When you need protection for the electrical power systems you have installed, you use the surge arrester. This is a device that helps prevent the surge voltage arising from the lightning from reaching the domestic circuits. Though similar in construction to the lightning arresters, they have a significantly different function.
Stop unwanted voltages
The surge protector or surge diverter helps prevent unwanted voltages from reaching the electrical device by blocking or grounding the voltage. It grounds any voltage that is above the safe, normal voltage. To understand this, one must know how the surges occur in the domestic circuit.
Internal and external surge
There are two instances for the start of surges in the electrical circuit. The first is when some internal switching mechanism is in operation or there is some installation taking place in the domestic circuit. Even when you stop and start electrical devices, a surge occurs.
Creation of power surge
The main work concerns the lighting when it strikes near the house. The power surges occur due to the sudden increase in the magnetic field when the lighting passes close to the conductor carrying the voltage supply to the house. The induced voltage creates a spike and this hugely magnified voltage begins to travel towards the house. Such a huge voltage will destroy the electrical devices in the house and pose a threat to the life of the people too. To prevent the start of anything unforeseen, one uses surge arresters.
Method of working
The working of the Surge Arresters is simple. They will block the huge voltages that travel towards the domestic circuit. These arresters remain placed on the transmission towers that carry the voltage to the house. You also find them near the house, at the place where the conductors bring the electric power into the house. The surge arresters remain placed at these points to make sure that the current gets grounded before they reach the house.
Surge arresters do not protect against a direct lightning strike. For that, you use the lightning arrester. The surge protection device suppresses, diverters, and ground the surge voltages alone. The surge protector in your house will stay at 10 metres distance from the switchboard. So, when lightning strikes, the surge protector will draw the current away, and ground it.
Construction of the surge protection device
The surge protector consists of a gap that is non-conducting at normal ranges of voltages as it is when there is no lightning. This gap may have any dielectric material such as metal oxide. When the voltage exceeds a certain limit, this gap closes and becomes conducting. This provides an alternate path for the high voltage. This will lead to the ground and thus the surge caused by the lightning will remain earthed safely.
You need to use a safety device in places where lightning strikes abound. These surge protection devices have a design in accordance with the industry standards and will have a long life. One may also use a silicon avalanche diode to suppress the voltage spikes. However, these have a low capacity for absorbing energy. Another option is to use the thyristor surge protection devices. These are solid-state electronic devices. You can use them in crowbar circuits to get protection against lightning strikes.