New type 2 surge arrester with three-stage fault indication
November 2006
Electrical Power & Protection
Dehn has introduced a new Dehnguardr family of Type 2 surge arresters with 'Pro-Active Thermo Control' technology to meet the increasing requirements of electrical systems in industrial, commercial and domestic environments. 'Pro-Active Thermal Control' allows the user to exchange surge protection devices (SPDs) before electrical installations are threatened by overloads to ensure permanent surge protection.
'Pro-Active Thermal Control' observes the power that is dissipated by the surge arrester. If the energy dissipated by the varistors exceeds a predefined limit value, there is a risk of irreversible damage to the structure of the varistor. This results in failure of the surge protection due to the disconnection of the SPD from the power supply in case of further surges. Without limiting the performance of the SPD, the user is informed about a potentially imminent failure of the SPD via the activated yellow indicator and the integrated Dehnguard T H LI remote signalling contact. At this stage, the user is recommended to replace the surge protection modules. If the protection modules are not replaced, further loads on the SPD, such as repeated discharge of lightning currents, can lead considerably to increasing varistor leakage currents.
During the performance test, without pause times, 'Pro-Active Thermo Control' activates the pre-warning stage via a yellow indication and by activating the remote signalling contact. With the new intelligent 'Pro-Active Thermo Control' concept, the 'Thermo Dynamic Control' disconnector, which has proven itself in all types of Dehnguard devices, has been supplemented by an additional active (Pro-Active) SPD controlling element.
Advantages of the Dehnguard T H . LI devices include reliable control due to the 'Pro-Active Thermo Control' feature, three-stage < GREEN - YELLOW - RED> visual indication and immediate exchange of the protection module as soon as the SPD is threatened by overloads. In addition, the devices provide remote signalling due to the floating changeover contact. The Dehnguard T H . LI devices have a high discharge capacity (Imax = 65 kA (8/20 μs) due to powerful zinc oxide varistors and/or zinc oxide varistors/spark gaps of the Dehnguard TT H230 400 LI. The devices have a low <1,25 kV voltage protection level.
Dehn's surge protection devices correspond to international, European and national product standards IEC 61643-1 and (DIN) EN 61643-11. Dehnguard T H . LI are two-part units consisting of a base part and plugged-in protection components. The surge arresters are suitable for DIN rail mounting and energy coordination is possible with upstream lightning current arresters such as the Dehnbloc Maxi.
For more information contact Paul Van As, Surgetek, 011 792 1303, [email protected], www.surgetek.co.za
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