Wire & Cable Basics – Medium Voltage Cable

Electrical distributors who routinely serve customers in the industrial, commercial, and/or utility categories are no doubt familiar with medium voltage (MV) products. Medium voltage cables range from 2.4kV up to 35kV. For the most part, the basic construction of this type of cable along with its physical and electrical performance properties are similar from one manufacturer to another. However, insulations, metallic shields, and jackets are all areas that can vary based on the specific power system requirements, installation rigors, service conditions, and environmental factors.

Construction:

Shielded medium-voltage designs are usually constructed as follows:

  • An aluminum or copper conductor (typically copper)
  • A conductor shield—which is usually made of some type of semiconductor material
  • Insulation
  • An insulation shield, which again can be a semiconductor or a metallic braid or tape
  • Jacketing

Unshielded MV designs are typically made up of:

  • A conductor
  • Insulation
  • Jacket

Materials:

Copper and aluminum are the two main conductor materials. Copper is used mostly in medium voltage designs, while the lighter weight aluminum is used more often in high voltage cables. A variety of materials are used in medium voltage jacketing. Cross-linked polyethylene or XLP and ethylene-propylene rubber or EPR are among the most recommended. An important factor to consider when selecting a cable and its jacket material is whether the wall thickness is suitable, especially according to UL standards. Electrical distributors should ensure that end-users consider how the jacket will hold up to specific environments, such as sunlight, heat, cold, etc. Different design requirements also exist if MV cables are going to be direct buried. For example, if there is a fault the copper tape or copper braid insulation shield must carry a current. As a result, the cable must have a specified area or mass for the shield to be able to carry a fault if something goes wrong.

Applications:

Medium voltage cable is used in both wet or dry environments and can be installed by way of direct burial, conduit, open tray, raceways, aerial installations, and underground ducts. Industrial and commercial uses for MV cables include power substations, mining operations, petrochemical plants, steel mills, water treatment facilities, railroads, and paper mills among others uses.

Medium voltage products are typically associated with large projects and can often provide electrical distributors with valuable business intelligence that can lead to additional business. MV cables tend to be installed in the early construction stages and are often a leading indicator of additional project needs from the end-user.

 

Looking for more information or a quote on medium voltage cables? Contact your DWC Account Manager today!