The Coupling Network CDN 110 serves to inject the following standardized surge pulses from the surge generator into the mains supply to the device under test: Voltage surge of up to 6 kV which follows the 1.2/50 (js curve (open-circuit) Current surge of up to 3 kA which follows the 8/20 ¿/s curve (short circuit conditions). The CDN 110 permits test pulses of up to 6 kV and is proofed for up to 10 kV. The unit is used in conjunction with a surge generator in setting up a test rig. Surge pulse tests can be carried out on equipment, systems and installations that are in operation. Such tests are prescribed in IEEE 587, ANSI/IEEE C62.45, ¡EC 801-5, VDE 0109, etc, The CDN 110 is designed to be used with an EUT supply of up to 420 Veff (phase to phase) or 230 Veff (phase to earth) at 16 A. Operation is simpie and designed to be safe. This coupling unit is built into a table-top housing which can be adapted for 19s-rack installation by the addition of the appropriate mounting brackets. The construction takes into account the relevant specifications issued by the VDE and lEC concerning personal safety. Interlock circuits prevent dangerous voltages from reaching the connections to the device under test in an unnoticed or unprotected manner. A prerequisite is the assembly of a correctly built test rig. In order to make the assembly of the test rig easier for the user, protective enclosures, external warning lamps, coupling modules, etc. are available as accessories.