Berkeys / Berkeys Blog

November 18, 2016

Surge Arrester For Dallas Homeowners

Not all surge arresters protect systems from lightning. While lightning current arresters (Class 1) are used to protect against direct lightning surge currents, surge arresters (Class 2) protect equipment from induced surges in electrical wiring. Surge arresters and lightning current arresters from DEHN offer reliable protection against these hazards.

A short and simple overview of a lightning arrester for the non-technical.

How Does a Surge Arrester Work?

The purpose of a surge arrestor is to protect insulation/components from high DV/DT that peak at instantaneous values that are in excess of the breakdown of the insulation or component. Lightning is one common cause of voltage surges. Another common cause is switching in an inductive circuit.

It is possible to capture the occurrence of a voltage surge. Some surge arresters are equipped with ‘surge counters’ that capture the fact that the arrester has discharged current. It is also possible to use other phenomena (sound measurement, light measurement, electric field measurement, etc) to capture the occurrence of a discharge. Meteorologists routinely capture and record lightning discharges using both ground-based and satellite-based instruments.

It is also possible to capture and record voltage surges, but here the technology gets complicated. A common issue is that a voltage surge is inherently a high-frequency phenomenon, and in order to capture and record (ie, quantify) the event, the measurement system must have a high-frequency response. The kind of instruments that are commonly applied for fundamental frequency voltage measurements don’t have sufficient frequency response to accurately capture and record high-frequency voltage transients. They may be able to capture the occurrence of the event, but it is not always possible to accurately quantify the event using those devices.

A surge arrester is a device that protects electrical power systems from damages caused by lightning. A typical surge arrester has both a ground terminal and a high-voltage terminal. When a powerful electric surge travels from the power system to the surge arrester, the high voltage current is sent directly to the insulation or to the ground to avoid damaging the system.

Lightning and Electrical Surges

When a powerful surge or a lightning strikes a particular electrical system, it damages the whole system and any electrical devices connected to the system. Electrical devices work at a certain voltage range. When these devices receive a voltage way higher than the specified voltage sufficient for their operation, they blow up or get damaged. However, electrical systems that are protected by a surge arrester do not get damaged, because the arrester ensures that the high voltage does not get into the electrical system.

Diverting Lighting and Electrical Surges Using MOV

The surge arrester does not absorb all of the high voltage that passes through it. It simply diverts it to the ground or clamps it to minimize the voltage that passes through it. The secret to the arrester’s success in diverting lightning or high electrical surges is the MOV or the Metal Oxide Varistor. MOV is a semiconductor that is highly sensitive to voltage. At normal voltages, the MOV works as an insulator and does not allow current to pass through. But at high voltages, the MOV acts as a conductor. It works as a switch that is open when there are a standard AC voltage and a switch that is closed when lightning or high voltage is present.

Importance Of Surge Arrester

A surge arrester is a voltage activated the device that protects computers and other electronic equipment from surges or transient voltages in electrical power or data cables, whether it be from lightning or a switching surge. A surge arrester works by diverting the extra voltage into the earth wire, rather than flowing through the electronic devices, while at the same time allowing the normal voltage to continue along its path.