What Happens If Water Enter Into Power Cable

How Water Enter Into Power Cable and Damage it?

Fig: 400kV underground power cables laid for transfer power from a power plant to grid substation.

What actually happens if water or moisture entered into the power cable?

We who are engaged with power cable management everyone very concuss to prevent enter water or moisture into cables. In the design and production line, they take some options to prevent moisture enter into cables; similarly, the cable installation and storage team also take tight action to prevent water or moisture enter into the cables. 

Cable Conductors Materials:

Widely used power cable conductors materials are Copper and Aluminum. 100% pure Copper and 99.5% or better pure Aluminum is used for better performance power cable conductor. A small amount of impurity may reduce a large percentage of conductivity. Silver is a very good conductor, but high cost and extreme softness is the obligation to use as wide scale. Compare to Copper Aluminum is inexpensive and softer.

Aluminum Uses in Power Cable:

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Many Copper conductors also use Aluminum as an armoured or metal sheath. Aluminium is very much sensitive to water in insulated power cables. So, the presence of water in Aluminum causes several problems. In Aluminum, if there is water in absence of Oxygen, chemically there will be hydrolyzing. 

Aluminium and Water Chemical Reaction:

The chemical reaction of Aluminum and water will be as follows:

2 Al + 6 H₂O   =   2Al(OH)₃ +3H₂  

So, if water entered into having Aluminum in the insulated power cable, in absence of Oxygen Aluminum and water chemically combine and produce Aluminum-Hydroxide and Hydrogen gas.

Aluminum Hydroxide:

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Aluminum Hydroxide is a white and powder type materials having a very good insulating character that degrades the conductor conductivity.

This is the theoretical and chemical reaction of water present inside the cable. Moreover, water presence in the vicinity of the cable for a long time may cause cable damage shortening the cable lifetime and unexpected breakdown may happen.

 

Thunderstorm and Lightning:Electrical Development

Fig- Stages of a thunderstorm's life.
picture from Wikipedia

Developing Thunderstorm and Lightning in Space

Storms are forming all over the world continuously and the number is around 5,000. These storms are going together with lightning and cause a serious risk for both people and equipment.  The hitting rate of strokes of lightning at the ground is about 30 to 100 strokes per second. The earth is struck by about 3 billion strokes of lightning each year.

All over the world, thousands of people are struck by lightning and a lot of animals are killed every year. It also causes a large number of fires which destroying the forest, industries, commercial & residential building.  Lightning mainly affects the equipment of the electrical and electronic system, appliances of the residential and industrial sector; the financial figure for damage is very high.

Electrical Development of a Storm Cloud and Stages of a thunderstorm's Life Cycle: 

Hot air rising from the ground and it collects water droplets until it becomes a cloud. The droplets are separated and transformed into ice crystals by aggressive rising and falling air current. Positive and negative electrical charges are generated by collation between water and ice particles.

The positively charged ice crystals stay in the upper part and negatively charged water droplets remain in the bottom of the cloud. Lightning begins to develop inside the storm cloud and this cloud forms an enormous capacitor with the ground. Then flashes of lightning begin to form between the cloud and the ground which is called strokes of lightning and caused appears the first rain.

Next time the cloud gradually becomes less active while the ground lightning increases. It also convoys with heavy rains and strong winds as a result, hundreds of thousands of tones of rainwater.

Safety and Awareness about Lightning and Thunderstorm

Safety and awareness frequently overlap each other. Generally, thunderstorm safety refers to what people should do during a storm. Some common and important points are as-

• Avoid close to the storm to hear thunder can be struck by lightning, hearing thunder immediate action should be taken.

• Close and stay away from windows and doors.

• Do not have a bath or shower during thundering.

• Avoid the use of electrical and electronic appliances, corded & cordless telephones, mobile etc. during a thunderstorm.

• Thunder normally hit at the highest point, so if it is an open field and safe buildings are not possible, bend as low as and minimize contact with the ground.

How Calculate the Speed of Lightning?

You can find roughly the speed of lightning or how far are you from a lightning crush. Yes, just count the number of seconds that pass between a flash of lightning and the crack of thunder. Then divide the counted number by five. The result is how many miles away you are from where lightning just struck.

The distance of lightning (in mile)= time (in second) flash of lightning and the crack of thunder/5

For example, if the time 10 second between the flash of lightning and the crack of thunder, then the distance will be 10/5= 2 miles; and similar way.

Flash-to-Bang 

This lightning distance calculation technique is known as the Flash-to-Bang method.

What is the Safe Distance of Lightning for Human?

As per the national weather department recommendation, they say a 6-mile distance is a safe distance for human.  This means if the time between the lightning flash and the rumble of thunder is 30 seconds or less.