High Voltage Cable vs Medium Voltage Cable: Key Differences You Should Know

Electrical​‍​‌‍​‍‌ cables, though not seen, play a major role in the current power-dependent world. They form the backbone through which electrical power is transmitted safely and with minimum loss. Whether it's a home, a commercial building or a factory, the choice of electrical cable to be used is a decision of critical importance. Medium Voltage (MV) and High Voltage (HV) are two of the most common categories of cables discussed by the MV Cable Suppliers.

On the surface, their names may look similar, but the differences between them run deep and have a considerable bearing on aspects such as safety, performance, cost, and application. Therefore, it is vital for engineers, project planners, contractors, and buyers (who have done their research) to have a clear understanding of these factors.

The following is a detailed and easy-to-understand point-wise comparison of medium-voltage cables versus high-voltage cables by the High Voltage Cable supplier to assist you in understanding their differences and respective use cases.

Understanding Voltage Classification

It is necessary to comprehend the real voltage levels implied by the words "medium" and "high" before even thinking of comparing the two.

●       Medium Voltage (MV) Cables

○       Usually have a voltage range between 1 kV and 33 kV

○       Are the most common type of cable used to distribute power locally

○       Basically, act as a linking point between low-voltage systems and high-voltage transmission

●       High Voltage (HV) Cables

○       Have a voltage over 33 kV and can be as high as 66 kV, 110 kV, 220 kV or even higher

○       Are used predominantly for power transmission over long distances

○       Are made to be able to carry large amounts of power with very little loss

Core Purpose and Application

Usage of cables forms a vital difference between the two.

●       Medium Voltage Cable Applications

○       Distribution of power in cities and towns

○       Various areas of industrial plants and manufacturing facilities

○       Commercial buildings, hospitals, and data centers

○       Solar and wind farms, i.e., renewable energy projects

○       Systems for underground and overhead distribution networks

●       High Voltage Cable Applications

○       Transmission of electricity over long distances between substations

○       National and regional power grids

○       Power plants connecting to transmission networks

○       Undersea and underground transmission projects

○       Bulk power transfer in huge infrastructure ​‍​‌‍​‍‌projects

Insulation​‍​‌‍​‍‌ Design and Thickness

Insulation mainly determines the maximum voltage that a cable can be safely energized with.

●       Medium Voltage Cable Insulation

○       Generally, the medium voltage cable insulation is thinner than the High Voltage one

○       XLPE and EPR are the most common insulation materials in this case

○       The main purpose of the medium voltage insulation is to handle electrical stress at a moderate level

○       Incorporates flexibility and ease of installation into its features

●       High Voltage Cable Insulation

○       There are insulation layers which are much thicker and more complicated than the typical ones found in HV cables

○       The main purpose of HV cables is to manage very high levels of electrical stress

○       Made up of several layers such as conductor screens, insulation screens, and metallic sheaths

○       Helps to prevent the formation of partial discharges and the electrical breakdown which can happen in a long ​‍​‌‍​‍‌cable

Electrical​‍​‌‍​‍‌ Stress and Performance

The level of voltage is one of the key factors that influence the performance of a cable under load.

●       Medium Voltage Cables

○       Medium-voltage cables result in lower electrical stress of the insulation

○       Appropriate for transmission over short distances

○       Have slightly higher transmission losses than high-voltage systems over longer distances

○       Work well for local distribution networks

●       High Voltage Cables

○       High-voltage cables are made to deal with a very high level of electrical stress

○       Under the same power level, the current will be lower, which means losses will be reduced

○       These are the most efficient wires for the transmission of electric power over very long distances

○       H.V. cables need very special care in their design to prevent insulation breakdown

Construction Complexity

Cable manufacturing technology varies largely between MV and HV classes.

●       Medium Voltage Cable Construction

○       A medium-voltage cable has a less complex internal composition

○       It has fewer layers of insulation and shielding

○       Can be manufactured and tailored in a more simple way

○       Has a lighter weight and smaller diameter

●       High Voltage Cable Construction

○       A high-voltage cable has a very complex and highly engineered multilayer internal composition

○       Contains metallic shielding and armoring not only for electric but also mechanical safety

○       Has a larger diameter and is heavier

○       Requires advanced manufacturing techniques and strict quality control

Choosing the Right Cable

Deciding between high-voltage and medium-voltage cables should be based on the requirements of the project rather than on one's preferences.

Choose medium voltage cables if:

●       Your power distribution will be at a local or regional level

●       You have limited space and budget

●       Speed of installation and flexibility are important to you

●       Your voltage requirements will not exceed 33 kV

Choose high-voltage cables if:

●       It is necessary to transmit power over long distances

●       The electrical loads are very large ones

●       It is critical to be efficient and minimize losses

●       The infrastructure is able to support the high safety and cost levels required

Final Thoughts

The roles of HV and MV cables, though somewhat different, are both indispensable in the electrical power sector. MV cables are more about adaptability, cost-effectiveness, and local distribution, whereas HV cables stand for efficiency, reliability, and long-distance transmission.

Being aware of the differences in their voltage range, structure, insulation, safety, cost, and use can lead to helping you make the right decisions, enhancing safety, and achieving optimal system performance. The cable choice is not merely a technical matter but a strategic decision with a direct effect on the reliability, efficiency, and success over the long ​‍​‌‍​‍‌term.

Also Read: What Is SWA Cable? Complete Guide to Steel Wire Armoured Cables and Their Uses