Weidmüller is launching a new PU I Class I arrester with varistor technology. In comparison with spark-gap based Class I arresters available on the market, the PU I offers a compelling range of extensive functions as well as cost-saving benefits. It is claimed to be the slimmest varistor-based Class I arrester for TN systems; for example, the one-pole version is just 17.5mm wide. The PU I fulfils the requirements of IEC 62305-3 (VDE 0185-305-3) and can be utilised in buildings classified in lightning protection zones III/IV.
Featuring a high discharge current of 12.5 kA (10/350us), a non-expulsion arrester and a high-quality design, this overvoltage protection device also boasts a small footprint, which ensures it fits comfortably in sub-distribution boards and switchgear assemblies. Its key component, the varistor, is pluggable and therefore simple to replace following a tripping operation - with no need to disconnect the wiring. The tripping operation itself is indicated by a red/green functional display on the front of the device. The colour green indicates 100 per cent unrestricted protection; red indicates that the arrester is defective and must be replaced immediately. The optional remote signalling contact is integrated in the compact installation housing without increasing the size of the device.
The bases can be rotated through 180degrees so that pluggable devices ensure a clear overview of the electrical cabinet interior: wire termination can be performed from above or below. Consequently, the arrester is always used correctly. That also simplifies the connection with cross-connectors behind an RCD (residual current protective) device. All protection elements are mechanically coded to prevent inadvertent replacement of arresters with different voltage ratings. Furthermore, clearly legible marking guarantees correct voltage coding.
Another very positive feature is that the new PU I does not require decoupling to the following Class II and Class III arresters, a cost-saving benefit from which customers profit. With its low residual voltage of <1.3kV the PU I can also be utilised for Class II overvoltage protection. All PU I devices are suitable for use in buildings classified in lightning protection zones III/IV - for example in hotels, libraries or public swimming baths. PU I products are useful for applications with different earthing systems (TN, TT) and common mains voltages (230/400V) where they provide effective protection against overvoltages and transient power disturbances. Developed with the characteristic Weidmüller design, the PU I devices feature a black base and orange-red arrester. They are rated for use in operating temperatures between -40 to 70degC. All PU I overvoltage protection devices are tested in accordance with IEC 61643-1 and EN 61643-11.