what is electrical power cable ? defination construction advantages and disadvantages

ELECTRICAL POWER CABLE

An electrical power cable serves as a means to transfer energy between locations. It plays a role, in distribution systems connecting power sources like generators or substations to various destinations such as homes, businesses and industrial equipment. These cables are specifically engineered to ensure the efficient transmission of current while safeguarding the conductors, against environmental influences and physical harm.it is used in extra high voltage transmission and distribution purpose where overhead line are not in used .for eg. under the sea, and at congested areas for distribution purpose.generally underground cables are more costly then overhead lines and that is the one of the main  disadvantage of under ground electrical power cables.

construction of electrical cable

conductor:

The conductor serves as the component of the cable for carrying the electrical current. Typically it is made of either copper or aluminum due, to their conductivity. The choice of conductor material and its size depend on the intended purpose of the cable and the amount of current it needs to handle.

insulation:

Surrounding the conductor is a material that prevents any leakage or short circuits of the current. Commonly used insulation materials for cables include CrossLinked Polyethylene (XLPE) Ethylene Propylene Rubber (EPR) and Polyvinyl Chloride (PVC).

Overlapping with this layer is a bedding material often made from PVC or low density polyethylene (LDPE). The purpose of this bedding layer is to protect against damage and prevent water from entering.

Lead sheath:

In order to protect the cable from moisture, gases or other damaging liquids (acids or alkalis) in the soil and atmosphere, a metallic sheath of lead or aluminum is provided over the insulation as shown in the figure. It has minimum dielectric stress in a cable.

Bedding: 

Over the metallic sheath is applied a layer of bedding which consists of fibrous material like jute or hessian tape. It is to protect the metallic sheath against corrosion and from mechanical injury due to armouring.

Armoring:

If required some underground cables are equipped with an armoring layer. This metallic armor, made from steel wires or tapes offers protection, against damage. This feature becomes particularly crucial in situations where direct burial or enhanced mechanical protection's necessary.

Serving:

In order to protect armouring from atmospheric conditions, a layer of fibrous material (like jute) similar to bedding is provided over the armouring. This is known as serving.

Advantages and disadvantages of cables

Power cables have different advantages and disadvantages depending on the application, type, and specific requirements of the electrical system in which they are used. Some of the main advantages and disadvantages of power cables are listed below.

Advantages:

1.Efficient Electrical Transmission:

Power cables are designed to efficiently transmit electrical energy over long distances. Low electrical resistance reduces energy loss during transmission.

2.Safety: 

Cables provide a safe way to transmit electricity by insulating conductors, preventing electric shock, and minimizing the risk of short circuits and fire.

3.Concealment:

Underground cables can be buried, allowing for concealed and aesthetically pleasing power distribution. This is especially important in urban areas.

4.Environmental protection:

Many power cables are equipped with protective layers such as insulation, shielding, and jacketing that protect against moisture, chemicals, UV rays, and physical damage. This increases durability and longevity.

5.Low Maintenance:

Properly installed power cables typically require less maintenance than overhead power lines, which are exposed to weather and environmental influences.

6.Reliability:

Underground cables are less susceptible to weather-related disturbances such as wind, ice, and lightning that can affect overhead lines. This increases reliability in certain situations.

7.Reduced Electromagnetic Interference (EMI):

Shielded power cables minimize electromagnetic interference and are suitable for sensitive applications such as data centers.

Disadvantages:

1.Installation Costs:

Underground power cable installations can be more expensive than overhead power lines due to the labor and materials involved in trenching and directional excavation.

2.Restricted Access:

Once underground cables are installed, they are difficult to access for maintenance and repair. Finding and fixing errors can be difficult and time-consuming.

3.Limited Ampacity:

The ampacity (ampacity) of underground cables is limited compared to overhead lines. This limitation can be a disadvantage when higher power transfer is required.

4.Heat Dissipation:

Underground cables have more limited heat dissipation and can therefore experience increased temperatures. This can affect cable efficiency and lifespan.

5.Longer repair times:

When underground cables fail, repairs often require digging, which can disrupt other nearby utilities. It may take some time.

6.Environmental Impacts:

Excavation and installation of underground cables can have environmental impacts, including soil disturbance and potential disruption to local ecosystems.

7.Voltage Drop:

Power cables can experience voltage drops over long distances, which can affect the quality of power delivered to the end user.

This is a Quantity of protection given to an underground cables shown in figure: