Seda Çelebi -Sigma Electrical Product Manager

Electrical energy, which is an indispensable element of the modern world, brings system and equipment failures. As a result of the examination of 7,750 electrical system failures, it was observed that the most common cause of damage was temporary overvoltages with a rate of 28%.

Transient overvoltages are very short-term increases of the mains voltage, and quickly the mains voltage tends to return to its main sine form. These short-term increases in voltage can occur due to atmospheric origin, switching or as a result of the interruption of fault currents.

Overvoltages Caused by Atmospheric Events

Lightning, the incredible power of nature, causes more than 24,000 fires and $407 million in property damage to the world every year**. The fact that lightning currents carrying very high energy fall to the ground is the direct effect of lightning impact, some of the lightning current is dampened in the soil and the other part is included in the grid While these high-energy lightning currents are inevitable to cause material damage to the electrical system, they can also pose a fire risk as a result of very severe overheating of materials.

The indirect effect of lightning current is a more frequently observed effect, it occurs as a result of the voltage rise in the energy transmission lines by electromagnetic induction of the lightning pulse.

According to the lightning current-cumulative ratio table in IEC 62305-1 standard, 50% of lightning strikes have a current exceeding 35kA and 5% exceeding 100kA.

Overvoltages Caused by Switching

Electromagnetic induction is the production of potential difference (voltage) over a conductor exposed to a changing field. It was discovered in 1831 by Michael Faraday. Instantaneous current changes occur when a high-power electrical charge is turned off and on. As a result of the inrush current change, voltage induction occurs on the conductors located in the nearby region according to Faraday's law. In daily life, we generally see this situation with voltage rises as a result of inductive loads, motors, transformers being activated and exiting sudden current changes. Compared to overvoltages caused by atmospheric events, overvoltages due to switching are observed much more frequently with a rate of 60-80%, but they generate lower energy pulses.*

Voltage Protection Elements Surge Arresters

The increasingly widespread trend of reaching smaller sizes in IoT and electronic devices brings with it the use of more transistors. This means that the devices will become more sensitive to voltage rises. The protection of the systems against sudden overvoltage impacts is only provided by correctly made grounding, equivalent grounding and surge arresters.

Surge arresters are the elements that protect the electrical installation and the devices connected to the electrical installation against lightning-induced voltage pulses and sudden impacts in the electrical installation. The surge arresters are connected parallel to the system and have a high internal resistance that does not allow current to pass over them under normal conditions. In case of sudden voltage rise, the circuit elements in it become conductive and flow the excess currents into the ground.

Why Use Sigma Surge Arrester

With Sigma surge arresters produced in accordance with TS EN and European standards, electrical installations and equipment connected to this installation are safely protected. Sigma AG surge arresters are shipped with fault signal contact for all other surge arresters except Class I Type 1 B. In this way, when the impact voltage occurs, a warning signal is received if desired. The caps of Class II, Class I+II, Class III surge arresters can be easily replaced, thus reducing maintenance costs. Sigma surge arresters provide complete protection with a wide range of product selection, preventing all possible risks.

Source*: https://www.nemasurge.org/history/

Source**: https://earthdata.nasa.gov/learn/articles/iss-lis-provisional-data

Why Use Sigma Surge Arrester? We invite those who are curious about the answers to the question to watch our video.

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