What are high-voltage cables?

By AJ Born

Meet the Connector: High-Voltage Cables

High-voltage (HV) cable, is a highly insulated, heavy-duty cable necessary for high-voltage power transmission. It is used in instruments, ignition systems, and alternating current (AC) and direct current (DC) power transmission in many environments.

High voltage cable is used in electric vehicles (EVs) to transmit power from the battery to the motor, inverter, and charger, and for communication signals to vehicle monitoring and management systems. Voltages in EVs can be as high as 1500V and require thicker insulation and cables that are heavier and stiffer. Weight impacts performance and range. Stiffness creates challenges for routing the cable within the car.

The structural elements of high-voltage cables include one or more conductors, the conductor shield, the insulation, the insulation shield, the metallic shield, and a protective jacket. A fully rated insulation system consists of insulation, semi-con layers, and a metallic shield. To prevent failure due to electrical stress at 2K volts and above, additional internal layers in the insulation system are required to control the electric field around and between conductors.

“The main characteristic of high voltage wire or cable is its ability to withstand the application of high voltage in AC or DC current throughout its service life, about 20,000 hours,” said Eric Coulon, research & development technician at Axon’ Cable with expertise in testing high voltage cables. The temperature of the product application, he said, is a determining factor in the choice of insulation material when defining the minimum insulation thickness needed to withstand the HV customer’s requirements. “The temperature is an important parameter because the thermoplastic materials don’t all operate on the same temperature range.”

Other factors to consider include radiation in the environment; a high or low pressure application, chemical exposure, and whether the application is static or dynamic.

The insulation of the cable must not deteriorate due to the high-voltage stress, ozone produced by electric discharges in air, or tracking (the formation of a conductive path on the surface of the insulating material). Cable joints and terminals must also be designed to control high-voltage stress that can result in breakdown of the insulation.

High-voltage cables may require short lengths of several feet for use in equipment or machinery, or much longer lengths running within a building, buried across an industrial plant, for power distribution, or even under the ocean for power transmission.

Design Notes

Material specifications

Conducting materials: copper (flexible, excellent conductor) or aluminum (lighter weight, less expensive, but not as good a conductor)

Insulation material: A variety of thermoplastics are used. Depending on the application, the material is selected for resistance to environmental conditions and for high dielectric strength. Common options are cross-linked polyethylene (XLPE), ethylene propylene rubber (EPR), and, in some cases, polyvinyl chloride (PVC) is used for its fire resistance and flexibility. Other options include fluorinated thermoplastic (high temperature resistance up to 300 °C, resistance to chemicals, and high dielectric strength), polyimide thermoplastic (high radiation/UV resistance and atomic resistance [LEO], high temperature resistance up to 230 °C, high dielectric strength), and PEEK thermoplastic (very high radiation resistance, high temperature resistance up to 200 °C, high dielectric strength).

Teledyne’s Quiet Line  product is continuously extruded high-voltage cable with a high inductance core coated directly over the center conductor. This high inductance “loss core” dissipates high frequency signals, making it a great choice for filtering out unwanted radio frequencies and suppressing external EMI. High frequency signals that travel across the center conductor are attenuated proportionally to the cable length used.

Sheathing material: Sheathing on the outside of the cable provides environmental protection. It is typically polyethylene (PE) or PVC. Metal sheathing is used in underwater or underground applications.

Environmental considerations: Depending on the application, high-voltage cables must be able to withstand a variety of conditions, including:

  • High vacuum applications: low outgassing
  • High and low pressure
  • High and low temperatures
  • Radiation (total ionizing dose up to 70 MGy)
  • UV
  • Atomic oxygen (in space)
  • High mechanical resistance
  • Chemical exposure
  • Water/moisture exposure
  • Very long lifetime (> 25 years)

PSL200 high-voltage cable from JPC Connectivity is used for the connection between battery packs for the applications in BMS and energy storage.

 

Electrical properties: High voltage is generally considered above 1000V for systems using alternating current (AC) and above 1500V for direct current (DC). However, the definition of high voltage varies from application to application. For example, high-voltage in aeronautics ranges from 540V-3000V; in oil & gas it is 1000V to 8000V; and in research it is 1000V to 30,000V.

Gauge: Typically ranges between 2 AWG and 28 AWG.

Voltage rating (maximum safe voltage): High voltage cables commonly start at 1000V (1 kV) and can go up to 35 kV or higher for a maximum voltage rating. For safety and to protect the insulation, the voltage rating must match the system’s operating voltage.

Temperature range: Indicates the highest and lowest temperature that the cable components can safely tolerate. Many HV cables fall between –40 °C to 90 °C, but XLPE and EPR can accommodate a broader range (75 ⁰C to +250 ⁰C) that is ideal for environments with high thermal stress.

Markets 

Military & Aerospace, Industrial, Automotive, Transportation, Medical

Applications

Sub-sea operations, space applications, nuclear fusion & research, aeronautics, defense, oil & gas exploration, medical equipment, research and testing, EVs, power plants, wind and solar farms, industrial equipment, mass transit and rail, and mining

Suppliers 

High-voltage cables are available for various applications from many suppliers, including:

Axon’ Cable, JPC Connectivity, Rosenberger, TE Connectivity, Teledyne Reynolds, Trexon, and Winchester Interconnect

Related Products

High-Voltage Connectors

Nuclear Connectors

Connectors for EV Applications

Like this article? Check out our other Meet the Connector and Connector Basics articles, our Military and Aerospace Market Page, and our 2024 and 2025 Article Archives

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AJ Born
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