The Lightning stroke is a natural phenomenon and the effect of it is really unpredictable. Sometimes lightning creates hazard situations and in order to protect from lightning, there are several preventive measures taken into action. High voltage transmission lines are the one of the most common equipment which is prone to obtain lightning. There are three possibilities that the lightning stroke can induce surge on different parts of this Structure. In here we are a plan to discuss three main areas which lightning occur in high voltage transmission lines.
1.Lightning stroke to shield wire
Lightning stroke can directly hit the shield wire where the current can discharge to the ground through the high voltage tower.
When the current is discharging due to the earth resistance of the tower there will be a high ground potential rise in the tower body.
If this potential is higher than the insulator insulations strength, there can be a flashover from the cross are to phase conductor across the insulator string.
This can induce an additional voltage of a phase conductor this is called as shield failure which can damage the system.
This is the most common area where the lightning hitting on the high voltage transmission line
2. Lightning stroke to the phase conductor
In this scenario, the lightning charges directly and discharge into the transmission line if the line is a long distance from the substation the surge flows along the line in both directions. Damaging insulation and sometimes even weakening pole unit until all energy of the surge is spent. If the strike is adjacent to the substation then the damage to the substation equipment is certain and since it is doubtful whether the lightning arrestor will deliver a full charge to earth without allowing the part to be transmitted to the substation equipment.
Damaging insulation and sometimes even weakening pole unit until all energy of the surge is spent. If the strike is adjacent to the substation then the damage to the substation equipment is certain and since it is doubtful whether the lightning arrestor will deliver a full charge to earth without allowing the part to be transmitted to the substation equipment.
It is really essential to protect the lightning stroke directly into the phase conductor and there are a lot of protections measures take into action in order to safeguard the phase conductor where current is passing on.
3. Lightning stroke to the tower
If there is a direct strike is fall into the transmission line the current would get discharge to the metal part of the tower and it goes to the earth.
This can cause a potential difference between the top part of the tower and the bottom. The potential difference between the transmission tower and the phase of conduct play a major role in here. The phase conductor is the value which exceeds the strength of the insulator then the flashover occurs to the from the tower to the conductor and its named as back flashover.
So it is important to make really concern in the mentioned area for the lightning in transmission lines. In a future article, we are a plan to discuss the preventive protection measures which can take action to protect High voltage power transmission lines from lightning.
There are so many protection measures and actions take against to protect High voltage power lines and we are a plan to discuss these protection methods in our future articles.
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