How Do Type 1+2 (B+C) Class Surge Protectors Differ from Type 2 (Class C) Surge Protectors?

Recently, we have witnessed that LV SURGE ARRESTER products, especially among switchgear materials, are being sold far from technical knowledge (like apples and pears). This, as in many issues where trade precedes technique in our country, leads to incorrect protection of systems, damage to the systems of investors and facility owners who are unaware of the issue, and huge financial losses as a result of a possible lightning impulse. Surge arresters technically have many classes, and product selection is of great importance at this point. When we look at the low voltage surge arrester system located inside the panel only as a surge arrester, the issue will lead to serious economic losses in the long run, and above all, it causes our national wealth to melt away for nothing. Protection products must really be selected in accordance with their purpose and used to protect systems. However, it is seen as an insignificant product, especially among switchgear materials, and wrong products are used extensively just because some switchgear companies write their brands on them. As Yılkomer, we have 2400 types of products in our product range; if the issue were that simple, we would not need so many surge arrester types. Therefore, for the correct product selection, we wanted to summarize the most basic subject of the event, Type 1 Class B and Type 2 Class C surge arrester subject once again in this article. We think that at least conscious users will read our technical explanations to realize the importance of the issue.

Basically, the purpose of use of LV Surge Arresters is to prevent Sudden Overvoltage Impulses directed at our system from damaging the entire electrical and automation system. A possible lightning impulse can cause very serious damage. On the other hand, a sudden voltage surge can burn the most important card of our facility. However, these two impulses are different; as engineers, we need to select products according to impulse characteristics by considering all possibilities. Basically, in the literature, LV Surge Arrester products can be divided into 2 basic categories as Surge Protection and Lightning Protection. If it will protect our facility against sudden overvoltage, switching, harmonics, and sudden voltage surges, we can use products with Surge Protection Device features. However, if the subject is lightning, we must use products whose test and characteristic curves have been tested correctly.

Products protecting against lightning impulses are named Type 1, Class B, Class 1. Products protecting against grid impulses, switching elements, and sudden voltage surges are named Type 2, Class C, Class 2. Products protecting against both impulses are named Type 1+2, Class B+C. Yes, when you look at the products, their types may look the same, but when you look on them, you can see their differences at least basically with letters like T1-T2. The subject has many details. However, you can understand the basic difference primarily by looking at the product. Protection values as T1 and T2 are written on the products. Product protection values may vary according to product feature, impulse power, and usage area, but the basic difference is that they are classified as T1 and T2. A product with only T2 protection value written on it does not protect against Lightning; on the contrary, when exposed to lightning impulse, it leads to very dangerous results such as melting, explosion, arcing, so the surge arrester class is very important. The same rules apply to AC and DC. If we are going to buy a surge arrester and use it in our building entrance panel or in a solar project in an open field, the product must definitely have T1 +T2 protection values.

After this basic difference in the product visual, it is time to read the datasheet and examine the subject technically. It is a difficult possibility but let’s say; you did not understand its class by looking at the product, as the 2nd step we need to look at the technical values in the datasheet. The impulse curve of secondary impulses such as switching elements, switching impulses, voltage surges is 8/20ms; the 8/20ms curve shows protection against other impulses, not against lightning. LV Surge Arresters that need to be tested within the scope of IEC 61643-11 Standard have protection values in the datasheet on the 8/20ms curve. Surge arresters tested only on the 8/20ms curve are called Class C, Class 2, Type 2 Surge Arrester . These products generally provide protection against a maximum of 40kA grid impulse and are generally of varistor character. Due to the impulse speed, they activate in 25 nanoseconds; it is not correct to install these products in panels as lightning protection. The usage point of these products is the sub-distribution panels located inside the buildings after the main panel. In solar systems, on DC and AC Lines, especially in projects located in fields, we definitely recommend not using Type 2 Surge Arresters; our systems remain unprotected with the burning effect of the lightning impulse. However, as in panels, this deception is also done inside inverters, and products containing only Type 2 surge arresters are sent to the fields by saying that protected products are being sold.

Products named Type 1, Class B, T1, Class 1 are lightning hunters. Lightning impulses cannot pass these products. These products have 25 kA, 50 kA, 100 kA Imax protection values according to the product test value according to the region feature. However, what is important at this point is the 10/350ms curve that you need to see in the datasheet again. This value states that the lightning impulse reaches the maximum level in 10 ms and is dampened in a period of 350ms, and the test value according to the IEC 61643-11 value in the 10/350 ms curve must be in the datasheet. If a product is Type 1, the protection value at 10/350ms value must be written in the datasheet. Lightning protected products should be able to activate in 100 ns and are generally not in varistor structure like Type 2 LV Surge Arresters; varistors are easily damaged in lightning impulses, therefore Gas Discharge Tubes, called the airbag of surge arresters, form a structure supporting varistors.

Products that have test values in both 8/20 and 10/350ms curves and are tested commonly against Lightning and grid impulses are named B+C-Type 1+2 LV Surge Arrester. It is not correct to use Class B and C surge arresters side by side. In such cases, it is necessary to select coordinated products. However, choosing VG technology products that create both impulse values compactly and provide protection value appears as the most correct solution. With developing technology, there is a serious increase in the damping numbers of these products, providing long-lasting protection.

In surge arrester selections, there are many criteria ensuring the correct selection of products such as system earthing type, Inominal value, Up reduction level, kA level difference, warning output feature, single-phase and three-phase distinction, Uc continuous voltage difference. However, the class difference in panel protection products is the most basic distinction. If we do not pay attention to this class distinction when choosing a product, other details are of secondary importance. Besides panel type surge arresters, Type 3 Class D surge arresters protecting all weak current and automation systems have a serious importance. However, primarily, we need to ensure class distinction according to the cascaded protection principle.

You can always reach the expert staff of Yılkomer Lightning Protection Center to get information about product selection or whether the products you bought are the right products.