network (WAN).
Medical equipment: data transmission and signaling for devices such as electrocardiographs and monitors.

  1. 5 kV unshielded TECK90 cables in Canada and 5 kV shielded armored cables in the United States UL 1072 and UL 1569

In Canada, 5 kV unshielded TECK90 cables are manufactured in accordance with CSA C22.2 No. 131-17 with an insulation thickness of 90 mil for sizes 6 AWG to 1000 kcmil However, 5 kV shielded HVTECK cables are manufactured in accordance with CSA C68.10-14 with two insulation thicknesses for sizes 8 AWG to 1000 kcmil: 100% (90 mil) and 133% (115 mil).

In the U.S., shielding is required for rated voltages above 2400 V according to Table 1.1 of UL 1072, 4th Edition. For 5 kV shielded armored cables, they are manufactured in accordance with UL 1072 and UL 1569 and are available in two insulation thicknesses for sizes 8 AWG to 1000 kcmil: 100% (90 mil) and 133% (115 mil).

  1. Electromagnetic interference protection:

Shielded cable: can effectively prevent external electromagnetic interference on the signal interference, but also to reduce the electromagnetic radiation generated by the cable itself, suitable for complex electromagnetic environment or high signal quality requirements of the occasion, such as data centers, hospitals, factory automation systems.
Non-shielded cable: weak protection against electromagnetic interference, easy to be affected by external interference, resulting in a decline in the quality of signal transmission, applicable to the electromagnetic environment is relatively clean or interference is not sensitive to the occasion, such as ordinary office area network cabling.

  1. Installation and cost:

Shielded cable: the installation is more complex, requiring special shielding connectors and grounding measures to ensure the shielding effect, increasing the cost of installation and technical difficulties.
Unshielded cable: easy to install, lower cost, does not require special shielding treatment, suitable for projects with limited budget or easy installation priority.

  1. Cautions

When selecting cables, the use of shielded cables should be determined according to specific application scenarios and needs.
For high-voltage cables, such as 5 kV cables, due to their special electrical characteristics and safety requirements, more care should be taken when selecting cables to ensure that the insulation and electrical performance of the cables meet the relevant standards and requirements.

For 5 kV class applications, although it is less common to talk directly about shielded or unshielded high-voltage power cables, the above distinction between shielded and unshielded still applies if what is being considered is a 5 kV-rated control or instrumentation cable (e.g., for monitoring the transmission of signals from high-voltage equipment). In this case, shielded cables may be chosen because the system has stringent requirements for signal integrity or because of strong electromagnetic interference in the operating environment. Unshielded cables, on the other hand, may be used for simple control loops or in environments where interference is low and cost-sensitive.

TST CABLES introduces 5 kV rated high performance shielded cables
In the complex and changing industrial field and high-end control applications, every bit of signal accuracy is critical, TST CABLES for you to create unparalleled signal purity and system stability. TST CABLES cable built-in multi-layer precision metal shielding, effectively blocking the external electromagnetic interference (EMI), while suppressing their own signal radiation, to ensure that the data transmission zero error, for your critical equipment to put on a strong and durable. 5 kV shielded cables and unshielded cables are significantly different in terms of definition, structure, function, features and application scenarios, etc. TST CABLES recommends that you take into account specific application requirements and scenarios when selecting cables to ensure their performance and safety. If you have needs or questions about 5 kV shielded cables or unshielded cables, please feel free to contact us by email.

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