Maintaining the safety of the electrical circuits is important. We use a variety of instruments to this effect. One such is used to arrest the lightning and prevent any harm from befalling the users.
Action of the lightning arrester
The lightning arresters in the modern telecommunicatoin and electrical network do the work of keeping the surge voltage under control when a lightning strikes. The lightning surge that travels along the wires comes to a halt by the action of the lightning arresters. This excess current is grounded.
Use of surge protectors
Thus, you can see in the telephone wires, a surge protector is provided at the point where the electrical lines enter a building. This is done to help safeguard the electronic equipment as well as to keep the people safe. We call the huge ones the lightning arresters while the small ones we call as the surge protectors.
Grounding the excess current
Through the action of the surge protectors or the lightning arresters, when a high-voltage current flows through the lines, these arresters provide them a passage to the ground. They are not allowed to enter the circuit where the domestic appliances are. You can see how the failure of these devices could result in thousands of kilovolts entering the household circuit and damaging the lines, appliances, and equipment.
Difference between surge protectors and lightning arresters
The essential working principle for the surge protector or lightning arrester circuit is like this. We have two or three gaps in the circuit that may have silicon carbide or any other semiconducting material such as zinc oxide. In the normal course they use air but some semiconductor material may also be used. These gases will ionize when the voltage reach a preset level and thus help make the gap conducting.
Action of the arrester
When a high voltage current enters the circuit, the air gap becomes conducting. The lightning is passed to the ground. The ordinary supply does not have the capacity to close the circuit having the air gap.
Surge arresters are also called transient voltage surge suppressor (TVSS) or surge protection device (SPD) these devices are essentially protectors in the transmission and distribution network. You can choose the insulation material by comparing the energy criterion. This has to have a low impulse ratio so the surge is bypassed to the ground.
These surge protectors do not protect the installation from a direct lightning strike. Rather, it helps protect against the transient current by a lightning strike in the vicinity of the conductor. The lightning that strikes the earth produces ground currents which travel over the buried conductors and in doing so, induce a transient current. This transient current travels to the ends of the conductor. This phenomenon takes place in the overhead conductors also.
Different types of surge protectors
This energy is considerably lesser than that produced by a direct lightning strike. However, the amount is big enough to cause severe damage and even loss of life. So, we have to provide adequate protection.
We see many kinds of arresters in use today. They are as follows:
1. Common valve arrester (station type)
2. Distribution arrester
3. Plug-in signal arrester
4. Neutral protection arrester
5. Line magnetic blow valve arrester
6. Magnetic blow valve station arrester
7. Low voltage surge arrester
8. Fibre tube arrester
9. DC valve type arrester
10. Arrester for protection of rotating machines
Use of arresters and protectors is mandatory in all electrical circuits. Adequate grounding is needed all the time so that we have enough safety.