Different types of cables range from extra low to extra-high voltage. In this article, we are going to focus on medium voltage cables. If you read the following information, you will learn more about how this type of cable is made and what it’s used for.
What are these cables like?
The term medium voltage (MV) cable has not always existed. In the past, only low and high voltage categories were used to classify cables.
However, as the range of voltages increased, there arose a need to create more categories. Now there is a medium voltage cable category. In addition, extra-low and extra-high voltage categories are now being used in the cable classification system.
The International Electrotechnical Commission (IEC) recognizes cables with 1kV to 100kV as medium voltage (MV) cables. But not everyone uses this specific range to classify MV cables.
The voltage range of MV cables depends on the country and the particular system that is being used. Some common medium voltages are:
- 5,000v
- 8,000v
- 15,000v
- 25,000v
- 35,000v
Cable structure and materials
Medium voltage power cables are often designed with added protection in mind. This is to avoid the accumulation of charges at any point in the cable.
MV cables are made of an aluminum or copper conductor and a conductor shield. Copper is the more commonly used material for MV cable conductors while the shield is often composed of semiconductor material.
The medium voltage cables also consist of insulation, an insulation shield, and jacketing material. The choice of jacketing material depends on the environment that the jacket will be exposed to.
Here are some common materials that are used to create the jacket:
- Cross-linked polyethylene (XLPE)
- Ethylene-propylene rubber (EPR)
- Chlorinated polyethylene (CPE)
- Neoprenes
When looking at the various MV power cables available on the market, it’s important to understand the difference between shielded and nonshielded cables.
- Shielded Cables – This type of cable uses a shield to guard against signal interferences. There are different levels and types of shielding.
- Unshielded Twisted Cables (UTP) – This type of cable lacks the shield that protects the signal. But its twisted wire design is meant to prevent electromagnetic interference.
So, which is the best choice? The answer depends on the cable’s application and setting. UTP cables can be an appealing option when you consider their ease of installation and maintenance, and relatively cheap price.
However, before choosing UTP cables, make sure you understand the limits of this type of cable. You must also make sure that your project doesn’t require shielded cables.
It should be noted that unshielded medium voltage cables are typically utilized in tight spaces, such as the inside of equipment. And any issues that arise inside of equipment that contains UTP cables must be handled by a trained professional.
Accessories
Medium voltage cable accessories are necessary for setting up an MV cable network. These additional parts make it possible to join cables and terminate them to equipment or overhead lines.
Although the production of medium voltage wire is a tightly controlled procedure, the manufacturing process involving cable accessories is not under the same oversight. Furthermore, the accessories are provided to cable joiners in kits.
Being safe and easy to install are required qualities for all types of cable accessories, yet the success of the installation mostly depends on the skills of the MV cable accessory installer.
To give you a better idea of the need for cable accessories, here are a few examples of how they are used:
- Connecting cables to equipment;
- Connecting cables to overhead lines;
- Connecting two cables to each other;
Here are some MV cable accessories that are often utilized:
- Straight Cable Joints – Used for connecting similar cables to each other.
- Transition Cable Joints – Used for connecting cables that vary in design.
- Branch Cable Joints – Used for connecting branch cables to the main cable.
- Cable Terminations – Used to form a connection between cables and equipment or overhead lines.
- Screen Separable Connectors – Used to connect terminating cables to equipment.
The technologies used for installing MV cable accessories include:
- Heat-shrink
- Cold-shrink
- Push-on systems
MV cable accessories are frequently made of silicone or EPDM. Silicone is used more often for terminations, while both options are commonly used for cable joints. EPDM is frequently utilized for the outer cones of separable connectors.
When to use these cables
Common MV cable applications include:
- Mobile substation equipment
- Distributing power in industrial settings
- Distributing power to tools and equipment used in mining settings
- Maintenance and repairs, which allows the scheduling of downtime in order to perform maintenance tasks or repairs
- Wind Farms
- Public transportation infrastructures for supplying power to trains and metro lines
- Weather-proof networks, which allows power to be transported underground so that severe storms do not disrupt the supply of power.
Do you think you need medium voltage cables? Contact us to find out! We can guide you in making the right choice.
